6.使用@Autowired注解

第一步：创建javaweb项目

第二步：导入必要的IOC包，这儿有五个

“commons-logging.jar”

“spring-beans-3.2.8.RELEASE.jar”

“spring-context-3.2.8.RELEASE.jar”

“spring-core-3.2.8.RELEASE.jar”

“spring-expression-3.2.8.RELEASE.jar”

第三步：导入spring配置文件，我这儿是applicationContext.xml，

<!-- 开启IOC组件扫描 -->
<context:component-scan
base-package="com.zxy"/>

第四步：创建并且声明bean

@Component("computer")
public class Computer implements Serializable{

/**
*
*/
private static final long serialVersionUID = 1L;

}

创建Programmer类，并使用@Component注解将其声明到容器中，然后使用@Autowired注解在构造器上将Computer注入进来，代码如下：

构造器方式注入bean

@Component
public class Programer implements Serializable{
private Computer computer;

@Autowired
public  Programer(@Qualifier("computer")Computer computer){
this.computer = computer;
}

public Computer getComputer() {
return computer;
}

public void setComputer(Computer computer) {
this.computer = computer;
}
}

setter方式注入bean

@Component
public class Teacher implements Serializable {
private Computer computer;
@Autowired
public void setComputer(@Qualifier("computer") Computer computer) {
this.computer = computer;
System.out.println("Computer");
}

public Computer getComputer() {
return computer;
}
}

属性加注解注入bean

@Component
public class Student implements Serializable {
@Autowired
@Qualifier("computer")
private Computer computer;
public Computer getComputer() {
return computer;
}
public void setComputer(Computer computer) {
this.computer = computer;
System.out.println("Computer");
}
}

第五步：写测试代码（注意这个就需要导入Junit 4的包）对应的测试代码

@Test
public void test4() {
String conf = "applicationContext.xml";
ApplicationContext ctx = new ClassPathXmlApplicationContext(conf);
Programer prog = ctx.getBean("programer", Programer.class);
System.out.println(prog);
System.out.println(prog.getComputer());
}

@Test
public void test5() {
String conf = "applicationContext.xml";
ApplicationContext ctx = new ClassPathXmlApplicationContext(conf);
Teacher teacher = ctx.getBean("teacher", Teacher.class);
System.out.println(teacher);
System.out.println(teacher.getComputer());
}

@Test
public void test6() {
String conf = "applicationContext.xml";
ApplicationContext ctx = new ClassPathXmlApplicationContext(conf);
Student student = ctx.getBean("student", Student.class);
System.out.println(student);
System.out.println(student.getComputer());
}

第六步：测试结果：

com.zxy.bean.Programer@72e8a021

com.zxy.bean.Computer@6691177

这儿详细说明注解的意义：

@Autowired是概述Spring要将数据注入进来

@Qualifier是告诉Spring要注入的bean的ID，如果要注入的bean是单例的,@Qualifier可以省略，届时Spring会类型自动找到这个单例的bean，大部分的bean是单例的，所以@Qualifier往往是省略的