when servlet receive xml data , there is a error

Question

servelt code

System.out.println(" ================servlet==================");
InputStream in = request.getInputStream();
int a = in.available();
byte[] b = new byte[a];
in.read(b);
String stringValue = new String(b,"utf-8");
System.out.println("receive data==="+stringValue);
OutputStream dataOut = response.getOutputStream();
String responseData = "<test>test</test>";
System.out.println("response datea==="+responseData);
dataOut.write(responseData.getBytes("utf-8"));
dataOut.flush();
dataOut.close();

client code

System.out.println("================client======================");
java.net.URL url = new java.net.URL("test address");
HttpURLConnection con = (HttpURLConnection) url.openConnection();
con.setUseCaches(false);
con.setDoOutput(true);
con.setDoInput(true);
con.setRequestMethod("POST");
String sendData = "<data>send</data>";
System.out.println("send data="+sendData);
OutputStream dataOut = con.getOutputStream();
dataOut.write(sendData.getBytes("utf-8"));
dataOut.flush();
dataOut.close();
InputStream in = con.getInputStream();
int a = in.available();
byte[] b = new byte[a];
in.read(b);
String stringValue = new String(b,"utf-8");
in.close();
System.out.println("receive data="+stringValue);

I get the print results servlet console ================servlet================== receive data=== response datea===test

client console

================client======================
send data=<data>send</data>
receive data=<test>test</test>

My question is that servlet can't receive the data from the client

who can help me?

Then what is the reason you posted it here.Dealing with people in right manner matters !!! — Suresh Atta
– Suresh Atta, Commented Jun 20, 2013 at 6:27

Jon Skeet · Accepted Answer · 2013-06-20 06:27:38Z

4

My question is that servlet can't receive the data from the client

It may not be the only problem, but this code is completely broken:

int a = in.available();
byte[] b = new byte[a];
in.read(b);

You're assuming that all the data is available right at the start. You should instead be reading from the stream until it runs out of data. Given that you want the result as text, I'd wrap the stream in an InputStreamReader and read from there. For example:

BufferdReader reader = new BufferedReader(new InputStreamReader(in, "UTF-8"));
String line;
while ((line = reader.readLine()) != null) {
    System.out.println("Servlet read line: " + line);
}

If you actually want to read it as XML, you should be able to pass the InputStream (or Reader) to an XML parser library to create a DOM.

You should be doing the same thing in the client code too, by the way. Basically:

Never ignore the return value of InputStream.read
Avoid using available(); it's rarely appropriate
Use an InputStreamReader to read text from a stream, rather than constructing it yourself from the bytes
Use an XML API to read XML rather than handling it as raw text

answered Jun 20, 2013 at 6:27

Jon Skeet

1.5m893 gold badges9.3k silver badges9.3k bronze badges

Sign up to request clarification or add additional context in comments.

2 Comments

fenger Over a year ago

If I do this Document document = null; SAXReader reader = new SAXReader (); document = reader.read (new InputStreamReader (conn.getInputStream (), "UTF-8")); I get the exception org.dom4j.DocumentException: Error on line -1 of document : Premature end of file. Nested exception: Premature end of file. thanks

Jon Skeet Over a year ago

@fenger: That suggests the data isn't actually getting to the servlet then. Why are you using DataOutputStream in the client? It seems pointless to me. I suggest you use Wireshark to diagnose what's happening at a network level.

me_digvijay · Accepted Answer · 2013-06-20 06:54:57Z

0

As of now I can see that the value of int b is 0 so it is not reading any data from the input stream.

According to this documentation

available

will always return 0 for InputStream which has been extended byt the ServletInputStream. As told by Jon or Edit:

InputStream is=request.getInputStream();
OutputStream os=response.getOutputStream();
byte[] buf = new byte[1024];
int chunk = is.read(buf);

edited Jun 20, 2013 at 6:54

answered Jun 20, 2013 at 6:36

me_digvijay

5,53210 gold badges52 silver badges86 bronze badges

1 Comment

fenger Over a year ago

so how can I get the data?

Collectives™ on Stack Overflow

when servlet receive xml data , there is a error

2 Answers 2

2 Comments

1 Comment

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

2 Answers 2

2 Comments

1 Comment

Your Answer

Sign up or log in

Post as a guest

Related