Android分別使用HTTP協議和TCP協議實現上傳文件

Android上傳文件有兩種方式，第一種是基於Http協議的HttpURLConnection，第二種是基於TCP協議的Socket。 這兩種方式的區別是使用HttpURLConnection上傳時內部有緩存機制，如果上傳較大文件會導致內存溢出。如果用TCP協議Socket方式上傳就會解決這種弊端。

HTTP協議HttpURLConnection

1. 通過URL封裝路徑打開一個HttpURLConnection

2.設置請求方式以及頭字段：Content-Type、Content-Length、Host

3.拼接數據發送

示例：

1. private static final String BOUNDARY = "---------------------------7db1c523809b2";//數據分割線
3. public boolean uploadHttpURLConnection(String username, String password, String path) throws Exception {
4. //找到sdcard上的文件
5. File file = new File(Environment.getExternalStorageDirectory(), path);
6. //仿Http協議發送數據方式進行拼接
7. StringBuilder sb = new StringBuilder();
8. sb.append("--" + BOUNDARY + "\r\n");
9. sb.append("Content-Disposition: form-data; name=\"username\"" + "\r\n");
10. sb.append("\r\n");
11. sb.append(username + "\r\n");
13. sb.append("--" + BOUNDARY + "\r\n");
14. sb.append("Content-Disposition: form-data; name=\"password\"" + "\r\n");
15. sb.append("\r\n");
16. sb.append(password + "\r\n");
18. sb.append("--" + BOUNDARY + "\r\n");
19. sb.append("Content-Disposition: form-data; name=\"file\"; filename=\"" + path + "\"" + "\r\n");
20. sb.append("Content-Type: image/pjpeg" + "\r\n");
21. sb.append("\r\n");
23. byte[] before = sb.toString().getBytes("UTF-8");
24. byte[] after = ("\r\n--" + BOUNDARY + "--\r\n").getBytes("UTF-8");
26. URL url = new URL("http://192.168.1.16:8080/14_Web/servlet/LoginServlet");
27. HttpURLConnection conn = (HttpURLConnection) url.openConnection();
28. conn.setRequestMethod("POST");
29. conn.setRequestProperty("Content-Type", "multipart/form-data; boundary=" + BOUNDARY);
30. conn.setRequestProperty("Content-Length", String.valueOf(before.length + file.length() + after.length));
31. conn.setRequestProperty("HOST", "192.168.1.16:8080");
32. conn.setDoOutput(true);
34. OutputStream out = conn.getOutputStream();
35. InputStream in = new FileInputStream(file);
37. out.write(before);
39. byte[] buf = new byte[1024];
40. int len;
41. while ((len = in.read(buf)) != -1)
42. out.write(buf, 0, len);
44. out.write(after);
46. in.close();
47. out.close();
48. return conn.getResponseCode() == 200;
49. }

TCP協議Socket

1.我們可以使用Socket發送TCP請求，將上傳數據分段發送

示例：

1. public boolean uploadBySocket(String username, String password, String path) throws Exception {
2. // 根據path找到SDCard中的文件
3. File file = new File(Environment.getExternalStorageDirectory(), path);
4. // 組裝表單字段和文件之前的數據
5. StringBuilder sb = new StringBuilder();
7. sb.append("--" + BOUNDARY + "\r\n");
8. sb.append("Content-Disposition: form-data; name=\"username\"" + "\r\n");
9. sb.append("\r\n");
10. sb.append(username + "\r\n");
12. sb.append("--" + BOUNDARY + "\r\n");
13. sb.append("Content-Disposition: form-data; name=\"password\"" + "\r\n");
14. sb.append("\r\n");
15. sb.append(password + "\r\n");
17. sb.append("--" + BOUNDARY + "\r\n");
18. sb.append("Content-Disposition: form-data; name=\"file\"; filename=\"" + path + "\"" + "\r\n");
19. sb.append("Content-Type: image/pjpeg" + "\r\n");
20. sb.append("\r\n");
22. // 文件之前的數據
23. byte[] before = sb.toString().getBytes("UTF-8");
24. // 文件之後的數據
25. byte[] after = ("\r\n--" + BOUNDARY + "--\r\n").getBytes("UTF-8");
27. URL url = new URL("http://192.168.1.199:8080/14_Web/servlet/LoginServlet");
29. // 由於HttpURLConnection中會緩存數據, 上傳較大文件時會導致內存溢出, 所以我們使用Socket傳輸
30. Socket socket = new Socket(url.getHost(), url.getPort());
31. OutputStream out = socket.getOutputStream();
32. PrintStream ps = new PrintStream(out, true, "UTF-8");
34. // 寫出請求頭
35. ps.println("POST /14_Web/servlet/LoginServlet HTTP/1.1");
36. ps.println("Content-Type: multipart/form-data; boundary=" + BOUNDARY);
37. ps.println("Content-Length: " + String.valueOf(before.length + file.length() + after.length));
38. ps.println("Host: 192.168.1.199:8080");
40. InputStream in = new FileInputStream(file);
42. // 寫出數據
43. out.write(before);
45. byte[] buf = new byte[1024];
46. int len;
47. while ((len = in.read(buf)) != -1)
48. out.write(buf, 0, len);
50. out.write(after);
52. in.close();
53. out.close();
55. return true;
56. }