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<bean class="">

@Component("id")取代 <beanid="" class="">

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

beans.xml:

<?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"><!-- 组件扫描，扫描含有注解的类 --><context:component-scan base-package="com.itheima.g_annotation.a_ioc"></context:component-scan></beans>

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 {@Testpublic 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<beanclass="">

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

<?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"><!-- 组件扫描，扫描含有注解的类 --><context:component-scan base-package="com.itheima.g_annotation.b_web"></context:component-scan></beans>

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 {@Testpublic 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 {@Overridepublic void addUser() {System.out.println("d_scope add user");}@PostConstructpublic void myInit(){System.out.println("初始化");}@PreDestroypublic void myDestroy(){System.out.println("销毁");}}

beans.xml:

<?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"><!-- 组件扫描，扫描含有注解的类 --><context:component-scan base-package="com.itheima.g_annotation.c_other"></context:component-scan></beans>

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 {@Testpublic 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();}}