Retrieving JSON Object Literal from HttpServletRequest

Question

I am writing code that needs to extract an object literal posted to a servlet  I have studied the API for the HttpServletRequest object  but it is not clear to me how to get the JSON object out of the request since it is not posted from a form element on a web page   Any insight is appreciated    Thanks

User · Answer

This is simple method to get request data from HttpServletRequest using Java 8 Stream API   String requestData   request getReader   lines   collect Collectors joining

User · Answer

The easiest way is to populate your bean would be from a Reader object  this can be done in a single call   BufferedReader reader   request getReader    Gson gson   new Gson     MyBean myBean   gson fromJson reader  MyBean class

User · Answer

are you looking for this     Override protected void doPost HttpServletRequest request  HttpServletResponse response          throws ServletException  IOException       StringBuilder sb   new StringBuilder        BufferedReader reader   request getReader        try           String line          while   line   reader readLine       null                sb append line  append   n                    finally           reader close              System out println sb toString

User · Answer

If you re trying to get data out of the request body  the code above works  But  I think you are having the same problem I was    If the data in the body is in JSON form  and you want it as a Java object  you ll need to parse it yourself  or use a library like google-gson to handle it for you  You should look at the docs and examples at the project s website to know how to use it  It s fairly simple

User · Answer

make use of the jackson JSON processor   ObjectMapper mapper   new ObjectMapper      Book book   mapper readValue request getInputStream   Book class

User · Answer

Converting the retreived data from the request object to json object is as below using google-gson  Gson gson   new Gson    ABCClass c1   gson fromJson data  ABCClass class      ABC class is a class whose strcuture matches to the data variable retrieved

User · Answer

There is another way to do it  using org apache commons io IOUtils to extract the String from the request  String jsonString   IOUtils toString request getInputStream       Then you can do whatever you want  convert it to JSON or other object with Gson  etc   JSONObject json   new JSONObject jsonString   MyObject myObject   new Gson   fromJson jsonString  MyObject class

[json] Retrieving JSON Object Literal from HttpServletRequest

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