Getting request payload from POST request in Java servlet

Question

I have a javascript library that is sending a POST request to my Java servlet  but in the doPost method  I can t seem to get the contents of the request payload  In chrome Developer Tools  all the content is in the Request Payload section in the headers tab  and the content is there  and I know that the POST is being received by the doPost method  but it just comes up blank   For the HttpServletRequest object  what way can I get the data in the request payload   Doing request getParameter   or request getAttributes   both end up with no data

User · Answer

You only need      request getParameterMap     for getting the POST and GET - Parameters   The Method returns a Map lt String String   gt    You can read the parameters in the Map by  Map lt String  String   gt  map   request getParameterMap      Reading the Map   Works for GET  amp  amp  POST Method for String paramName map keySet          String   paramValues   map get paramName          Get Values of Param Name     for String valueOfParam paramValues              Output the Values         System out println  Value of Param with Name   paramName      valueOfParam

User · Answer

If you are able to send the payload in JSON  this is a most convenient way to read the playload   Example data class   public class Person       String firstName      String lastName         Getters and setters         Example payload  request body       firstName     John    lastName     Doe      Code to read payload in servlet  requires com google gson      Person person   new Gson   fromJson request getReader    Person class     That s all  Nice  easy and clean  Don t forget to set the content-type header to application json

User · Answer

With Apache Commons IO you can do this in one line   IOUtils toString request getReader

User · Answer

Java 8 streams  String body   request getReader   lines        reduce      accumulator  actual  - gt  accumulator   actual

User · Answer

You can use Buffer Reader from request to read        Read from request     StringBuilder buffer   new StringBuilder        BufferedReader reader   request getReader        String line      while   line   reader readLine       null            buffer append line           buffer append System lineSeparator               String data   buffer toString

User · Answer

Using Java 8 try with resources       StringBuilder stringBuilder   new StringBuilder        try BufferedReader bufferedReader   new BufferedReader new InputStreamReader request getInputStream                char   charBuffer   new char 1024           int bytesRead          while   bytesRead   bufferedReader read charBuffer    gt  0                stringBuilder append charBuffer  0  bytesRead

User · Answer

If the contents of the body are a string in Java 8 you can do   String body   request getReader   lines   collect Collectors joining

User · Answer

String payloadRequest   getBody request     Using this method   public static String getBody HttpServletRequest request  throws IOException        String body   null      StringBuilder stringBuilder   new StringBuilder        BufferedReader bufferedReader   null       try           InputStream inputStream   request getInputStream            if  inputStream    null                bufferedReader   new BufferedReader new InputStreamReader inputStream                char   charBuffer   new char 128               int bytesRead   -1              while   bytesRead   bufferedReader read charBuffer    gt  0                    stringBuilder append charBuffer  0  bytesRead                           else               stringBuilder append                      catch  IOException ex            throw ex        finally           if  bufferedReader    null                try                   bufferedReader close                  catch  IOException ex                    throw ex                                     body   stringBuilder toString        return body

User · Answer

Simple answer  Use getReader   to read the body of the request  More info  There are two methods for reading the data in the body    getReader   returns a BufferedReader that will allow you to read the body of the request   getInputStream   returns a ServletInputStream if you need to read binary data     Note from the docs    Either method  may be called to read the body  not both

[java] Getting request payload from POST request in Java servlet

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