Google Gson 字段过滤：基于 Gson 版本

本文内容大多基于官方文档和网上前辈经验总结，经过个人实践加以整理积累，仅供参考。

当为生成的 Google Gson 对象指定版本信息时，可以使用 @Since 和 @Until 注释实现字段过滤。@Since 和 @Until 都接收一个 double 类型参数。

@Since 当设置的 Gson 对象版本大于或等于其所接收的参数时导出该字段

@Until 当设置的 Gson 对象版本小于其所接收的参数时导出该字段

示例

(1) POJO 对象

public class User {

private String account;

@Since(2)
private String password;

private String name;

@Until(4)
private int age;

public User() {}

public User(String account, String password, String name, int age) {
this.account = account;
this.password = password;
this.name = name;
this.age = age;
}

public String getAccount() {
return account;
}

public void setAccount(String account) {
this.account = account;
}

public String getPassword() {
return password;
}

public void setPassword(String password) {
this.password = password;
}

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;
}

@Override
public String toString() {
return "User [account=" + account + ", password=" + password + ", name=" + name + ", age=" + age + "]";
}

}

(2) 测试代码

@Test
public void test() throws IOException {
User user = new User("admin", "123456", "John", 30);
String userStr = "{\"account\":\"normal\",\"password\":\"xyz123\",\"name\":\"Normal\",\"age\":25}";

Gson gson = new GsonBuilder()
.setVersion(1)
.create();
System.out.println(gson.toJson(user));
System.out.println(gson.fromJson(userStr, User.class));

gson = new GsonBuilder()
.setVersion(2)
.create();
System.out.println(gson.toJson(user));
System.out.println(gson.fromJson(userStr, User.class));

gson = new GsonBuilder()
.setVersion(3)
.create();
System.out.println(gson.toJson(user));
System.out.println(gson.fromJson(userStr, User.class));

gson = new GsonBuilder()
.setVersion(4)
.create();
System.out.println(gson.toJson(user));
System.out.println(gson.fromJson(userStr, User.class));

gson = new GsonBuilder()
.setVersion(5)
.create();
System.out.println(gson.toJson(user));
System.out.println(gson.fromJson(userStr, User.class));
}

运行结果：