spring04 spel注入

1.创建需要的实体类对象

public class Student {   //学生实体类

    private  String   name;  //姓名
    private  Integer  age;  //年龄
    private  Grade   grade;  //年级

    @Override
    public String toString() {
        return "Student [name=" + name + ", age=" + age + ", grade=" + grade
                + "]";
    }

    public Student() {
        super();
    }
    public Student(String name, Integer age, Grade grade) {
        super();
        this.name = name;
        this.age = age;
        this.grade = grade;
    }
    public String getName() {
        return name;
    }
    public void setName(String name) {
        this.name = name;
    }
    public Integer getAge() {
        return age;
    }
    public void setAge(Integer age) {
        this.age = age;
    }
    public Grade getGrade() {
        return grade;
    }
    public void setGrade(Grade grade) {
        this.grade = grade;
    }

  //根据年龄的不同返回age不同的值
    public  Integer   changeAge(){
        return (this.age>25)?20:this.age;
    }

}

Student实体类

public class Grade {   //年级实体类
    private String  name;  //年级名称

    @Override
    public String toString() {
        return "Grade [name=" + name + "]";
    }

    public Grade() {
        super();
    }

    public Grade(String name) {
        super();
        this.name = name;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

}

Grade实体类

2.创建对应的配置文件

<?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:p="http://www.springframework.org/schema/p"
    xmlns:c="http://www.springframework.org/schema/c"
    xsi:schemaLocation="
        http://www.springframework.org/schema/beans
         http://www.springframework.org/schema/beans/spring-beans.xsd">
  <!--  spel 注入    spring el表达式   需要实体类中 有对应的get（）
                       第一个学生 -->
     <bean id="student1" class="cn.bdqn.bean.Student">
     <property name="name" value="小黑"/>
     <property name="age" value="#{T(java.lang.Math).random()*50}"/>
     </bean>

    <!-- 第二个学生  name属性值 是 第一个学生的   age值  是方法中获取的  -->
     <bean id="student2" class="cn.bdqn.bean.Student">
     <property name="name" value="#{student1.name}"/>
    <!--  <property name="age" value="#{student1.age>30?25:student1.age}"/> -->
       <!--直接把年龄的判断写在类中 并且得到返回值  -->
     <property name="age" value="#{student1.changeAge()}"/>
     </bean>

    <!--匿名内部bean  年级只属于指定的Student  -->
   <!--   <bean id="student" class="cn.bdqn.bean.Student">
     <property name="name" value="小黑"/>
     <property name="age" value="50"/>
     <property name="grade">
      其他的bean中 无法访问
       <bean id="grade" class="cn.bdqn.bean.Grade" p:name="1年级"/>
     </property>
     </bean> -->

</beans>

applicationContext.xml文件

3.创建测试类

public class StudentTest {

    //使用spel注入
    @Test
    public  void  test01(){
        ApplicationContext context=
                new ClassPathXmlApplicationContext("applicationContext.xml");
        Student student1=(Student) context.getBean("student1");
         Student student2=(Student) context.getBean("student2");
        System.out.println("student1信息："+student1);
        System.out.println("student2信息："+student2);
    }

    //匿名内部bean
    @Test
    public  void  test02(){
        ApplicationContext context=
                new ClassPathXmlApplicationContext("applicationContext.xml");
        Student student=(Student) context.getBean("student");
        System.out.println("student信息："+student);
    }
}

测试类