Spring框架学习笔记4

SpringDI
属于SpringIOC的内容
1为什么学习DI？
给创建好的对象的全局成员属性或对象赋值操作；
主要是给jar包里面的属性赋值！！！
2DI方式
A 使用set方法
B 有参构造
C 自动注入
3实现
Clazz.java

package SpringDI;

public class Clazz {
    private String classNo;
    private String className;

    public Clazz(String classNo, String className) {
        this.classNo = classNo;
        this.className = className;
    }

    public String getClassNo() {
        return classNo;
    }

    public void setClassNo(String classNo) {
        this.classNo = classNo;
    }

    public String getClassName() {
        return className;
    }

    public void setClassName(String className) {
        this.className = className;
    }

    @Override
    public String toString() {
        return "Clazz{" +
                "classNo='" + classNo + '\'' +
                ", className='" + className + '\'' +
                '}';
    }

    public Clazz() {
    }
}

Student.java

package SpringDI;

public class Student {
    private String stuNo;
    private String stuName;
    private Clazz cla;

    public Student(String stuNo, String stuName, Clazz cla) {
        this.stuNo = stuNo;
        this.stuName = stuName;
        this.cla = cla;
    }

    public String getStuNo() {
        return stuNo;
    }

    public void setStuNo(String stuNo) {
        this.stuNo = stuNo;
    }

    public String getStuName() {
        return stuName;
    }

    public void setStuName(String stuName) {
        this.stuName = stuName;
    }

    public Clazz getCla() {
        return cla;
    }

    public void setCla(Clazz cla) {
        this.cla = cla;
    }

    public Student() {
    }

    @Override
    public String toString() {
        return "Student{" +
                "stuNo='" + stuNo + '\'' +
                ", stuName='" + stuName + '\'' +
                ", cla=" + cla +
                '}';
    }
}

Test.java

package SpringDI;

import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;

public class Test {
    public static void main(String[] args) {
        ApplicationContext applicationContext = new ClassPathXmlApplicationContext("applicationContext.xml");
        Student stu = (Student)applicationContext.getBean("stu");
        System.out.println(stu);
        System.out.println("-----------------------------------");
        Student stu2 = (Student)applicationContext.getBean("stu2");
        System.out.println(stu2);
    }
}

applicationContext.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"
       xsi:schemaLocation="http://www.springframework.org/schema/beans
        http://www.springframework.org/schema/beans/spring-beans.xsd">
    <bean id="cla" class="SpringDI.Clazz">
        <constructor-arg name="classNo" value="20"></constructor-arg>
        <constructor-arg name="className" value="二十"></constructor-arg>
    </bean>
    <bean id="stu" class="SpringDI.Student">
        <!-- 构造器参数 -->
        <!-- 位置无所谓 -->
        <!-- name 对应构造方法的形参名 value 对应实参名-->
        <constructor-arg name="stuNo" value="25"></constructor-arg>
        <constructor-arg name="stuName" value="小王"></constructor-arg>
        <constructor-arg name="cla" ref="cla"></constructor-arg>
    </bean>
    <bean id="stu2" class="SpringDI.Student">
        <property name="cla" ref="cla"></property>
    </bean>
</beans>

解释：
注入方式之一是有参构造方法，上面使用的 constructor-arg就是。name与形参一致。
另一种方式是set方法，下面property就是。name与属性名一致。更加常用！！
给jar包赋值举例

<bean id="beanMetaDataAttribute" class="org.springframework.beans.BeanMetadataAttribute">
    <property name="source" ref="a"></property>
</bean>