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.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
Employee(String name) 函数被调用..
大明
希望本文所述对大家java程序设计有所帮助。
