Java by API/java.lang.reflect/Constructor
Содержание
Constructor: getExceptionTypes()
<source lang="java">
import java.lang.reflect.Constructor; import java.lang.reflect.Field; import java.lang.reflect.Member; import java.lang.reflect.Method; import java.lang.reflect.Modifier; public class Main{
public static void main(String[] args) throws ClassNotFoundException {
Class c = Class.forName(args[0]);
print_class(c);
}
public static void print_class(Class c) {
if (c.isInterface()) {
System.out.print(Modifier.toString(c.getModifiers()) + " " + typename(c));
} else if (c.getSuperclass() != null) {
System.out.print(Modifier.toString(c.getModifiers()) + " class " + typename(c) + " extends "
+ typename(c.getSuperclass()));
} else {
System.out.print(Modifier.toString(c.getModifiers()) + " class " + typename(c));
}
Class[] interfaces = c.getInterfaces();
if ((interfaces != null) && (interfaces.length > 0)) {
if (c.isInterface())
System.out.print(" extends ");
else
System.out.print(" implements ");
for (int i = 0; i < interfaces.length; i++) {
if (i > 0)
System.out.print(", ");
System.out.print(typename(interfaces[i]));
}
}
System.out.println(" {");
Constructor[] constructors = c.getDeclaredConstructors();
for (int i = 0; i < constructors.length; i++)
print_method_or_constructor(constructors[i]);
Field[] fields = c.getDeclaredFields();
for (int i = 0; i < fields.length; i++){
print_field(fields[i]);
}
Method[] methods = c.getDeclaredMethods();
for (int i = 0; i < methods.length; i++)
print_method_or_constructor(methods[i]);
System.out.println("}");
}
public static String typename(Class t) {
String brackets = "";
while (t.isArray()) {
brackets += "[]";
t = t.getComponentType();
}
String name = t.getName();
int pos = name.lastIndexOf(".");
if (pos != -1)
name = name.substring(pos + 1);
return name + brackets;
}
public static String modifiers(int m) {
if (m == 0)
return "";
else
return Modifier.toString(m) + " ";
}
public static void print_field(Field f) {
System.out.println(" " + modifiers(f.getModifiers()) + typename(f.getType()) + " "
+ f.getName() + ";");
}
public static void print_method_or_constructor(Member member) {
Class returntype = null, parameters[], exceptions[];
if (member instanceof Method) {
Method m = (Method) member;
returntype = m.getReturnType();
parameters = m.getParameterTypes();
exceptions = m.getExceptionTypes();
System.out.print(" " + modifiers(member.getModifiers()) + typename(returntype) + " "
+ member.getName() + "(");
} else {
Constructor c = (Constructor) member;
parameters = c.getParameterTypes();
exceptions = c.getExceptionTypes();
System.out.print(" " + modifiers(member.getModifiers()) + typename(c.getDeclaringClass())
+ "(");
}
for (int i = 0; i < parameters.length; i++) {
if (i > 0)
System.out.print(", ");
System.out.print(typename(parameters[i]));
}
System.out.print(")");
if (exceptions.length > 0)
System.out.print(" throws ");
for (int i = 0; i < exceptions.length; i++) {
if (i > 0)
System.out.print(", ");
System.out.print(typename(exceptions[i]));
}
System.out.println(";");
}
}
</source>
Constructor: getModifiers()
<source lang="java">
import static java.lang.System.out; import java.lang.reflect.Constructor; import java.lang.reflect.Modifier; public class Main {
public static void main(String... args) throws Exception {
Class<?> c = Class.forName(args[0]);
Constructor[] allConstructors = c.getDeclaredConstructors();
for (Constructor ctor : allConstructors) {
int searchMod = modifierFromString(args[1]);
int mods = accessModifiers(ctor.getModifiers());
if (searchMod == mods) {
out.format("%s%n", ctor.toGenericString());
out.format(" [ synthetic=%-5b var_args=%-5b ]%n", ctor.isSynthetic(), ctor.isVarArgs());
}
}
}
private static int accessModifiers(int m) {
return m & (Modifier.PUBLIC | Modifier.PRIVATE | Modifier.PROTECTED);
}
private static int modifierFromString(String s) {
if ("public".equals(s))
return Modifier.PUBLIC;
else if ("protected".equals(s))
return Modifier.PROTECTED;
else if ("private".equals(s))
return Modifier.PRIVATE;
else if ("package-private".equals(s))
return 0;
else
return -1;
}
}
</source>
Constructor: getName()
<source lang="java">
/* java.util.ArrayList: java.util.ArrayList: Collection java.util.ArrayList: int
*/
import java.lang.reflect.Constructor; public class MainClass {
public static void main(String[] args) {
try {
Class c = Class.forName("java.util.ArrayList");
Constructor constructors[] = c.getConstructors();
for (int i = 0; i < constructors.length; i++) {
System.out.print(constructors[i].getName() + ": ");
Class parameters[];
parameters = constructors[i].getParameterTypes();
for (int j = 0; j < parameters.length; j++) {
String s = parameters[j].getName();
s = s.substring(s.lastIndexOf(".") + 1, s.length());
System.out.print(s + " ");
}
System.out.println("");
}
} catch (Exception ex) {
ex.printStackTrace();
}
}
}
</source>
Constructor: getParameterTypes()
<source lang="java">
/* java.util.ArrayList: java.util.ArrayList: Collection java.util.ArrayList: int
*/
import java.lang.reflect.Constructor; public class MainClass {
public static void main(String[] args) {
try {
Class c = Class.forName("java.util.ArrayList");
Constructor constructors[] = c.getConstructors();
for (int i = 0; i < constructors.length; i++) {
System.out.print(constructors[i].getName() + ": ");
Class parameters[];
parameters = constructors[i].getParameterTypes();
for (int j = 0; j < parameters.length; j++) {
String s = parameters[j].getName();
s = s.substring(s.lastIndexOf(".") + 1, s.length());
System.out.print(s + " ");
}
System.out.println("");
}
} catch (Exception ex) {
ex.printStackTrace();
}
}
}
</source>
Constructor: newInstance(Object... initargs)
<source lang="java">
import java.lang.reflect.Constructor; public class Main {
public static void main(final String[] args) throws Exception {
final Class[] ARG_TYPES = new Class[] { String.class };
Constructor cst = Integer.class.getConstructor(ARG_TYPES);
System.out.println(cst.newInstance(new Object[] { "45" }));
}
}
</source>
Constructor: setAccessible(boolean flag)
<source lang="java">
import java.lang.reflect.Constructor; import java.lang.reflect.Field; import java.lang.reflect.Method; public class Main {
public static void main(String[] argv) throws Exception {
Class cls = java.lang.String.class;
Method method = cls.getMethods()[0];
Field field = cls.getFields()[0];
Constructor constructor = cls.getConstructors()[0];
field.setAccessible(true);
constructor.setAccessible(true);
method.setAccessible(true);
}
}
</source>
Constructor: toGenericString()
<source lang="java">
import static java.lang.System.out; import java.lang.reflect.Constructor; import java.lang.reflect.Modifier; public class Main {
public static void main(String... args) throws Exception {
Class<?> c = Class.forName(args[0]);
Constructor[] allConstructors = c.getDeclaredConstructors();
for (Constructor ctor : allConstructors) {
int searchMod = modifierFromString(args[1]);
int mods = accessModifiers(ctor.getModifiers());
if (searchMod == mods) {
out.format("%s%n", ctor.toGenericString());
out.format(" [ synthetic=%-5b var_args=%-5b ]%n", ctor.isSynthetic(), ctor.isVarArgs());
}
}
}
private static int accessModifiers(int m) {
return m & (Modifier.PUBLIC | Modifier.PRIVATE | Modifier.PROTECTED);
}
private static int modifierFromString(String s) {
if ("public".equals(s))
return Modifier.PUBLIC;
else if ("protected".equals(s))
return Modifier.PROTECTED;
else if ("private".equals(s))
return Modifier.PRIVATE;
else if ("package-private".equals(s))
return 0;
else
return -1;
}
}
</source>
