Server cannot read entire content

Question

I have a servlet which receives via POST method a large JSON string (> 10,000 characters).

If i read the content of the request like this:

try(Reader reader = new InputStreamReader(new BufferedInputStream(request.getInputStream()), StandardCharsets.UTF_8))
{
    char[] buffer = new char[request.getContentLength()];
    reader.read(buffer);
    System.out.println(new String(buffer));
}

i don´t get the entire content! The buffer size is correct. But the length of the created string is not.

But if i do it like this:

try(BufferedInputStream input = new BufferedInputStream(request.getInputStream()))
{
    byte[] buffer = new byte[request.getContentLength()];
    input.read(buffer);
    System.out.println(new String(buffer, StandardCharsets.UTF_8));
}

it works perfectly.

So where am i wrong in the first case?

score 1 · Answer 1 · edited May 23 '17 at 10:25

The way you are using InputStreamReader is not really the intended way. A call to read is not guaranteed to read any specific number of bytes (it depends on the stream you are reading from), which is why the return value of this method is the number of bytes that were read. You would need to keep reading from the stream and buffering until it indicates it has reached the end (it will return -1 as the number of bytes that were read). Some good examples of how to do this can be found here: Convert InputStream to byte array in Java

But since you want this as character data, you should probably use request.getReader() instead. A good example of how to do this can be found here: Retrieving JSON Object Literal from HttpServletRequest

Server cannot read entire content

1 Answers1