ajax与json总结

1.jquery中调用ajax方法

$.ajax({
  async:true,
  type:"post",
  url:"xxxServlet",
  data:{"account":"jack","pwd":"123"},
  success:function(data){
      //dowork
  },
  //error:function(){alert("error!");},
  dataType:"json"
});
注:指定dataType为json时,不要用var obj = eval("("+data+")");去再次解析,会报错

2.json格式

1.json对象
  {key:value,key:value}
  {"name":"jack","sex":"男","age":"25"}
2.json数组或集合格式
  [{key:value,key:value},{key:value,key:value}]
  [{"name":"jack","sex":"男","age":"25"},     {"name":"tom","sex":"男","age":"26"}]
3.json对象,数组嵌套
  {  
        "param":[{key:value,key:value},{key:value,key:value}] 
  }
  {
	"param1":[{key:value,key:value},{key:value,key:value}],
	"param2":[{key:value,key:value},{key:value,key:value}],
	"param3":[{key:value,key:value},{key:value,key:value}]
  }
  {
	 "param1":"value1",
	 "param2":{},
	 "param3":[{key:value,key:value},{key:value,key:value}]
  }

3.谷歌的gson包

  Gson gson = new Gson();
  String json = gson.toJson(car);
  resp.getWriter().write(json);

4.阿里的fastjson包

JSON-jsonString(toJOSNString) 
JSONObject-map集合(put) 
JSONArray-list集合(add)

4.1.响应jsonString

String jsonString = JSON.toJSONString(car);
resp.getWriter().write(jsonString);

4.2.响应json对象

JSONObject data=JSONObject.parseObject(JSON.toJSONString(car));
resp.getWriter().print(data);

4.3.JSONObject对象

JSONObject jo = new JSONObject();
jo.put("message", "用户名可注册!");
resp.getWriter().print(jo);

4.4.JSONArray数组

JSONObject jo1 = new JSONObject();
JSONObject jo2 = new JSONObject();
JSONArray ja = new JSONArray();
ja.add(jo1);
ja.add(jo2);
resp.getWriter().println(ja);