如何防止Gson序列化/反序列化字段的第一个字符(下划线)?

时间:2013-02-19 19:13:08

标签: json parsing gson

我的课程:

class ExampleBean {
   private String _firstField;
   private String _secondField;
   // respective getters and setters
}

我想表现如下:

{
     "FirstField":"value",
     "SecondField":"value"
}

不喜欢这个

{
     "_FirstField":"value",
     "_SecondField":"value"
}

我按如下方式初始化解析器:

GsonBuilder builder = new GsonBuilder();
    builder.setDateFormat(DateFormat.LONG);
    builder.setFieldNamingPolicy(FieldNamingPolicy.UPPER_CAMEL_CASE);
    builder.setPrettyPrinting();
    set_defaultParser(builder.create());

我可以看到API以及“FieldNamePolicy”的documentation,但我很惊讶不提供跳过“_”的选项 我也知道我可以使用注释...

@ SerializedName (" custom_naming ")

...但是我不想为alllllll我的领域写这个...

区分局部变量和类的字段对我非常有用。 :(任何想法?

编辑:会有很多明显的解决方案,(继承,gson覆盖方法,常规表达)。我的问题更侧重于是否存在gson的原生解决方案或更少侵入性的修复?

也许我们可以建议新的FieldNamePolicy?

2 个答案:

答案 0 :(得分:13)

GsonBuilder提供了一种方法setFieldNamingStrategy(),可让您通过自己的FieldNamingStrategy实施。

请注意,这会取代对setFieldNamingPolicy()的调用 - 如果您查看GsonBuilder的来源,这两个方法是互斥的,因为它们设置了相同的内部字段(FieldNamingPolicy枚举< em>是 FieldNamingStrategy)。

public class App
{
    public static void main(String[] args)
    {
        Gson gson = new GsonBuilder()
                        .setFieldNamingStrategy(new MyFieldNamingStrategy())
                        .setPrettyPrinting()
                        .create();

        System.out.println(gson.toJson(new ExampleBean()));
    }
}

class ExampleBean
{

    private String _firstField = "first field value";
    private String _secondField = "second field value";
    // respective getters and setters
}

class MyFieldNamingStrategy implements FieldNamingStrategy
{
    public String translateName(Field field)
    {
        String fieldName = 
            FieldNamingPolicy.UPPER_CAMEL_CASE.translateName(field);
        if (fieldName.startsWith("_"))
        {
            fieldName = fieldName.substring(1);
        }
        return fieldName;
    }
}

输出:

{
  "FirstField": "first field value",
  "SecondField": "second field value"
}

答案 1 :(得分:0)

你想要的是

import java.lang.reflect.Field;
import java.text.DateFormat;

import com.google.gson.FieldNamingStrategy;
import com.google.gson.Gson;
import com.google.gson.GsonBuilder;

public class GsonExample {

    public static void main(String... args) throws Exception {
        final GsonBuilder builder = new GsonBuilder();
        builder.setDateFormat(DateFormat.LONG);
        builder.setPrettyPrinting();
        builder.setFieldNamingStrategy(new FieldNamingStrategy() {
            @Override
            public String translateName(Field f) {
                String fieldName = f.getName();
                if(fieldName.startsWith("_") && fieldName.length() > 1) {
                    fieldName = fieldName.substring(1, 2).toUpperCase() + fieldName.substring(2);
                }
                return fieldName;
            }
        });
        final Gson gson = builder.create();
        System.out.println(gson.toJson(new ExampleBean("example", "bean")));
    }


    private static class ExampleBean {
        private final String _firstField;
        private final String _secondField;

        private ExampleBean(String _firstField, String _secondField) {
            this._firstField = _firstField;
            this._secondField = _secondField;
        }
    }
}

生成

{"FirstField":"example","SecondField":"bean"}