在Java中使用Gson的FieldNamingPolicy枚举?
Gson 库提供命名约定作为枚举 **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 字段名称从驼峰式更改为小写字段名称,每个单词之间用短划线 (-) 分隔。
- **LOWER_CASE_WITH_UNDERSCORES** - 使用此命名策略,将 Java 字段名称从驼峰式更改为小写字段名称,每个单词之间用下划线 (_) 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,并且单词之间用空格分隔。
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"}
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