简单解释一下注入：就是给对象赋值（直接给出代码，解释全部在代码里面 ）
前提是你已经配置好了spring的环境，如果还不会配置可以去看我的入门spring配置
1、所用到的实体类
1-1 car类
package spring.bean;
public class Car {
private String color;
private String name;
public String getColor() {
return color;
}
public void setColor(String color) {
this.color = color;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
@Override
public String toString() {
return "Car [color=" + color + ", name=" + name + "]";
}
}
1-2 User类
package spring.bean;
public class User {
private String name;
private int age;
private Car car;
public User() {
super();
}
public User(String name, Car car) {
this.name = name;
this.car = car;
}
public Car getCar() {
return car;
}
public void setCar(Car car) {
this.car = car;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public int getAge() {
return age;
}
public void setAge(int age) {
this.age = age;
}
@Override
public String toString() {
return "User [name=" + name + ", age=" + age + ", car=" + car + "]";
}
}
2、applicationContext.xml （核心)
<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xmlns="http://www.springframework.org/schema/beans"
xmlns:p="http://www.springframework.org/schema/p"
xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-4.2.xsd ">
<!--beans 第三行是如果要使用p名称空间才需要加上 -->
<!-- 如果看不到bena中的基本配置，可以去看我的spring入门配置，里面有详解 -->
<!-- set方式注入 -->
<bean name="user" class="spring.bean.User">
<!-- 值类型注入 ： 为user对象中名为name的属性注入tom作为值 -->
<property name="name" value="tom"></property>
<property name="age" value="19"></property>
<!-- 引用类型注入 ： 为car属性注入下面的car对象 -->
<property name="car" ref="car"></property>
</bean>
<!-- 将car对象配置到容器中 -->
<bean name="car" class="spring.bean.Car">
<property name="name" value="大众"></property>
<property name="color" value="黄色"></property>
</bean>
<!-- !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! -->
<!-- 构造函数注入 (必须提供相对应的构造方法) -->
<bean name="user2" class="spring.bean.User">
<!--
name属性：构造函数的参数名
index属性：构造函数的参数索引
type属性：构造函数的参数类型
index:主要是解决这样的情况
public User(String name, Car car) {
this.name = name;
this.car = car;
}
public User(Car car, String name) {
this.name = name;
this.car = car;
}
type:主要是解决这样的情况
public User(String name, Car car) {
this.name = name;
this.car = car;
}
public User(Integer name, Car car) {
this.car = car;
}
-->
<constructor-arg name="name" value="jerry" index="" type=""></constructor-arg>
<constructor-arg name="car" ref="car" index=""></constructor-arg>
</bean>
<!-- !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! -->
<!--
p名称空间注入
值类型：p ： 属性名 = "值"
对象类型： p : 属性名-ref="bean名称"
-->
<bean name="user3" class="spring.bean.User" p:name="jack" p:age="18" p:car-ref="car"></bean>
<!-- !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! -->
<!--
spel注入： spring Expression Language spring表达式语言
-->
<bean name="user4" class="spring.bean.User" >
<property name="name" value="#{user.name}"></property>
<property name="age" value="#{user3.age}"></property>
<property name="car" ref="car"></property>
</bean>
</beans>
3、Demo测试
package spring.injection;
import org.junit.Test;
import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;
import spring.bean.User;
public class Demo {
@Test
public void fun1(){
ApplicationContext ac = new ClassPathXmlApplicationContext("spring/injection/applicationContext.xml");
User u = (User) ac.getBean("user");
System.out.println(u);
}
//构造函数注入
@Test
public void fun2(){
ApplicationContext ac = new ClassPathXmlApplicationContext("spring/injection/applicationContext.xml");
User u = (User) ac.getBean("user2");
System.out.println(u);
}
//p名称空间注入
@Test
public void fun3(){
ApplicationContext ac = new ClassPathXmlApplicationContext("spring/injection/applicationContext.xml");
User u = (User) ac.getBean("user3");
System.out.println(u);
}
//spel注入
@Test
public void fun4(){
ApplicationContext ac = new ClassPathXmlApplicationContext("spring/injection/applicationContext.xml");
User u = (User) ac.getBean("user4");
System.out.println(u);
}
}