Java/Reflection/Type
Содержание
Data type utilities
<source lang="java">
// // Copyright 2004-2005 Mort Bay Consulting Pty. Ltd. // ------------------------------------------------------------------------ // Licensed under the Apache License, Version 2.0 (the "License"); // you may not use this file except in compliance with the License. // You may obtain a copy of the License at // http://www.apache.org/licenses/LICENSE-2.0 // Unless required by applicable law or agreed to in writing, software // distributed under the License is distributed on an "AS IS" BASIS, // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. // See the License for the specific language governing permissions and // limitations under the License. //
import java.io.IOException; import java.io.InputStream; import java.lang.reflect.Constructor; import java.lang.reflect.InvocationTargetException; import java.lang.reflect.Method; import java.net.URL; import java.util.HashMap;
/* ------------------------------------------------------------ */ /** TYPE Utilities.
* Provides various static utiltiy methods for manipulating types and their * string representations. * * @since Jetty 4.1 * @author Greg Wilkins (gregw) */
public class TypeUtil {
public static int CR = "\015";
public static int LF = "\012";
/* ------------------------------------------------------------ */
private static final HashMap name2Class=new HashMap();
static
{
name2Class.put("boolean",java.lang.Boolean.TYPE);
name2Class.put("byte",java.lang.Byte.TYPE);
name2Class.put("char",java.lang.Character.TYPE);
name2Class.put("double",java.lang.Double.TYPE);
name2Class.put("float",java.lang.Float.TYPE);
name2Class.put("int",java.lang.Integer.TYPE);
name2Class.put("long",java.lang.Long.TYPE);
name2Class.put("short",java.lang.Short.TYPE);
name2Class.put("void",java.lang.Void.TYPE);
name2Class.put("java.lang.Boolean.TYPE",java.lang.Boolean.TYPE);
name2Class.put("java.lang.Byte.TYPE",java.lang.Byte.TYPE);
name2Class.put("java.lang.Character.TYPE",java.lang.Character.TYPE);
name2Class.put("java.lang.Double.TYPE",java.lang.Double.TYPE);
name2Class.put("java.lang.Float.TYPE",java.lang.Float.TYPE);
name2Class.put("java.lang.Integer.TYPE",java.lang.Integer.TYPE);
name2Class.put("java.lang.Long.TYPE",java.lang.Long.TYPE);
name2Class.put("java.lang.Short.TYPE",java.lang.Short.TYPE);
name2Class.put("java.lang.Void.TYPE",java.lang.Void.TYPE);
name2Class.put("java.lang.Boolean",java.lang.Boolean.class);
name2Class.put("java.lang.Byte",java.lang.Byte.class);
name2Class.put("java.lang.Character",java.lang.Character.class);
name2Class.put("java.lang.Double",java.lang.Double.class);
name2Class.put("java.lang.Float",java.lang.Float.class);
name2Class.put("java.lang.Integer",java.lang.Integer.class);
name2Class.put("java.lang.Long",java.lang.Long.class);
name2Class.put("java.lang.Short",java.lang.Short.class);
name2Class.put("Boolean",java.lang.Boolean.class);
name2Class.put("Byte",java.lang.Byte.class);
name2Class.put("Character",java.lang.Character.class);
name2Class.put("Double",java.lang.Double.class);
name2Class.put("Float",java.lang.Float.class);
name2Class.put("Integer",java.lang.Integer.class);
name2Class.put("Long",java.lang.Long.class);
name2Class.put("Short",java.lang.Short.class);
name2Class.put(null,java.lang.Void.TYPE);
name2Class.put("string",java.lang.String.class);
name2Class.put("String",java.lang.String.class);
name2Class.put("java.lang.String",java.lang.String.class);
}
/* ------------------------------------------------------------ */
private static final HashMap class2Name=new HashMap();
static
{
class2Name.put(java.lang.Boolean.TYPE,"boolean");
class2Name.put(java.lang.Byte.TYPE,"byte");
class2Name.put(java.lang.Character.TYPE,"char");
class2Name.put(java.lang.Double.TYPE,"double");
class2Name.put(java.lang.Float.TYPE,"float");
class2Name.put(java.lang.Integer.TYPE,"int");
class2Name.put(java.lang.Long.TYPE,"long");
class2Name.put(java.lang.Short.TYPE,"short");
class2Name.put(java.lang.Void.TYPE,"void");
class2Name.put(java.lang.Boolean.class,"java.lang.Boolean");
class2Name.put(java.lang.Byte.class,"java.lang.Byte");
class2Name.put(java.lang.Character.class,"java.lang.Character");
class2Name.put(java.lang.Double.class,"java.lang.Double");
class2Name.put(java.lang.Float.class,"java.lang.Float");
class2Name.put(java.lang.Integer.class,"java.lang.Integer");
class2Name.put(java.lang.Long.class,"java.lang.Long");
class2Name.put(java.lang.Short.class,"java.lang.Short");
class2Name.put(null,"void");
name2Class.put(java.lang.String.class,"java.lang.String");
}
/* ------------------------------------------------------------ */
private static final HashMap class2Value=new HashMap();
static
{
try
{
Class[] s ={java.lang.String.class};
class2Value.put(java.lang.Boolean.TYPE,
java.lang.Boolean.class.getMethod("valueOf",s));
class2Value.put(java.lang.Byte.TYPE,
java.lang.Byte.class.getMethod("valueOf",s));
class2Value.put(java.lang.Double.TYPE,
java.lang.Double.class.getMethod("valueOf",s));
class2Value.put(java.lang.Float.TYPE,
java.lang.Float.class.getMethod("valueOf",s));
class2Value.put(java.lang.Integer.TYPE,
java.lang.Integer.class.getMethod("valueOf",s));
class2Value.put(java.lang.Long.TYPE,
java.lang.Long.class.getMethod("valueOf",s));
class2Value.put(java.lang.Short.TYPE,
java.lang.Short.class.getMethod("valueOf",s));
class2Value.put(java.lang.Boolean.class,
java.lang.Boolean.class.getMethod("valueOf",s));
class2Value.put(java.lang.Byte.class,
java.lang.Byte.class.getMethod("valueOf",s));
class2Value.put(java.lang.Double.class,
java.lang.Double.class.getMethod("valueOf",s));
class2Value.put(java.lang.Float.class,
java.lang.Float.class.getMethod("valueOf",s));
class2Value.put(java.lang.Integer.class,
java.lang.Integer.class.getMethod("valueOf",s));
class2Value.put(java.lang.Long.class,
java.lang.Long.class.getMethod("valueOf",s));
class2Value.put(java.lang.Short.class,
java.lang.Short.class.getMethod("valueOf",s));
}
catch(Exception e)
{
e.printStackTrace();
}
}
/* ------------------------------------------------------------ */
private static Class[] stringArg = { java.lang.String.class };
/* ------------------------------------------------------------ */
private static int intCacheSize=
Integer.getInteger("org.mortbay.util.TypeUtil.IntegerCacheSize",600).intValue();
private static Integer[] integerCache = new Integer[intCacheSize];
private static String[] integerStrCache = new String[intCacheSize];
private static Integer minusOne = new Integer(-1);
/* ------------------------------------------------------------ */
/** Class from a canonical name for a type.
* @param name A class or type name.
* @return A class , which may be a primitive TYPE field..
*/
public static Class fromName(String name)
{
return (Class)name2Class.get(name);
}
/* ------------------------------------------------------------ */
/** Canonical name for a type.
* @param type A class , which may be a primitive TYPE field.
* @return Canonical name.
*/
public static String toName(Class type)
{
return (String)class2Name.get(type);
}
/* ------------------------------------------------------------ */
/** Convert String value to instance.
* @param type The class of the instance, which may be a primitive TYPE field.
* @param value The value as a string.
* @return The value as an Object.
*/
public static Object valueOf(Class type, String value)
{
try
{
if (type.equals(java.lang.String.class))
return value;
Method m = (Method)class2Value.get(type);
if (m!=null)
return m.invoke(null,new Object[] {value});
if (type.equals(java.lang.Character.TYPE) ||
type.equals(java.lang.Character.class))
return new Character(value.charAt(0));
Constructor c = type.getConstructor(stringArg);
return c.newInstance(new Object[] {value});
}
catch(NoSuchMethodException e)
{
// LogSupport.ignore(log,e);
}
catch(IllegalAccessException e)
{
// LogSupport.ignore(log,e);
}
catch(InstantiationException e)
{
// LogSupport.ignore(log,e);
}
catch(InvocationTargetException e)
{
if (e.getTargetException() instanceof Error)
throw (Error)(e.getTargetException());
// LogSupport.ignore(log,e);
}
return null;
}
/* ------------------------------------------------------------ */
/** Convert String value to instance.
* @param type classname or type (eg int)
* @param value The value as a string.
* @return The value as an Object.
*/
public static Object valueOf(String type, String value)
{
return valueOf(fromName(type),value);
}
/* ------------------------------------------------------------ */
/** Convert int to Integer using cache.
*/
public static Integer newInteger(int i)
{
if (i>=0 && i<intCacheSize)
{
if (integerCache[i]==null)
integerCache[i]=new Integer(i);
return integerCache[i];
}
else if (i==-1)
return minusOne;
return new Integer(i);
}
/* ------------------------------------------------------------ */
/** Convert int to String using cache.
*/
public static String toString(int i)
{
if (i>=0 && i<intCacheSize)
{
if (integerStrCache[i]==null)
integerStrCache[i]=Integer.toString(i);
return integerStrCache[i];
}
else if (i==-1)
return "-1";
return Integer.toString(i);
}
/* ------------------------------------------------------------ */
/** Convert long to String using cache.
*/
public static String toString(long i)
{
if (i>=0 && i<intCacheSize)
{
if (integerStrCache[(int)i]==null)
integerStrCache[(int)i]=Long.toString(i);
return integerStrCache[(int)i];
}
else if (i==-1)
return "-1";
return Long.toString(i);
}
/* ------------------------------------------------------------ */
/** Parse an int from a substring.
* Negative numbers are not handled.
* @param s String
* @param offset Offset within string
* @param length Length of integer or -1 for remainder of string
* @param base base of the integer
* @exception NumberFormatException
*/
public static int parseInt(String s, int offset, int length, int base)
throws NumberFormatException
{
int value=0;
if (length<0)
length=s.length()-offset;
for (int i=0;i<length;i++)
{
char c=s.charAt(offset+i);
int digit=c-"0";
if (digit<0 || digit>=base || digit>=10)
{
digit=10+c-"A";
if (digit<10 || digit>=base)
digit=10+c-"a";
}
if (digit<0 || digit>=base)
throw new NumberFormatException(s.substring(offset,offset+length));
value=value*base+digit;
}
return value;
}
/* ------------------------------------------------------------ */
/** Parse an int from a byte array of ascii characters.
* Negative numbers are not handled.
* @param b byte array
* @param offset Offset within string
* @param length Length of integer or -1 for remainder of string
* @param base base of the integer
* @exception NumberFormatException
*/
public static int parseInt(byte[] b, int offset, int length, int base)
throws NumberFormatException
{
int value=0;
if (length<0)
length=b.length-offset;
for (int i=0;i<length;i++)
{
char c=(char)(0xff&b[offset+i]);
int digit=c-"0";
if (digit<0 || digit>=base || digit>=10)
{
digit=10+c-"A";
if (digit<10 || digit>=base)
digit=10+c-"a";
}
if (digit<0 || digit>=base)
throw new NumberFormatException(new String(b,offset,length));
value=value*base+digit;
}
return value;
}
/* ------------------------------------------------------------ */
public static byte[] parseBytes(String s, int base)
{
byte[] bytes=new byte[s.length()/2];
for (int i=0;i<s.length();i+=2)
bytes[i/2]=(byte)TypeUtil.parseInt(s,i,2,base);
return bytes;
}
/* ------------------------------------------------------------ */
public static String toString(byte[] bytes, int base)
{
StringBuffer buf = new StringBuffer();
for (int i=0;i<bytes.length;i++)
{
int bi=0xff&bytes[i];
int c="0"+(bi/base)%base;
if (c>"9")
c= "a"+(c-"0"-10);
buf.append((char)c);
c="0"+bi%base;
if (c>"9")
c= "a"+(c-"0"-10);
buf.append((char)c);
}
return buf.toString();
}
/* ------------------------------------------------------------ */
/**
* @param b An ASCII encoded character 0-9 a-f A-F
* @return The byte value of the character 0-16.
*/
public static byte convertHexDigit( byte b )
{
if ((b >= "0") && (b <= "9")) return (byte)(b - "0");
if ((b >= "a") && (b <= "f")) return (byte)(b - "a" + 10);
if ((b >= "A") && (b <= "F")) return (byte)(b - "A" + 10);
return 0;
}
/* ------------------------------------------------------------ */
public static String toHexString(byte[] b)
{
StringBuffer buf = new StringBuffer();
for (int i=0;i<b.length;i++)
{
int bi=0xff&b[i];
int c="0"+(bi/16)%16;
if (c>"9")
c= "A"+(c-"0"-10);
buf.append((char)c);
c="0"+bi%16;
if (c>"9")
c= "a"+(c-"0"-10);
buf.append((char)c);
}
return buf.toString();
}
/* ------------------------------------------------------------ */
public static String toHexString(byte[] b,int offset,int length)
{
StringBuffer buf = new StringBuffer();
for (int i=offset;i<offset+length;i++)
{
int bi=0xff&b[i];
int c="0"+(bi/16)%16;
if (c>"9")
c= "A"+(c-"0"-10);
buf.append((char)c);
c="0"+bi%16;
if (c>"9")
c= "a"+(c-"0"-10);
buf.append((char)c);
}
return buf.toString();
}
/* ------------------------------------------------------------ */
public static byte[] fromHexString(String s)
{
if (s.length()%2!=0)
throw new IllegalArgumentException(s);
byte[] array = new byte[s.length()/2];
for (int i=0;i<array.length;i++)
{
int b = Integer.parseInt(s.substring(i*2,i*2+2),16);
array[i]=(byte)(0xff&b);
}
return array;
}
public static void dump(Class c)
{
System.err.println("Dump: "+c);
dump(c.getClassLoader());
}
public static void dump(ClassLoader cl)
{
System.err.println("Dump Loaders:");
while(cl!=null)
{
System.err.println(" loader "+cl);
cl = cl.getParent();
}
}
/* ------------------------------------------------------------ */
public static byte[] readLine(InputStream in) throws IOException
{
byte[] buf = new byte[256];
int i=0;
int loops=0;
int ch=0;
while (true)
{
ch=in.read();
if (ch<0)
break;
loops++;
// skip a leading LF"s
if (loops==1 && ch==LF)
continue;
if (ch==CR || ch==LF)
break;
if (i>=buf.length)
{
byte[] old_buf=buf;
buf=new byte[old_buf.length+256];
System.arraycopy(old_buf, 0, buf, 0, old_buf.length);
}
buf[i++]=(byte)ch;
}
if (ch==-1 && i==0)
return null;
// skip a trailing LF if it exists
if (ch==CR && in.available()>=1 && in.markSupported())
{
in.mark(1);
ch=in.read();
if (ch!=LF)
in.reset();
}
byte[] old_buf=buf;
buf=new byte[i];
System.arraycopy(old_buf, 0, buf, 0, i);
return buf;
}
}
</source>
Is Type Compatible
<source lang="java">
// //$Id: IntrospectionUtil.java 1540 2007-01-19 12:24:10Z janb $ //Copyright 2006 Mort Bay Consulting Pty. Ltd. //------------------------------------------------------------------------ //Licensed under the Apache License, Version 2.0 (the "License"); //you may not use this file except in compliance with the License. //You may obtain a copy of the License at //http://www.apache.org/licenses/LICENSE-2.0 //Unless required by applicable law or agreed to in writing, software //distributed under the License is distributed on an "AS IS" BASIS, //WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. //See the License for the specific language governing permissions and //limitations under the License. //
import java.lang.reflect.Method; import java.util.Arrays; import java.util.List; public class Utils {
public static boolean isTypeCompatible(Class formalType, Class actualType, boolean strict) {
if (formalType == null && actualType != null)
return false;
if (formalType != null && actualType == null)
return false;
if (formalType == null && actualType == null)
return true;
if (strict)
return formalType.equals(actualType);
else
return formalType.isAssignableFrom(actualType);
}
}
</source>
Returns an array of Type objects representing the actual type arguments to targetType used by clazz
<source lang="java">
import java.util.Map; import java.util.HashMap; import java.util.Collection; import java.util.ArrayList; import java.util.List; import java.util.Set; import java.util.HashSet; import java.util.SortedSet; import java.util.TreeSet; import java.util.Queue; import java.util.LinkedList; import java.util.SortedMap; import java.util.TreeMap; import java.util.Arrays; import java.util.concurrent.ConcurrentHashMap; import java.lang.annotation.Annotation; import java.lang.reflect.Method; import java.lang.reflect.Field; import java.lang.reflect.Modifier; import java.lang.reflect.ParameterizedType; import java.lang.reflect.Type; import static java.lang.reflect.Modifier.isPublic; import java.beans.PropertyDescriptor; import java.beans.BeanInfo; import java.beans.Introspector; import java.beans.IntrospectionException; /**
* Common utilty methods that are useful when working with reflection. * * @author Tim Fennell */
public class ReflectUtil {
/** A cache of property descriptors by class and property name */
private static Map<Class<?>, Map<String, PropertyDescriptor>> propertyDescriptors =
new ConcurrentHashMap<Class<?>, Map<String, PropertyDescriptor>>();
/** Static helper class, shouldn"t be constructed. */
private ReflectUtil() {}
/**
* Holds a map of commonly used interface types (mostly collections) to a class that
* implements the interface and will, by default, be instantiated when an instance
* of the interface is needed.
*/
protected static final Map<Class<?>,Class<?>> interfaceImplementations = new HashMap<Class<?>,Class<?>>();
/**
* Holds a map of primitive type to the default value for that primitive type. Isn"t it
* odd that there"s no way to get this programmatically from the Class objects?
*/
protected static final Map<Class<?>,Object> primitiveDefaults = new HashMap<Class<?>,Object>();
static {
interfaceImplementations.put(Collection.class, ArrayList.class);
interfaceImplementations.put(List.class, ArrayList.class);
interfaceImplementations.put(Set.class, HashSet.class);
interfaceImplementations.put(SortedSet.class, TreeSet.class);
interfaceImplementations.put(Queue.class, LinkedList.class);
interfaceImplementations.put(Map.class, HashMap.class);
interfaceImplementations.put(SortedMap.class, TreeMap.class);
primitiveDefaults.put(Boolean.TYPE, false);
primitiveDefaults.put(Character.TYPE, "\0");
primitiveDefaults.put(Byte.TYPE, new Byte("0"));
primitiveDefaults.put(Short.TYPE, new Short("0"));
primitiveDefaults.put(Integer.TYPE, new Integer(0));
primitiveDefaults.put(Long.TYPE, new Long(0l));
primitiveDefaults.put(Float.TYPE, new Float(0f));
primitiveDefaults.put(Double.TYPE, new Double(0.0));
}
/**
* The set of method that annotation classes inherit, and should be avoided when
* toString()ing an annotation class.
*/
private static final Set<String> INHERITED_ANNOTATION_METHODS =
new HashSet(Arrays.asList("toString", "equals", "hashCode", "annotationType"));
/**
* Looks up the default implementing type for the supplied interface. This is done
* based on a static map of known common interface types and implementing classes.
*
* @param iface an interface for which an implementing class is needed
* @return a Class object representing the implementing type, or null if one is
* not found
*/
public static Class<?> getImplementingClass(Class<?> iface) {
return interfaceImplementations.get(iface);
}
/**
* Attempts to determine an implementing class for the interface provided and instantiate
* it using a default constructor.
*
* @param interfaceType an interface (or abstract class) to make an instance of
* @return an instance of the interface type supplied
* @throws InstantiationException if no implementation type has been configured
* @throws IllegalAccessException if thrown by the JVM during class instantiation
*/
@SuppressWarnings("unchecked")
public static <T> T getInterfaceInstance(Class<T> interfaceType)
throws InstantiationException, IllegalAccessException {
Class impl = getImplementingClass(interfaceType);
if (impl == null) {
throw new InstantiationException(
"Stripes needed to instantiate a property who"s declared type as an " +
"interface (which obviously cannot be instantiated. The interface is not " +
"one that Stripes is aware of, so no implementing class was known. The " +
"interface type was: "" + interfaceType.getName() + "". To fix this " +
"you"ll need to do one of three things. 1) Change the getter/setter methods " +
"to use a concrete type so that Stripes can instantiate it. 2) in the bean"s " +
"setContext() method pre-instantiate the property so Stripes doesn"t have to. " +
"3) Bug the Stripes author ;) If the interface is a JDK type it can easily be " +
"fixed. If not, if enough people ask, a generic way to handle the problem " +
"might get implemented.");
}
else {
return (T) impl.newInstance();
}
}
/**
* Utility method used to load a class. Any time that Stripes needs to load of find a
* class by name it uses this method. As a result any time the classloading strategy
* needs to change it can be done in one place! Currently uses
* {@code Thread.currentThread().getContextClassLoader().loadClass(String)}.
*
* @param name the fully qualified (binary) name of the class to find or load
* @return the Class object representing the class
* @throws ClassNotFoundException if the class cannot be loaded
*/
@SuppressWarnings("unchecked") // this allows us to assign without casting
public static Class findClass(String name) throws ClassNotFoundException {
return Thread.currentThread().getContextClassLoader().loadClass(name);
}
/**
* A better (more concise) toString method for annotation types that yields a String * that should look more like the actual usage of the annotation in a class. The String produced * is similar to that produced by calling toString() on the annotation directly, with the * following differences:
**
-
*
- Uses the classes simple name instead of it"s fully qualified name. *
- Only outputs attributes that are set to non-default values.
**
If, for some unforseen reason, an exception is thrown within this method it will be * caught and the return value will be {@code ann.toString()}. * * @param ann the annotation to convert to a human readable String * @return a human readable String form of the annotation and it"s attributes */ public static String toString(Annotation ann) { try { Class<? extends Annotation> type = ann.annotationType(); StringBuilder builder = new StringBuilder(128); builder.append("@"); builder.append(type.getSimpleName()); boolean appendedAnyParameters = false; Method[] methods = type.getMethods(); for (Method method : methods) { if (!INHERITED_ANNOTATION_METHODS.contains(method.getName())) { Object defaultValue = method.getDefaultValue(); Object actualValue = method.invoke(ann); // If we have arrays, they have to be treated a little differently Object[] defaultArray = null, actualArray = null; if ( Object[].class.isAssignableFrom(method.getReturnType()) ) { defaultArray = (Object[]) defaultValue; actualArray = (Object[]) actualValue; } // Only print an attribute if it isn"t set to the default value if ( (defaultArray != null && !Arrays.equals(defaultArray, actualArray)) || (defaultArray == null && !actualValue.equals(defaultValue)) ) { if (appendedAnyParameters) { builder.append(", "); } else { builder.append("("); } builder.append(method.getName()); builder.append("="); if (actualArray != null) { builder.append( Arrays.toString(actualArray) ); } else { builder.append(actualValue); } appendedAnyParameters = true; } } } if (appendedAnyParameters) { builder.append(")"); } return builder.toString(); } catch (Exception e) { return ann.toString(); } } /** * Fetches all methods of all access types from the supplied class and super * classes. Methods that have been overridden in the inheritance hierarchy are * only returned once, using the instance lowest down the hierarchy. * * @param clazz the class to inspect * @return a collection of methods */ public static Collection<Method> getMethods(Class<?> clazz) { Collection<Method> found = new ArrayList<Method>(); while (clazz != null) { for (Method m1 : clazz.getDeclaredMethods()) { boolean overridden = false; for (Method m2 : found) { if ( m2.getName().equals(m1.getName()) && Arrays.deepEquals(m1.getParameterTypes(), m2.getParameterTypes())) { overridden = true; break; } } if (!overridden) found.add(m1); } clazz = clazz.getSuperclass(); } return found; } /** * Fetches all fields of all access types from the supplied class and super * classes. Fieldss that have been overridden in the inheritance hierarchy are * only returned once, using the instance lowest down the hierarchy. * * @param clazz the class to inspect * @return a collection of fields */ public static Collection<Field> getFields(Class<?> clazz) { Map<String,Field> fields = new HashMap<String, Field>(); while (clazz != null) { for (Field field : clazz.getDeclaredFields()) { if ( !fields.containsKey(field.getName()) ) { fields.put(field.getName(), field); } } clazz = clazz.getSuperclass(); } return fields.values(); } /** * Fetches the property descriptor for the named property of the supplied class. To * speed things up a cache is maintained of propertyName to PropertyDescriptor for * each class used with this method. If there is no property with the specified name, * returns null. * * @param clazz the class who"s properties to examine * @param property the String name of the property to look for * @return the PropertyDescriptor or null if none is found with a matching name */ public static PropertyDescriptor getPropertyDescriptor(Class<?> clazz, String property) { Map<String,PropertyDescriptor> pds = propertyDescriptors.get(clazz); if (pds == null) { try { BeanInfo info = Introspector.getBeanInfo(clazz); PropertyDescriptor[] descriptors = info.getPropertyDescriptors(); pds = new HashMap<String, PropertyDescriptor>(); for (PropertyDescriptor descriptor : descriptors) { pds.put(descriptor.getName(), descriptor); } propertyDescriptors.put(clazz, pds); } catch (IntrospectionException ie) { throw new RuntimeException("Could not examine class "" + clazz.getName() + "" using Introspector.getBeanInfo() to determine property information.", ie); } } return pds.get(property); } /** * <p>Attempts to find an accessible version of the method passed in, where accessible * is defined as the method itself being public and the declaring class being public. * Mostly useful as a workaround to the situation when * {@link PropertyDescriptor#getReadMethod()} and/or * {@link java.beans.PropertyDescriptor#getWriteMethod()} returns methods that are not * accessible (usually due to public implementations of interface methods in private * classes).
**
Checks the method passed in and if it already meets these criteria it is returned * immediately. In general this leads to very little performance overhead
**
If the method does not meet the criteria then the class" interfaces are scanned * for a matching method. If one is not found, then the class" superclass hierarchy * is searched. Finally, if no matching method can be found the original method is * returned.
*
* @param m a method that may or may not be accessible
* @return either an accessible version of the same method, or the method passed in if
* an accessible version cannot be found
*/
public static Method findAccessibleMethod(final Method m) {
// If the passed in method is accessible, then just give it back.
if (isPublic(m.getModifiers()) && isPublic(m.getDeclaringClass().getModifiers())) return m;
if (m.isAccessible()) return m;
final Class<?> clazz = m.getDeclaringClass();
final String name = m.getName();
final Class<?>[] ptypes = m.getParameterTypes();
// Else, loop through the interfaces for the declaring class, looking for a
// public version of the method that we can call
for (Class<?> iface : clazz.getInterfaces()) {
try {
Method m2 = iface.getMethod(name, ptypes);
if (m2.isAccessible()) return m2;
if (isPublic(iface.getModifiers()) && isPublic(m2.getModifiers())) return m2;
}
catch (NoSuchMethodException nsme) { /* Not Unexpected. */ }
}
// Else loop through the superclasses looking for a public method
Class<?> c = clazz.getSuperclass();
while (c != null) {
try {
Method m2 = c.getMethod(name, ptypes);
if (m2.isAccessible()) return m2;
if (isPublic(c.getModifiers()) && isPublic(m2.getModifiers())) return m2;
}
catch (NoSuchMethodException nsme) { /* Not Unexpected. */ }
c = c.getSuperclass();
}
// If we haven"t found anything at this point, just give up!
return m;
}
/**
* Looks for an instance (i.e. non-static) public field with the matching name and
* returns it if one exists. If no such field exists, returns null.
*
* @param clazz the clazz who"s fields to examine
* @param property the name of the property/field to look for
* @return the Field object or null if no matching field exists
*/
public static Field getField(Class<?> clazz, String property) {
try {
Field field = clazz.getField(property);
return !Modifier.isStatic(field.getModifiers()) ? field : null;
}
catch (NoSuchFieldException nsfe) {
return null;
}
}
/**
* Returns an appropriate default value for the class supplied. Mirrors the defaults used
* when the JVM initializes instance variables.
*
* @param clazz the class for which to find the default value
* @return null for non-primitive types and an appropriate wrapper instance for primitives
*/
public static Object getDefaultValue(Class<?> clazz) {
if (clazz.isPrimitive()) {
return primitiveDefaults.get(clazz);
}
else {
return null;
}
}
/**
* Returns a set of all interfaces implemented by class supplied. This includes all
* interfaces directly implemented by this class as well as those implemented by
* superclasses or interface superclasses.
*
* @param clazz
* @return all interfaces implemented by this class
*/
public static Set<Class<?>> getImplementedInterfaces(Class<?> clazz)
{
Set<Class<?>> interfaces = new HashSet<Class<?>>();
if (clazz.isInterface())
interfaces.add(clazz);
while (clazz != null) {
for (Class<?> iface : clazz.getInterfaces())
interfaces.addAll(getImplementedInterfaces(iface));
clazz = clazz.getSuperclass();
}
return interfaces;
}
/**
* Returns an array of Type objects representing the actual type arguments
* to targetType used by clazz.
*
* @param clazz the implementing class (or subclass)
* @param targetType the implemented generic class or interface
* @return an array of Type objects or null
*/
public static Type[] getActualTypeArguments(Class<?> clazz, Class<?> targetType) {
Set<Class<?>> classes = new HashSet<Class<?>>();
classes.add(clazz);
if (targetType.isInterface())
classes.addAll(getImplementedInterfaces(clazz));
Class<?> superClass = clazz.getSuperclass();
while (superClass != null) {
classes.add(superClass);
superClass = superClass.getSuperclass();
}
for (Class<?> search : classes) {
for (Type type : (targetType.isInterface() ? search.getGenericInterfaces()
: new Type[] { search.getGenericSuperclass() })) {
if (type instanceof ParameterizedType) {
ParameterizedType parameterizedType = (ParameterizedType) type;
if (targetType.equals(parameterizedType.getRawType()))
return parameterizedType.getActualTypeArguments();
}
}
}
return null;
}
}
</source>
Returns true if type is a iterable type
<source lang="java">
// $Id: ReflectionHelper.java 16271 2009-04-07 20:20:12Z hardy.ferentschik $ /*
- JBoss, Home of Professional Open Source
- Copyright 2008, Red Hat Middleware LLC, and individual contributors
- by the @authors tag. See the copyright.txt in the distribution for a
- full listing of individual contributors.
- Licensed under the Apache License, Version 2.0 (the "License");
- you may not use this file except in compliance with the License.
- You may obtain a copy of the License at
- http://www.apache.org/licenses/LICENSE-2.0
- Unless required by applicable law or agreed to in writing, software
- distributed under the License is distributed on an "AS IS" BASIS,
- WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- See the License for the specific language governing permissions and
- limitations under the License.
- /
import java.beans.Introspector; import java.lang.annotation.Annotation; import java.lang.reflect.AccessibleObject; import java.lang.reflect.Field; import java.lang.reflect.InvocationTargetException; import java.lang.reflect.Member; import java.lang.reflect.Method; import java.lang.reflect.Modifier; import java.lang.reflect.ParameterizedType; import java.lang.reflect.Type; import java.lang.reflect.WildcardType; import java.util.ArrayList; import java.util.Arrays; import java.util.Iterator; import java.util.List; import java.util.Map;
/**
* Some reflection utility methods. * * @author Hardy Ferentschik */
public class ReflectionHelper {
/** * @param type the type to check. * * @return Returnstrueiftypeis a iterable type,falseotherwise. */ public static boolean isIterable(Type type) { if ( type instanceof Class && isIterableClass( ( Class ) type ) ) { return true; } if ( type instanceof ParameterizedType ) { return isIterable( ( ( ParameterizedType ) type ).getRawType() ); } if ( type instanceof WildcardType ) { Type[] upperBounds = ( ( WildcardType ) type ).getUpperBounds(); return upperBounds.length != 0 && isIterable( upperBounds[0] ); } return false; } /** * Checks whether the specified class parameter is an instance of a collection class. * * @param clazzClassto check. * * @returntrueisclazzis instance of a collection class,falseotherwise. */ private static boolean isIterableClass(Class<?> clazz) { List<Class<?>> classes = new ArrayList<Class<?>>(); computeClassHierarchy( clazz, classes ); return classes.contains( Iterable.class ); } /** * Get all superclasses and interfaces recursively. * * @param clazz The class to start the search with. * @param classes List of classes to which to add all found super classes and interfaces. */ private static void computeClassHierarchy(Class<?> clazz, List<Class<?>> classes) { for ( Class current = clazz; current != null; current = current.getSuperclass() ) { if ( classes.contains( current ) ) { return; } classes.add( current ); for ( Class currentInterface : current.getInterfaces() ) { computeClassHierarchy( currentInterface, classes ); } } }
}
</source>
TYPE Utilities
<source lang="java">
// // $Id: TypeUtil.java,v 1.12 2004/05/09 20:33:04 gregwilkins Exp $ // Copyright 2002-2004 Mort Bay Consulting Pty. Ltd. // ------------------------------------------------------------------------ // Licensed under the Apache License, Version 2.0 (the "License"); // you may not use this file except in compliance with the License. // You may obtain a copy of the License at // http://www.apache.org/licenses/LICENSE-2.0 // Unless required by applicable law or agreed to in writing, software // distributed under the License is distributed on an "AS IS" BASIS, // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. // See the License for the specific language governing permissions and // limitations under the License. //
import java.lang.reflect.Constructor; import java.lang.reflect.InvocationTargetException; import java.lang.reflect.Method; import java.util.HashMap;
/* ------------------------------------------------------------ */ /** TYPE Utilities.
* Provides various static utiltiy methods for manipulating types and their * string representations. * * @since Jetty 4.1 * @version $Revision: 1.12 $ * @author Greg Wilkins (gregw) */
public class TypeUtil {
/* ------------------------------------------------------------ */
private static final HashMap name2Class=new HashMap();
static
{
name2Class.put("boolean",java.lang.Boolean.TYPE);
name2Class.put("byte",java.lang.Byte.TYPE);
name2Class.put("char",java.lang.Character.TYPE);
name2Class.put("double",java.lang.Double.TYPE);
name2Class.put("float",java.lang.Float.TYPE);
name2Class.put("int",java.lang.Integer.TYPE);
name2Class.put("long",java.lang.Long.TYPE);
name2Class.put("short",java.lang.Short.TYPE);
name2Class.put("void",java.lang.Void.TYPE);
name2Class.put("java.lang.Boolean.TYPE",java.lang.Boolean.TYPE);
name2Class.put("java.lang.Byte.TYPE",java.lang.Byte.TYPE);
name2Class.put("java.lang.Character.TYPE",java.lang.Character.TYPE);
name2Class.put("java.lang.Double.TYPE",java.lang.Double.TYPE);
name2Class.put("java.lang.Float.TYPE",java.lang.Float.TYPE);
name2Class.put("java.lang.Integer.TYPE",java.lang.Integer.TYPE);
name2Class.put("java.lang.Long.TYPE",java.lang.Long.TYPE);
name2Class.put("java.lang.Short.TYPE",java.lang.Short.TYPE);
name2Class.put("java.lang.Void.TYPE",java.lang.Void.TYPE);
name2Class.put("java.lang.Boolean",java.lang.Boolean.class);
name2Class.put("java.lang.Byte",java.lang.Byte.class);
name2Class.put("java.lang.Character",java.lang.Character.class);
name2Class.put("java.lang.Double",java.lang.Double.class);
name2Class.put("java.lang.Float",java.lang.Float.class);
name2Class.put("java.lang.Integer",java.lang.Integer.class);
name2Class.put("java.lang.Long",java.lang.Long.class);
name2Class.put("java.lang.Short",java.lang.Short.class);
name2Class.put("Boolean",java.lang.Boolean.class);
name2Class.put("Byte",java.lang.Byte.class);
name2Class.put("Character",java.lang.Character.class);
name2Class.put("Double",java.lang.Double.class);
name2Class.put("Float",java.lang.Float.class);
name2Class.put("Integer",java.lang.Integer.class);
name2Class.put("Long",java.lang.Long.class);
name2Class.put("Short",java.lang.Short.class);
name2Class.put(null,java.lang.Void.TYPE);
name2Class.put("string",java.lang.String.class);
name2Class.put("String",java.lang.String.class);
name2Class.put("java.lang.String",java.lang.String.class);
}
/* ------------------------------------------------------------ */
private static final HashMap class2Name=new HashMap();
static
{
class2Name.put(java.lang.Boolean.TYPE,"boolean");
class2Name.put(java.lang.Byte.TYPE,"byte");
class2Name.put(java.lang.Character.TYPE,"char");
class2Name.put(java.lang.Double.TYPE,"double");
class2Name.put(java.lang.Float.TYPE,"float");
class2Name.put(java.lang.Integer.TYPE,"int");
class2Name.put(java.lang.Long.TYPE,"long");
class2Name.put(java.lang.Short.TYPE,"short");
class2Name.put(java.lang.Void.TYPE,"void");
class2Name.put(java.lang.Boolean.class,"java.lang.Boolean");
class2Name.put(java.lang.Byte.class,"java.lang.Byte");
class2Name.put(java.lang.Character.class,"java.lang.Character");
class2Name.put(java.lang.Double.class,"java.lang.Double");
class2Name.put(java.lang.Float.class,"java.lang.Float");
class2Name.put(java.lang.Integer.class,"java.lang.Integer");
class2Name.put(java.lang.Long.class,"java.lang.Long");
class2Name.put(java.lang.Short.class,"java.lang.Short");
class2Name.put(null,"void");
name2Class.put(java.lang.String.class,"java.lang.String");
}
/* ------------------------------------------------------------ */
private static final HashMap class2Value=new HashMap();
static
{
try
{
Class[] s ={java.lang.String.class};
class2Value.put(java.lang.Boolean.TYPE,
java.lang.Boolean.class.getMethod("valueOf",s));
class2Value.put(java.lang.Byte.TYPE,
java.lang.Byte.class.getMethod("valueOf",s));
class2Value.put(java.lang.Double.TYPE,
java.lang.Double.class.getMethod("valueOf",s));
class2Value.put(java.lang.Float.TYPE,
java.lang.Float.class.getMethod("valueOf",s));
class2Value.put(java.lang.Integer.TYPE,
java.lang.Integer.class.getMethod("valueOf",s));
class2Value.put(java.lang.Long.TYPE,
java.lang.Long.class.getMethod("valueOf",s));
class2Value.put(java.lang.Short.TYPE,
java.lang.Short.class.getMethod("valueOf",s));
class2Value.put(java.lang.Boolean.class,
java.lang.Boolean.class.getMethod("valueOf",s));
class2Value.put(java.lang.Byte.class,
java.lang.Byte.class.getMethod("valueOf",s));
class2Value.put(java.lang.Double.class,
java.lang.Double.class.getMethod("valueOf",s));
class2Value.put(java.lang.Float.class,
java.lang.Float.class.getMethod("valueOf",s));
class2Value.put(java.lang.Integer.class,
java.lang.Integer.class.getMethod("valueOf",s));
class2Value.put(java.lang.Long.class,
java.lang.Long.class.getMethod("valueOf",s));
class2Value.put(java.lang.Short.class,
java.lang.Short.class.getMethod("valueOf",s));
}
catch(Exception e)
{
}
}
/* ------------------------------------------------------------ */
private static Class[] stringArg = { java.lang.String.class };
/* ------------------------------------------------------------ */
private static int intCacheSize=
Integer.getInteger("org.mortbay.util.TypeUtil.IntegerCacheSize",600).intValue();
private static Integer[] integerCache = new Integer[intCacheSize];
private static String[] integerStrCache = new String[intCacheSize];
private static Integer minusOne = new Integer(-1);
/* ------------------------------------------------------------ */
/** Class from a canonical name for a type.
* @param name A class or type name.
* @return A class , which may be a primitive TYPE field..
*/
public static Class fromName(String name)
{
return (Class)name2Class.get(name);
}
/* ------------------------------------------------------------ */
/** Canonical name for a type.
* @param type A class , which may be a primitive TYPE field.
* @return Canonical name.
*/
public static String toName(Class type)
{
return (String)class2Name.get(type);
}
/* ------------------------------------------------------------ */
/** Convert String value to instance.
* @param type The class of the instance, which may be a primitive TYPE field.
* @param value The value as a string.
* @return The value as an Object.
*/
public static Object valueOf(Class type, String value)
{
try
{
if (type.equals(java.lang.String.class))
return value;
Method m = (Method)class2Value.get(type);
if (m!=null)
return m.invoke(null,new Object[] {value});
if (type.equals(java.lang.Character.TYPE) ||
type.equals(java.lang.Character.class))
return new Character(value.charAt(0));
Constructor c = type.getConstructor(stringArg);
return c.newInstance(new Object[] {value});
}
catch(InvocationTargetException e)
{
if (e.getTargetException() instanceof Error)
throw (Error)(e.getTargetException());
}
return null;
}
/* ------------------------------------------------------------ */
/** Convert String value to instance.
* @param type classname or type (eg int)
* @param value The value as a string.
* @return The value as an Object.
*/
public static Object valueOf(String type, String value)
{
return valueOf(fromName(type),value);
}
/* ------------------------------------------------------------ */
/** Convert int to Integer using cache.
*/
public static Integer newInteger(int i)
{
if (i>=0 && i<intCacheSize)
{
if (integerCache[i]==null)
integerCache[i]=new Integer(i);
return integerCache[i];
}
else if (i==-1)
return minusOne;
return new Integer(i);
}
/* ------------------------------------------------------------ */
/** Convert int to String using cache.
*/
public static String toString(int i)
{
if (i>=0 && i<intCacheSize)
{
if (integerStrCache[i]==null)
integerStrCache[i]=Integer.toString(i);
return integerStrCache[i];
}
else if (i==-1)
return "-1";
return Integer.toString(i);
}
/* ------------------------------------------------------------ */
/** Parse an int from a substring.
* Negative numbers are not handled.
* @param s String
* @param offset Offset within string
* @param length Length of integer or -1 for remainder of string
* @param base base of the integer
* @exception NumberFormatException
*/
public static int parseInt(String s, int offset, int length, int base)
throws NumberFormatException
{
int value=0;
if (length<0)
length=s.length()-offset;
for (int i=0;i<length;i++)
{
char c=s.charAt(offset+i);
int digit=c-"0";
if (digit<0 || digit>=base || digit>=10)
{
digit=10+c-"A";
if (digit<10 || digit>=base)
digit=10+c-"a";
}
if (digit<0 || digit>=base)
throw new NumberFormatException(s.substring(offset,offset+length));
value=value*base+digit;
}
return value;
}
/* ------------------------------------------------------------ */
public static byte[] parseBytes(String s, int base)
{
byte[] bytes=new byte[s.length()/2];
for (int i=0;i<s.length();i+=2)
bytes[i/2]=(byte)TypeUtil.parseInt(s,i,2,base);
return bytes;
}
/* ------------------------------------------------------------ */
public static String toString(byte[] bytes, int base)
{
StringBuffer buf = new StringBuffer();
for (int i=0;i<bytes.length;i++)
{
int bi=0xff&bytes[i];
int c="0"+(bi/base)%base;
if (c>"9")
c= "a"+(c-"0"-10);
buf.append((char)c);
c="0"+bi%base;
if (c>"9")
c= "a"+(c-"0"-10);
buf.append((char)c);
}
return buf.toString();
}
/* ------------------------------------------------------------ */
/**
* @param b An ASCII encoded character 0-9 a-f A-F
* @return The byte value of the character 0-16.
*/
public static byte convertHexDigit( byte b )
{
if ((b >= "0") && (b <= "9")) return (byte)(b - "0");
if ((b >= "a") && (b <= "f")) return (byte)(b - "a" + 10);
if ((b >= "A") && (b <= "F")) return (byte)(b - "A" + 10);
return 0;
}
/* ------------------------------------------------------------ */
public static String toHexString(byte[] b)
{
StringBuffer buf = new StringBuffer();
for (int i=0;i<b.length;i++)
{
int bi=0xff&b[i];
int c="0"+(bi/16)%16;
if (c>"9")
c= "A"+(c-"0"-10);
buf.append((char)c);
c="0"+bi%16;
if (c>"9")
c= "a"+(c-"0"-10);
buf.append((char)c);
}
return buf.toString();
}
/* ------------------------------------------------------------ */
public static String toHexString(byte[] b,int offset,int length)
{
StringBuffer buf = new StringBuffer();
for (int i=offset;i<offset+length;i++)
{
int bi=0xff&b[i];
int c="0"+(bi/16)%16;
if (c>"9")
c= "A"+(c-"0"-10);
buf.append((char)c);
c="0"+bi%16;
if (c>"9")
c= "a"+(c-"0"-10);
buf.append((char)c);
}
return buf.toString();
}
/* ------------------------------------------------------------ */
public static byte[] fromHexString(String s)
{
if (s.length()%2!=0)
throw new IllegalArgumentException(s);
byte[] array = new byte[s.length()/2];
for (int i=0;i<array.length;i++)
{
int b = Integer.parseInt(s.substring(i*2,i*2+2),16);
array[i]=(byte)(0xff&b);
}
return array;
}
public static void dump(Class c)
{
System.err.println("Dump: "+c);
dump(c.getClassLoader());
}
public static void dump(ClassLoader cl)
{
System.err.println("Dump Loaders:");
while(cl!=null)
{
System.err.println(" loader "+cl);
cl = cl.getParent();
}
}
}
</source>
