DI依赖注入

一.依赖注入

1.构造器注入

 2.set方式注入【重点】

依赖注入：set注入！

依赖：bean对象的创建依赖容器!

注入：bean中所有对象的属性，由容器来注入！

二.【环境搭建】

1.复杂类型

package top.lostyou.pojo;

public class Address {
    private String address;

    public String getAddress() {
        return address;
    }

    public void setAddress(String address) {
        this.address = address;
    }
}

2.真实测试对象

public class Student {
    private String name;
    private Address address;
    private String[] books;
    private List<String> hobbys;
    private Map<String,String> card;
    private Set<String> games;
    private String wife;
    private Properties info;

3.beans.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="address" class="top.lostyou.pojo.Address">
    <property name="address" value="重庆"/>
</bean>
<bean id="Student" class="top.lostyou.pojo.Student">
    <!-- 第一种，普通值注入 -->
    <property name="name" value="msf"/>
    <!-- 第二种，bean（对象）注入 -->
    <property name="address" ref="address"/>
    <!-- 数组注入 -->
    <property name="books">
        <array>
            <value>三国演义</value>
            <value>西游记</value>
            <value>水浒传</value>
            <value>红楼梦</value>
        </array>
    </property>
    <!-- list(集合)注入 -->
    <property name="hobbys">
        <list>
            <value>听歌</value>
            <value>写程序</value>
            <value>看电视剧</value>
        </list>
    </property>
    <!-- map注入 -->
    <property name="card">
        <map>
            <entry key="username" value="maming"/>
            <entry key="password" value="123456"/>
        </map>
    </property>
    <!-- set注入 -->
    <property name="games">
        <set>
            <value>原神</value>
            <value>部落冲突</value>
            <value>数独</value>
        </set>
    </property>
    <!-- null注入 -->
    <property name="wife">
        <null/>
    </property>
    <!-- properties注入 -->
    <property name="info">
        <props>
            <prop key="driver">mysql.jdbc.java.Driver</prop>
            <prop key="username">root</prop>
            <prop key="password">123456</prop>
        </props>
    </property>
</bean>

</beans>

4.测试类

public class mytest {
    public static void main(String[] args) {
        ClassPathXmlApplicationContext context = new ClassPathXmlApplicationContext("beans.xml");
        Student student = (Student) context.getBean("Student");
        System.out.println(student.toString());
    }
}

 5.测试结果

 总结：spring为了给我们提供容器，把绝大部分的属性和对象类型装载了，十分方便的可以是我们完成注入，其中最常用的包括：普通注入，bean注入，数组注入，map注入