c3p0 连接池的使用

1、写xml文件

c3p0-config.xml

<?xml version="1.0" encoding="UTF-8"?>
<c3p0-config>

    <default-config>
        <property name="driverClass">com.mysql.jdbc.Driver</property>
        <property name="jdbcUrl">jdbc:mysql:///web08</property>
        <property name="user">root</property>
        <property name="password">root</property>
        <property name="initialPoolSize">5</property>
        <property name="maxPoolSize">20</property>
    </default-config>

    <named-config name="itheima">
        <property name="driverClass">com.mysql.jdbc.Driver</property>
        <property name="jdbcUrl">jdbc:mysql:///web08</property>
        <property name="user">root</property>
        <property name="password">root</property>
    </named-config>


</c3p0-config>

2、用来获取连接的工具类

C3P0Utils.java

package cn.itheima.jdbc.utils;

import java.sql.Connection;
import java.sql.SQLException;

import javax.sql.DataSource;

import com.mchange.v2.c3p0.ComboPooledDataSource;

public class C3P0Utils {
    private static ComboPooledDataSource dataSource = new ComboPooledDataSource();//获取默认配置
    private static ComboPooledDataSource dataSource = new ComboPooledDataSource("itheima");

    public static DataSource getDataSource() {
        return dataSource;
    }

    public static Connection getConnection() {
        try {
            return dataSource.getConnection();
        } catch (SQLException e) {
            throw new RuntimeException(e);
        }
    }
}

3、测试类

TestC3P0.java

package cn.itheima.jdbc.test;

import java.sql.Connection;
import java.sql.PreparedStatement;

import org.junit.Test;

import com.mchange.v2.c3p0.ComboPooledDataSource;

import cn.itheima.jdbc.utils.C3P0Utils;
import cn.itheima.jdbc.utils.JDBCUtils_V3;

public class TestC3P0 {
    @Test
    public void testAddUser1() {
        Connection conn = null;
        PreparedStatement pstmt = null;
        try {
            // 2.从池子中获取连接
            conn = C3P0Utils.getConnection();
            String sql = "insert into tbl_user values(null,?,?)";
            pstmt = conn.prepareStatement(sql);
            pstmt.setString(1, "吕布3");
            pstmt.setString(2, "貂蝉3");
            int rows = pstmt.executeUpdate();
            if (rows > 0) {
                System.out.println("添加成功!");
            } else {
                System.out.println("添加失败!");
            }
        } catch (Exception e) {
            throw new RuntimeException(e);
        } finally {
            JDBCUtils_V3.release(conn, pstmt, null);
        }
    }

    @Test
    public void testAddUser() {
        Connection conn = null;
        PreparedStatement pstmt = null;
        // 1.创建自定义连接池对象
        ComboPooledDataSource dataSource = new ComboPooledDataSource();// 加载默认的配置
        // ComboPooledDataSource dataSource = new
        // ComboPooledDataSource("itheima");//加载有名称的配置
        try {
            // 2.从池子中获取连接
            conn = dataSource.getConnection();
            String sql = "insert into tbl_user values(null,?,?)";
            pstmt = conn.prepareStatement(sql);
            pstmt.setString(1, "吕布2");
            pstmt.setString(2, "貂蝉2");
            int rows = pstmt.executeUpdate();
            if (rows > 0) {
                System.out.println("添加成功!");
            } else {
                System.out.println("添加失败!");
            }
        } catch (Exception e) {
            throw new RuntimeException(e);
        } finally {
            JDBCUtils_V3.release(conn, pstmt, null);
        }
    }
}

附加类JDBCUtils_V3

package cn.itheima.jdbc.utils;

import java.io.IOException;
import java.io.InputStream;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.util.Properties;
import java.util.ResourceBundle;

/**
 * 提供获取连接和释放资源的 方法
 * 
 * @author Never Say Never
 * @date 2016年7月29日
 * @version V1.0
 */
public class JDBCUtils_V3 {
    private static String driver;
    private static String url;
    private static String username;
    private static String password;

    /**
     * 静态代码块加载配置文件信息
     */
    static {
        try {
            // 1.通过当前类获取类加载器
            ClassLoader classLoader = JDBCUtils_V3.class.getClassLoader();
            // 2.通过类加载器的方法获得一个输入流
            InputStream is = classLoader.getResourceAsStream("db.properties");
            // 3.创建一个properties对象
            Properties props = new Properties();
            // 4.加载输入流
            props.load(is);
            // 5.获取相关参数的值
            driver = props.getProperty("driver");
            url = props.getProperty("url");
            username = props.getProperty("username");
            password = props.getProperty("password");
        } catch (IOException e) {
            e.printStackTrace();
        }

    }

    /**
     * 获取连接方法
     * 
     * @return
     */
    public static Connection getConnection() {
        Connection conn = null;
        try {
            Class.forName(driver);
            conn = DriverManager.getConnection(url, username, password);
        } catch (Exception e) {
            e.printStackTrace();
        }
        return conn;
    }

    /**
     * 释放资源方法
     * 
     * @param conn
     * @param pstmt
     * @param rs
     */
    public static void release(Connection conn, PreparedStatement pstmt, ResultSet rs) {
        if (rs != null) {
            try {
                rs.close();
            } catch (SQLException e) {
                e.printStackTrace();
            }
        }
        if (pstmt != null) {
            try {
                pstmt.close();
            } catch (SQLException e) {
                e.printStackTrace();
            }
        }
        if (conn != null) {
            try {
                conn.close();
            } catch (SQLException e) {
                e.printStackTrace();
            }
        }

    }
}