Spring配置数据源（连接池）

1.数据源（连接池）的作用

• 数据源（连接池）是提高程序性能出现的
• 事先实例化数据源，初始化部分连接资源
• 使用连接资源时从数据源中获取
• 使用完毕后将连接资源归还给数据源

常见的数据源（连接池）：DBCP、C3P0、BoneCP、Druid

2.手动创建C3P0的数据源

 

 配置pom.xml

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

<project xmlns="http://maven.apache.org/POM/4.0.0"
         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>

    <groupId>com.company</groupId>
    <artifactId>spring_ioc_anno</artifactId>
    <version>1.0-SNAPSHOT</version>
    <dependencies>
        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
            <version>5.1.44</version>
        </dependency>
        <dependency>
            <groupId>com.mchange</groupId>
            <artifactId>c3p0</artifactId>
            <version>0.9.5.4</version>
        </dependency>
        <dependency>
            <groupId>com.alibaba</groupId>
            <artifactId>druid</artifactId>
            <version>1.0.9</version>
        </dependency>
        <dependency>
            <groupId>junit</groupId>
            <artifactId>junit</artifactId>
            <version>4.12</version>
            <scope>test</scope>
        </dependency>
    </dependencies>

</project>

　　DataSourceTest.java

package com.company.test;

import com.mchange.v2.c3p0.ComboPooledDataSource;

import org.junit.Test;

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

public class DataSourceTest {
    @Test
    // 测试手动创建c3p0数据源
    public void test1() throws PropertyVetoException, SQLException {
        ComboPooledDataSource dataSource = new ComboPooledDataSource();
        dataSource.setDriverClass("com.mysql.jdbc.Driver");
        dataSource.setJdbcUrl("jdbc:mysql://localhost:3306/db1");
        dataSource.setUser("root");
        dataSource.setPassword("123456");
        Connection connection = dataSource.getConnection();
        System.out.println(connection);
        connection.close();
    }
}

 3.手动创建Druid的数据源

 手动创建Druid数据源

    @Test
    // 测试手动创建druid数据源
    public void test2() throws SQLException {
        DruidDataSource dataSource = new DruidDataSource();
        dataSource.setDriverClassName("com.mysql.jdbc.Driver");
        dataSource.setUrl("jdbc:mysql://localhost:3306/db1");
        dataSource.setUsername("root");
        dataSource.setPassword("123456");
        DruidPooledConnection druidPooledConnection = dataSource.getConnection();
        System.out.println(druidPooledConnection);
        druidPooledConnection.close();

    }

 4.Spring产生数据源对象

可以将DataSource的创建权交给Spring容器去完成

（1）Spring容器产生c3p0数据源对象

    @Test
    // 测试Spring容器产生c3p0数据源对象
    public void test3() throws SQLException {
        ApplicationContext applicationContext = new ClassPathXmlApplicationContext("applicationContext.xml");
        DataSource dataSource = applicationContext.getBean(DataSource.class);
        Connection connection = dataSource.getConnection();
        System.out.println(connection);
        connection.close();
    }

　　applicationContext.xml

 

（2）Spring容器产生druid数据源对象

    @Test
    //测试Spring容器产生druid数据源对象
    public void test4() throws SQLException {
        ApplicationContext applicationContext = new ClassPathXmlApplicationContext("applicationContext.xml");
        DataSource dataSource = applicationContext.getBean(DataSource.class);
        Connection connection = dataSource.getConnection();
        System.out.println(connection);
        connection.close();
    }

　　applicationContext.xml

（3）applicationContext.xml中加载外部的properties文件

首先，需要引入context命名空间和约束路径：

命名空间：xmlns:context="http://www.springframework.org/schema/context"

约束路径：http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context.xsd

Spring容器加载properties文件：

 如果这个文件在resources（类加载路径）下，前面加classpath。

用SpEL（spring表达式）可以获取Spring容器中那个key指定的值

 

jdbc_c3p0.properties

jdbc.driver=com.mysql.jdbc.Driver
jdbc.url=jdbc:mysql://127.0.0.1:3306/db1
jdbc.username=root
jdbc.password=123456

 完整代码：

package com.company.test;

import com.alibaba.druid.pool.DruidDataSource;
import com.alibaba.druid.pool.DruidPooledConnection;
import com.mchange.v2.c3p0.ComboPooledDataSource;

import org.junit.Test;
import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;

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

import javax.sql.DataSource;

public class DataSourceTest {
    @Test
    // 测试手动创建c3p0数据源
    public void test1() throws PropertyVetoException, SQLException {
        ComboPooledDataSource dataSource = new ComboPooledDataSource();
        dataSource.setDriverClass("com.mysql.jdbc.Driver");
        dataSource.setJdbcUrl("jdbc:mysql://localhost:3306/db1");
        dataSource.setUser("root");
        dataSource.setPassword("123456");
        Connection connection = dataSource.getConnection();
        System.out.println(connection);
        connection.close();
    }

    @Test
    // 测试手动创建druid数据源
    public void test2() throws SQLException {
        DruidDataSource dataSource = new DruidDataSource();
        dataSource.setDriverClassName("com.mysql.jdbc.Driver");
        dataSource.setUrl("jdbc:mysql://localhost:3306/db1");
        dataSource.setUsername("root");
        dataSource.setPassword("123456");
        DruidPooledConnection druidPooledConnection = dataSource.getConnection();
        System.out.println(druidPooledConnection);
        druidPooledConnection.close();

    }

    @Test
    // 测试Spring容器产生c3p0数据源对象
    public void test3() throws SQLException {
        ApplicationContext applicationContext = new ClassPathXmlApplicationContext("applicationContext.xml");
        DataSource dataSource = applicationContext.getBean(DataSource.class);
        Connection connection = dataSource.getConnection();
        System.out.println(connection);
        connection.close();
    }

    @Test
    //测试Spring容器产生druid数据源对象
    public void test4() throws SQLException {
        ApplicationContext applicationContext = new ClassPathXmlApplicationContext("applicationContext.xml");
        DataSource dataSource = applicationContext.getBean(DataSource.class);
        Connection connection = dataSource.getConnection();
        System.out.println(connection);
        connection.close();
    }
}