在Android中使用HttpURLConnection重新使用套接字

Question

我想重新使用由HttpURLConnection創建的套接字。但我發現當我調查從遠程Web服務器傳入/傳出的原始數據包時，它始終會創建新的套接字。 以下是我的代碼來訪問我的遠程Web服務器。

public String getFromServer() throws IOException 
{ 
    URL url = new URL("http://192.168.137.2/test.jsp"); 
    HttpURLConnection http = (HttpURLConnection)url.openConnection(); 
    http.setRequestProperty("Content-type", "application/x-www-form-urlencoded;charset=utf8"); 
    http.setRequestProperty("Connection", "keep-alive"); 
    http.setUseCaches(true); 
    http.setFixedLengthStreamingMode(0); 

    http.connect(); 
    InputStream is = http.getInputStream(); 
    BufferedReader in = new BufferedReader(new InputStreamReader(is));  

    int c; 
    StringBuffer buffer =new StringBuffer(); 
    while((c=in.read())!=-1) 
    { 
     buffer.append((char)c); 
    } 
    Log.i("hv","debug3:"+buffer); 
    is.close(); 
    return buffer.toString(); 
} 

然後調用該函數兩次。

try { 
    java.net.CookieManager cookieManager = new java.net.CookieManager(); 
    System.setProperty("http.keepAlive","true"); 
    getFromServer(); 
    getFromServer(); 
} catch (Exception e) { 
    e.printStackTrace(); 
} 

正如你可以看到我的代碼，我刪除服務器IP爲192.168.137.2。而我的設備IP是192.168.3.117。我預料當我嘗試這段代碼時，服務器和設備之間只有一個TCP連接。但是設備中有兩次與不同TCP端口的TCP連接。以下是服務器中的tcpdump日誌。

15:40:01.739295 IP 192.168.3.117.48427 > 192.168.137.2.80: Flags [S], seq 2864255093, win 14600, options [mss 1460,sackOK,TS val 15969200 ecr 0,nop,wscale 6], length 0 
E..<..@.?.r....u.....+.P...u......9............ 
............ 
15:40:01.739322 IP 192.168.137.2.80 > 192.168.3.117.48427: Flags [S.], seq 3335569309, ack 2864255094, win 14480, options [mss 1460,sackOK,TS val 28276944 ecr 15969200,nop,wscale 7], length 0 
..........,........u.P.+.......v..8. 
..x......... 
15:40:01.741673 IP 192.168.3.117.48427 > 192.168.137.2.80: Flags [.], ack 1, win 229, options [nop,nop,TS val 15969202 ecr 28276944], length 0 
E..4..@.?.r5...u.....+.P...v........A...... 
......x. 
15:40:01.742168 IP 192.168.3.117.48427 > 192.168.137.2.80: Flags [P.], seq 1:252, ack 1, win 229, options [nop,nop,TS val 15969203 ecr 28276944], length 251 
E../..@.?.q9...u.....+.P...v............... 
......x.GET /test.jsp HTTP/1.1 
Content-type: application/x-www-form-urlencoded;charset=utf8 
Connection: keep-alive 
User-Agent: Dalvik/1.6.0 (Linux; U; Android 4.0.4; SHV-E210S Build/IMM76D) 
Host: 192.168.137.2 
Accept-Encoding: gzip 
Content-Length: 0 


15:40:01.742193 IP 192.168.137.2.80 > 192.168.3.117.48427: Flags [.], ack 252, win 122, options [nop,nop,TS val 28276945 ecr 15969203], length 0 
......@.@.e........u.P.+.......q...z 
..x..... 
15:40:01.743685 IP 192.168.137.2.80 > 192.168.3.117.48427: Flags [P.], seq 1:396, ack 252, win 122, options [nop,nop,TS val 28276945 ecr 15969203], length 395 
E....P@.@.d .......u.P.+.......q...zQ...... 
..x.....HTTP/1.1 200 OK 
Date: Fri, 15 Feb 2013 06:40:01 GMT 
Set-Cookie: JSESSIONID=AA93F68D2C44CDCAB57554AB70B91058; Path=/ 
Content-Type: text/html;charset=utf8 
Vary: Accept-Encoding 
Content-Encoding: gzip 
Content-Length: 112 
Keep-Alive: timeout=5, max=100 
Connection: Keep-Alive 

.............)I-........I.-*J.+.s+.TpKMR04."+..+.C.....#.Cc.}.*.....R.v......}..(....Z\....j.`.......[.....'}... 
15:40:01.745860 IP 192.168.3.117.48427 > 192.168.137.2.80: Flags [.], ack 396, win 245, options [nop,nop,TS val 15969203 ecr 28276945], length 0 
E..4..@.?.r3...u.....+.P...q...)....?8..... 
......x. 
15:40:01.765863 IP 192.168.3.117.48427 > 192.168.137.2.80: Flags [F.], seq 252, ack 396, win 245, options [nop,nop,TS val 15969207 ecr 28276945], length 0 
E..4..@.?.r2...u.....+.P...q...)....?3..... 
......x. 
15:40:01.765939 IP 192.168.137.2.80 > 192.168.3.117.48427: Flags [F.], seq 396, ack 253, win 122, options [nop,nop,TS val 28276950 ecr 15969207], length 0 
......@.@.e........u.P.+...)...r...z 
..x..... 
15:40:01.768316 IP 192.168.3.117.48427 > 192.168.137.2.80: Flags [.], ack 397, win 245, options [nop,nop,TS val 15969208 ecr 28276950], length 0 
E..4..@.?.r1...u.....+.P...r...*....?,..... 
......x. 
15:40:01.773846 IP 192.168.3.117.40642 > 192.168.137.2.80: Flags [S], seq 343617337, win 14600, options [mss 1460,sackOK,TS val 15969209 ecr 0,nop,wscale 6], length 0 
E..<..@.?..s...u.......P.{/9......9.q.......... 
............ 
15:40:01.773855 IP 192.168.137.2.80 > 192.168.3.117.40642: Flags [S.], seq 2163692151, ack 343617338, win 14480, options [mss 1460,sackOK,TS val 28276952 ecr 15969209,nop,wscale 7], length 0 
..........,........u.P....Rw.{/:..8. 
..x......... 
15:40:01.775312 IP 192.168.3.117.40642 > 192.168.137.2.80: Flags [.], ack 1, win 229, options [nop,nop,TS val 15969209 ecr 28276952], length 0 
E..4..@.?..z...u.......P.{/:..Rx........... 
......x. 
15:40:01.775952 IP 192.168.3.117.40642 > 192.168.137.2.80: Flags [P.], seq 1:305, ack 1, win 229, options [nop,nop,TS val 15969209 ecr 28276952], length 304 
E..d..@.?..I...u.......P.{/:..Rx....}...... 
......x.GET /test.jsp HTTP/1.1 
Content-type: application/x-www-form-urlencoded;charset=utf8 
Connection: keep-alive 
User-Agent: Dalvik/1.6.0 (Linux; U; Android 4.0.4; SHV-E210S Build/IMM76D) 
Host: 192.168.137.2 
Accept-Encoding: gzip 
Cookie: JSESSIONID=AA93F68D2C44CDCAB57554AB70B91058 
Content-Length: 0 
15:40:01.775977 IP 192.168.137.2.80 > 192.168.3.117.40642: Flags [.], ack 305, win 122, options [nop,nop,TS val 28276953 ecr 15969209], length 0 
......@.@..[.......u.P....Rx.{0j...z 
..x..... 
15:40:01.776954 IP 192.168.137.2.80 > 192.168.3.117.40642: Flags [P.], seq 1:332, ack 305, win 122, options [nop,nop,TS val 28276953 ecr 15969209], length 331 
E...*.@.@..........u.P....Rx.{0j...zlq..... 
..x.....HTTP/1.1 200 OK 
Date: Fri, 15 Feb 2013 06:40:01 GMT 
Content-Type: text/html;charset=utf8 
Vary: Accept-Encoding 
Content-Encoding: gzip 
Content-Length: 113 
Keep-Alive: timeout=5, max=100 
Connection: Keep-Alive 

.............)I-........I.-*J.+.s+.TpKMR04."+..+.C.....#.Cc.}.*.....R.v......}..(....Z\....j..`...........~..~... 
15:40:01.778945 IP 192.168.3.117.40642 > 192.168.137.2.80: Flags [.], ack 332, win 245, options [nop,nop,TS val 15969210 ecr 28276953], length 0 
E..4..@.?..x...u.......P.{0j..S............ 
......x. 
15:40:01.781966 IP 192.168.3.117.40642 > 192.168.137.2.80: Flags [F.], seq 305, ack 332, win 245, options [nop,nop,TS val 15969210 ecr 28276953], length 0 
E..4..@.?..w...u.......P.{0j..S............ 
......x. 
15:40:01.782049 IP 192.168.137.2.80 > 192.168.3.117.40642: Flags [F.], seq 332, ack 306, win 122, options [nop,nop,TS val 28276955 ecr 15969210], length 0 
......@.@..Y.......u.P....S..{0k...z 
..x..... 
15:40:01.783749 IP 192.168.3.117.40642 > 192.168.137.2.80: Flags [.], ack 333, win 245, options [nop,nop,TS val 15969211 ecr 28276955], length 0 
E..4..@.?..v...u.......P.{0k..S............ 
......x. 

在第一次連接時，TCP端口48427用於連接服務器。在下一次，我希望重新使用TCP套接字，但是，TCP連接新創建與TCP端口40642.有什麼我想念重新使用套接字？

ADD： 我在tcpdump日誌中發現了一些不期望的行爲。 Web服務器發送HTML頁面中的'Keep-Alive：timeout = 5，max = 100'和'Connection：Keep-Alive'選項。 但是，設備立即發送FIN而無需等待5秒鐘。我懷疑設備可能無法解析保持活動或超時選項。我使用Android 4.0.4在Galaxy S3中測試了這些代碼。

Answer 1

看起來像這是Android中的一個錯誤。 Keep-Alive不適用於gzip內容。

https://code.google.com/p/android/issues/detail?id=43132