spring装配bean(基于注解)

装配bean(基于注解)

l  注解：就是一个类，使用@注解名称

l  开发中：使用注解 取代 xml配置文件。

 

l  注解使用前提，添加命名空间，让spring扫描含有注解类

1. @Component

@Component取代

@Component("id")取代

UserService:

package com.itheima.g_annotation.a_ioc;

public interface UserService {
	
	public void addUser();

}

UserServiceImpl:

package com.itheima.g_annotation.a_ioc;

import org.springframework.stereotype.Component;

@Component("userServiceId")
public class UserServiceImpl implements UserService {

	@Override
	public void addUser() {
		System.out.println("g_annotation.a_ioc add user");
	}

}

beans.xml:

TestAnnoIoC:

package com.itheima.g_annotation.a_ioc;

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

public class TestAnnoIoC {
	
	@Test
	public void demo02(){
		//从spring容器获得
		String xmlPath = "com/itheima/g_annotation/a_ioc/beans.xml";
		ApplicationContext applicationContext = new ClassPathXmlApplicationContext(xmlPath);
		UserService userService = (UserService) applicationContext.getBean("userServiceId");
		userService.addUser();
		
	}

}

2.web开发

提供3个@Component注解衍生注解（功能一样）取代

       @Repository：dao层

       @Service：service层

       @Controller：web层

3.依赖注入    

给私有字段设置，也可以给setter方法设置

       普通值：@Value("")

       引用值：

              方式1：按照【类型】注入

                     @Autowired

              方式2：按照【名称】注入1

                     @Autowired

                     @Qualifier("名称")

              方式3：按照【名称】注入2

                     @Resource("名称")

StudentDao:

package com.itheima.g_annotation.b_web;

public interface StudentDao {

	void save();

}

StudentDaoImpl:

package com.itheima.g_annotation.b_web;

import org.springframework.stereotype.Repository;

@Repository("studentDaoId")
public class StudentDaoImpl implements StudentDao {

	@Override
	public void save() {
		System.out.println("dao");
	}

}

StudentService:

package com.itheima.g_annotation.b_web;

public interface StudentService {

	void addStudent();

}

StudentServiceImpl:

package com.itheima.g_annotation.b_web;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.beans.factory.annotation.Qualifier;
import org.springframework.stereotype.Service;


@Service
public class StudentServiceImpl implements StudentService {
	
	private StudentDao studentDao;
	
	@Autowired
	@Qualifier("studentDaoId")
	public void setStudentDao(StudentDao studentDao) {
		this.studentDao = studentDao;
	}

	@Override
	public void addStudent() {
		studentDao.save();
	}

}

StudentAction:

package com.itheima.g_annotation.b_web;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Controller;

@Controller("studentActionId")
public class StudentAction {
	
	@Autowired //默认按照类型
	private StudentService studentService;

	public void execute() {
		studentService.addStudent();
	}

}

beans.xml:

TestAnnoWeb:

package com.itheima.g_annotation.b_web;

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

public class TestAnnoWeb {
	
	@Test
	public void demo02(){
		//从spring容器获得
		String xmlPath = "com/itheima/g_annotation/b_web/beans.xml";
		ApplicationContext applicationContext = new ClassPathXmlApplicationContext(xmlPath);
		StudentAction studentAction = (StudentAction) applicationContext.getBean("studentActionId");
		
		studentAction.execute();
		
	}

}

4.生命周期

       初始化：@PostConstruct

       销毁：@PreDestroy

5.作用域

       @Scope("prototype")多例

UserService:

package com.itheima.g_annotation.c_other;

public interface UserService {
	
	public void addUser();

}

UserServiceImpl:

package com.itheima.g_annotation.c_other;

import javax.annotation.PostConstruct;
import javax.annotation.PreDestroy;

import org.springframework.context.annotation.Scope;
import org.springframework.stereotype.Service;

@Service("userServiceId")
//@Scope("prototype")
public class UserServiceImpl implements UserService {

	@Override
	public void addUser() {
		System.out.println("d_scope add user");
	}
	
	@PostConstruct
	public void myInit(){
		System.out.println("初始化");
	}
	@PreDestroy
	public void myDestroy(){
		System.out.println("销毁");
	}

}

beans.xml:

TestOther:

package com.itheima.g_annotation.c_other;

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

public class TestOther {
	
	@Test
	public void demo02(){
		//spring 工厂
		String xmlPath = "com/itheima/g_annotation/c_other/beans.xml";
		ClassPathXmlApplicationContext applicationContext = new ClassPathXmlApplicationContext(xmlPath);
		UserService userService = applicationContext.getBean("userServiceId" ,UserService.class);
		UserService userService2 = applicationContext.getBean("userServiceId" ,UserService.class);
		
		System.out.println(userService);
		System.out.println(userService2);
		
		applicationContext.close();
	}

}