Question

我正在尝试在HttpURLConnection中编写一些消息，我试图在Servlet中检索相同的消息。这是两个不同的应用程序。

邮件编写代码 （无异常处理）

   public static void formUrlAndWrite() 
   {
    URL url = null;
    HttpURLConnection httpConnection = null;
    OutputStreamWriter outStream = null;
    String host = "http://127.0.0.1:8080/HttpTester";
    url = new URL(host);
    httpConnection = (HttpURLConnection) url.openConnection();
    httpConnection.setDoOutput(true);
    httpConnection.setAllowUserInteraction(true);
    httpConnection.setDefaultUseCaches(false);  
    outStream = new OutputStreamWriter(httpConnection.getOutputStream());
    outStream.write("This is a plain text");
    outStream.flush();
}

Servlet代码 （无异常处理）

protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException
{
        BufferedReader reader = null;
        PrintWriter out = null;
        StringBuffer buffer = new StringBuffer();
        try
        {
            //reader = new BufferedReader(new InputStreamReader(request.getInputStream()));
            reader = request.getReader();
            int read = 0;
            char[] charArray = new char[2000];

            while((read=reader.read(charArray))>-1)
            {
                buffer.append(charArray, 0, read);
            }
            response.setContentType("text/html");
            out = response.getWriter();

            out.println("<html><body>");
            out.print("<h2> Request Buffer is"+buffer+"</h2>");
            out.println("</body></html>");
        } 
}

这两个应用程序是异步运行的，我没有从servlet获取输出。我的疑问是，如果我运行消息编写应用程序，它将在数据库中写入数据。然后，当我运行servlet时，它是如何获取请求的？可能我在这方面做错了。任何帮助表示赞赏。

我尝试过以下网址，这与我的问题非常相似，但没有帮助。

Getting request payload from POST request in Java servlet

Answer 1

如果您无法检索第二个servlet中的任何数据，可能是因为您在某处调用request.getParameter() /getParameterValues()/getParameterMap()之类的内容。实际上，这些方法会调用getInputStream()，您只能读取一次请求的内容。

Answer 2

我在android中使用过此代码，它可能对你有帮助，可能不是完整的解决方案

写入服务器

 try{

               String u="hello";
               String p="world";

                 URL url=new URL("http://localhost:8080/LoginExample/LoginServlet?"+"key1="+u+"&key2="+p);

                HttpURLConnection urlConnection=(HttpURLConnection)url.openConnection();

                urlConnection.setRequestMethod("GET");
                urlConnection.connect();


            }catch(Exception e)
                {
                e.printStackTrace();    
                System.out.println("ERROR IN URL CONNECTION---"+e);
                }

ServletPage

import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;

public class LoginServlet extends HttpServlet {

public void doGet(HttpServletRequest request, HttpServletResponse response) 
               throws ServletException, java.io.IOException {

    try
    {       
        System.out.println("-----servlet--------------");
        // UserBean user = new UserBean();
        String uname=request.getParameter("key1");
        String password=request.getParameter("key2");

        System.out.println("uname ins ervlet==="+uname);

        System.out.println("password in servlet==="+password);
    }               
    catch (Throwable theException)      
    {
        System.out.println(theException); 
    }

 }

 }

Answer 3

我认为您应该将结果转换为字符串，以便代码与此类似（在Servlet页面中）：

String uname=(String)request.getParameter("key1");//cast to string
String password=(String)request.getParameter("key2");//cast to string

无法从Servlet检索数据

3 个答案: