需求：map转成json字符串，要求字段按字母升序排列

package com.data.test;import java.util.HashMap;
import java.util.Map;
import java.util.TreeMap;
import com.alibaba.fastjson.JSONObject;
import com.alibaba.fastjson.serializer.SerializerFeature;public class Test {public static void main(String[] args) {//Map<String,String> amap = new TreeMap<>();Map<String,String> amap = new HashMap<>();amap.put("d", "d1");amap.put("c", "c1");amap.put("a", "a1");amap.put("b", "b1");System.out.println(amap);//String astr = JSONObject.toJSONString(amap, SerializerFeature.SortField);String astr = JSONObject.toJSONString(amap, SerializerFeature.MapSortField);System.out.println(astr);}
}