当servlet接收xml数据时，会出现错误

servelt code

servelt代码

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();
System.out.println("