我正在尝试学习如何使用Apache HttpComponents发送HttpResponse。我在Apache网站上找到了some examples但是它们非常令人困惑且不清楚。
在下面的代码中，我看不到生成HttpResponse的位置并将其发送回客户端。在代码中跟随之后，似乎必须在HttpFileHandler类的handle()方法中进行，但不清楚在哪里。该课程以
...
response.setEntity(body);
System.out.println("File " + file.getPath() + " not found");
...
没有实际发送回复。最后设置Entity。
在此代码中，将响应发送回客户端的位置实际上在哪里？
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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) {
}
}
}
}
}
答案 0 :(得分：2)
您正在此处运行服务器。
＆＃34;谈论HTTP＆＃34;的通用代码已经由图书馆实施。
您只需插入＆＃34;业务逻辑＆＃34; （以HTTPRequestHandler的形式）。
您的业务逻辑＆＃34;获取HTTPResponse的实例作为参数。该库已为您创建此对象。您可以设置参数并将数据写入。
当你的处理程序方法返回时（或甚至在你操作响应对象之前），库会负责通过网络获取数据。
在此代码中，将响应发送回客户端的位置实际上在哪里？
作为方法handle的结果，响应对象现在包含一个可以写出文件的内部类的实体。将调用该代码来发送数据。
在代码中放置断点并逐步执行（包括句柄返回后的部分）以查看控制流可能是有益的（或可能是压倒性的）。