Android之利用NanoHttpd搭建伺服器

NanoHttpd是一個開源庫，使用Java實現，可以在非常方便地整合到Android應用中去，實現了一個輕量級的 Web Server。

專案地址： https://github.com/NanoHttpd/nanohttpd

使用方法：在下面下載連結中下載nanohttpd-2.2.0.jar匯入到Android專案中的libs目錄下。

https://github.com/NanoHttpd/nanohttpd/releases

在介紹使用NanoHttpd實現簡易WebServer之前，我們首先熟悉下區域網Socket通訊。一個Client工程，程式碼地址為https://github.com/jltxgcy/AppVulnerability/tree/master/MyClient。一個Server工程，程式碼地址為https://github.com/jltxgcy/AppVulnerability/tree/master/MyServer。

兩個工程要在要同樣的Wifi環境下，MyClient工程要修改連線目標的IP地址。如下：

clientSocket = new Socket("10.10.154.74",6100);
這個IP地址可以通過設定->關於手機->狀態資訊->IP地址獲取。如下圖：

具體的程式碼就不介紹了，大家自己分析。

0x01

下面介紹使用NanoHttpd實現簡易WebServer。程式碼地址為https://github.com/jltxgcy/AppVulnerability/tree/master/NanoHttpD。

執行NanoHttpD後，在本機的UC瀏覽器輸入http://127.0.0.1:8088，會返回it works。在其他連線相同wifi的手機瀏覽器上輸入http://10.10.154.12(也就是執行NanoHttpD的手機IP)，也會出現it works。

那麼這個本地webServer是什麼原理呢？

我們先看主Activity，程式碼如下：

public class MainActivity extends Activity {

   private SimpleServer server;
   @Override
   protected void onCreate(Bundle savedInstanceState) {
       super.onCreate(savedInstanceState);
       setContentView(R.layout.activity_main);

       server = new SimpleServer();
       try {

           // 因為程式模擬的是html放置在asset目錄下，
           // 所以在這裡儲存一下AssetManager的指標。
           server.asset_mgr = this.getAssets();

           // 啟動web服務
           server.start();

           Log.i("Httpd", "The server started.");
       } catch(IOException ioe) {
       Log.w("Httpd", "The server could not start.");
       }
   }
......
}
   建立了SimpleServer物件，然後呼叫了它的start方法。我們來看SimpleServer類的程式碼：

public class SimpleServer extends NanoHTTPD {
   AssetManager asset_mgr;

public SimpleServer() {
   // 埠是8088，也就是說要通過http://127.0.0.1:8088來訪當問
super(8088);
}

public Response serve(String uri, Method method,
Map<String, String> header,
Map<String, String> parameters,
Map<String, String> files)
{
int len = 0;
       byte[] buffer = null;
       Log.d("jltxgcy", header.get("remote-addr"));

       // 預設傳入的url是以“/”開頭的，需要刪除掉，否則就變成了絕對路徑
   String file_name = uri.substring(1);

   // 預設的頁面名稱設定為index.html
   if(file_name.equalsIgnoreCase("")){
       file_name = "index.html";
   }

   try {

       //通過AssetManager直接開啟檔案進行讀取操作
           InputStream in = asset_mgr.open(file_name, AssetManager.ACCESS_BUFFER);

           //假設單個網頁檔案大小的上限是1MB
          buffer = new byte[1024*1024];

          int temp=0;
   while((temp=in.read())!=-1){
       buffer[len]=(byte)temp;
   len++;
   }
       in.close();
       } catch (IOException e) {
           // TODO Auto-generated catch block
           e.printStackTrace();
       }

   // 將讀取到的檔案內容返回給瀏覽器
return new NanoHTTPD.Response(new String(buffer,0,len));

}
}
    SimpleServer繼承了NanoHTTPD，server.start()實際上呼叫NanoHTTPD類的start方法。如下：

public void start() throws IOException {
myServerSocket = new ServerSocket();
myServerSocket.bind((hostname != null) ? new InetSocketAddress(hostname, myPort) : new InetSocketAddress(myPort));

myThread = new Thread(new Runnable() {
@Override
public void run() {
do {
try {
final Socket finalAccept = myServerSocket.accept();
registerConnection(finalAccept);
finalAccept.setSoTimeout(SOCKET_READ_TIMEOUT);
final InputStream inputStream = finalAccept.getInputStream();
if (inputStream == null) {
safeClose(finalAccept);
unRegisterConnection(finalAccept);
} else {
asyncRunner.exec(new Runnable() {
@Override
public void run() {
OutputStream outputStream = null;
try {
outputStream = finalAccept.getOutputStream();
TempFileManager tempFileManager = tempFileManagerFactory.create();
HTTPSession session = new HTTPSession(tempFileManager, inputStream, outputStream, finalAccept.getInetAddress());
while (!finalAccept.isClosed()) {
session.execute();
}
} catch (Exception e) {
// When the socket is closed by the client, we throw our own SocketException
// to break the "keep alive" loop above.
if (!(e instanceof SocketException && "NanoHttpd Shutdown".equals(e.getMessage()))) {
e.printStackTrace();
}
} finally {
safeClose(outputStream);
safeClose(inputStream);
safeClose(finalAccept);
unRegisterConnection(finalAccept);
}
}
});
}
} catch (IOException e) {
}
} while (!myServerSocket.isClosed());
}
});
myThread.setDaemon(true);
myThread.setName("NanoHttpd Main Listener");
myThread.start();
}
建立了一個Socket Server，myServerSocket.accept()阻塞等待連線，當在本機瀏覽器輸入http://127.0.0.1:8088，建立連線，接下來去處理這個連線，myThread執行緒會繼續執行到session.execute。我們來看那這個函式的程式碼：

@Override
public void execute() throws IOException {
try {
// Read the first 8192 bytes.
// The full header should fit in here.
// Apache's default header limit is 8KB.
// Do NOT assume that a single read will get the entire header at once!
byte[] buf = new byte[BUFSIZE];
splitbyte = 0;
rlen = 0;
{
int read = -1;
try {
read = inputStream.read(buf, 0, BUFSIZE);
} catch (Exception e) {
safeClose(inputStream);
safeClose(outputStream);
throw new SocketException("NanoHttpd Shutdown");
}
if (read == -1) {
// socket was been closed
safeClose(inputStream);
safeClose(outputStream);
throw new SocketException("NanoHttpd Shutdown");
}
while (read > 0) {
rlen += read;
splitbyte = findHeaderEnd(buf, rlen);
if (splitbyte > 0)
break;
read = inputStream.read(buf, rlen, BUFSIZE - rlen);
}
}

if (splitbyte < rlen) {
ByteArrayInputStream splitInputStream = new ByteArrayInputStream(buf, splitbyte, rlen - splitbyte);
SequenceInputStream sequenceInputStream = new SequenceInputStream(splitInputStream, inputStream);
inputStream = sequenceInputStream;
}

parms = new HashMap<String, String>();
if(null == headers) {
headers = new HashMap<String, String>();
}

// Create a BufferedReader for parsing the header.
BufferedReader hin = new BufferedReader(new InputStreamReader(new ByteArrayInputStream(buf, 0, rlen)));

// Decode the header into parms and header java properties
Map<String, String> pre = new HashMap<String, String>();
decodeHeader(hin, pre, parms, headers);

method = Method.lookup(pre.get("method"));
if (method == null) {
throw new ResponseException(Response.Status.BAD_REQUEST, "BAD REQUEST: Syntax error.");
}

uri = pre.get("uri");

cookies = new CookieHandler(headers);

// Ok, now do the serve()
Response r = serve(this);
if (r == null) {
throw new ResponseException(Response.Status.INTERNAL_ERROR, "SERVER INTERNAL ERROR: Serve() returned a null response.");
} else {
cookies.unloadQueue(r);
r.setRequestMethod(method);
r.send(outputStream);
}
} catch (SocketException e) {
// throw it out to close socket object (finalAccept)
throw e;
} catch (SocketTimeoutException ste) {
   throw ste;
} catch (IOException ioe) {
Response r = new Response(Response.Status.INTERNAL_ERROR, MIME_PLAINTEXT, "SERVER INTERNAL ERROR: IOException: " + ioe.getMessage());
r.send(outputStream);
safeClose(outputStream);
} catch (ResponseException re) {
Response r = new Response(re.getStatus(), MIME_PLAINTEXT, re.getMessage());
r.send(outputStream);
safeClose(outputStream);
} finally {
tempFileManager.clear();
}
}
    這個函式解析http://127.0.0.1:8088(資料來源於finalAccept.getInputStream())，然後呼叫了SimpleServer的serve方法，這個server方法返回的就是顯示在瀏覽器中的內容。
    我們根據除錯，看一下public Response serve(String uri, Method method, Map<String, String> header, Map<String, String> parameters, Map<String, String> files)，這些引數返回的值到底是多少？

url為/，method為GET，head為{accept=text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8,UC/145,plugin/1,alipay/un, accept-encoding=gzip, host=127.0.0.1:8088, accept-language=zh-CN, http-client-ip=127.0.0.1, cache-control=max-age=0, x-ucbrowser-ua=dv(Nexus 6);pr(UCBrowser/10.7.0.634);ov(Android 5.1.1);ss(411*683);pi(1440*2392);bt(UM);pm(1);bv(1);nm(0);im(0);sr(0);nt(2);, remote-addr=127.0.0.1, user-agent=Mozilla/5.0 (Linux; U; Android 5.1.1; zh-CN; Nexus 6 Build/LMY47Z) AppleWebKit/534.30 (KHTML, like Gecko) Version/4.0 UCBrowser/10.7.0.634 U3/0.8.0 Mobile Safari/534.30, connection=keep-alive}，parameters為{NanoHttpd.QUERY_STRING=null}，files為{}。

如果請求的地址為http://127.0.0.1:8088/adv?d=1，則url為adv，parameter為{d=1, NanoHttpd.QUERY_STRING=d=1}。

---------------------
作者：jltxgcy
來源：CSDN
原文：https://blog.csdn.net/jltxgcy/article/details/50680394
版權宣告：本文為博主原創文章，轉載請附上博文連結！

Android之利用NanoHttpd搭建伺服器

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