Spring框架SSM之IOC详解

2025-11-10 09:50:35 作者：北城以北Iris

本文介绍了Spring框架中IOC（控制反转/依赖注入）的两种实现方式,每种方式结合实例代码给大家介绍的非常详细,感兴趣的朋友一起看看吧

Spring框架之IOC

1.Spring框架搭建

在pom文件中引入jar包

<properties>
    <spring.version>4.0.2.RELEASE</spring.version>
</properties>
<!-- spring框架包 -->
<dependency>
    <groupId>org.springframework</groupId>
    <artifactId>spring-test</artifactId>
    <version>${spring.version}</version>
</dependency>
<dependency>
    <groupId>org.springframework</groupId>
    <artifactId>spring-core</artifactId>
    <version>${spring.version}</version>
</dependency>
<dependency>
    <groupId>org.springframework</groupId>
    <artifactId>spring-oxm</artifactId>
    <version>${spring.version}</version>
</dependency>
<dependency>
    <groupId>org.springframework</groupId>
    <artifactId>spring-tx</artifactId>
    <version>${spring.version}</version>
</dependency>
<dependency>
    <groupId>org.springframework</groupId>
    <artifactId>spring-jdbc</artifactId>
    <version>${spring.version}</version>
</dependency>
<dependency>
    <groupId>org.springframework</groupId>
    <artifactId>spring-aop</artifactId>
    <version>${spring.version}</version>
</dependency>
<dependency>
    <groupId>org.springframework</groupId>
    <artifactId>spring-context</artifactId>
    <version>${spring.version}</version>
</dependency>
<dependency>
    <groupId>org.springframework</groupId>
    <artifactId>spring-context-support</artifactId>
    <version>${spring.version}</version>
</dependency>
<dependency>
    <groupId>org.springframework</groupId>
    <artifactId>spring-expression</artifactId>
    <version>${spring.version}</version>
</dependency>
<dependency>
    <groupId>org.springframework</groupId>
    <artifactId>spring-orm</artifactId>
    <version>${spring.version}</version>
</dependency>
<dependency>
    <groupId>org.springframework</groupId>
    <artifactId>spring-web</artifactId>
    <version>${spring.version}</version>
</dependency>
<dependency>
    <groupId>org.springframework</groupId>
    <artifactId>spring-webmvc</artifactId>
    <version>${spring.version}</version>
</dependency>
<dependency>
    <groupId>junit</groupId>
    <artifactId>junit</artifactId>
    <version>4.12</version>
    <scope>test</scope>
</dependency>
<dependency>
    <groupId>org.projectlombok</groupId>
    <artifactId>lombok</artifactId>
    <version>1.18.8</version>
</dependency>

2.IOC(控制反转/依赖注入)

将程序的控制权从代码本身转移到外部容器

组件化的思想：分离关注点，使用接口，不再关注实现

依赖的注入：将组件的构建和使用分开

2.1在配置文件中进行控制反转和依赖注入

dao层

/**
 * 显示信息
 */
public interface UserDao {
    public void show() ;
}
public class UserDaoImpl implements UserDao {
    @Override
    public void show() {
        System.out.println("输出UserDaoImpl信息");
    }
}

service层

public interface UserService {
    /**
     * 显示信息
     */
    public void show() ;
}
public class UserServiceImpl implements UserService {
    @Setter
    private UserDao userDao;
    @Override
    public void show() {
        userDao.show();
    }
}

在resources文件夹下创建一个spring.xml配置文件

<?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">
</beans>

xml配置文件

<!--    配置userDao bean-->
<bean  id="userDao" class="com.hz.dao.impl.UserDaoImpl"></bean>
<bean id="userService" class="com.hz.service.impl.UserServiceImpl">
<!--        配置userDao属性，ref引用userDao bean -->
	<property name="userDao" ref="userDao"></property>
</bean>

读取配置文件并运行

//使用ClassPathXmlApplicationContext读取配置文件
ApplicationContext context = new ClassPathXmlApplicationContext("spring.xml");
UserService userService =(UserService) context.getBean("userService");
userService.show();

2.2使用注解的形式实现

@Component：实现Bean组件的定义

@Repository([实例化名称]) ：用于标注DAO类默认使用当前类的类名（首字母小写）作为bean的别名

@Service([实例化名称]) ：用于标注Service业务类默认使用当前类的类名（首字母小写）作为bean的别名

@Autowired+@Qualiﬁer(“userDao”)等价于@Resource(name = “userDao”)

dao层

/**
 * 显示信息
 */
public interface UserDao {
 /**
   * 删除学生
   * @param id
   */
  public int delStudent(Integer id);
}
@Repository
public class UserDaoImpl implements UserDao {
       @Override
    public int delStudent(Integer id) {
        System.out.println("删除id为"+id+"的学生");
        return 0;
    }
}

service层

public interface UserService {
      /**
     * 删除学生
     * @param id
     */
    public  int delStudent(Integer id);
}
@Service
public class UserServiceImpl implements UserService {
  //@Resource(name = "userDaoImpl")
    @Autowired
 //@Qualifier("userDaoImpl")
    private UserDao userDao;
    @Override
    public int delStudent(Integer id) {
        userDao.delStudent(id);
       return  100;
    }
}

注：JDK17把@Resource废除，如果需要使用此注解需导入jar包

<dependency>
      <groupId>javax.annotation</groupId>
      <artifactId>javax.annotation-api</artifactId>
      <version>1.2</version>
</dependency>

在配置文件中开启注解

<?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">
      <!--    配置组件扫描，扫描com.hz.dao和com.hz.service和com.hz.aop包下的类 -->
    <context:component-scan base-package="com.hz.dao,com.hz.service"/>
</beans>

读取配置文件

//使用ClassPathXmlApplicationContext读取配置文件
ApplicationContext context = new ClassPathXmlApplicationContext("spring.xml");
//因为@Repository默认使用当前类的简单类名（首字母小写）作为bean的别名，所以使用getBean("userServiceImpl")获取对象
UserService userService =(UserService) context.getBean("userServiceImpl");
userService.delStudent(1001);

2.3@Autowired和@Resource区别

Resource 按照名称依赖注入，如果没有对应则按照类型注入
Autowired 按照依赖类型注入

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