This article mainly introduces the json data interaction controller method of springmvc. The return value is a simple type, which is very practical. Friends in need can refer to it
When the return value of the controller method is a simple type such as String How to interact with json?
Use @RequestBody
For example, the code is as follows:
@RequestMapping(value="/ceshijson",produces="application/json;charset=UTF-8") @ResponseBody public String ceshijson(@RequestBody String channelId) throws IOException{ return channelId;
If the code is the above situation, the front desk sends json When using @RequestBody, it should be written like this (there are many ways to write it, just use it)
function channel(){ //先获取选中的值 var channelId = $("#channelId option:selected").val(); //来判断发送的链接 if(channelId ==2){ $.ajax({ url:"ceshijson", type:"post", dataType:'json', contentType:'application/json;charset=utf-8', data:JSON.stringify({'channelId':channelId}), success:function(data){ alert(data.channelId); }, error:function(XMLHttpRequest, textStatus, errorThrown){ alert("Error") alert(XMLHttpRequest.status); alert(XMLHttpRequest.readyState); alert(textStatus); } }); } }
Special attention needs to be paid here: As emphasized in the previous article, when @RequestBody is used, it requires String channelId to receive data as json String . That is, if data is written like this: data:{'channelId':channelId}, it is wrong. Because this is jsonobject form.
If you don’t want to use the JSON.stringify() function, then manually splice the strings yourself:
data:'{"channelId":'+channelId+'}'
Also note that channelId is in double quotes and cannot be written as Single quotes because this is a json syntax rule. If you change it to single quotes, that is,
**wrong way of writing
data:"{'channelId':"+channelId+"}"
, although it can be passed to the background, the data returned from the background will be undefined. That is, key must be surrounded by double quotes.
Do not use @RequestBody
@RequestMapping(value="/ceshijson",produces="application/json;charset=UTF-8") @ResponseBody public String ceshijson(String channelId) throws IOException{ Map<String,Object> map = new HashMap<String,Object>(); map.put("channelId", channelId); ObjectMapper mapper = new ObjectMapper(); channelId = mapper.writeValueAsString(map); return channelId; }
Front-end code
$.ajax({ url:"ceshijson", type:"post", dataType:'json', //contentType:'application/json;charset=utf-8', data:"channelId="+channelId, success:function(data){ alert(data); }, error:function(XMLHttpRequest, textStatus, errorThrown){ alert("Error") alert(XMLHttpRequest.status); alert(XMLHttpRequest.readyState); alert(textStatus); } });
This method uses writeValueAsString in ObjectMapper to convert Java objects into json strings.
Summary: This method actually does not have much practical meaning, because data is generally not received in this way. Just understand!
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