Bean的装配方式之annotation注解装配--（超详细，适合小白入门）

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文章标签 spring java xml 自动装配 文章分类 代码人生

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Bean的装配方式之annotation注解装配

下面是annotation装配的方式–
annotation分为以下几种

@Component 注解描述Sping中的bean，可用于任何层次。
@Repository 注解数据访问层
@Service 注解业务层
@Controller注解控制层
@Autowired 用于对Bean的属性变量，属性的setter方法及构造进行标注，配合对应的注解完成装配工作，默认按照bean类型进行装配。
@ Resource 有两个重要属性 name=“bean实例名称” type=“bean实例类型”，如果不指定name或者type默认按name进行装配；
@Qualifier 与@Autowired配合使用，会讲默认按bean类型装配修改为按照bean实例名称装配。

下面在代码中进一步说明–

代码中有Student类，Teacher类以及Worker类分别实现Person接口,
假定 Teacher为管理类， Worker为服务类，Student为数据访问类

package charpter0615;
public interface Person {
public void say();
}

package com.test.chapter0615;
import javax.annotation.Resource;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Controller;
import charpter0615.Person;

@Controller("teacher")//老师是控制层吧
public class Teacher implements Person{
  private String TeacherName;
  private String TeacherSubject;
    public Teacher() {
    }
  
public void setTeacherName(String teacherName) {
    TeacherName = teacherName;
  }
  public void setTeacherSubject(String teacherSubject) {
    TeacherSubject = teacherSubject;
  }
@Resource(name="student") 
private Student student;
@Autowired//自动注入student
public void setStudent(Student student) {
  this.student=student;
}
@Resource(name="worker")
@Autowired//自动注入worker
private Worker worker;

public void setWorker(Worker worker) {
  this.worker=worker;
}
  @Override
  public void say() {
    this.student.say();
    System.out.println("同学们好！！我是你们的老师--"+this.TeacherName+"从今天起教你们--"+this.TeacherSubject);
    this.worker.say();
  }
}

package com.test.chapter0615;
import org.springframework.stereotype.Repository;
import charpter0615.Person;
@Repository("student")//使用@Repository注解将Student类识别为bean
public class Student implements Person {
private String studentName;
private String studentGrade;
private int studentAge;
  public Student(String studentName ,String studentGrade,int studentAge) {
    this.studentName=studentName;
    this.studentAge=studentAge;
    this.studentGrade=studentGrade;
  }
    @Override
  public void say() {
    // TODO Auto-generated method stub
    System.out.println("老师好！！我是"+this.studentName+"--"+this.studentGrade+"班的学生"+"今年"+this.studentAge+"岁");
  }
}

package com.test.chapter0615;
import org.springframework.stereotype.Service;
import charpter0615.Person;
@Service("worker")//使用@Service注解将Worker类识别为bean
public class Worker implements Person{
  @Override
  public void say() {
    // TODO Auto-generated method stub
    System.out.println("Work said : It's my pleasure to service for you!");
  }
}

配置xml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-4.3.xsd
       http://www.springframework.org/schema/context
        http://www.springframework.org/schema/context/spring-context-4.3.xsd">
        <context:annotation-config/>
        <bean id="student" class="com.test.chapter0615.Student" autowire="byName">
        <constructor-arg index="0" value="李二狗"/>
         <constructor-arg index="1" value="三年二班"/>
          <constructor-arg index="2" value="10"/>
        </bean>
        <bean id="worker" class="com.test.chapter0615.Worker"/>
         <bean id="teacher" class="com.test.chapter0615.Teacher" autowire="byName">
         <property name="student" ref="student"></property>
        <property name="worker" ref="worker"></property>
        <property name="TeacherName" value="张三"></property>
        <property name="TeacherSubject" value="数学"></property>
        </bean>
</beans>

创建测试类–

package com.test.chapter0615;

import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;
import charpter0615.Person;
public class Testtwo {
  public static void main(String[] args) {
    
ApplicationContext app = new ClassPathXmlApplicationContext("applicationcontext.xml");
  Person per =(Person )app.getBean("teacher");
  per.say();
}
}

Bean的装配方式之annotation注解装配--（超详细，适合小白入门）_spring