Android版Web服务器实现(三)HTTP响应

《Android版Web服务器实现(二)使用服务来监听HTTP请求》一文实现了HTTP请求的监听，那么我们要如何作出响应呢？在响应时，有几种情况。

1、请求的方法不支持。比如服务端仅支持了GET/POST方法，而请求却有DELETE等，此时回复501。

2、请求的资源不存在。在服务端不存在该资源文件，将回复404页面。

3、请求的类型不支持。服务端可能存在该资源，但是该资源的类型没有支持，将回复404.7。

4、请求正常。服务端将相应的资源回复给客户端。

5、其他情况。

下面是依据这些情况的代码实现。

SessionThread.java

package com.sparkle.webservice;

import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.net.Socket;

import android.util.Log;

public class SessionThread extends Thread {

	private Socket _clientSocket = null;
	private final int BUFFER_MAX = 8192;
	private DataHandle _dataHandle = null;
	private MyLog _myLog = new MyLog(getClass().getName());

	public SessionThread(Socket clientSocket) {
		this._clientSocket = clientSocket;
	}

	public void closeSocket() {
		if (_clientSocket == null) {
			return;
		}
		try {
			_clientSocket.close();
		} catch (IOException e) {
			_myLog.e(e.getMessage());
		}
	}

	public void run() {
		try {

			InputStream socketInput = _clientSocket.getInputStream();
			byte[] buffer = new byte[BUFFER_MAX];
			socketInput.read(buffer);
			_dataHandle = new DataHandle(buffer);
			byte[] content = _dataHandle.fetchContent();

			sendResponse(_clientSocket, content);

		} catch (Exception e) {
			_myLog.l(Log.DEBUG, "Exception in TcpListener");
		}
	}

	private void sendResponse(Socket clientSocket, byte[] content) {
		try {
			OutputStream socketOut = clientSocket.getOutputStream();

			byte[] header = _dataHandle.fetchHeader(content.length);

			socketOut.write(header);
			socketOut.write(content);

			socketOut.close();
			clientSocket.close();
		} catch (Exception e) {
		}
	}

}

注：

1、在收到请求后，新建一个SessionThread来处理请求（在上一篇中有说到）。

2、SessionThread建立后，在run中新建DataHandle来处理数据，具体请参看后文代码。

3、在sendResponse来回应请求。

4、在响应时，先发送header，再发送content来响应

DataHandle.java

package com.sparkle.webservice;

import java.io.UnsupportedEncodingException;

import com.sparkle.io.FileSp;

import android.annotation.SuppressLint;
import android.util.Log;

public class DataHandle {

	private String _receiveInfo = "";
	private HttpHeader _httpHeader = null;
	private String _encoding = "utf-8";
	private String _serverName = "Simple Web Server";
	private String _responseCode = "200 OK";
	private String _contentType = "text/html";

	public DataHandle(byte[] recieveData) {
		try {
			this._receiveInfo = new String(recieveData, _encoding);
		} catch (UnsupportedEncodingException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}
		_httpHeader = new HttpHeader(_receiveInfo);
	}

	public byte[] fetchContent() {
		byte[] backData = null;
		if (!isSupportMethod()) {
			backData = fetchNotSupportMethodBack();
			return backData;
		}

		String filePath = fetchFilePath();
		boolean hasFile=FileSp.isExist(filePath);
		Log.e("FilePath", filePath+"   "+hasFile);
		if (!hasFile) {
			backData = fetchNotFoundBack();
			return backData;
		}

		if (!isSupportExtension()) {
			backData = fetchNotSupportFileBack();
			return backData;
		}

		backData = fetchBackFromFile(filePath);
		return backData;
	}

	public byte[] fetchHeader(int contentLength) {
		byte[] header = null;
		try {
			header = ("HTTP/1.1 " + _responseCode + "
" 
					+ "Server: "+ _serverName + "
" 
					+ "Content-Length: " + contentLength+ "
"
					+ "Connection: close
" 
					+ "Content-Type: "+ _contentType + ";charset="+_encoding+"

").getBytes(_encoding);
		} catch (UnsupportedEncodingException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}
		return header;
	}

	@SuppressLint("DefaultLocale")
	private boolean isSupportMethod() {
		String method = _httpHeader.getMethod();
		if (method == null || method.length() <= 0) {
			return false;
		}
		method = method.toUpperCase();
		if (method.equals("GET") || method.equals("POST")) {
			return true;
		}

		return false;
	}

	private boolean isSupportExtension() {
		String contentType = _httpHeader.getContentType();
		if (contentType == null || contentType.length() <= 0) {
			return false;
		}
		_contentType=contentType;
		return true;
	}

	private byte[] fetchNotSupportMethodBack() {
		byte[] backData = null;
		String notImplementMethod = "<html><head><meta http-equiv="Content-Type" content="text/html; charset=utf-8"></head><body><h2>"
				+ _serverName
				+ "</h2><div>501 - Method Not Implemented</div></body></html>";
		try {
			backData = notImplementMethod.getBytes(_encoding);
		} catch (UnsupportedEncodingException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}
		return backData;
	}

	private byte[] fetchNotSupportFileBack() {
		byte[] backData = null;
		String notImplementMethod = "<html><head><meta http-equiv="Content-Type" content="text/html; charset=utf-8"></head><body><h2>"
				+ _serverName
				+ "</h2><div>404.7 Not Found(Type Not Support)</div></body></html>";
		try {
			backData = notImplementMethod.getBytes(_encoding);
		} catch (UnsupportedEncodingException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}
		return backData;
	}

	private byte[] fetchBackFromFile(String filePath) {

		byte[] content = null;

		content = FileSp.read(filePath);
		return content;
	}

	private String fetchFilePath() {
		String root = Defaults.getRoot();
	
		String fileName = _httpHeader.getFileName();
		String filePath = "";

		if (fileName.startsWith("/") || fileName.startsWith("\")) {
			filePath = root + fileName.substring(1);
		} else {
			filePath = root + fileName;
		}

		return filePath;
	}

	private byte[] fetchNotFoundBack() {
		byte[] notFoundData = null;
		String notFoundStr = "<html><head><meta http-equiv="Content-Type" content="text/html; charset=utf-8"></head><body><h2>"
				+ _serverName + "</h2><div>404 - Not Found</div></body></html>";
		try {
			notFoundData = notFoundStr.getBytes(_encoding);
		} catch (UnsupportedEncodingException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}
		return notFoundData;
	}
}

注：

1、isSupportMethod判断是否是支持的方法，如果不支持，从fetchNotSupportMethodBack获取数据进行响应。

2、判断请求的资源是否存在，如果不存在，从fetchNotFoundBack获取数据进行响应。

3、isSupportExtension判断是否是支持的数据类型，如果不支持，从fetchNotSupportFileBack获取数据进行响应。

4、请求方法支持、请求资源存在，且请求类型支持，将从fetchBackFromFile获取数据进行响应。

在对HTTP作出相应的响应之后，现在就剩下如果在界面中实现相应的控制了，具体请看下一篇。

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