从java main方法调用servlet

import java.net.*; import java.io.*; public class sample { public static void main (String args[]) { String line; try { URL url = new URL( "http://localhost:8080/WeighPro/CommPortSample" ); BufferedReader in = new BufferedReader(new InputStreamReader(url.openStream())); line = in.readLine(); System.out.println( line ); in.close(); } catch (Exception e) { System.out.println("Hello Project::"+e.getMessage()); } } } 

我的Servlet正在调用另一个Jsp页面，如下所示，

  RequestDispatcher rd=request.getRequestDispatcher("index.jsp"); rd.forward(request, response); 

我没有在浏览器中得到任何反应/输出，一旦调用它就必须执行servlet。

我错过了这个过程的任何基本步骤吗？ 请帮忙！！！

Answer 1

如果你想在浏览器中打开它试试这个

 java.awt.Desktop.getDesktop().browse(java.net.URI.create("http://localhost:8080/WeighPro/CommPortSample")); 

Answer 2

你的问题不明确。 您是否真的想从Main方法调用Servlet，或者您想要向Web应用程序发出HTTP请求？

如果你想发一个HTTP请求，我上面的代码看不到任何明显的问题，这让我相信问题在于Servlet。 您还提到您在浏览器中没有得到任何内容，但上面运行您的程序不涉及浏览器。

你是说当你去的时候没有得到回应

 http://localhost:8080/WeighPro/CommPortSample 

在浏览器中？

正如Suresh所说，你不能直接从main方法调用Servlet。 您的Servlet应该调用其他类的方法，而其他类应该可以从main方法或Test Cases中调用。 您需要构建应用程序以使其成为可能。

Answer 3

 import java.io.BufferedInputStream; import java.io.OutputStream; import java.io.OutputStreamWriter; import java.net.HttpURLConnection; import java.net.URL; public class OutBoundSimul { public static void main(String[] args) { sendReq(); } public static void sendReq() { String urlString = "http://ip:port/applicationname/servletname"; String respXml = text; URL url = null; HttpURLConnection urlConnection = null; OutputStreamWriter out = null; BufferedInputStream inputStream = null; try { System.out.println("URL:"+urlString); url = new URL(urlString); urlConnection = (HttpURLConnection)url.openConnection(); urlConnection.setDoInput(true); urlConnection.setDoOutput(true); urlConnection.setRequestMethod("POST"); System.out.println("SendindData"); out = new OutputStreamWriter(urlConnection.getOutputStream()); System.out.println("Out:"+out); out.write(respXml); out.flush(); inputStream = new BufferedInputStream(urlConnection.getInputStream()); int character = -1; StringBuffer sb = new StringBuffer(); while ((character = inputStream.read()) != -1) { sb.append((char) character); } System.out.println("Resp:"+sb.toString()); } catch (Exception e) { e.printStackTrace(); } } } 

Answer 4

使用查询参数调用Servlet Form Main方法

Java IO

 public static String accessResource_JAVA_IO(String httpMethod, String targetURL, String urlParameters) { HttpURLConnection con = null; BufferedReader responseStream = null; try { if (httpMethod.equalsIgnoreCase("GET")) { URL url = new URL( targetURL+"?"+urlParameters ); responseStream = new BufferedReader(new InputStreamReader( url.openStream() )); }else if (httpMethod.equalsIgnoreCase("POST")) { con = (HttpURLConnection) new URL(targetURL).openConnection(); // inform the connection that we will send output and accept input con.setDoInput(true); con.setDoOutput(true); con.setRequestMethod("POST"); con.setUseCaches(false); // Don't use a cached version of URL connection. con.setRequestProperty("Content-Type", "application/x-www-form-urlencoded"); con.setRequestProperty("Content-Length", Integer.toString(urlParameters.getBytes().length)); con.setRequestProperty("Content-Language", "en-US"); DataOutputStream requestStream = new DataOutputStream ( con.getOutputStream() ); requestStream.writeBytes(urlParameters); requestStream.close(); responseStream = new BufferedReader(new InputStreamReader( con.getInputStream(), "UTF-8" )); } StringBuilder response = new StringBuilder(); // or StringBuffer if not Java 5+ String line; while((line = responseStream.readLine()) != null) { response.append(line).append('\r'); } responseStream.close(); return response.toString(); } catch (Exception e) { e.printStackTrace(); return null; } finally { if(con != null) con.disconnect(); } } 

Apache Commons 使用commons-~ .jar { httpclient ， logging }

 public static String accessResource_Appache_commons(String url){ String response_String = null; HttpClient client = new HttpClient(); GetMethod method = new GetMethod( url ); // PostMethod method = new PostMethod( url ); method.setRequestHeader("Content-type", "text/xml; charset=ISO-8859-1"); method.setQueryString(new NameValuePair[] { new NameValuePair("param1","value1"), new NameValuePair("param2","value2") }); //The pairs are encoded as UTF-8 characters. try{ int statusCode = client.executeMethod(method); System.out.println("Status Code = "+statusCode); //Get data as a String OR BYTE array method.getResponseBody() response_String = method.getResponseBodyAsString(); method.releaseConnection(); } catch(IOException e) { e.printStackTrace(); } return response_String; } 

Apache使用httpclient.jar

 public static String accessResource_Appache(String url) throws ClientProtocolException, IOException{ try { CloseableHttpClient httpclient = HttpClients.createDefault(); URIBuilder builder = new URIBuilder( url ) .addParameter("param1", "appache1") .addParameter("param2", "appache2"); HttpGet method = new HttpGet( builder.build() ); // HttpPost method = new HttpPost( builder.build() ); // Create a custom response handler ResponseHandler responseHandler = new ResponseHandler() { @Override public String handleResponse( final HttpResponse response) throws IOException { int status = response.getStatusLine().getStatusCode(); if (status >= 200 && status < 300) { HttpEntity entity = response.getEntity(); return entity != null ? EntityUtils.toString(entity) : null; } return ""; } }; return httpclient.execute( method, responseHandler ); } catch (URISyntaxException e) { e.printStackTrace(); } return null; } 

JERSY 使用 JARS {客户端，核心，服务器}

 public static String accessResource_JERSY( String url ){ ClientConfig config = new DefaultClientConfig(); Client client = Client.create(config); WebResource service = client.resource( url ); ClientResponse response = service.accept(MediaType.TEXT_PLAIN).get(ClientResponse.class); if (response.getStatus() != 200) { System.out.println("GET request failed >> "+ response.getStatus()); }else{ String str = response.getEntity(String.class); if(str != null && !str.equalsIgnoreCase("null") && !"".equals(str)){ return str; } } return ""; } 

Java Main方法

 public static void main(String[] args) throws IOException { String targetURL = "http://localhost:8080/ServletApplication/sample"; String urlParameters = "param1=value11&param2=value12"; String response = ""; // java.awt.Desktop.getDesktop().browse(java.net.URI.create( targetURL+"?"+urlParameters )); // response = accessResource_JAVA_IO( "POST", targetURL, urlParameters ); // response = accessResource_Appache_commons( targetURL ); // response = accessResource_Appache( targetURL ); response = accessResource_JERSY( targetURL+"?"+urlParameters ); System.out.println("Response:"+response); } 

Answer 5

你不能这样做。

Web容器将生成响应和请求对。 您无法生成响应对象并发送到浏览器。

顺便说一下您希望获得响应的客户端/浏览器？ 不知道。 对 ？

当容器从客户端收到请求时，它会生成响应对象，并且您可以在服务方法中访问该响应。

如果您想查看/测试响应，则必须从那里请求。