spring通过构造函数注入实现方法分析

2019-11-26 08:24:30

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本文实例讲述了spring通过构造函数注入实现方法。分享给大家供大家参考，具体如下：

一通过构造函数注入

set注入的缺点是无法清晰表达哪些属性是必须的，哪些是可选的，构造注入的优势是通过构造强制依赖关系，不可能实例化不完全的或无法使用的bean。

二举例

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) 函数被调用..");        this.name = name;        this.age = age;    }        public Employee(String name, int age) {        System.out.println("Employee(String name, int age) 函数被调用..");        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.xsdhttp://www.springframework.org/schema/contexthttp://www.springframework.org/schema/context/spring-context-2.5.xsdhttp://www.springframework.org/schema/txhttp://www.springframework.org/schema/tx/spring-tx-2.5.xsd";><!-- 配置一个雇员对象 --><bean id="employee" class="com.hsp.constructor.Employee"><!-- 通过构造函数来注入属性值 --><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());  }}

三测试结果