Опитвам се да науча как да използвам Apache HttpComponents за изпращане на HttpResponse. Намерих някои примери на сайта на Apache, но те са много объркващи и неясни .
В кода по-долу не мога да видя къде се генерира HttpResponse и се изпраща обратно на клиента. След проследяване на кода изглежда, че трябва да се случва в метода handle() на класа HttpFileHandler, но не е ясно къде. Класът просто завършва с
...
response.setEntity(body);
System.out.println("File " + file.getPath() + " not found");
...
без реално изпращане на отговора. Завършва с настройка на Entity.
Къде всъщност се случва изпращането на отговора обратно към клиента в този код?
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package org.apache.http.examples;
import java.io.File;
import java.io.IOException;
import java.io.InterruptedIOException;
import java.io.OutputStream;
import java.io.OutputStreamWriter;
import java.net.ServerSocket;
import java.net.Socket;
import java.net.URLDecoder;
import java.util.Locale;
import org.apache.http.ConnectionClosedException;
import org.apache.http.HttpEntity;
import org.apache.http.HttpEntityEnclosingRequest;
import org.apache.http.HttpException;
import org.apache.http.HttpRequest;
import org.apache.http.HttpResponse;
import org.apache.http.HttpResponseInterceptor;
import org.apache.http.HttpServerConnection;
import org.apache.http.HttpStatus;
import org.apache.http.MethodNotSupportedException;
import org.apache.http.entity.ContentProducer;
import org.apache.http.entity.EntityTemplate;
import org.apache.http.entity.FileEntity;
import org.apache.http.impl.DefaultConnectionReuseStrategy;
import org.apache.http.impl.DefaultHttpResponseFactory;
import org.apache.http.impl.DefaultHttpServerConnection;
import org.apache.http.params.CoreConnectionPNames;
import org.apache.http.params.CoreProtocolPNames;
import org.apache.http.params.HttpParams;
import org.apache.http.params.SyncBasicHttpParams;
import org.apache.http.protocol.BasicHttpContext;
import org.apache.http.protocol.HttpContext;
import org.apache.http.protocol.HttpProcessor;
import org.apache.http.protocol.HttpRequestHandler;
import org.apache.http.protocol.HttpRequestHandlerRegistry;
import org.apache.http.protocol.HttpService;
import org.apache.http.protocol.ImmutableHttpProcessor;
import org.apache.http.protocol.ResponseConnControl;
import org.apache.http.protocol.ResponseContent;
import org.apache.http.protocol.ResponseDate;
import org.apache.http.protocol.ResponseServer;
import org.apache.http.util.EntityUtils;
/**
* Basic, yet fully functional and spec compliant, HTTP/1.1 file server.
* <p>
* Please note the purpose of this application is demonstrate the usage of
* HttpCore APIs. It is NOT intended to demonstrate the most efficient way of
* building an HTTP file server.
*
*
*/
public class ElementalHttpServer {
public static void main(String[] args) throws Exception {
args = new String[] { "e:/tutoring/236369/Tutorials/httpCoreExamples/" };
if (args.length < 1) {
System.err.println("Please specify document root directory");
System.exit(1);
}
Thread t = new RequestListenerThread(8080, args[0]);
t.setDaemon(false);
t.start();
}
static class HttpFileHandler implements HttpRequestHandler {
private final String docRoot;
public HttpFileHandler(final String docRoot) {
super();
this.docRoot = docRoot;
}
@Override
public void handle(final HttpRequest request,
final HttpResponse response, final HttpContext context)
throws HttpException, IOException {
String method = request.getRequestLine().getMethod()
.toUpperCase(Locale.ENGLISH);
if (!method.equals("GET") && !method.equals("HEAD")
&& !method.equals("POST")) {
throw new MethodNotSupportedException(method
+ " method not supported");
}
String target = request.getRequestLine().getUri();
if (request instanceof HttpEntityEnclosingRequest) {
HttpEntity entity = ((HttpEntityEnclosingRequest) request)
.getEntity();
byte[] entityContent = EntityUtils.toByteArray(entity);
System.out.println("Incoming entity content (bytes): "
+ entityContent.length);
}
final File file = new File(this.docRoot, URLDecoder.decode(target));
if (!file.exists()) {
response.setStatusCode(HttpStatus.SC_NOT_FOUND);
EntityTemplate body = new EntityTemplate(new ContentProducer() {
@Override
public void writeTo(final OutputStream outstream)
throws IOException {
OutputStreamWriter writer = new OutputStreamWriter(
outstream, "UTF-8");
writer.write("<html><body><h1>");
writer.write("File ");
writer.write(file.getPath());
writer.write(" not found");
writer.write("</h1></body></html>");
writer.flush();
}
});
body.setContentType("text/html; charset=UTF-8");
response.setEntity(body);
System.out.println("File " + file.getPath() + " not found");
} else if (!file.canRead() || file.isDirectory()) {
response.setStatusCode(HttpStatus.SC_FORBIDDEN);
EntityTemplate body = new EntityTemplate(new ContentProducer() {
@Override
public void writeTo(final OutputStream outstream)
throws IOException {
OutputStreamWriter writer = new OutputStreamWriter(
outstream, "UTF-8");
writer.write("<html><body><h1>");
writer.write("Access denied");
writer.write("</h1></body></html>");
writer.flush();
}
});
body.setContentType("text/html; charset=UTF-8");
response.setEntity(body);
System.out.println("Cannot read file " + file.getPath());
} else {
response.setStatusCode(HttpStatus.SC_OK);
FileEntity body = new FileEntity(file, "text/html");
response.setEntity(body);
System.out.println("Serving file " + file.getPath());
}
}
}
static class RequestListenerThread extends Thread {
private final ServerSocket serversocket;
private final HttpParams params;
private final HttpService httpService;
public RequestListenerThread(int port, final String docroot)
throws IOException {
this.serversocket = new ServerSocket(port);
this.params = new SyncBasicHttpParams();
this.params
.setIntParameter(CoreConnectionPNames.SO_TIMEOUT, 5000)
.setIntParameter(CoreConnectionPNames.SOCKET_BUFFER_SIZE,
8 * 1024)
.setBooleanParameter(
CoreConnectionPNames.STALE_CONNECTION_CHECK, false)
.setBooleanParameter(CoreConnectionPNames.TCP_NODELAY, true)
.setParameter(CoreProtocolPNames.ORIGIN_SERVER,
"HttpComponents/1.1");
// Set up the HTTP protocol processor
HttpProcessor httpproc = new ImmutableHttpProcessor(
new HttpResponseInterceptor[] { new ResponseDate(),
new ResponseServer(), new ResponseContent(),
new ResponseConnControl() });
// Set up request handlers
HttpRequestHandlerRegistry reqistry = new HttpRequestHandlerRegistry();
reqistry.register("*", new HttpFileHandler(docroot));
// Set up the HTTP service
this.httpService = new HttpService(httpproc,
new DefaultConnectionReuseStrategy(),
new DefaultHttpResponseFactory(), reqistry, this.params);
}
@Override
public void run() {
System.out.println("Listening on port "
+ this.serversocket.getLocalPort());
while (!Thread.interrupted()) {
try {
// Set up HTTP connection
Socket socket = this.serversocket.accept();
DefaultHttpServerConnection conn = new DefaultHttpServerConnection();
System.out.println("Incoming connection from "
+ socket.getInetAddress());
conn.bind(socket, this.params);
// Start worker thread
Thread t = new WorkerThread(this.httpService, conn);
t.setDaemon(true);
t.start();
} catch (InterruptedIOException ex) {
break;
} catch (IOException e) {
System.err
.println("I/O error initialising connection thread: "
+ e.getMessage());
break;
}
}
}
}
static class WorkerThread extends Thread {
private final HttpService httpservice;
private final HttpServerConnection conn;
public WorkerThread(final HttpService httpservice,
final HttpServerConnection conn) {
super();
this.httpservice = httpservice;
this.conn = conn;
}
@Override
public void run() {
System.out.println("New connection thread");
HttpContext context = new BasicHttpContext(null);
try {
while (!Thread.interrupted() && this.conn.isOpen()) {
this.httpservice.handleRequest(this.conn, context);
}
} catch (ConnectionClosedException ex) {
System.err.println("Client closed connection");
} catch (IOException ex) {
System.err.println("I/O error: " + ex.getMessage());
} catch (HttpException ex) {
System.err.println("Unrecoverable HTTP protocol violation: "
+ ex.getMessage());
} finally {
try {
this.conn.shutdown();
} catch (IOException ignore) {
}
}
}
}
}
