D

package myProject;import java.math.BigDecimal;import java.util.ArrayList;import java.util.List;import com.alibaba.fastjson.JSON;import com.alibaba.fastjson.JSONObject;import com.alibaba.fastjson.serializer.SerializerFeature;public class FastJsonTest {        private int a;    private BigDecimal b;    private String c;    private List
     
       list;        public String getC() {        return c;    }    public void setC(String c) {        this.c = c;    }    public int getA() {        return a;    }    public void setA(int a) {        this.a = a;    }    public BigDecimal getB() {        return b;    }    public void setB(BigDecimal b) {        this.b = b;    }    public List
      
        getList() {        return list;    }    public void setList(List
       
         list) {        this.list = list;    }    public static void main(String[] args) {        FastJsonTest f=new FastJsonTest();        String json1=JSON.toJSONString(f);        String json2=JSON.toJSONString(f,SerializerFeature.WriteMapNullValue,SerializerFeature.WriteNullListAsEmpty,SerializerFeature.WriteNullStringAsEmpty,SerializerFeature.WriteNullNumberAsZero);        System.out.println("json1"+json1);        System.out.println("json2"+json2);            }}
       
      
     

输出结果为：

json1{"a":0}

json2{"a":0,"b":0,"c":"","list":[]}

可见，BigDecimal类型，String类型，List类型在不添加对应参数，都不会显示出来。