四种连接数据库的方法

}
}
private static DataSourcePool pool = new DataSourcePool();
//创建对象就初始化size个数据库连接
private DataSourcePool(){
if(list.size()>0){
//取到连接，即从list中弹出一个Connection 连接
final Connection conn = list.pop();
//动态代理，返回一个代理对象
return (Connection) Proxy.newProxyInstance(DataSourcePool.class.getClassLoade(), conn.getClass().getInterfaces(), new InvocationHandler(){
for(int i=0;i<size;i++){
try {
Connection conn = DriverManager.getConnection(url, username, password);
package ngzi.jdbc.DataSource;
import java.io.InputStream;
import java.io.PrintWriter;
import ng.reflect.InvocationHandler;
throws SQLException {
// TODO Auto-generated method stub
return null;
}
@Override
public PrintWriter getLogWriter() throws SQLException {
// TODO Auto-generated method stub
if(method.getName().equals("close")){
list.push(conn);
return null;
}
return method.invoke(conn, args);
import javax.sql.DataSource;
public class DataSourcePool implements DataSource {
private static String url = null;
private static String username = null;
private static String password = "123456";
private static Connection conn = null;
static{
try {
//注册驱动
}
@Override
public boolean isWrapperFor(Class<?> iface) throws SQLException {
} catch (Exception e) {
throw new RuntimeException(e);
}
}
public static Connection getConnection() throws SQLException{
private static String password = null;
private static int size = 10;
private static LinkedList<Connection> list = new LinkedList<Connection>();
一、环境
1、数据库驱动jar文件
2、DBCP方法
Commons-dbcp.jar：连接池的实现
Commons-pool.jar：连接池实现的依赖库
资源文件
3、c3p0方法：
c3p0-0.9.1.2.jar
配置文件：c3p0-config.xml
二、连接操作
"cn/langzi/jdbc/DataSource/DBConnection.properties");
Properties prop = new Properties();
prop.load(in);
conn = DriverManager.getConnection(url, username, password);
return conn;
}
}
2.使用DataSource子类方法;

资源文件DBConnection.properties
return null;
}
@Override
public int getLoginTimeout() throws SQLException {
// TODO Auto-generated method stub
return 0;
}
@Override
public void setLogWriter(PrintWriter out) throws SQLException {
import ng.reflect.Method;
import ng.reflect.Proxy;
import java.sql.Connection;
import java.sql.DriverManager;
// TODO Auto-generated method stub
}
@Override
public void setLoginTimeout(int seconds) throws SQLException {
// TODO Auto-generated method stub
System.out.println(conn);
list.add(conn);
} catch (SQLException e) {
e.printStackTrace();
import java.sql.SQLException;
import java.util.LinkedList;
import java.util.Properties;
import javax.sql.DataSource;
}
});
}
//连接用完
throw new RuntimeException("对不起，服务器繁忙！！！");
}
@Override
public Connection getConnection(String username, String password)
password = prop.getProperty("password");
} catch (Exception e) {
throw new ExceptionInInitializerError(e);
// 不要把conn = DriverManager.getConnection(url, username, password);
//放在这里。防止所有用户都用一个Connection
Class.forName(driverClass);
static{
try {
InputStream in = DataSourcePool.class.getClassLoader()
.getResourceAsStream(
public Object invoke(Object proxy, Method method, Object[] args)
throws Throwable {
//如果Connection调用的是close方法就将连接返回给数据连接池
private static String driverClass = "com.mysql.jdbc.Driver";
private static String url = "jdbc:mysql://localhost:3306/test";
private static String username = "root";
driverClass = com.mysql.jdbc.Driver
url = jdbc:mysql://localhost:3306/test
username = root
password = 123456
模拟数据连接池 DataSourcePool.java
1.DriverManager方法;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.SQLException;
public class DBConnection {
Class.forName(prop.getProperty("driverClass"));
url = prop.getProperty("url");
username = prop.getProperty("username");
}
}
}
public static DataSourcePool getInstance(){
return pool;
}
@Override