Spring - constructor-arg和property的使用示例

一、说明
    constructor-arg：通过构造函数注入。 
    property：通过setter对应的方法注入。

二、property使用实例

1、Model代码：

public class Person { private String name; private int age; private String className; private String grade; private List<Person> friends = new ArrayList<>(); public List<Person> getFriends() { return friends; } public void setFriends(List<Person> friends) { this.friends = friends; } public String getName() { return name; } public void setName(String name) { this.name = name; } public int getAge() { return age; } public void setAge(int age) { this.age = age; } public String getClassName() { return className; } public void setClassName(String className) { this.className = className; } public String getGrade() { return grade; } public void setGrade(String grade) { this.grade = grade; } public String toString(){ return "Person [name=" + name + ", classname=" + className +", age=" + age+", grade=" + grade+", friends=\n" +friends+ "]"; } }

 2、xml配置：

<bean id="person" class="models.Person">
        <property name="age" value="22"/>  //通过setXXX方法，所以Person对象属性不用全部设置，classname和grade未设置
        <property name="name" value="liuzg"/>
        <property name="friends">         //通过ref 传入已经初始化的bean wangxin和lirifeng
            <list>                        //liuzg有两个朋友 wangxin和lirifeng
                <ref bean="wangxin"/>    //local只能在同一个XML中实现id引入，而bean可以跨XML文件引入，同时bean可以根据name属性进行引用，使用范围明显较广，更强大。
                <ref bean="lirifeng"/>
            </list>
        </property>
    </bean>
    <bean id="wangxin" class="models.Person">
        <property name="age" value="22"/>
        <property name="name" value="wangxin"/>
    </bean>
    <bean id="lirifeng" class="models.Person">
        <property name="age" value="22"/>
        <property name="name" value="lirifeng"/>
    </bean>

三、constructor-arg使用实例

1、Model代码：

public class Student { private String name; private int age; private String className; private String grade; private List<Person> friends = new ArrayList<>(); public Student() { } public Student(String name,int age,String className,String grade,List<Person> friends){ this.friends = friends; this.name = name; this.age = age; this.className = className; this.grade = grade; } public String toString(){ return "student [name=" + name + ", classname=" + className +", age=" + age+", grade=" + grade+", friends=\n" +friends+ "]"; } }

2.xml配置

 <bean id="liangyuqi" class="models.Student">
        <constructor-arg index="0" value="liangyuqi"/>   //通过构造函数，需根据函数形参 全部设置
        <constructor-arg name="age" value="18"/>         //可以根据index或者name设置属性，下标从0开始。boolean的值既可以用0/1填充，也可以用true/false填充。
        <constructor-arg index="2" value="1401"/>
        <constructor-arg index="3" value="95"/>
        <constructor-arg index="4" ref="person"/>
    </bean>

 

四、Test

1.测试代码

public class MyTest { public void testSpring(){ ApplicationContext context = new ClassPathXmlApplicationContext("test.xml"); //1.读取spring初始化的配置文件   Object p = context.getBean("liangyuqi"); //2.根据bean获取Student实现类对象 p  System.out.println(p); } }

2.输出结果 :      liangyuqi的朋友有liuzg，以及显示liuzg的friends set wnagxin，lirifeng