urlConnection.getInputStream()试图在应用程序和servlet之间连接时抛出filenotf

Question

我想开发一个应用程序，该应用程序在tomcat上运行的servlet文件之间。

以下是我的应用程序中的代码，该代码正在尝试连接到此servlet，发送请求并获取响应。

 private URLConnection getServletConnection() {
    try {
        URL servletURL = new URL("http://localhost:8080/test/servlet");
        URLConnection conn = servletURL.openConnection();
        conn.setDoInput(true);
        conn.setDoOutput(true);
        conn.setUseCaches(false);
        return conn;
    } catch (MalformedURLException e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
    } catch (IOException e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
    }
    return null;
}

及以下是抛出例外的代码：

URLConnection conn = getServletConnection();
OutputStream outputStream = conn.getOutputStream();
ObjectOutputStream oos = new ObjectOutputStream(outputStream);
ServletRequestMessage srm = new ServletRequestMessage(2, username, password);
oos.writeObject(srm);
oos.flush();
oos.close();
InputStream inputStream = conn.getInputStream();

例外是：

java.io.FileNotFoundException: http://localhost:8080/test/servlet

有人可以帮我吗？谢谢。

Answer 1

服务器端

public class ServletImpl extends HttpServlet implements Servlet {
    ....
    public ServletImpl() {
      super();      
    }
 public void init(ServletConfig config) throws ServletException{
    super.init(config);         

    /*
     Application scope 
     Shared between all servlets, JSP pages, and custom tags within a J2EE application 
     or within the whole container if no applications are defined.
     The programmatic interface to the application scope is the 'ServletContext' object.         
     */

    ServletContext context = config.getServletContext();
    context.setAttribute("base", config.getInitParameter("base"));
      /* where "base" is iniy param in web.xml
         <init-param>
    <param-name>base</param-name>
    <param-value>/ServlrtName/sys</param-value>
    </init-param>       

       */

....

}
    ....
protected void doGet(HttpServletRequest request,HttpServletResponse response) throws ServletException, IOException
{
    doPost(request, response);
}

    protected void doPost(HttpServletRequest request,HttpServletResponse response) throws ServletException, IOException
   {
    Enumeration<?> paramNames = request.getParameterNames();

    while(paramNames.hasMoreElements()) {
        String paramName = (String)paramNames.nextElement();
        String[] paramValues = request.getParameterValues(paramName);

         if("sub".equals(paramName)){
            paramValues = request.getParameterValues(paramName);
            if(paramValues.length > 0){
                String param = paramValues[0];
                // do something
                ....
            }               
        }           
    }
}

....
// prepear response 
    response.setContentType("text/html");
    PrintWriter out = response.getWriter();
    out.println(mMessageResponseStr);
    out.close();

在这里我使用了sub标签，请参阅：if("sub".equals(paramName)){。

web.xml

<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns="http://java.sun.com/xml/ns/javaee" xmlns:web="http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd" xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd" id="WebApp_ID" version="2.5">
 <display-name>ServlrtName</display-name>
 <servlet>
    <description>
    </description>
    <display-name>ServlrtName</display-name>
    <servlet-name>ServlrtName</servlet-name>
    <servlet-class>com.demo.servlet.ServletImpl</servlet-class>
  <init-param>
    <param-name>base</param-name>
    <param-value>/ServlrtName/sys</param-value>
    </init-param>
  <init-param>
        ....
</servlet>
...
 <servlet-mapping>
    <servlet-name>ServlrtName</servlet-name>
    <url-pattern>/sys/*</url-pattern>
  </servlet-mapping>

客户端

我使用了DefaultHttpClient和HttpPost。我发送sub标签。这是一种将数据发送到Servlet的方法：

 public boolean send(String data) {
    DefaultHttpClient httpclient = null;
    boolean success = false;
    try {           
        httpclient = new DefaultHttpClient();
        String url = "your URL";

        HttpPost httpost = new HttpPost(url);
        List <NameValuePair> nvps = new ArrayList <NameValuePair>();
        nvps.add(new BasicNameValuePair("sub", data));

        httpost.setEntity(new UrlEncodedFormEntity(nvps, HTTP.UTF_8));

        HttpResponse response = httpclient.execute(httpost);
        HttpEntity entity = response.getEntity();
        if (entity != null) {
            StatusLine statusLine = response.getStatusLine();
            int statusCode = statusLine.getStatusCode();
            if(statusCode != 200){
                mResErr.onErrorResponse(statusCode);                    
            }
            InputStream is = entity.getContent();
            InputStreamReader isr = new InputStreamReader(is);
            BufferedReader br = new BufferedReader(isr);
            String line = null;
            while ( (line = br.readLine()) != null) {
                // get data from line

            }
            is.close();

        } else {
            //response is null/
        }
        success = true;
        mRes.onHttpResponse(mArr);

    } catch (Exception e) {
        mResErr.onErrorResponse(e);
        e.getStackTrace();
    }
    if (httpclient != null) {
        // resource cleanup
        httpclient.getConnectionManager().shutdown();
    }
    return success;
}   

**注释，在开始检查连接之前，请从服务器端删除用户/密码。如果所有操作都按预期工作，则将其换回并在客户端使用：

Credentials cred = new UsernamePasswordCredentials("user", "pswd");

         httpclient.getCredentialsProvider().setCredentials(
                    new AuthScope(AuthScope.ANY_HOST, AuthScope.ANY_PORT, AuthScope.ANY_REALM),
                    cred);