DI依赖注入

• 依赖：bean对象的创建依赖于容器
• 注入：bean对象中所有属性由容器来注入

DI注入的几种方式：

• 构造器注入-详见：https://www.cnblogs.com/kakafa/p/15753718.html

  

• set方式注入（重点）

• 其他拓展方式注入

  可以利用p命名空间和c命名空间进行注入
  

set方式注入

Address.java:

package com.kakafa.pojo;

public class Address {
    private String address;

    public String getAddress() {
        return address;
    }

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

    @Override
    public String toString() {
        return "Address{" +
                "address='" + address + '\'' +
                '}';
    }
}

Student.java:

package com.kakafa.pojo;

import java.util.*;

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

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public Address getAddress() {
        return address;
    }

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

    public String[] getBooks() {
        return books;
    }

    public void setBooks(String[] books) {
        this.books = books;
    }

    public List<String> getHobbies() {
        return hobbies;
    }

    public void setHobbies(List<String> hobbies) {
        this.hobbies = hobbies;
    }

    public Map<String, String> getCard() {
        return card;
    }

    public void setCard(Map<String, String> card) {
        this.card = card;
    }

    public Set<String> getGames() {
        return games;
    }

    public void setGames(Set<String> games) {
        this.games = games;
    }

    public String getWife() {
        return wife;
    }

    public void setWife(String wife) {
        this.wife = wife;
    }

    public Properties getInfo() {
        return info;
    }

    public void setInfo(Properties info) {
        this.info = info;
    }

    @Override
    public String toString() {
        return "Student{" +
                "name='" + name + '\'' +
                ", address=" + address.toString() +
                ", books=" + Arrays.toString(books) +
                ", hobbies=" + hobbies +
                ", card=" + card +
                ", games=" + games +
                ", wife='" + wife + '\'' +
                ", info=" + info +
                '}';
    }
}

bean.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="com.kakafa.pojo.Address">
        <property name="address" value="地球村2662号"/>
    </bean>

    <bean id="student"  class="com.kakafa.pojo.Student">
        <!--第一种，普通值注入,value-->
        <property name="name" value="许魏洲"/>
        <!--第二种，bean注入,ref-->
        <property name="address" ref="address"/>
        <!--数组注入-->
        <property name="books" >
            <array>
                <value>红楼梦</value>
                <value>水浒传</value>
                <value>三国演绎</value>
                <value>西游记</value>
            </array>
        </property>
        <!--List注入-->
        <property name="hobbies" >
            <list>
                <value>看书</value>
                <value>打乒乓球</value>
                <value>游泳</value>
                <value>听歌</value>
            </list>
        </property>
        <!--Map注入-->
        <property name="card">
            <map>
                <entry key="学号" value="202201064455"/>
                <entry key="学院" value="音乐学院"/>
            </map>
        </property>
        <!--Set注入-->
        <property name="games">
            <set>
                <value>王者荣耀</value>
                <value>英雄联盟</value>
                <value>使命召唤</value>
            </set>
        </property>
        <!--设置为null-->
        <property name="wife">
            <null/>
        </property>
        <!--如果要设置为空值，如下:
        <property name="wife" value=""/>
        -->

        <!--Properties-->
        <property name="info">
            <props>
                <prop key="年级">大一</prop>
                <prop key="班级">一班</prop>
            </props>
        </property>

    </bean>

</beans>

test:

import com.kakafa.pojo.Student;
import org.springframework.context.support.ClassPathXmlApplicationContext;

public class MyTest {

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

        /*
        * Student{
        * name='许魏洲',
        * address=Address{address='地球村2662号'},
        * books=[红楼梦, 水浒传, 三国演绎, 西游记],
        * hobbies=[看书, 打乒乓球, 游泳, 听歌],
        * card={学号=202201064455, 学院=音乐学院},
        * games=[王者荣耀, 英雄联盟, 使命召唤],
        * wife='null',
        * info={班级=一班, 年级=大一}}
         * */

    }
}