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spring通過構(gòu)造函數(shù)注入實(shí)現(xiàn)方法分析

更新時(shí)間：2019年10月31日 11:29:14 作者：cakincqm

這篇文章主要介紹了spring通過構(gòu)造函數(shù)注入實(shí)現(xiàn)方法,結(jié)合實(shí)例形式分析了spring通過構(gòu)造函數(shù)注入的原理、實(shí)現(xiàn)步驟及相關(guān)操作注意事項(xiàng),需要的朋友可以參考下

本文實(shí)例講述了spring通過構(gòu)造函數(shù)注入實(shí)現(xiàn)方法。分享給大家供大家參考，具體如下：

一通過構(gòu)造函數(shù)注入

set注入的缺點(diǎn)是無法清晰表達(dá)哪些屬性是必須的，哪些是可選的，構(gòu)造注入的優(yōu)勢是通過構(gòu)造強(qiáng)制依賴關(guān)系，不可能實(shí)例化不完全的或無法使用的bean。

二舉例

1 Employee

package com.hsp.constructor;
public class Employee {
    private String name;
    private int age;
    public Employee(String name) {
        System.out.println("Employee(String name) 函數(shù)被調(diào)用..");
        this.name = name;
        this.age = age;
    }    
    public Employee(String name, int age) {
        System.out.println("Employee(String name, int age) 函數(shù)被調(diào)用..");
        this.name = name;
        this.age = age;
    }
    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;
    }
}

2 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";
        xmlns:context="http://www.springframework.org/schema/context";
        xmlns:tx="http://www.springframework.org/schema/tx";
        xsi:schemaLocation="http://www.springframework.org/schema/beanshttp://www.springframework.org/schema/beans/spring-beans-2.5.xsd
http://www.springframework.org/schema/contexthttp://www.springframework.org/schema/context/spring-context-2.5.xsd
http://www.springframework.org/schema/txhttp://www.springframework.org/schema/tx/spring-tx-2.5.xsd";>
<!-- 配置一個(gè)雇員對(duì)象 -->
<bean id="employee" class="com.hsp.constructor.Employee">
<!-- 通過構(gòu)造函數(shù)來注入屬性值 -->
<constructor-arg index="0" type="java.lang.String" value="大明" />
</bean>
</beans>

3 App1

package com.hsp.constructor;
import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;
public class App1 {
  /**
   * @param args
   */
  public static void main(String[] args) {
    // TODO Auto-generated method stub
    ApplicationContext ac=new ClassPathXmlApplicationContext("com/hsp/constructor/beans.xml");
    Employee ee=(Employee) ac.getBean("employee");
    System.out.println(ee.getName());
  }
}

三測試結(jié)果