Spring设置注入和构造注入

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在Spring中注入方式有设置注入和构造注入。设置注入就是指要被注入的类中定义有一个setter（）方法，并在参数中定义需要注入的对象。简单的看个例子。

定义有User类，并覆写了toString（）方法。

package com.zcl.spring.setterinjection;public class User {private String name ;private int age ;private String country ;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;}public String getCountry() {return country;}public void setCountry(String country) {this.country = country;}public String toString(){return name + " is " + age + " years old,living in " + country ; }}

配置beans.xml文件，通过设置注入为类中属性注入值

<?xml version="1.0" encoding="UTF-8"?><beans xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns="http://www.springframework.org/schema/beans"> <bean id="user" class="com.zcl.spring.setterinjection.User"><property name="name" value="Zhao" /><property name="age" value="22" /><property name="country" value="China" /></bean></beans>

测试一下：

package com.zcl.spring.setterinjection;import org.springframework.context.ApplicationContext;import org.springframework.context.support.ClassPathXmlApplicationContext;public class Main {public static void main(String args[]){ApplicationContext context = new ClassPathXmlApplicationContext("beans.xml") ;User user = (User)context.getBean("user") ;System.out.println(user) ;}}

输入结果：

Zhao is 22 years old,living in China

现在我们来看写构造注入，所谓构造注入就是指要被注入的类中声明一个构造方法，并在此方法的参数中定义要注入的对象。修改下刚刚的User类。

package com.zcl.spring.setterinjection;public class User {private String name ;private int age ;private String country ;public User(String name, int age, String country) {this.name = name;this.age = age;this.country = country;}public String toString(){return name + " is " + age + " years old,living in " + country ; }}

配置beans.xml文件：

<?xml version="1.0" encoding="UTF-8"?><beans xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns="http://www.springframework.org/schema/beans"> <bean id="user" class="com.zcl.spring.setterinjection.User"><constructor-arg value="Zhao" /><constructor-arg value="22" /><constructor-arg value="China" /></bean></beans>

测试函数一样，打印结果也一样。