2021-09-27c3p0连接池

1. 先写c3p0.properties
   注意。前面名称可以随便写，后面的内容不能错

jdbc.driver=com.mysql.jdbc.Driver
jdbc.url=jdbc:mysql://localhost:3306/rent
jdbc.username=root
jdbc.password=123

2. 封装工具类读取properties文件

package utils;

import com.mchange.v2.c3p0.ComboPooledDataSource;

import java.beans.PropertyVetoException;
import java.io.File;
import java.io.FileInputStream;
import java.io.IOException;
import java.lang.reflect.Field;
import java.sql.*;
import java.util.ArrayList;
import java.util.List;
import java.util.Properties;

public class C3p0JdbcUtils2 {
    private static  String DRIVER;
    private static  String USERNAME;
    private static  String PASSWORD;
    private static  String URL;
    //使用c3p0数据库连接池的方式，获取数据库的连接
    private  static  ComboPooledDataSource comboPooledDataSource= new ComboPooledDataSource();


    static {
    
       Properties properties = new Properties();
        try {
        读取properties文件
            properties.load(new FileInputStream(new File("C:\Users\bears\IdeaProjects\20210926Spring\src\properties\jdbc2.properties")));
            //properties.getProperty方式获取文件的driver，url，username，password
            DRIVER = properties.getProperty("jdbc.driver");
            URL = properties.getProperty("jdbc.url");
            USERNAME = properties.getProperty("jdbc.username");
            PASSWORD = properties.getProperty("jdbc.password");
//c3p0与数据库的一个连接            comboPooledDataSource.setDriverClass(DRIVER);
            comboPooledDataSource.setJdbcUrl(URL);
            comboPooledDataSource.setUser(USERNAME);
            comboPooledDataSource.setPassword(PASSWORD);

        } catch (IOException | PropertyVetoException e) {
            e.printStackTrace();
        }
    }
    
    public  static Connection getConnection() throws SQLException, PropertyVetoException {
    //连接池的连接
        return comboPooledDataSource.getConnection();
    }
}

3. 测试

package test;

import com.mchange.v2.c3p0.ComboPooledDataSource;
import utils.C3p0JdbcUtils;
import utils.C3p0JdbcUtils2;
import utils.JdbcUtils;

import java.beans.PropertyVetoException;
import java.sql.Connection;
import java.sql.SQLException;

public class C3p0Test {
    public static void main(String[] args) throws PropertyVetoException, SQLException {
//获取连接
        Connection connection = C3p0JdbcUtils2.getConnection();
        System.out.println(connection);


    }
}

test

 package test;

import com.mchange.v2.c3p0.ComboPooledDataSource;
import utils.C3p0JdbcUtils;
import utils.C3p0JdbcUtils2;
import utils.JdbcUtils;

import java.beans.PropertyVetoException;
import java.sql.Connection;
import java.sql.SQLException;

public class C3p0Test {
    public static void main(String[] args) throws PropertyVetoException, SQLException {
       //创建c3p0连接池对象
        ComboPooledDataSource dataSource = new ComboPooledDataSource();
        //提供数据库对象
        dataSource.setDriverClass("com.mysql.jdbc.Driver");
        dataSource.setJdbcUrl("jdbc:mysql://localhost:3306/rent");
        dataSource.setUser("root");
        dataSource.setPassword("123");
        Connection connection = dataSource.getConnection();
        System.out.println("初始化连接池大小"+dataSource.getInitialPoolSize());
        System.out.println(connection);

    }
}

1. 编写c3p0-config.xml文件

    
    
        root
        123
        jdbc:mysql://localhost:3306/rent
        com.mysql.jdbc.Driver

    

2. 工具类
   //c3p0连接池的配置文件放在某一个路径(src源码包路径)下 然后使用下面这个构造器构建连接池对象的时候
   //会自动匹配这个配置文件去读取其中的configName
   //配置文件的名字必须叫c3p0-config.xml

package utils;

import com.mchange.v2.c3p0.ComboPooledDataSource;
import com.mchange.v2.c3p0.DataSources;

import javax.sql.DataSource;
import java.beans.PropertyVetoException;
import java.io.File;
import java.io.FileInputStream;
import java.io.IOException;
import java.lang.reflect.Field;
import java.sql.*;
import java.util.ArrayList;
import java.util.List;
import java.util.Properties;

public class C3p0JdbcUtils {
    //读取xml文件
    private static DataSource dataSource= new ComboPooledDataSource("haa");
    
    public  static Connection getConnection() throws SQLException, PropertyVetoException {
        return dataSource.getConnection();        

3. 进行测试

package test;

import com.mchange.v2.c3p0.ComboPooledDataSource;
import utils.C3p0JdbcUtils;
import utils.C3p0JdbcUtils2;
import utils.JdbcUtils;

import java.beans.PropertyVetoException;
import java.sql.Connection;
import java.sql.SQLException;

public class C3p0Test {
    public static void main(String[] args) throws PropertyVetoException, SQLException {

 
        Connection connection = C3p0JdbcUtils.getConnection();
        System.out.println(connection);


    }
}