[英]Invoking servlet from java main method
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,浏览器一旦被调用就必须在其中执行。
我是否缺少此过程的任何基本步骤? 请帮忙!!!
如果要在浏览器中打开它,请尝试此操作
java.awt.Desktop.getDesktop().browse(java.net.URI.create("http://localhost:8080/WeighPro/CommPortSample"));
您的问题不清楚。 您实际上是要从Main方法调用Servlet,还是要向Web应用程序发出HTTP请求?
如果您要发出HTTP请求,则上面的代码看不到任何明显的问题,这使我相信问题出在Servlet中。 您还提到,浏览器中什么也没有,但是在上面运行程序并不涉及浏览器。
您的意思是说您去时没有得到回应
http://localhost:8080/WeighPro/CommPortSample
在浏览器中?
正如Suresh所说,您不能直接从main方法调用Servlet。 相反,您的Servlet应该在其他类上调用方法,并且这些其他类应该可以从main方法或Test Cases中调用。 您需要设计您的应用程序以使其成为可能。
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();
}
}
}
调用带有查询参数的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;
}
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<String> responseHandler = new ResponseHandler<String>() {
@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,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¶m2=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);
}
简直你做不到。
Web容器将生成一个响应和请求对。 您无法生成响应对象并发送到浏览器。
您期望通过哪个客户端/浏览器获得响应? 不知道。 对 ?
当容器收到来自客户端的请求时,它将生成响应对象并为您提供服务,您可以使用服务方法访问该响应。
如果要查看/测试响应,则必须从那里进行请求。
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