import javax.servlet.*;
import javax.servlet.http.*;
import java.io.*;public class SerAndApp extends HttpServlet{
  String respData;
  public void service(HttpServletRequest req,HttpServletResponse resp)
  {
    try
    {
      DataInputStream in=new DataInputStream(req.getInputStream());
      resp.setContentType("application/octest-stream");
      ByteArrayOutputStream byteout=new ByteArrayOutputStream();
      DataOutputStream out=new DataOutputStream(byteout);
      //String response=in.readUTF();
      String response=in.readUTF();
      out.writeUTF(response);
      out.flush();
      byte buf[]=byteout.toByteArray();
      resp.setContentLength(buf.length);
      ServletOutputStream servletout=resp.getOutputStream();
      servletout.write(buf);
      servletout.close();
    }catch(java.io.IOException e){}
  }
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你贴的代码
其中
      resp.setContentType("application/octest-stream");
有错