[Java知识库]SSM框架系列——数据源配置day2-1

数据源

数据源（连接池）作用

数据源(连接池)是提高程序性能而出现的
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

开发步骤

1. 导入数据源的坐标和数据库驱动坐标
2. 创建数据源对象
3. 设置数据源的基本连接数据
4. 使用数据源获取连接资源和归还连接资源

示例代码（Druid）

由于现在druid是最热门的所以我就用druid，其他的也差不多，不过我基本没用过

1. 导入数据源的坐标和数据库驱动坐标

去maven中央仓库找到相应的坐标

仓库地址：https://mvnrepository.com

找到对应的版本

我mysql的版本是8.0.16

选择maven坐标复制

<!-- https://mvnrepository.com/artifact/mysql/mysql-connector-java -->
<dependency>
    <groupId>mysql</groupId>
    <artifactId>mysql-connector-java</artifactId>
    <version>8.0.16</version>
</dependency>

进入项目pom.xml文件导入并刷新maven

Druid也是一样

<!-- https://mvnrepository.com/artifact/com.alibaba/druid-spring-boot-starter -->
<dependency>
    <groupId>com.alibaba</groupId>
    <artifactId>druid-spring-boot-starter</artifactId>
    <version>1.2.9</version>
</dependency>

2. 创建数据源对象

 //创建数据源对象
DruidDataSource source = new DruidDataSource();

3. 设置数据源的基本连接数据

        source.setDriverClassName("com.mysql.cj.jdbc.Driver");
        source.setUrl("jdbc:mysql://localhost:3306/syf?useUnicode=true&characterEncoding=UTF-8&useSSL=false&serverTimezone=Asia/Shanghai&zeroDateTimeBehavior=CONVERT_TO_NULL&allowPublicKeyRetrieval=true");
        source.setUsername("root");
        source.setPassword("syf20020816");

4. 使用数据源获取连接资源和归还连接资源

 // 4. 使用数据源获取连接资源和归还连接资源
DruidPooledConnection connection = source.getConnection();
System.out.println(connection);
connection.close();

完整代码

package com.exampl.testUtil;

import com.alibaba.druid.pool.DruidDataSource;
import com.alibaba.druid.pool.DruidPooledConnection;
import org.junit.jupiter.api.Test;

import java.sql.SQLException;

public class TestDruid {

    @Test
    public void DruidTest() throws SQLException {
        //创建数据源对象
        DruidDataSource source = new DruidDataSource();
        // 3. 设置数据源的基本连接数据
        source.setDriverClassName("com.mysql.cj.jdbc.Driver");
        source.setUrl("jdbc:mysql://localhost:3306/syf?useUnicode=true&characterEncoding=UTF-8&useSSL=false&serverTimezone=Asia/Shanghai&zeroDateTimeBehavior=CONVERT_TO_NULL&allowPublicKeyRetrieval=true");
        source.setUsername("root");
        source.setPassword("syf20020816");
  // 4. 使用数据源获取连接资源和归还连接资源
        DruidPooledConnection connection = source.getConnection();
        System.out.println(connection);
      
        connection.close();
    }

    
}

结果以及说明截图

配置文件抽取（jdbcDruid.properties）

1.在test.resources下新建资源包

2.抽取配置

driverClassName=com.mysql.cj.jdbc.Driver
url:jdbc:mysql://localhost:3306/syf?useUnicode=true&characterEncoding=UTF-8&useSSL=false&serverTimezone=Asia/Shanghai&zeroDateTimeBehavior=CONVERT_TO_NULL&allowPublicKeyRetrieval=true
username:root
password:syf20020816

3.使用配置文件进行数据库连接

package com.exampl.testUtil;

import com.alibaba.druid.pool.DruidDataSourceFactory;
import com.alibaba.druid.pool.DruidPooledConnection;
import org.junit.jupiter.api.Test;

import javax.sql.DataSource;
import java.io.IOException;
import java.io.InputStream;
import java.sql.Connection;
import java.util.Properties;
import java.util.ResourceBundle;

public class TestDruidPro {

    @Test
    public void testDruidPro() throws Exception {
        //读取配置文件
        Properties properties = new Properties();
        InputStream resourceAsStream = TestDruidPro.class.getClassLoader().getResourceAsStream("jdbcDruid.properties");
        properties.load(resourceAsStream);
        System.out.println(resourceAsStream);
        //连接
        DataSource dataSource = DruidDataSourceFactory.createDataSource(properties);
        Connection connection = dataSource.getConnection();
        System.out.println(connection);

    }
}

结果截图

Spring配置数据源

使用set方法注入

1.导入依赖

这里是我所有的依赖，mysql,druid,junit,spring你们自己找没有的加进去就行

<dependencies>
        <!-- https://mvnrepository.com/artifact/mysql/mysql-connector-java -->
        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
            <version>8.0.16</version>
        </dependency>

        <!-- https://mvnrepository.com/artifact/com.alibaba/druid-spring-boot-starter -->
        <dependency>
            <groupId>com.alibaba</groupId>
            <artifactId>druid-spring-boot-starter</artifactId>
            <version>1.2.9</version>
        </dependency>

        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-context</artifactId>
            <version>5.2.9.RELEASE</version>
        </dependency>

        <dependency>
            <groupId>org.junit.jupiter</groupId>
            <artifactId>junit-jupiter-api</artifactId>
            <version>${junit.version}</version>
            <scope>test</scope>
        </dependency>
        <dependency>
            <groupId>org.junit.jupiter</groupId>
            <artifactId>junit-jupiter-engine</artifactId>
            <version>${junit.version}</version>
            <scope>test</scope>
        </dependency>
    </dependencies>

2.编写applicationContext.xml

注意点

在xml中&符要使用&进行代替

<property name="url" value="jdbc:mysql://localhost:3306/syf?useUnicode=true&amp;characterEncoding=UTF-8&amp;useSSL=false&amp;serverTimezone=Asia/Shanghai&amp;zeroDateTimeBehavior=CONVERT_TO_NULL&amp;allowPublicKeyRetrieval=true"></property>

完整配置

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
       xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
       xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
    <bean id="dataSource" class="com.alibaba.druid.pool.DruidDataSource">
        <property name="driverClassName" value="com.mysql.cj.jdbc.Driver"></property>
        <property name="username" value="root"></property>
        <property name="password" value="syf20020816"></property>
        <property name="url" value="jdbc:mysql://localhost:3306/syf?useUnicode=true&amp;characterEncoding=UTF-8&amp;useSSL=false&amp;serverTimezone=Asia/Shanghai&amp;zeroDateTimeBehavior=CONVERT_TO_NULL&amp;allowPublicKeyRetrieval=true"></property>
    </bean>
</beans>

3.测试

package com.exampl.testUtil;

import com.alibaba.druid.pool.DruidDataSource;
import com.alibaba.druid.pool.DruidPooledConnection;
import org.junit.jupiter.api.Test;
import org.springframework.context.support.ClassPathXmlApplicationContext;

import javax.sql.DataSource;
import java.sql.Connection;
import java.sql.SQLException;

public class TestDruid {

    @Test
    public void springDruid() throws SQLException {
        //加载spring配置文件
        ClassPathXmlApplicationContext app = new ClassPathXmlApplicationContext("applicationContext.xml");
        DataSource dataSource = (DataSource) app.getBean("dataSource");
        Connection connection = dataSource.getConnection();
        System.out.println(connection);
        connection.close();
    }


}

结果

优化Spring配置数据源

我们优化方案就是将jdbc配置文件和spring的配置文件分离，形成独立的两个域，再把域进行调用即可

1.引入命名空间和地址

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
       xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
       xmlns:context="http://www.springframework.org/schema/context"
       xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd
       http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context.xsd">

2.加载外部properties

<context:property-placeholder location="classpath:jdbcDruid.properties"></context:property-placeholder>

3.改写< property >

<bean id="dataSource" class="com.alibaba.druid.pool.DruidDataSource">
        <property name="driverClassName" value="${driverClassName}"></property>
        <property name="username" value="${username}"></property>
        <property name="password" value="${password}"></property>
        <property name="url"
                  value="${url}"></property>
    </bean>

完整applicationContext.xml

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
       xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
       xmlns:context="http://www.springframework.org/schema/context"
       xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd
       http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context.xsd">
    <context:property-placeholder location="classpath:jdbcDruid.properties"></context:property-placeholder>
    <bean id="dataSource" class="com.alibaba.druid.pool.DruidDataSource">
        <property name="driverClassName" value="${driverClassName}"></property>
        <property name="username" value="${username}"></property>
        <property name="password" value="${password}"></property>
        <property name="url"
                  value="${url}"></property>
    </bean>
</beans>

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