Getting request payload from POST request in Java servlet
JavaHttpServletsPostJava Problem Overview
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
Java Solutions
Solution 1 - Java
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."
Solution 2 - Java
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)) > 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;
}
Solution 3 - Java
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()
Solution 4 - Java
Java 8 streams
String body = request.getReader().lines()
.reduce("", (accumulator, actual) -> accumulator + actual);
Solution 5 - Java
With Apache Commons IO you can do this in one line.
IOUtils.toString(request.getReader())
Solution 6 - Java
If the contents of the body are a string in Java 8 you can do:
Solution 7 - Java
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.
Solution 8 - Java
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)) > 0) {
stringBuilder.append(charBuffer, 0, bytesRead);
}
}
Solution 9 - Java
You only need
> request.getParameterMap()
for getting the POST and GET - Parameters.
The Method returns a Map<String,String[]>
.
You can read the parameters in the Map by
Map<String, String[]> map = request.getParameterMap();
//Reading the Map
//Works for GET && 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);
}
}