何为依赖注入？
- 依赖是指通过IOC容器创建对象
- 注入是指对象的成员变量由容器来设置和装配
注入方式
1，构造器注入 ，即通过constructor-arg这个字段进行有参构造
<bean id="helloarg" class="com.hys.pojo.Hello" scope="singleton" >
<constructor-arg name="str" value="kokokoko"/>
</bean>
2.set注入 重点 不同类型的注入方式，测试类的变量包含数组，set，list，map集合，引用对象，properties，如下
public class Student {
private String name;
private teacher teacher;
private String[] hobby;
private List<String> book;
private Set<String> games;
private Map<String,String> cards;
private Properties prop;
public void setName(String name) {
this.name = name;
}
public void setTeacher(com.hys.pojo.teacher teacher) {
this.teacher = teacher;
}
public void setHobby(String[] hobby) {
this.hobby = hobby;
}
public void setBook(List<String> book) {
this.book = book;
}
public void setGames(Set<String> games) {
this.games = games;
}
public void setCards(Map<String, String> cards) {
this.cards = cards;
}
public void setProp(Properties prop) {
this.prop = prop;
}
}
针对以上不同类型变量的注入方式，如下：
<?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
https://www.springframework.org/schema/beans/spring-beans.xsd">
<bean id="mingqiang" class="com.hys.pojo.teacher">
<property name="name">
<null></null>
</property>
<property name="id" value="12313"/>
</bean>
<bean id="student" name="s1,s2,s3" class="com.hys.pojo.Student">
<property name="name" value=""/>
<property name="teacher" ref="mingqiang"/>
<property name="hobby">
<array>
<value>游戏</value>
<value>逻辑推理</value>
<value>足球</value>
<value>羽毛球</value>
</array>
</property>
<property name="book">
<list>
<value>平凡的世界</value>
<value>罗斯蔡德尔家族</value>
<value>茶花女</value>
</list>
</property>
<property name="games">
<set>
<value>英雄联盟</value>
<value>炉石传说</value>
<value>王者荣耀</value>
</set>
</property>
<property name="cards">
<map>
<entry key="学生证" value="1315212015"/>
<entry key="卡号" value="1304821"/>
</map>
</property>
<property name="prop">
<props>
<prop key="username">123456789</prop>
<prop key="pwd">1111</prop>
</props>
</property>
</bean>
</beans>