问题描述

实体中字段为Boolean时 想将对应空值转成“”时报错，
其中active 修饰为public的时候正常，
请问这种情况是设计如此还是存在bug？
补充一下 似乎 Integer也有这个问题，自定义的ObjectWriter 不生效

@DaTa
class User {
public String name;
public Integer age;
private Boolean active;

public User(String name, Integer age, Boolean active) {
    this.name = name;
    this.age = age;
    this.active = active;
}

}

public class Fastjson2ValueFilterExample {
public static void main(String[] args) {
User user = new User("Alice", null, null);

    // 定义一个 ValueFilter，将 null 值修改为默认值
    ValueFilter filter = (object, name, value) -> {
        if (value == null) {
            return "N/A"; // 如果字段值为 null，改为 "N/A"
        }
        return value;
    };

    // 使用 ValueFilter 序列化
    String jsonString = JSON.toJSONString(user, filter, JSONWriter.Feature.WriteNulls);
    System.out.println(jsonString);
    // 输出：{"name":"Alice","age":"N/A","active":"N/A"}
}

}

提示报错
Exception in thread "main" java.lang.ClassCastException: java.lang.String cannot be cast to java.lang.Boolean
at com.alibaba.fastjson2.writer.ObjectWriterImplBoolean.write(ObjectWriterImplBoolean.java:25)
at com.alibaba.fastjson2.writer.ObjectWriterAdapter.writeWithFilter(ObjectWriterAdapter.java:577)
at com.alibaba.fastjson2.writer.ObjectWriter3.write(ObjectWriter3.java:63)
at com.alibaba.fastjson2.JSON.toJSONString(JSON.java:3083)
at com.itime.debtdefuse.assets.util.Fastjson2ValueFilterExample.main(Fastjson2ValueFilterExample.java:34)

似乎Integer字段也有这个问题

参考代码：

import com.alibaba.fastjson2.JSON;
import com.alibaba.fastjson2.JSONWriter;
import com.alibaba.fastjson2.writer.ObjectWriter;

import java.lang.reflect.Type;
import java.math.BigDecimal;
import java.util.HashMap;
import java.util.Map;

/**

• @author Baoyi Chen
  */
  public class Main {
  public static void main(String[] args) {
  JSON.register(Integer.class, new ObjectWriter() {
  @OverRide
  public void write(JSONWriter jsonWriter, Object object, Object fieldName, Type fieldType, long features) {
  Integer value = (Integer) object;
  if (value == null) jsonWriter.writeNull(); else jsonWriter.writeString(Long.toString(value));
  }
  });

   JSON.register(BigDecimal.class, new ObjectWriter<BigDecimal>() {
       @Override
       public void write(JSONWriter jsonWriter, Object object, Object fieldName, Type fieldType, long features) {
           BigDecimal value = (BigDecimal) object;
           if (value == null) jsonWriter.writeNull(); else jsonWriter.writeString(value.toPlainString());
       }
   });
  
   Map<String, Long> map = new HashMap<>();
   map.put("0", 0L);
   String s = JSON.toJSONString(map);
   System.out.println(s);
  
   Test t = new Test();
   t.setValue(0);
   t.setValue1(new BigDecimal("0.11"));
   s = JSON.toJSONString(t);
   System.out.println(s);
  

  }

  public static class Test {
  private Integer value;
  private BigDecimal value1;

   public Integer getValue() {
       return value;
   }
  
   public BigDecimal getValue1() {
       return value1;
   }
  
   public void setValue(Integer value) {
       this.value = value;
   }
  
   public void setValue1(BigDecimal value1) {
       this.value1 = value1;
   }
  

  }
  }