Spring构造器注入

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在类被实例化时，它的构造方法被调用并且只能调用一次。所以构造器常被用于类的初始化操作。<constructor-arg>是<bean>元素的子元素。通过<constructor-arg>元素的<value>子元素可以为构造器传参。

实例如下：

JavaBean对象User:

package com.home.web.dto;public class User {    private String name;    private Integer age;    private String sex;    public User() {        super();    }    public User(String name, Integer age, String sex) {        super();        this.name = name;        this.age = age;        this.sex = sex;    }    public void printInfo() {        System.out.println("用户姓名：" + name);        System.out.println("用户年龄：" + age);        System.out.println("用户性别：" + sex);    }    public String getName() {        return name;    }    public void setName(String name) {        this.name = name;    }    public Integer getAge() {        return age;    }    public void setAge(Integer age) {        this.age = age;    }    public String getSex() {        return sex;    }    public void setSex(String sex) {        this.sex = sex;    }}

applicationContext.xml：

关于User的配置：

   <!-- User Bean --><bean name="user" class="com.home.web.dto.User"><constructor-arg index="0" type="String"><value>小明</value></constructor-arg ><constructor-arg index="1" type="Integer"><value>25</value></constructor-arg ><constructor-arg index="2" type="String"><value>男</value></constructor-arg></bean>

Manger.java：

package com.home.web.manager;import org.springframework.beans.factory.BeanFactory;import org.springframework.beans.factory.xml.XmlBeanFactory;import org.springframework.core.io.ClassPathResource;import org.springframework.core.io.Resource;import com.home.web.dto.User;public class Manager {    public static void main(String[] args) {        Resource resource = new ClassPathResource("applicationContext.xml");        BeanFactory factory = new XmlBeanFactory(resource);        User user = (User) factory.getBean("user");        user.printInfo();    }}

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