HttpServletRequest get JSON POST data
Normaly you can GET and POST parameters in a servlet the same way:
request.getParameter("cmd");
But only if the POST data is encoded as key-value pairs of content type: "application/x-www-form-urlencoded" like when you use a standard HTML form.
If you use a different encoding schema for your post data, as in your case when you post a json data stream, you need to use a custom decoder that can process the raw datastream from:
BufferedReader reader = request.getReader();
Json post processing example (uses org.json package )
public void doPost(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
StringBuffer jb = new StringBuffer();
String line = null;
try {
BufferedReader reader = request.getReader();
while ((line = reader.readLine()) != null)
jb.append(line);
} catch (Exception e) { /*report an error*/ }
try {
JSONObject jsonObject = HTTP.toJSONObject(jb.toString());
} catch (JSONException e) {
// crash and burn
throw new IOException("Error parsing JSON request string");
}
// Work with the data using methods like...
// int someInt = jsonObject.getInt("intParamName");
// String someString = jsonObject.getString("stringParamName");
// JSONObject nestedObj = jsonObject.getJSONObject("nestedObjName");
// JSONArray arr = jsonObject.getJSONArray("arrayParamName");
// etc...
}
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Lydon Ch
Updated on May 11, 2021Comments
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Lydon Ch almost 3 years
I am HTTP POST-ing to URL http://laptop:8080/apollo/services/rpc?cmd=execute
with POST data
{ "jsondata" : "data" }
Http request has Content-Type of
application/json; charset=UTF-8
How do I get the POST data (jsondata) from HttpServletRequest?
If I enumerate the request params, I can only see one param, which is "cmd", not the POST data.
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Dmitry Stolbov about 7 yearsThis is simple method to get request data
request.getReader().lines().collect(Collectors.joining())
-
Patrick about 7 yearsthe above mentioned throws stream already closed exception
-
Felipe Leão about 6 yearsIf you use the
getReader()
the stream will get closed, since originally it can only be read once. There are a number of alternatives on Wrapper implementations to allow multiple calls togetReader()
-
Ionut Ciuta over 5 yearsThe easiest way you can solve this is using Jackson's
ObjectMapper
. Its overloaded methodreadValue
has a variation which accepts aReader
and aClass<T>
. What you end up with is:new ObjectMapper().readValue(request.getReader(), YourBodyType.class)
- and there you have it. Short and slick.
-
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B T about 13 yearsIt seems like you can only get the post data from request.getReader once. Is this true? When I tried this myself, subsequent calls to get the post-data of the request fail.
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Kdeveloper about 13 yearsThat's correct you can read the request body content only once.
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rajesh_kw about 10 yearsthis really saved my day...but what is getReader and how do the json data get populated there? is it specifically for JSON? or any other object ? any helpful links please.
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Vadzim about 10 yearsWhy not just to pass
getReader()
to json parser as here: stackoverflow.com/a/15109169/603516 ? This wouldn't require extra copy loop. -
semisided1 over 9 yearsJSONObject jsonObject = HTTP.toJSONObject(jb.toString()); toJSONObject must have been moved to be a static method in the org.json.HTTP class
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X.Creates over 9 yearsWhy I cannot find the
fromObject(String string)
method inside the documentation? json.org/javadoc/org/json/JSONObject.html -
jds over 9 years@X.Li, see the comment directly above yours.
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Mirimas over 8 yearsYou can use StringBuilder here, and you need close reader in finally block. Just in case :)
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Newbie almost 7 yearsShould be: JSONObject jsonObject = new JSONObject(jb.toString());
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Admin almost 6 yearsget POST body
BufferedReader reader = request.getReader();