★ 场景和问题
在Java开发时，需要来回交换大量的数据，比如要为方法传入参数，也要获取方法的返回值，该如何能更好的进行数据的交互？
★ 基本的编写步骤
◎第1步：写一个类，实现可序列化（如果以后数据是往数据库里存的，那么可以不序列化，节省资源）
◎第2步：私有化所有属性，保持一个默认构造方法(public无参)
◎第3步：为每个属性提供get()、set()方法（如果是boolean型变量，最好把get改成is）
◎第4步：推荐覆盖实现equals()、hashCode()和toString()方法
值对象的本质是“封装数据”
User 类：
package cn.hncu.pattern.factory.vo.v2.vo;
import java.io.Serializable;
public class User implements Serializable{
//只能将支持 java.io.Serializable 接口的对象写入流中,必须实现这个接口
private String userId;
private String tel;
private String address;
private int age;
private boolean isMale;
public User() {
}
public User(String userId, String tel, String address, int age){
this.userId = userId;
this.tel = tel;
this.address = address;
this.age = age;
}
public String getTel() {
return tel;
}
public void setTel(String tel) {
this.tel = tel;
}
public String getAddress() {
return address;
}
public void setAddress(String address) {
this.address = address;
}
public int getAge() {
return age;
}
public void setAge(int age) {
this.age = age;
}
public String getUserId() {
return userId;
}
public void setUserId(String userId) {
this.userId = userId;
}
public boolean isMale() {
return isMale;
}
public void setMale(boolean isMale) {
this.isMale = isMale;
}
@Override
public int hashCode() {
final int prime = 31;
int result = 1;
result = prime * result + ((userId == null) ? 0 : userId.hashCode());
return result;
}
@Override
public boolean equals(Object obj) {
if (this == obj)
return true;
if (obj == null)
return false;
if (getClass() != obj.getClass())
return false;
User other = (User) obj;
if (userId == null) {
if (other.userId != null)
return false;
} else if (!userId.equals(other.userId))
return false;
return true;
}
@Override
public String toString() {
return "User [userId=" + userId + ", tel=" + tel + ", address="
+ address + ", age=" + age + "]";
}
}
B类：
package cn.hncu.pattern.factory.vo.v2;
import cn.hncu.pattern.factory.vo.v2.vo.User;
public class B {
String userId=null;
User user = null;
public boolean sendData(User user){ //Value Object ----Model
System.out.println("数据已经接受到。。。");
operate(user);
return true;
}
private void operate(User user) {
this.user = user;
this.user.setUserId("CN_"+user.getUserId());
System.out.println("处理数据...");
}
public User getData(){
return user;
}
public String getUserId(){
return userId;
}
}
A类：
package cn.hncu.pattern.factory.vo.v2;
import cn.hncu.pattern.factory.vo.v2.vo.User;
public class A {
public static void main(String[] args) {
B obj = new B();
User user = new User("A001", "13512345678", "hncu",20);
obj.sendData(user);
User data = obj.getData();
System.out.println( data.getUserId() );
System.out.println(data);
User user2 = new User();
user2.setAge(21);
user2.setUserId("A002");
System.out.println(user2);
obj.sendData(user2);
System.out.println(user2);
//可以做得更好的：
// Id可以用唱票模型 2318,2319,......
}
}
输出:
数据已经接受到。。。
处理数据...
CN_A001
User [userId=CN_A001, tel=13512345678, address=hncu, age=20]
User [userId=A002, tel=null, address=null, age=21]
数据已经接受到。。。
处理数据...
User [userId=CN_A002, tel=null, address=null, age=21]