基于XML的DI

1.通过set方法设值注入
设置值的时候用set，获取值的时候用get
public class Student {
private String name;
private int age;
public String getName() {
return name;
}
public void setName(String name) {
System.out.println("========");
this.name = name;
}
public int getAge() {
return age;
}
public void setAge(int age) {
System.out.println("--------");
this.age = age;
}
@Override
public String toString() {
return "Student [name=" + name + ", age=" + age + "]";
}
}

<bean id="myStudent" class="com.di01.Student">
<property name="name" value="林平之"></property>
<property name="age" value="21"></property>
</bean>

@Test
public void test01() {
// 加载Spring配置文件，创建Spring容器对象
ApplicationContext ac = new ClassPathXmlApplicationContext("com/di01/applicationContext.xml");
// 从容器中获取指定的bean对象
Student student = (Student) ac.getBean("myStudent");
System.out.println(student);
}
导入头文件，可以走windows-preference-xmlfiles-editor-templates-add添加，记得复制原码
<bean id="myStudent" class="com.di01.Student">
<property name="name" value="林平之"></property>
<property name="age" value="21"></property>
<property name="school" ref="mySchool"></property>
</bean>

<bean id="mySchool" class="com.di01.School">
    <property name="sname" value="林远镖局"></property>
    
</bean>

2.构造注入（不需要调无参构造器，但是最好还是带上）
public class Student {
private String name;
private int age;
private School school;// 域属性
public Student() {
System.out.println("---------"); // 无参构造器
}
public Student(String name, int age, School school) {
super(); // 有参构造器
this.name = name;
this.age = age;
this.school = school;
}
@Override
public String toString() {
return "Student [name=" + name + ", age=" + age + ", school=" + school + "]";
}
}
<bean id="myStudent" class="com.di02.Student"> // 构造注入的方法，使用index，name，或者直接value只要保证顺序和构造器的一致即可，选择合适的就行
<constructor-arg index="0" value="linda"></constructor-arg>
<constructor-arg index="1" value="20"></constructor-arg>
<constructor-arg index="2" ref="mySchool"></constructor-arg>
</bean>
<bean id="mySchool" class="com.di02.School">
<property name="sname" value="林远镖局"></property>
</bean>

3.集合属性注入
private School[] schools; //每个元素都是对象引用
private List<String> myList;
private Set<String> mySet;
private Map<String, Object> myMap;
private Properties myPros;// 健和值都是字符串

<bean id="school1" class="com.di03.School">
    <property name="sname" value="南京大学"></property>
</bean>

<bean id="school2" class="com.di03.School">
    <property name="sname" value="东南大学"></property>
</bean>

<bean id="some" class="com.di03.Some">
    <property name="schools">
        <array>
            <ref bean="school1" />
            <ref bean="school2" />
        </array>
    </property>

    <property name="myList">
        <list>
            <value>lucy</value>
            <value>lily</value>
        </list>
    </property>

    <property name="mySet">
        <set>
            <value>天涯</value>
            <value>海角</value>
        </set>
    </property>

    <property name="myMap">  //map是键值对输入
        <map>
            <entry key="av1" value="武藤兰"></entry>
            <entry key="av2" value="小泽玛莉亚"></entry>
        </map>
    </property>

    <property name="myPros">
        <props>
            <prop key="联系方式">深圳</prop>
            <prop key="具体说明">东莞一条龙</prop>
        </props>
    </property>
</bean>

<property name="arrs" value="abc,def"></property>
<property name="myList" value="张三,李四" />
<property name="mySet" value="天涯,海角" /> //对于字符串可以直接写，对于键值对和数组无法使用。

4.对于域属性的自动注入
<bean id="myStudent" class="com.di05.Student" autowire="byName">
<property name="name" value="林平之"></property>
<property name="age" value="21"></property>
</bean>
<bean id="school" class="com.di05.School">
<property name="sname" value="林远镖局"></property>
</bean>

<bean id="myStudent" class="com.di06.Student" autowire="byType">
<property name="name" value="林平之"></property>
<property name="age" value="21"></property>
</bean>

5.使用SPEL注入
Spring EL表达式语言，SPEL以#开头，后跟一对大括号，用法： <bean id="" value="#{}"/>
public int computeAge() {
return page > 25 ? 25 : page;
}
<bean id="myPerson" class="com.di07.Person">
<property name="pname" value="lucy"></property>
<property name="page" value="#{T(java.lang.Math).random()*50}"></property>
</bean>

<bean id="myStudent" class="com.di07.Student">
    <property name="name" value="#{myPerson.pname}"></property>
    <property name="age" value="#{myPerson.computeAge()}"></property>
</bean>

要有get方法，可以在类中定义方法，在Bean中进行调用

6.内部匿名Bean
<bean id="myStudent" class="com.di06.Student" autowire="byType">
<property name="name" value="林平之"></property>
<property name="age" value="21"></property>
<property name="school">
<bean class="com.di06.School">
<property name="sname" value="daxue"/>
</bean>
</property>
</bean>

7. 同类抽象Bean
   遇到相同的内容，会想到继承关系，可以使用parent属性，格式如 <bean id="" parent="">

8. 异常抽象Bean
   不是同类使用abstract，格式 <bean id="base" abstract="true">

9.为应用指定多个Spring配置文件(平等关系)
目录下有好几个bean文件,格式相同，比如spring-beans，spring-base，
可以在test写成di/spring-*.xml
格式不相同，把每个列出来，资源需要。
applicationContext ac=new classpathxmlapplicationContext(r1,r2);
也可放入数组中进行配置
String[] resources={r1,r2};
(包含关系)