Spring注解

注解方式可以简化spring的IOC容器的配置!

使用注解步骤:

         1)先引入context名称空间

                   xmlns:context="http://www.springframework.org/schema/context"

         2)开启注解扫描

                   <context:component-scan base-package="com.loaderman.e_anno2"></context:component-scan>

         3)使用注解

                   通过注解的方式,把对象加入ioc容器。

            创建对象以及处理对象依赖关系,相关的注解:

                   @Component   指定把一个对象加入IOC容器

@Repository   作用同@Component; 在持久层使用

@Service      作用同@Component; 在业务逻辑层使用

@Controller    作用同@Component; 在控制层使用

@Resource     属性注入

总结:

         1) 使用注解,可以简化配置,且可以把对象加入IOC容器,及处理依赖关系(DI)
         2) 注解可以和XML配置一起使用。


 

 

package loaderman.e_anno;


import org.junit.Test;
import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;
public class App {

    // 创建容器对象
    private ApplicationContext ac =
            new ClassPathXmlApplicationContext("loaderman/e_anno/bean.xml");

    @Test
    public void testExecuteAction() {
        // 从容器中获取Action
        UserAction userAction = (UserAction) ac.getBean("userAction");
        userAction.execute();
    }
}
package loaderman.e_anno;

import javax.annotation.Resource;

import org.springframework.stereotype.Component;

@Component("userAction")  // 加入IOC容器
public class UserAction {

    @Resource(name = "userService")
    private UserService userService;

    public void setUserService(UserService userService) {
        this.userService = userService;
    }


    public String execute() {
        userService.save();
        return null;
    }
}
package loaderman.e_anno;

import org.springframework.stereotype.Component;


// 把当前对象加入ioc容器
@Component("userDao")   //  相当于bean.xml 【<bean id=userDao class=".." />】
public class UserDao {

    public void save() {
        System.out.println("DB:保存用户!!!");
    }
}
package loaderman.e_anno;

import javax.annotation.Resource;

import org.springframework.stereotype.Component;

@Component("userService")  // userService加入ioc容器
public class UserService {

    // 会从IOC容器中找userDao对象,注入到当前字段
    /*
     * <bean id="" class="">
     *      <property name="userDao" ref="userDao" />    @Resource相当于这里的配置
     * </bean>
     */

    @Resource(name = "userDao")
    private UserDao userDao;

    public void setUserDao(UserDao userDao) {
        this.userDao = userDao;
    }

    public void save() {
        userDao.save();
    }
}
<?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:p="http://www.springframework.org/schema/p"
    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">
    
    <!-- 开启注解扫描 -->
    <context:component-scan base-package="loaderman.e_anno"></context:component-scan>
</beans>      


package loaderman.e_anno2;


import org.junit.Test;
import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;

public class App {

    // 创建容器对象
    private ApplicationContext ac =
            new ClassPathXmlApplicationContext("loaderman/e_anno2/bean.xml");

    @Test
    public void testExecuteAction() {
        // 从容器中获取Action
        UserAction userAction = (UserAction) ac.getBean("userAction");
        userAction.execute();
    }
}
package loaderman.e_anno2;

import javax.annotation.Resource;

import org.springframework.stereotype.Component;
import org.springframework.stereotype.Controller;

//@Component("userAction")  // 加入IOC容器

//@Component

@Controller  // 控制层的组件
public class UserAction {

    @Resource
    private UserService userService;

    public String execute() {
        userService.save();
        return null;
    }
}
package loaderman.e_anno2;

// 把当前对象加入ioc容器
//@Component("userDao")   //  相当于bean.xml 【<bean id=userDao class=".." />】

//@Component  // 加入ioc容器的UserDao对象的引用名称, 默认与类名一样, 且第一个字母小写

//@Repository   // 在持久层可以选择用这个注解
public class UserDao {

    public UserDao(){
        System.out.println("UserDao.UserDao()");
    }

    public UserDao(int id){
        System.out.println("UserDao.UserDao(int id)" + id);
    }

    public void save() {
        System.out.println("DB:保存用户!!!");
    }
}
package loaderman.e_anno2;

import javax.annotation.Resource;

import org.springframework.stereotype.Component;
import org.springframework.stereotype.Service;

//@Component("userService")  // userService加入ioc容器

//@Component

@Service   // 表示业务逻辑层的组件
public class UserService {

//    @Resource                    //  根据类型查找 【在容器中要确保该类型只有一个变量】

    @Resource(name = "userDao")  // 根据名称查找
    private UserDao userDao;  // 去容器中招UserDao类型的变量,找到后就赋值

    public void save() {
        userDao.save();
    }
}
<?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:p="http://www.springframework.org/schema/p"
    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">  
    <!-- 开启注解扫描 -->
    <context:component-scan base-package="loaderman.e_anno2"></context:component-scan>  
    <bean id="userDao" class="loaderman.e_anno2.UserDao" scope="prototype">
    </bean>  
</beans>      

 

posted on 2018-11-29 17:03  LoaderMan  阅读(175)  评论(0编辑  收藏  举报

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