Spring依赖注入与第三方Bean管理基础详解

@Service
public class BookServiceImpl implements BookService {
    //@Autowired：注入引用类型，自动装配模式，默认按类型装配
    @Autowired
    private BookDao bookDao;
    public void save() {
        System.out.println("book service save ...");
        bookDao.save();
    }
}

@Service
public class BookServiceImpl implements BookService {
    //@Autowired：注入引用类型，自动装配模式，默认按类型装配
    @Autowired
    //@Qualifier：自动装配bean时按bean名称装配
    @Qualifier("bookDao")
    private BookDao bookDao;
    public void save() {
        System.out.println("book service save ...");
        bookDao.save();
    }
}

package com.lin.dao.impl;
import com.lin.dao.BookDao;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.stereotype.Repository;
@Repository
public class BookDaoImpl implements BookDao {
    @Value("${name}")
    private String name;
    public void save() {
        System.out.println("Dao中的save"+" "+name);
    }
}

@Configuration
@ComponentScan("com.itheima")
//@PropertySource加载properties配置文件
@PropertySource({"classpath:jdbc.properties"}) //{}可以省略不写
public class SpringConfig {
}

public class JdbcConfig {
    //@Bean：表示当前方法的返回值是一个bean对象，添加到IOC容器中
    @Bean
    public DataSource dataSource(){
        DruidDataSource ds = new DruidDataSource();
        ds.setDriverClassName("com.mysql.jdbc.Driver");
        ds.setUrl("jdbc:mysql://localhost:3306/spring_db");
        ds.setUsername("root");
        ds.setPassword("root");
        return ds;
    }
}

@Configuration
@ComponentScan("com.itheima")
//@Import:导入配置信息
@Import({JdbcConfig.class})
public class SpringConfig {
}

jdbc.driver=com.mysql.jdbc.Driver
jdbc.url=jdbc:mysql://127.0.0.1:3306/db1
jdbc.username=root
jdbc.password=1234

package com.lin.config;
import com.alibaba.druid.pool.DruidDataSource;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.context.annotation.Bean;
import javax.sql.DataSource;
public class JdbcConfig {
    @Value("${jdbc.driver}")
    private String driverName;
    @Value("${jdbc.url}")
    private String url;
    @Value("${jdbc.username}")
    private String userName;
    @Value("jdbc.password")
    private String password;
    @Bean
    public DataSource getDataSource(){
        DruidDataSource dataSource = new DruidDataSource();
        dataSource.setDriverClassName(driverName);
        dataSource.setUrl(url);
        dataSource.setUsername(userName);
        dataSource.setPassword(password);
        return dataSource;
    }
}

//Spring会自动从IOC容器中找到BookDao对象赋值给参数bookDao变量，如果没有就会报错。
@Bean 
public DataSource dataSource(BookDao bookDao){
    System.out.println(bookDao);
    DruidDataSource ds = new DruidDataSource();
    ds.setDriverClassName(driver);
    ds.setUrl(url);
    ds.setUsername(userName);
    ds.setPassword(password);
    return ds;
}