Admin: 1 версия

2010-06-01T06:33:28Z

1 версия

в 18:01, 31 мая 2010

2010-05-31T18:01:44Z

Новая страница

== Predicate implementation ==



<source lang="java">

/*
JDBC Recipes: A Problem-Solution Approach (Problem-Solution Approach) (Hardcover)
by Mahmoud Parsian

# Publisher: Apress (September 15, 2005)
# Language: English
# ISBN: 1590595203
*/
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.SQLException;
import java.sql.Statement;
import javax.sql.RowSet;
import javax.sql.rowset.FilteredRowSet;
import javax.sql.rowset.Predicate;
import com.sun.rowset.FilteredRowSetImpl;
public class Main {
public static void main(String[] args) throws Exception {
Connection conn = getHSQLConnection();
System.out.println("Got Connection.");
Statement st = conn.createStatement();
st.executeUpdate("create table survey (id int,name varchar, age int);");
st.executeUpdate("insert into survey (id,name,age ) values (1,"nameValue", 10)");
st.executeUpdate("insert into survey (id,name,age ) values (2,"anotherValue", 100)");
FilteredRowSet frs = new FilteredRowSetImpl();
frs.setUsername("sa");
frs.setPassword("");
frs.setUrl("jdbc:hsqldb:data/tutorial");
frs.setCommand("SELECT id, name, age FROM survey");
frs.execute();
System.out.println("--- Unfiltered RowSet: ---");
while (frs.next()) {
System.out.println(frs.getRow() + " - " + frs.getString("id") + ":" + frs.getString("name")
+ ":" + frs.getInt("age"));
}
// create a filter that restricts entries in
// the age column to be between 7 and 10
AgeFilter filter = new AgeFilter(7, 10, 3);
// set the filter.
frs.beforeFirst();
frs.setFilter(filter);
// go to the beginning of the Rowset
System.out.println("--- Filtered RowSet: ---");
// show filtered data
while (frs.next()) {
System.out.println(frs.getRow() + " - " + frs.getString("id") + ":" + frs.getString("name")
+ ":" + frs.getInt("age"));
}
System.out.println("--- Try to insert new records ---");
// Try to add an employee with age = 90 (allowed by filter)
frs.moveToInsertRow();
frs.updateString(1, "999");
frs.updateString(2, "Andre");
frs.updateInt(3, 90);
frs.insertRow();
frs.moveToCurrentRow();
frs.acceptChanges();
// try to add an survey with age = 65 (not allowed by filter)
frs.moveToInsertRow();
frs.updateString(1, "123");
frs.updateString(2, "Jeff");
frs.updateInt(3, 65);
frs.insertRow();
frs.moveToCurrentRow();
frs.acceptChanges();
// scroll to first row of rowset
frs.beforeFirst();
// display rows in FilteredRowset
System.out.println("FilteredRowSet after trying to insert Jeff (age 65) and Andre (age 90):");
while (frs.next()) {
System.out.println(frs.getRow() + " - " + frs.getString("id") + ":" + frs.getString("name")
+ ":" + frs.getInt("age"));
}
frs.close();
st.close();
frs.close();
}
private static Connection getHSQLConnection() throws Exception {
Class.forName("org.hsqldb.jdbcDriver");
System.out.println("Driver Loaded.");
String url = "jdbc:hsqldb:data/tutorial";
return DriverManager.getConnection(url, "sa", "");
}
public static Connection getMySqlConnection() throws Exception {
String driver = "org.gjt.mm.mysql.Driver";
String url = "jdbc:mysql://localhost/demo2s";
String username = "oost";
String password = "oost";
Class.forName(driver);
Connection conn = DriverManager.getConnection(url, username, password);
return conn;
}
public static Connection getOracleConnection() throws Exception {
String driver = "oracle.jdbc.driver.OracleDriver";
String url = "jdbc:oracle:thin:@localhost:1521:databaseName";
String username = "userName";
String password = "password";
Class.forName(driver); // load Oracle driver
Connection conn = DriverManager.getConnection(url, username, password);
return conn;
}
}
class AgeFilter implements Predicate {
private int lowAge;
private int highAge;
private int columnIndex;
private String columnName;
public AgeFilter(int lowAge, int highAge, int columnIndex, String columnName) {
this.lowAge = lowAge;
this.highAge = highAge;
this.columnName = columnName;
this.columnIndex = columnIndex;
}
public AgeFilter(int lowAge, int highAge, int columnIndex) {
this(lowAge, highAge, columnIndex, "age");
}
public boolean evaluate(Object value, String columnName) {
boolean evaluation = true;
if (columnName.equalsIgnoreCase(this.columnName)) {
int columnValue = ((Integer) value).intValue();
if ((columnValue >= this.lowAge) && (columnValue <= this.highAge)) {
evaluation = true;
} else {
evaluation = false;
}
}
return evaluation;
}
public boolean evaluate(Object value, int columnNumber) {
boolean evaluation = true;
if (columnIndex == columnNumber) {
int columnValue = ((Integer) value).intValue();
if ((columnValue >= this.lowAge) && (columnValue <= this.highAge)) {
evaluation = true;
} else {
evaluation = false;
}
}
return evaluation;
}
public boolean evaluate(RowSet rs) {
if (rs == null) {
return false;
}
FilteredRowSet frs = (FilteredRowSet) rs;
boolean evaluation = false;
try {
int columnValue = frs.getInt(this.columnIndex);
if ((columnValue >= this.lowAge) && (columnValue <= this.highAge)) {
evaluation = true;
}
} catch (SQLException e) {
return false;
}
return evaluation;
}
}

</source>

← Предыдущая	Версия 06:33, 1 июня 2010
(нет различий)

Java/Database SQL JDBC/Predicate - История изменений

Admin: 1 версия

в 18:01, 31 мая 2010