DataSource 接口 简单池实现

Sun定义提供 connection工厂接口

实现方式

1.不加强Connection的close方法, 每次getConnection都新建一个连接

2.连接池方式实现

3.支持分布式事务, 多数据库联合封装

1方式比较基础 2方式只学了这个, 3方式现在还没接触

加强close用到了动态代理, 包装代码比较多,没写

import java.io.PrintWriter;
import java.lang.reflect.InvocationHandler;
import java.lang.reflect.Method;
import java.lang.reflect.Proxy;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.SQLException;
import java.sql.SQLFeatureNotSupportedException;
import java.util.ArrayList;
import java.util.List;
import java.util.logging.Logger;

import javax.sql.DataSource;

import org.junit.Test;

public class MyDataSource implements DataSource {

private List<Connection> pool = new ArrayList<Connection>();

public MyDataSource() {

try {
Class.forName("com.mysql.jdbc.Driver");

int i = 0;
String url = "jdbc:mysql://127.0.0.1:3306/mydb";
String user = "root";
String password = "root";

for (i = 0; i < 3; i++) {

final Connection connection = DriverManager.getConnection(url,
user, password);

Object connectionProxyObject = Proxy.newProxyInstance(
MyDataSource.class.getClassLoader(),
new Class[] { Connection.class },

new InvocationHandler() {

@Override
public Object invoke(Object proxy, Method method,
Object[] args) throws Throwable {

Object resultObject = null;

if (method.getName().equals("close")) {
synchronized (pool) {
pool.add((Connection) proxy);
}
resultObject = null;
} else {
resultObject = method.invoke(connection,
args);
}

return resultObject;
}
}

);

pool.add((Connection)connectionProxyObject);

}

} catch (ClassNotFoundException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} catch (SQLException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}

@Override
public PrintWriter getLogWriter() throws SQLException {
// TODO Auto-generated method stub
return null;
}

@Override
public int getLoginTimeout() throws SQLException {
// TODO Auto-generated method stub
return 0;
}

@Override
public Logger getParentLogger() throws SQLFeatureNotSupportedException {
// TODO Auto-generated method stub
return null;
}

@Override
public void setLogWriter(PrintWriter arg0) throws SQLException {
// TODO Auto-generated method stub

}

@Override
public void setLoginTimeout(int arg0) throws SQLException {
// TODO Auto-generated method stub

}

@Override
public boolean isWrapperFor(Class<?> arg0) throws SQLException {
// TODO Auto-generated method stub
return false;
}

@Override
public <T> T unwrap(Class<T> arg0) throws SQLException {
// TODO Auto-generated method stub
return null;
}

@Override
public Connection getConnection() throws SQLException {
synchronized (pool) {
while (true) {
if (pool.size() == 0) {
try {
pool.wait();
} catch (InterruptedException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
} else {
return pool.remove(0);
}
}
}

}

@Override
public Connection getConnection(String username, String password)
throws SQLException {
// TODO Auto-generated method stub
return null;
}

@Test
public void test(){

DataSource dataSource = new MyDataSource();

try {
Connection connection1 = dataSource.getConnection();
Connection connection2 = dataSource.getConnection();
Connection connection3 = dataSource.getConnection();

connection3.close();

System.out.println(connection1);
System.out.println(connection2);
System.out.println(connection3);

Connection connection4 = dataSource.getConnection();
System.out.println(connection4);	//输出同3

} catch (SQLException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
}