spring裝配bean(基於註解)
阿新 • • 發佈：2019-02-20
l 註解：就是一個類，使用@註解名稱
l 開發中：使用註解 取代 xml配置檔案。
l 註解使用前提，新增名稱空間，讓spring掃描含有註解類
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 {
@Override
public 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"> <!-- 元件掃描，掃描含有註解的類 --> <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 { @Test public void demo02(){ //從spring容器獲得 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開發
提供3個@Component註解衍生註解（功能一樣）取代<beanclass="">
@Repository：dao層
@Service：service層
@Controller：web層
3.依賴注入
給私有欄位設定，也可以給setter方法設定
普通值：@Value("")
引用值：
方式1：按照【型別】注入
@Autowired
方式2：按照【名稱】注入1
@Autowired
@Qualifier("名稱")
方式3：按照【名稱】注入2
@Resource("名稱")
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 //預設按照型別
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">
<!-- 元件掃描，掃描含有註解的類 -->
<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 {
@Test
public void demo02(){
//從spring容器獲得
String xmlPath = "com/itheima/g_annotation/b_web/beans.xml";
ApplicationContext applicationContext = new ClassPathXmlApplicationContext(xmlPath);
StudentAction studentAction = (StudentAction) applicationContext.getBean("studentActionId");
studentAction.execute();
}
}
4.生命週期
初始化：@PostConstruct
銷燬：@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("銷燬");
}
}
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">
<!-- 元件掃描，掃描含有註解的類 -->
<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 {
@Test
public void demo02(){
//spring 工廠
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();
}
}