java map json 格式化 java map转json对象

map 转json数据并返给前端，前端可以用JSON.parse()序列化

import java.util.HashMap;
import java.util.Map
public class MapToJson {
   public static String toJson(boolean success,String key,Integer val){
      Map<String,Integer> jsonMap = new HashMap<String, Integer>();
      jsonMap.put(key,val);
      return toJson(success,jsonMap);
  }
   public static String toJson(boolean success,Map<String,Integer> jsonMap){
    StringBuffer buffer = new StringBuffer();
    if (success){
        buffer.append("{\"success\":true,\"data\":[");
    }else{
        buffer.append("{success:false}");
    }
    if (jsonMap.size() >0){
        for (String key:jsonMap.keySet()){
            if(!key.equals(("class"))){
                buffer.append("{"+'"'+key+'"' + ":"+jsonMap.get(key)+"},");
            }
        }
        buffer.deleteCharAt(buffer.length()-1);
    }
    buffer.append("]}");
    return buffer.toString();
    }
}
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在网上搜搜到一位老哥的方法，但是输出的前端解析不了，最后重新检查，发现返回的json格式不正确，所以重新改了格式，然后就能解析，下面是前端代码

let fragment = document.createDocumentFragment();
let total = 0;
Tools.ajax({
   url:'/cart',
   data:{id:1},
   type:'post',
   success:function (req) {
        let rel = JSON.parse(req);
       console.log(typeof (req));
       console.log(req);
       console.log(rel);

    for(let i = 0; i < rel.data.length; i++){
        for(key in rel.data[i]);
            let div = document.createElement("div");
            div.innerHTML = "<span>商品名称:"+key+"</span><span>商品数量:"+rel.data[i][key]+"</span>";
            total+=rel.data[i][key];
        fragment.appendChild(div)
    }

    let cart = document.querySelector(".cart");
    cart.appendChild(fragment);
    console.log(total);
   }
 })复制代码