Spring中Bean的装配方式

最新推荐文章于 2025-05-13 11:22:03 发布

原创最新推荐文章于 2025-05-13 11:22:03 发布 · 3.4k 阅读

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本文介绍了Spring框架中依赖注入的两种主要方式：基于XML的装配和基于注解的装配，并通过具体示例展示了如何配置和使用这两种装配方式。

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Bean的装配可以理解为依赖关系注入Bean的装配方式即Bean依赖注入的方式.Spring容器支持多种形式的Bean的装配方式，如基于XML的装配、基于注解（Annotation）的装配和自动装配（其中最常用的是基于注解的装配），接下来将对前两种进行详细讲解.

1.基于xml的装配

(1)创建Java类,提供有参,无参构造方法,以及属性的set方法.

package xml;

import java.util.List;

public class User {
    private String username;
    private Integer password;
    private List<String> list;

    public void setUsername(String username) {
        this.username = username;
    }

    public void setPassword(Integer password) {
        this.password = password;
    }

    public void setList(List<String> list) {
        this.list = list;
    }

    public User(String username, Integer password, List<String> list) {
        super();
        this.username = username;
        this.password = password;
        this.list = list;
    }
    public User() {
        super();
    }

    public User(String i) {
        username = s;
    }

@Override public String toString() { return "User{" + "username='" + username + '\'' + ", password=" + password + ", list=" + list + '}'; }}

(2)配置xml

    <bean id="user1" class="xml.User">
        <constructor-arg index="0" value="tom"/>
    </bean>

    <bean id="user2" class="xml.User" >
        <property name="username" value="cat"/>
    </bean>

(3)测试类

public class Test {
    public static void main(String[] args) {
        ApplicationContext applicationContext =
                new ClassPathXmlApplicationContext("applicationContext.xml");
        System.out.println(applicationContext.getBean("user1"));
        System.out.println(applicationContext.getBean("user2"));
    }
}

运行结果如下:

2.Annotation注解:

基于XML的装配可能会导致XML配置文件过于臃肿，给后续的维护和升级带来一定的困难。为此，Spring提供了对Annotation（注解）技术的全面支持。

(1)xml配置

 <context:component-scan base-package="annotation" />

上面为自动扫描包下所有Bean.但是不会自动装配,在此结合注解使用.

(2)UserDao接口的配置(略)以及UserDaoImpl类:

@Repository("userDao")
public class UserDaoImpl implements UserDao {
    @Override
    public void save() {
        System.out.println("userdao...save...");
    }
}

(3)UserService接口的配置(略)以及UserServiceImpl类:

@Service("userService")
public class UserServiceImpl implements  UserService {
    @Resource(name="userDao")
    private UserDao userDao;
    @Override
    public void save() {
        this.userDao.save();
    }
}

(4)UserController

@Controller("userController")
public class UserController {
    @Resource(name="userService")
    private UserService userService;
    public void save(){
        this.userService.save();
    }
}

(5)测试类

public class Test1 {
    public static void main(String[] args) {
        ApplicationContext applicationContext =
                new ClassPathXmlApplicationContext("applicationContext.xml");
        UserController userController = (UserController) applicationContext.getBean("userController");
        userController.save();
    }
}

运行结果如下: