7 - Spring创建第三方bean对象以及引用外部配置文件

 3、Spring创建第三方bean对象

在导入如上druid、mysql的依赖后，在ico.xml配置文件中进行如下配置：

<!--spring管理第三方bean-->
    <bean id="dataSource" class="com.alibaba.druid.pool.DruidDataSource">
        <property name="username" value="root"></property>
        <property name="password" value="123456"></property>
        <property name="url" value="jbdc:mysql://localhost:3306/demo"></property>
        <property name="driverClassName" value="com.mysql.jdbc.Driver"></property>
    </bean>

然后，测试: 

public class MyTest {
    public static void main(String[] args) throws SQLException {
        ApplicationContext context = new ClassPathXmlApplicationContext("ioc.xml");

        DruidDataSource dataSource = context.getBean("dataSource", DruidDataSource.class);
        System.out.println(dataSource);
        //System.out.println(dataSource.getConnection());
    }
}

结果：

 如果一些信息不想像上面的ioc.xml配置文件中那样写死了，可以引入外部的配置文件。

4、spring引用外部配置文件

代码示例：

pom.xml配置文件：

<?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.zhoulz</groupId>
    <artifactId>spring_study_maven_3</artifactId>
    <version>1.0-SNAPSHOT</version>

    <dependencies>

        <!--添加的maven依赖-->
        <!-- https://mvnrepository.com/artifact/org.springframework/spring-context -->
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-context</artifactId>
            <version>5.2.3.RELEASE</version>
        </dependency>

        <!--添加的druid依赖-->
        <!-- https://mvnrepository.com/artifact/com.alibaba/druid -->
        <dependency>
            <groupId>com.alibaba</groupId>
            <artifactId>druid</artifactId>
            <version>1.2.14</version>
        </dependency>

        <!--添加的mysql依赖-->
        <!-- https://mvnrepository.com/artifact/mysql/mysql-connector-java -->
        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
            <version>5.1.48</version>
        </dependency>


    </dependencies>

</project>

ioc.xml配置文件：

注意，头部要进行如下设置：

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

       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
">

    <bean id="person" class="com.zhoulz.bean.Person" > <!--单例-->
        <property name="id" value="1"></property>
        <property name="name" value="lisi"></property>
        <property name="age" value="20"></property>
        <property name="gender" value="男"></property>
    </bean>

    <!--spring管理第三方bean-->
    <bean id="dataSource" class="com.alibaba.druid.pool.DruidDataSource">
        <property name="username" value="root"></property>
        <property name="password" value="123456"></property>
        <property name="url" value="jbdc:mysql://localhost:3306/demo"></property>
        <property name="driverClassName" value="com.mysql.jdbc.Driver"></property>
    </bean>

    <!--当需要引入外部的配置文件的时候，需要导入一些context的命名空间-->
    <context:property-placeholder location="classpath:db.properties"></context:property-placeholder>
    <!--
    在配置文件编写属性的时候，需要注意：
    spring容器在进行启动的时候，会读取当前系统的某些环境变量的配置，
    当前系统的用户名是用username来表示的，所以最好的方式是添加前缀来作区分,如，下面的username不能再加jbdc.了
    -->
    <bean id="dataSource2" class="com.alibaba.druid.pool.DruidDataSource">
        <property name="username" value="${username}"></property>
        <property name="password" value="${jbdc.password}"></property>
        <property name="url" value="${url}"></property>
        <property name="driverClassName" value="${driverClassName}"></property>
    </bean>

    <bean id="person2" class="com.zhoulz.bean.Person">
        <property name="name" value="${jbdc.username}"></property>
    </bean>


</beans>

在resource文件夹下新创建db.properties配置文件（文件类型为File）：

jbdc.username=root123
jbdc.password=123456
url=jbdc:mysql://localhost:3306/demo
driverClassName=com.mysql.jdbc.Driver

测试类：

import com.alibaba.druid.pool.DruidDataSource;
import com.zhoulz.bean.Person;
import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;

import java.sql.SQLException;

public class MyTest {
    public static void main(String[] args) throws SQLException {
        ApplicationContext context = new ClassPathXmlApplicationContext("ioc.xml");

       /* DruidDataSource dataSource = context.getBean("dataSource", DruidDataSource.class);
        System.out.println(dataSource);
        //System.out.println(dataSource.getConnection());*/

        /*DruidDataSource dataSource2 = context.getBean("dataSource2", DruidDataSource.class);
        System.out.println(dataSource2);
        //System.out.println(dataSource.getConnection());*/

        Person person2 = context.getBean("person2", Person.class);
        System.out.println(person2);

    }
}