spring 装配bean的混合使用

　　

　　在现实中，使用XML或者注解各有道理，建议在自己的工程中所开发的类尽量使用注解方式，因为使用它并不困难，甚至可以说更为简单，而对于引入第三方包或者服务的类，尽量使用XML方式，这样的好处是可以尽量对三方包或者服务的细节减少理解，也更加清晰和明朗。
　　Spring同时支持这两种形式的装配，所以可以自由选择，只是无论采用XML还是注解方式的装配都是将Bean装配到Spring IoC容器中，这样就可以通过Spring IoC容器去管理各类资源了。

　　spring-data.xml:

<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:component-scan base-package="com.ssm.chapter10.annotation"/>

    <bean id="dataSource" class="org.apache.commons.dbcp.BasicDataSource">
        <property name="driverClassName" value="com.mysql.cj.jdbc.Driver"/>
        <property name="url" value="jdbc:mysql://localhost:3306/springmvc?useSSL=false&amp;serverTimezone=Hongkong&amp;characterEncoding=utf-8&amp;autoReconnect=true"/>
        <property name="username" value="root"/>
        <property name="password" value="123456"/>
    </bean>

</beans>

　　使用注解@ImportResource，引入spring-data.xml所定义的内容

import org.springframework.context.annotation.Configuration;
import org.springframework.context.annotation.ImportResource;

@Configuration
// @ComponentScan(basePackages = {"com.ssm.chapter10.annotation"})
@ImportResource({"classpath:ssm/chapter10/spring-dataSource.xml"})
public class ApplicationConfig2 {
}

import com.ssm.chapter10.annotation.pojo.Role;
import com.ssm.chapter10.annotation.service.RoleDataSourceService;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.beans.factory.annotation.Qualifier;
import org.springframework.stereotype.Component;

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

@Component
public class RoleDataSourceServiceImpl implements RoleDataSourceService {

    @Autowired
    // @Qualifier("dataSource2")
    DataSource dataSource = null;

    // @Override
    public Role getRole(Long id) {
        Connection conn = null;
        ResultSet rs = null;
        PreparedStatement ps = null;
        Role role = null;
        try {
            conn = dataSource.getConnection();
            ps = conn.prepareStatement("select id, role_name, note from t_role where id = ?");
            ps.setLong(1, id);
            rs = ps.executeQuery();
            while (rs.next()) {
                role = new Role();
                role.setId(rs.getLong("id"));
                role.setRoleName(rs.getString("role_name"));
                role.setNote(rs.getString("note"));
            }
        } catch (SQLException e) {
            e.printStackTrace();
        } finally {
            /**********close database resources************/
            try {
                rs.close();
                ps.close();
                conn.close();
            } catch (SQLException e) {
                e.printStackTrace();
            }
        }
        return role;
    }
}

AnnotationConfigApplicationContext context = new AnnotationConfigApplicationContext(ApplicationConfig2.class);
RoleDataSourceServiceImpl roleDataSourceServiceImpl = context.getBean(RoleDataSourceServiceImpl.class);
Role role = roleDataSourceServiceImpl.getRole(1L);
System.out.println(role.toString());
context.close();