Ajax quickly solves the problem of parameters that are too long and cannot be submitted successfully

Below I will bring you an ajax quick solution to the problem of parameters that are too long and cannot be submitted successfully. Let me share it with you now and give it as a reference for everyone.

I checked a lot of information and said that the parameters of the get method are limited, but the length of the parameters of the post method is unlimited. This is also the advantage of post over get.

Use the post method in ajax and use the conventional parameter format: param1=a1¶m2=a2. When the parameter length is too long, the submission is still unsuccessful. For example, we often write an ajax post request like this:

$.ajax({
  type: "post",  // post or get
  contentType:"application/json;charset=utf-8",
  data: “requestTag=”+tag+"&content="+content,  //请求参数
  url: "postMockJson",   //地址
  dataType: "text",
  error: function (err) {
   outLog("错误"+err);
  },
  success: onSaveSuccess
});

When used like this, we find that if parameter 2: content contains too much content, for example, what I pass is A relatively large text content, when I obtain it from the background service (I use servlet):

String content= request.getParameter("content");

The value of content here is null.

There is also a quick way to check whether the ajax request is successful. Use the F12 developer tool to debug. After executing the ajax code, you can see the initiated request in the network options page in the F12 tool. , the requested parameters seen at this time have error prompts.

Solution:

There is another way to write the parameter format of ajax: the request parameter in json format, I can write it like this:

var param = "{requestTag:\"" requestTag "\",content:\"" content "\"}";
(ps: pay attention to the correct json format)

At this time, if you use F12 for debugging, you can see that the data of the requested parameters are correct.

Then the question is, the content I get in the servlet is still null. Why is this? ? ?

Since the request parameter is a json data block, of course the request.getParameter("content") method cannot obtain the data because it will not parse the json data for us.

So where is the parameter data we pass?

Here’s the point: the data is all in the request object.

Then we use the most primitive method to obtain the passed data through the data flow method, as follows:

request.setCharacterEncoding("UTF-8");
StringBuilder sb = new StringBuilder();
try(BufferedReader reader = request.getReader();) {
char[] buff = new char[1024];
int len;
 while((len = reader.read(buff)) != -1) {
  sb.append(buff,0, len);
  }
}catch (IOException e) {
   e.printStackTrace();
}

This At this time, our json data is all in the sb object. Next, we only need to parse the json object:

JSONObject jobject = JSONObject.fromObject(sb.toString());
String requestTag = jobject.getString("requestTag");
String content = jobject.getString("content");

Here, we You can get the content.

The above is what I compiled for everyone. I hope it will be helpful to everyone in the future.

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Two methods for Ajax to solve redundant refreshes

Ajax synchronization and asynchronous problems analysis and solutions

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