★ 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]
