034_jdbc-mysql-C3P0

1. 创建一个名称为JDBC_C3P0的Java工程

2. 添加c3p0的jar

3. 代码中设置连接数据库的信息

4. 在配置文件c3p0-config.xml(必须叫这个名字, 并且放置在src目录下, 因为这样可以自动加载)中设置连接数据库的信息

5. c3p0-config.xml配置详情

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

	<!-- default-config 默认的配置 -->
  <default-config>
    <property name="driverClass">com.mysql.cj.jdbc.Driver</property>
    <property name="jdbcUrl">jdbc:mysql://192.168.25.130:3306/studyjdbc?useSSL=true&amp;useUnicode=true&amp;characterEncoding=utf-8&amp;serverTimezone=Asia/Shanghai</property>
    <property name="user">root</property>
    <property name="password">lyw123456</property>
    
    <!-- 初始化连接池数量 -->
    <property name="initialPoolSize">10</property>
    <!-- 数据库连接最大空闲时间 -->
    <property name="maxIdleTime">30</property>
    <!-- 池子最大连接数 -->
    <property name="maxPoolSize">100</property>
    <!-- 池子最小连接数 -->
    <property name="minPoolSize">10</property>
    <!-- 最大Statements对象数 -->
    <property name="maxStatements">200</property>
  </default-config>
 
</c3p0-config>

6. 使用c3p0-config.xml配置文件建立数据库连接

7. 使用c3p0数据库连接池代码

package com.lywgames.myjdbc;

import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.SQLException;
import java.sql.Timestamp;
import com.mchange.v2.c3p0.ComboPooledDataSource;

public class MyJDBC {
    public static void main(String[] args) {
        c3p0UseConfig();
    }
    
    public static void c3p0() {
        Connection conn = null;
        PreparedStatement ps = null;
        
        try {
            //1. 创建datasource
            ComboPooledDataSource dataSource = new ComboPooledDataSource();
            //2. 设置连接数据库的信息
            dataSource.setDriverClass("com.mysql.cj.jdbc.Driver");
            dataSource.setJdbcUrl("jdbc:mysql://192.168.25.130:3306/studyjdbc?useSSL=true&useUnicode=true&characterEncoding=utf-8&serverTimezone=Asia/Shanghai");
            dataSource.setUser("root");
            dataSource.setPassword("lyw123456");
            //3. 得到连接对象
            conn = dataSource.getConnection();
            ps = conn.prepareStatement("insert into user values(null,?,?,?)");
            ps.setString(1, "machao");
            ps.setString(2, "123456");
            ps.setTimestamp(3, new Timestamp(System.currentTimeMillis()));
            
            ps.executeUpdate();
        } catch (Exception e) {
            e.printStackTrace();
        }finally {
            try {
                if(ps != null){
                    ps.close();
                }
            } catch (SQLException e) {
                e.printStackTrace();
            }finally{
                ps = null;
            }
        }
    }
    
    public static void c3p0UseConfig() {
        Connection conn = null;
        PreparedStatement ps = null;
        
        try {
            //1. 创建datasource通过类加载器查找c3p0-config.xml
            ComboPooledDataSource dataSource = new ComboPooledDataSource();
            //2. 得到连接对象
            conn = dataSource.getConnection();
            ps = conn.prepareStatement("insert into user values(null,?,?,?)");
            ps.setString(1, "pangjuan");
            ps.setString(2, "123456");
            ps.setTimestamp(3, new Timestamp(System.currentTimeMillis()));
            
            ps.executeUpdate();
        } catch (Exception e) {
            e.printStackTrace();
        }finally {
            try {
                if(ps != null){
                    ps.close();
                }
            } catch (SQLException e) {
                e.printStackTrace();
            }finally{
                ps = null;
            }
        }
    }
}