在 Java 中使用 Gson 的 FieldNamingPolicy 枚举?
javajsonobject oriented programmingprogramming
Gson 库提供了命名约定作为枚举 FieldNamingPolicy 的一部分。我们可以使用 GsonBuilder 类的 setFieldNamingPolicy() 方法设置字段命名策略。
FieldNamingPolicy 枚举常量
- IDENTITY − 使用此命名策略，字段名称保持不变。
- LOWER_CASE_WITH_DASHES −使用此命名策略，将 Java 字段名称从其驼峰式形式修改为小写字段名称，其中每个单词由破折号 (-) 分隔。
- LOWER_CASE_WITH_UNDERSCORES − 使用此命名策略，将 Java 字段名称从其驼峰式形式修改为小写字段名称，其中每个单词由下划线 (_) 分隔。
- UPPER_CAMEL_CASE − 使用此命名策略，确保 Java 字段名称的第一个"字母"在序列化为其 JSON 形式时大写。
- UPPER_CAMEL_CASE_WITH_SPACES − 使用此命名策略，确保 Java 字段名称的第一个"字母"在序列化为其 JSON 形式时大写，并且单词将由空格分隔。
语法
public enum FieldNamingPolicy extends Enum<FieldNamingPolicy> implements FieldNamingStrategy
示例
import com.google.gson.FieldNamingPolicy;
import com.google.gson.Gson;
import com.google.gson.GsonBuilder;
public class GsonFieldNamingPolicyTest {
public static void main(String[] args) {
Employee emp = new Employee();
emp.setEmpId(115);
emp.setFirstName("Raja");
emp.setLastName("Ramesh");
GsonBuilder gsonBuilder = new GsonBuilder();
Gson gson1 = gsonBuilder.setFieldNamingPolicy(FieldNamingPolicy.LOWER_CASE_WITH_DASHES).create();
String result1 = gson1.toJson(emp);
System.out.println("LOWER_CASE_WITH_DASHES: " + result1);
Gson gson2 = gsonBuilder.setFieldNamingPolicy(FieldNamingPolicy.LOWER_CASE_WITH_UNDERSCORES).create();
String result2 = gson2.toJson(emp);
System.out.println("LOWER_CASE_WITH_UNDERSCORES: " + result2);
Gson gson3 = gsonBuilder.setFieldNamingPolicy(FieldNamingPolicy.UPPER_CAMEL_CASE).create();
String result3 = gson3.toJson(emp);
System.out.println("UPPER_CAMEL_CASE: " + result3);
Gson gson4 = gsonBuilder.setFieldNamingPolicy(FieldNamingPolicy.UPPER_CAMEL_CASE_WITH_SPACES).create();
String result4 = gson4.toJson(emp);
System.out.println("UPPER_CAMEL_CASE_WITH_SPACES: " + result4);
Gson gson5 = gsonBuilder.setFieldNamingPolicy(FieldNamingPolicy.IDENTITY).create();
String result5 = gson5.toJson(emp);
System.out.println("IDENTITY: " + result5);
}
}
// Employee class
class Employee {
private int empId;
private String firstName;
private String lastName;
public int getEmpId() {
return empId;
}
public void setEmpId(int empId) {
this.empId = empId;
}
public String getFirstName() {
return firstName;
}
public void setFirstName(String firstName) {
this.firstName = firstName;
}
public String getLastName() {
return lastName;
}
public void setLastName(String lastName) {
this.lastName = lastName;
}
}
输出
LOWER_CASE_WITH_DASHES: {"emp-id":115,"first-name":"Raja","last-name":"Ramesh"}
LOWER_CASE_WITH_UNDERSCORES: {"emp_id":115,"first_name":"Raja","last_name":"Ramesh"}
UPPER_CAMEL_CASE: {"EmpId":115,"FirstName":"Raja","LastName":"Ramesh"}
UPPER_CAMEL_CASE_WITH_SPACES: {"Emp Id":115,"First Name":"Raja","Last Name":"Ramesh"}
IDENTITY: {"empId":115,"firstName":"Raja","lastName":"Ramesh"}
