Spring框架構(gòu)造注入type屬性實(shí)例詳解

package service.impl;

import service.UserService;
import dao.UserDao;
import entity.User;

/**
 * 用戶業(yè)務(wù)類，實(shí)現(xiàn)對User功能的業(yè)務(wù)管理
 */
public class UserServiceImpl implements UserService {

  // 聲明接口類型的引用，和具體實(shí)現(xiàn)類解耦合
  private UserDao dao;
  private String s1;
  private String s2;
  private int i1;
  

  // 生成無參構(gòu)造方法
  public UserServiceImpl() {

  }

  // 帶參數(shù)構(gòu)造方法  為dao進(jìn)行賦值
  public UserServiceImpl(UserDao dao) {
    this.dao = dao;
  }
  public UserServiceImpl(UserDao dao,String s1) {
    this.dao = dao;
    this.s1=s1;
  }
  public UserServiceImpl(String s2,UserDao dao) {
    this.dao = dao;
    this.s2=s2;
  }
  public UserServiceImpl(int i1,UserDao dao) {
    this.dao = dao;
    this.i1=i1;
  }


  public UserDao getDao() {
    return dao;
  }

  // dao 屬性的setter訪問器，會被Spring調(diào)用，實(shí)現(xiàn)設(shè)值注入
  public void setDao(UserDao dao) {
    this.dao = dao;
  }

  public void addNewUser(User user) {
    // 調(diào)用用戶DAO的方法保存用戶信息
    dao.save(user);
    System.out.println("s1="+s1);
    System.out.println("s2="+s2);
    System.out.println("i1="+i1);
  }
}

<bean id="UserService" class="service.impl.UserServiceImpl">
<!--通過構(gòu)造函數(shù)的方式，實(shí)現(xiàn)構(gòu)造注入 -->
<constructor-arg>
　　<ref bean="userDao" />
</constructor-arg>
<constructor-arg>
　　<value>123</value>
</constructor-arg>
</bean>

保存用戶信息到數(shù)據(jù)庫
s1=null
s2=123
i1=0

保存用戶信息到數(shù)據(jù)庫
s1=null
s2=null
i1=123