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.Mappublic class MapToJson {   public static String toJson(boolean success,String key,Integer val){      Map
    
      jsonMap = new HashMap
     
      ();      jsonMap.put(key,val);      return toJson(success,jsonMap);  }   public static String toJson(boolean success,Map
      
        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();    }}复制代码
      
     
    

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 = "商品名称:"+key+"商品数量:"+rel.data[i][key]+"";            total+=rel.data[i][key];        fragment.appendChild(div)    }    let cart = document.querySelector(".cart");    cart.appendChild(fragment);    console.log(total);   } })复制代码