Spring-配置数据源

传统配置使用数据源

配置mysql、junit、c3p0和德鲁伊

    <dependencies>
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-context</artifactId>
            <version>5.2.5.RELEASE</version>
        </dependency>

        <dependency>
            <groupId>junit</groupId>
            <artifactId>junit</artifactId>
            <version>4.10</version>
            <scope>test</scope>
        </dependency>

        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
            <version>8.0.28</version>
        </dependency>

        <dependency>
            <groupId>c3p0</groupId>
            <artifactId>c3p0</artifactId>
            <version>0.9.1.2</version>
        </dependency>

        <dependency>
            <groupId>com.alibaba</groupId>
            <artifactId>druid</artifactId>
            <version>1.0.9</version>
        </dependency>
    </dependencies>

编写jdbc.properties

注意8版本以下driver路径应为：com.mysql.jdbc.Driver

jdbc.driver=com.mysql.cj.jdbc.Driver
jdbc.url=jdbc:mysql://localhost:3306/数据库名称
jdbc.username=你的用户名
jdbc.password=你的密码

测试

以c3p0为例

import org.junit.Test;
import java.sql.Connection;
import java.util.ResourceBundle;
import com.mchange.v2.c3p0.ComboPooledDataSource;

    /**
     * 测试c3p0连接数据库
     * @throws Exception
     */
    @Test
    public void test_jdbc() throws Exception{
        // 读取配置文件
        ResourceBundle rb = ResourceBundle.getBundle("jdbc");
        String driver = rb.getString("jdbc.driver");
        String url = rb.getString("jdbc.url");
        String username = rb.getString("jdbc.username");
        String password = rb.getString("jdbc.password");
        // 创建数据源对象，设置链接参数
        ComboPooledDataSource source = new ComboPooledDataSource();
        source.setDriverClass(driver);
        source.setJdbcUrl(url);
        source.setUser(username);
        source.setPassword(password);

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

        connection.close();
    }

通过Bean创建数据源

仍然需要编写配置依赖和jdbc配置文件
我们在上面的例子中创建了第三方的对象

        ComboPooledDataSource source = new ComboPooledDataSource();

并且使用了第三方对象的set方法

        source.setDriverClass(driver);
        source.setJdbcUrl(url);
        source.setUser(username);
        source.setPassword(password);

那我们能否通过Spring配置文件的Bean标签结合set方法注入来帮助我们创建对象？
答案自然是可以的

配置文件书写

注意引入命名空间：

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

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

完整的编写

<?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"
       xmlns:p="http://www.springframework.org/schema/p"
       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
">

    <!--加载外部的properties文件-->
    <context:property-placeholder location="jdbc.properties" />
    <bean id="dataSource" class="com.mchange.v2.c3p0.ComboPooledDataSource">
        <property name="driverClass" value="${jdbc.driver}" />
        <property name="jdbcUrl" value="${jdbc.url}" />
        <property name="user" value="${jdbc.username}" />
        <property name="password" value="${jdbc.password}" />
    </bean>
</beans>

测试

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

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

    @Test
    public void test_c3p0() throws Exception{
        ApplicationContext app = new ClassPathXmlApplicationContext("appContext.xml");
        DataSource source = (DataSource) app.getBean("dataSource");
        Connection connection = source.getConnection();
        System.out.println(connection);
        connection.close();
    }