目录
2. 简单的StudentDI工程，展示了常见的注入方式的使用（配置）
2.3 类代码：StudentDI.java ， Address.java (该类被StudentDI引用)
补充：Eclipse中，一个快速生成getter和setter方法的小技巧
1. 背景概念
1.1 DI定义
（1） IoC的一个重点是：在系统运行中，动态的向某个对象提供它所需要的其他对象。这一点是通过DI来实现的。
（2）DI, 依赖注入：用一个单独的对象（装配器）来装配对象之间的依赖关系。DI，即组件之间的依赖关系由容器在运行期间决定，即由容器动态的将某个依赖关系注入到组件中。
（3）举例：
对象A要操作数据库，以前我们要在A中自己编写代码来获得一个Connection对象，有了Spring后我们就只需要告诉Spring， A中需要一个Connection. 至于怎么构造这个connection？何时构造？A不需要知道。这样就完成了对各个对象之间关系的控制。
（4）DI如何实现？通过反射。它允许程序在运行的时候动态的生成对象，执行对象的方法，改变对象的属性，Spring就是通过反射来实现注入的。
1.2 常见注入方式的xml配置
bean注入
数组注入
List注入
Map注入
set注入
null注入
Properties注入
2. 简单的StudentDI工程，展示了常见的注入方式的使用（配置）
2.1 maven系统的配置文件：pom.xml
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 https://maven.apache.org/xsd/maven-4.0.0.xsd">
<modelVersion>4.0.0</modelVersion>
<groupId>com.my.test</groupId>
<artifactId>SpringDIDemo</artifactId>
<version>0.0.1-SNAPSHOT</version>
<dependencies>
<dependency>
<groupId>org.springframework</groupId>
<artifactId>spring-webmvc</artifactId>
<version>5.3.3</version>
</dependency>
<dependency>
<groupId>org.aspectj</groupId>
<artifactId>aspectjweaver</artifactId>
<version>1.9.4</version>
</dependency>
</dependencies>
</project>
2.2 bean的配置文件： bean_di.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"
xmlns:context="http://www.springframework.org/schema/context"
xmlns:p="http://www.springframework.org/schema/p"
xmlns:c="http://www.springframework.org/schema/c"
xsi:schemaLocation="http://www.springframework.org/schema/beans
https://www.springframework.org/schema/beans/spring-beans.xsd
http://www.springframework.org/schema/context
https://www.springframework.org/schema/context/spring-context.xsd">
<context:annotation-config />
<bean id="addr" class="com.my.test.Address">
<property name="address" value="上海" />
</bean>
<bean id="student1" class="com.my.test.StudentDI">
<property name="name" value="Sheryl" />
<property name="address" ref="addr" />
<property name="books">
<array>
<value>数学</value>
<value>语文</value>
<value>英语</value>
</array>
</property>
<property name="hobbys">
<list>
<value>听歌</value>
<value>看电影</value>
<value>逛街</value>
</list>
</property>
<property name="card">
<map>
<entry key="招行" value="123456789" />
<entry key="工行" value="987654321" />
</map>
</property>
<property name="games">
<set>
<value>CS</value>
<value>斗地主</value>
<value>高尔夫</value>
</set>
</property>
<property name="wife">
<null />
</property>
<property name="info">
<props>
<prop key="学号">12345678</prop>
<prop key="性别">女</prop>
<prop key="姓名">Sheryl</prop>
</props>
</property>
</bean>
</beans>
2.3 类代码：StudentDI.java ， Address.java (该类被StudentDI引用)
（1）StudentDI.java
package com.my.test;
import java.util.List;
import java.util.Map;
import java.util.Properties;
import java.util.Set;
import com.my.test.Address;
public class StudentDI {
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;
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> getHobbys() {
return hobbys;
}
public void setHobbys(List<String> hobbys) {
this.hobbys = hobbys;
}
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;
}
public void showStudentInfo(){
System.out.println("name="+ name+ ",address="+ address.getAddress()+ ",books=");
for (String book:books){
System.out.print("<<"+book+">>\t");
}
System.out.println("\nhobbys:"+hobbys);
System.out.println("card:"+card);
System.out.println("games:"+games);
System.out.println("wife:"+wife);
System.out.println("info:"+info);
}
}
（2）Address.java
package com.my.test;
public class Address {
private String address;
public String getAddress() {
return address;
}
public void setAddress(String address) {
this.address = address;
}
}
2.4 测试类
package com.my.test.demo;
import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;
import com.my.test.StudentDI;
public class StudentDITest {
public static void main(String[] args) {
ApplicationContext context = new ClassPathXmlApplicationContext("bean_di.xml");
StudentDI studentDI = (StudentDI) context.getBean("student1");
studentDI.showStudentInfo();
}
}
输出结果：
name=Sheryl,address=上海,books=
<<数学>> <<语文>> <<英语>>
hobbys:[听歌, 看电影, 逛街]
card:{招行=123456789, 工行=987654321}
games:[CS, 斗地主, 高尔夫]
wife:null
info:{学号=12345678, 性别=女, 姓名=Sheryl}
补充：Eclipse中，一个快速生成getter和setter方法的小技巧