什麽是Socket?

所謂Socket通常也稱作“套接字”，用於描述IP地址和端口，是一個通信連的句柄，應用程序通常通過“套接字”向網絡發送請求或者應答網絡請求，它就是網絡通信過程中端點的抽象表示。它主要包括以下兩個協議：

TCP (Transmission Control Protocol 傳輸控制協議)：傳輸控制協議,提供的是面向連接、可靠的字節流服務。當客戶和服務器彼此交換數據前，必須先在雙方之間建立一個TCP連接，之後才能傳輸數據。TCP提供超時重發，丟棄重復數據，檢驗數據，流量控制等功能，保證數據能從一端傳到另一端。

詳細解說如下:

TCP傳輸和UDP不一樣，TCP傳輸是流式的，必須先建立連接，然後數據流沿已連接的線路(虛電路)傳輸。因此TCP的數據流不會像UDP數據報一樣，每個數據報都要包含目標地址和端口，因為每個數據報要單獨路由。TCP傳輸則只需要在建立連接時指定目標地址和端口就可以了。

　　形象的講，TCP就像打電話，UDP就像發電報。宏觀上來看UDP是不分客戶端和服務端的。通信雙方是平等的。微觀上來講只相對一個報文，發送端是客戶端，監聽端是服務端。發送端把數據報發給路由器就像把電報發給了郵局，後面的事情就是發送者無法控制，也無從知曉的了。所以說是不可靠的，可能會出現報文丟失而無從知曉。就像每張電報都要有收件人一樣，每個數據報都要有目的地址和端口。

　　而TCP每次連接都是分客戶端和服務端的。連接的發起者(相當與撥號打電話的人)是客戶端，監聽者(相當於在電話邊等著接電話的人)是服務端。發起者指定要連接的服務器地址和端口(相當於撥號)，監聽者通過和發起者三次握手建立連接(相當於聽到電話響去接電話)。建立連接後雙方可以互相發送和接受數據(打電話)。

Java如何操作Socket?

值得一提的是，Java分別為TCP和UDP提供了相應的類,TCP是java.NET中提供了兩個類Socket和ServerSocket，分別用來表示雙向連接的客戶端和服務端。這是兩個封裝得非常好的類，使用起來很方便！UDP是java.net.DatagramSocket.

127.0.0.1是回路地址,用於測試,相當於localhost本機地址,沒有網卡,不設DNS都可以訪問,端口地址在0~65535之間,其中0~1023之間的端口是用於一些知名的網絡服務和應用,用戶的普通網絡應用程序應該使用1024以上的端口.

Socket通信模型如下：

如果大家對Java Socket編程還有模糊的地方抓緊溫習(http://blog.csdn.net/shimiso/article/details/8529941),本文不在此贅述,下面我們以最常用的TCP協議舉例:

服務器，使用ServerSocket監聽指定的端口，端口可以隨意指定（由於1024以下的端口通常屬於保留端口，在一些操作系統中不可以隨意使用，所以建議使用大於1024的端口），等待客戶連接請求，客戶連接後，會話產生；在完成會話後，關閉連接。
客戶端，使用java socket通信對網絡上某一個服務器的某一個端口發出連接請求，一旦連接成功，打開會話；會話完成後，關閉Socket。客戶端不需要指定打開的端口，通常臨時的、動態的分配一個1024以上的端口。

TCP網絡連接模型：

Android客戶端程序代分析:

1. UploadActivity.java
3. package com.android.upload;
4. import java.io.File;
5. import java.io.OutputStream;
6. import java.io.PushbackInputStream;
7. import java.io.RandomAccessFile;
8. import java.net.Socket;
10. import android.app.Activity;
11. import android.os.Bundle;
12. import android.os.Environment;
13. import android.os.Handler;
14. import android.os.Message;
15. import android.view.View;
16. import android.view.View.OnClickListener;
17. import android.widget.Button;
18. import android.widget.EditText;
19. import android.widget.ProgressBar;
20. import android.widget.TextView;
21. import android.widget.Toast;
23. import com.android.service.UploadLogService;
24. import com.android.socket.utils.StreamTool;
27. public class UploadActivity extends Activity {
28. private EditText filenameText;
29. private TextView resulView;
30. private ProgressBar uploadbar;
31. private UploadLogService logService;
32. private boolean start=true;
33. private Handler handler = new Handler(){
34. @Override
35. public void handleMessage(Message msg) {
36. int length = msg.getData().getInt("size");
37. uploadbar.setProgress(length);
38. float num = (float)uploadbar.getProgress()/(float)uploadbar.getMax();
39. int result = (int)(num * 100);
40. resulView.setText(result+ "%");
41. if(uploadbar.getProgress()==uploadbar.getMax()){
42. Toast.makeText(UploadActivity.this, R.string.success, 1).show();
43. }
44. }
45. };
47. @Override
48. public void onCreate(Bundle savedInstanceState) {
49. super.onCreate(savedInstanceState);
50. setContentView(R.layout.main);
52. logService = new UploadLogService(this);
53. filenameText = (EditText)this.findViewById(R.id.filename);
54. uploadbar = (ProgressBar) this.findViewById(R.id.uploadbar);
55. resulView = (TextView)this.findViewById(R.id.result);
56. Button button =(Button)this.findViewById(R.id.button);
57. Button button1 =(Button)this.findViewById(R.id.stop);
58. button1 .setOnClickListener(new OnClickListener() {
60. @Override
61. public void onClick(View v) {
62. start=false;
64. }
65. });
66. button.setOnClickListener(new View.OnClickListener() {
67. @Override
68. public void onClick(View v) {
69. start=true;
70. String filename = filenameText.getText().toString();
71. if(Environment.getExternalStorageState().equals(Environment.MEDIA_MOUNTED)){
72. File uploadFile = new File(Environment.getExternalStorageDirectory(), filename);
73. if(uploadFile.exists()){
74. uploadFile(uploadFile);
75. }else{
76. Toast.makeText(UploadActivity.this, R.string.filenotexsit, 1).show();
77. }
78. }else{
79. Toast.makeText(UploadActivity.this, R.string.sdcarderror, 1).show();
80. }
81. }
82. });
83. }
84. /**
85. * 上傳文件
86. * @param uploadFile
87. */
88. private void uploadFile(final File uploadFile) {
89. new Thread(new Runnable() {
90. @Override
91. public void run() {
92. try {
93. uploadbar.setMax((int)uploadFile.length());
94. String souceid = logService.getBindId(uploadFile);
95. String head = "Content-Length="+ uploadFile.length() + ";filename="+ uploadFile.getName() + ";sourceid="+
96. (souceid==null? "" : souceid)+"\r\n";
97. Socket socket = new Socket("192.168.1.78",7878);
98. OutputStream outStream = socket.getOutputStream();
99. outStream.write(head.getBytes());
101. PushbackInputStream inStream = new PushbackInputStream(socket.getInputStream());
102. String response = StreamTool.readLine(inStream);
103. String[] items = response.split(";");
104. String responseid = items[0].substring(items[0].indexOf("=")+1);
105. String position = items[1].substring(items[1].indexOf("=")+1);
106. if(souceid==null){//代表原來沒有上傳過此文件，往數據庫添加一條綁定記錄
107. logService.save(responseid, uploadFile);
108. }
109. RandomAccessFile fileOutStream = new RandomAccessFile(uploadFile, "r");
110. fileOutStream.seek(Integer.valueOf(position));
111. byte[] buffer = new byte[1024];
112. int len = -1;
113. int length = Integer.valueOf(position);
114. while(start&&(len = fileOutStream.read(buffer)) != -1){
115. outStream.write(buffer, 0, len);
116. length += len;
117. Message msg = new Message();
118. msg.getData().putInt("size", length);
119. handler.sendMessage(msg);
120. }
121. fileOutStream.close();
122. outStream.close();
123. inStream.close();
124. socket.close();
125. if(length==uploadFile.length()) logService.delete(uploadFile);
126. } catch (Exception e) {
127. e.printStackTrace();
128. }
129. }
130. }).start();
131. }
132. }
133. StreamTool.java
135. package com.android.socket.utils;
137. import java.io.ByteArrayOutputStream;
138. import java.io.File;
139. import java.io.FileOutputStream;
140. import java.io.IOException;
141. import java.io.InputStream;
142. import java.io.PushbackInputStream;
144. public class StreamTool {
146. public static void save(File file, byte[] data) throws Exception {
147. FileOutputStream outStream = new FileOutputStream(file);
148. outStream.write(data);
149. outStream.close();
150. }
152. public static String readLine(PushbackInputStream in) throws IOException {
153. char buf[] = new char[128];
154. int room = buf.length;
155. int offset = 0;
156. int c;
157. loop: while (true) {
158. switch (c = in.read()) {
159. case -1:
160. case ‘\n‘:
161. break loop;
162. case ‘\r‘:
163. int c2 = in.read();
164. if ((c2 != ‘\n‘) && (c2 != -1)) in.unread(c2);
165. break loop;
166. default:
167. if (--room < 0) {
168. char[] lineBuffer = buf;
169. buf = new char[offset + 128];
170. room = buf.length - offset - 1;
171. System.arraycopy(lineBuffer, 0, buf, 0, offset);
173. }
174. buf[offset++] = (char) c;
175. break;
176. }
177. }
178. if ((c == -1) && (offset == 0)) return null;
179. return String.copyValueOf(buf, 0, offset);
180. }
182. /**
183. * 讀取流
184. * @param inStream
185. * @return 字節數組
186. * @throws Exception
187. */
188. public static byte[] readStream(InputStream inStream) throws Exception{
189. ByteArrayOutputStream outSteam = new ByteArrayOutputStream();
190. byte[] buffer = new byte[1024];
191. int len = -1;
192. while( (len=inStream.read(buffer)) != -1){
193. outSteam.write(buffer, 0, len);
194. }
195. outSteam.close();
196. inStream.close();
197. return outSteam.toByteArray();
198. }
199. }
201. UploadLogService.java
203. package com.android.service;
205. import java.io.File;
207. import android.content.Context;
208. import android.database.Cursor;
209. import android.database.sqlite.SQLiteDatabase;
211. public class UploadLogService {
212. private DBOpenHelper dbOpenHelper;
214. public UploadLogService(Context context){
215. this.dbOpenHelper = new DBOpenHelper(context);
216. }
218. public void save(String sourceid, File uploadFile){
219. SQLiteDatabase db = dbOpenHelper.getWritableDatabase();
220. db.execSQL("insert into uploadlog(uploadfilepath, sourceid) values(?,?)",
221. new Object[]{uploadFile.getAbsolutePath(),sourceid});
222. }
224. public void delete(File uploadFile){
225. SQLiteDatabase db = dbOpenHelper.getWritableDatabase();
226. db.execSQL("delete from uploadlog where uploadfilepath=?", new Object[]{uploadFile.getAbsolutePath()});
227. }
229. public String getBindId(File uploadFile){
230. SQLiteDatabase db = dbOpenHelper.getReadableDatabase();
231. Cursor cursor = db.rawQuery("select sourceid from uploadlog where uploadfilepath=?",
232. new String[]{uploadFile.getAbsolutePath()});
233. if(cursor.moveToFirst()){
234. return cursor.getString(0);
235. }
236. return null;
237. }
238. }
240. DBOpenHelper.java
242. package com.android.service;
244. import android.content.Context;
245. import android.database.sqlite.SQLiteDatabase;
246. import android.database.sqlite.SQLiteOpenHelper;
248. public class DBOpenHelper extends SQLiteOpenHelper {
250. public DBOpenHelper(Context context) {
251. super(context, "upload.db", null, 1);
252. }
254. @Override
255. public void onCreate(SQLiteDatabase db) {
256. db.execSQL("CREATE TABLE uploadlog (_id integer primary key autoincrement, uploadfilepath varchar(100), sourceid varchar(10))");
257. }
259. @Override
260. public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
261. db.execSQL("DROP TABLE IF EXISTS uploadlog");
262. onCreate(db);
263. }
265. }
267. main.xml
269. <?xml version="1.0" encoding="utf-8"?>
270. <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
271. android:orientation="vertical"
272. android:layout_width="fill_parent"
273. android:layout_height="fill_parent"
274. >
275. <TextView
276. android:layout_width="fill_parent"
277. android:layout_height="wrap_content"
278. android:text="@string/filename"
279. />
281. <EditText
282. android:layout_width="fill_parent"
283. android:layout_height="wrap_content"
284. android:text="022.jpg"
285. android:id="@+id/filename"
286. />
288. <Button
289. android:layout_width="wrap_content"
290. android:layout_height="wrap_content"
291. android:text="@string/button"
292. android:id="@+id/button"
293. />
294. <Button
295. android:layout_width="wrap_content"
296. android:layout_height="wrap_content"
297. android:text="暫停"
298. android:id="@+id/stop"
299. />
300. <ProgressBar
301. android:layout_width="fill_parent"
302. android:layout_height="20px"
303. style="?android:attr/progressBarStyleHorizontal"
304. android:id="@+id/uploadbar"
305. />
306. <TextView
307. android:layout_width="fill_parent"
308. android:layout_height="wrap_content"
309. android:gravity="center"
310. android:id="@+id/result"
311. />
312. </LinearLayout>
314. AndroidManifest.xml
316. <?xml version="1.0" encoding="utf-8"?>
317. <manifest xmlns:android="http://schemas.android.com/apk/res/android"
318. package="com.android.upload"
319. android:versionCode="1"
320. android:versionName="1.0" >
322. <uses-sdk android:minSdkVersion="8" />
324. <application
325. android:icon="@drawable/ic_launcher"
326. android:label="@string/app_name" >
327. <activity
328. android:name=".UploadActivity"
329. android:label="@string/app_name" >
330. <intent-filter>
331. <action android:name="android.intent.action.MAIN" />
333. <category android:name="android.intent.category.LAUNCHER" />
334. </intent-filter>
335. </activity>
336. </application>
337. <!-- 訪問網絡的權限 -->
338. <uses-permission android:name="android.permission.INTERNET"/>
339. <!-- 在SDCard中創建與刪除文件權限 -->
340. <uses-permission android:name="android.permission.MOUNT_UNMOUNT_FILESYSTEMS"/>
341. <!-- 往SDCard寫入數據權限 -->
342. <uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE"/>
343. </manifest>

Java服務端:

1. SocketServer.javapackage com.android.socket.server;
3. import java.io.File;
4. import java.io.FileInputStream;
5. import java.io.FileOutputStream;
6. import java.io.IOException;
7. import java.io.OutputStream;
8. import java.io.PushbackInputStream;
9. import java.io.RandomAccessFile;
10. import java.net.ServerSocket;
11. import java.net.Socket;
12. import java.text.SimpleDateFormat;
13. import java.util.Date;
14. import java.util.HashMap;
15. import java.util.Map;
16. import java.util.Properties;
17. import java.util.concurrent.ExecutorService;
18. import java.util.concurrent.Executors;
20. import com.android.socket.utils.StreamTool;
22. public class SocketServer {
23. private String uploadPath="D:/uploadFile/";
24. private ExecutorService executorService;// 線程池
25. private ServerSocket ss = null;
26. private int port;// 監聽端口
27. private boolean quit;// 是否退出
28. private Map<Long, FileLog> datas = new HashMap<Long, FileLog>();// 存放斷點數據，最好改為數據庫存放
30. public SocketServer(int port) {
31. this.port = port;
32. // 初始化線程池
33. executorService = Executors.newFixedThreadPool(Runtime.getRuntime()
34. .availableProcessors() * 50);
35. }
37. // 啟動服務
38. public void start() throws Exception {
39. ss = new ServerSocket(port);
40. while (!quit) {
41. Socket socket = ss.accept();// 接受客戶端的請求
42. // 為支持多用戶並發訪問，采用線程池管理每一個用戶的連接請求
43. executorService.execute(new SocketTask(socket));// 啟動一個線程來處理請求
44. }
45. }
47. // 退出
48. public void quit() {
49. this.quit = true;
50. try {
51. ss.close();
52. } catch (IOException e) {
53. e.printStackTrace();
54. }
55. }
57. public static void main(String[] args) throws Exception {
58. SocketServer server = new SocketServer(7878);
59. server.start();
60. }
62. private class SocketTask implements Runnable {
63. private Socket socket;
65. public SocketTask(Socket socket) {
66. this.socket = socket;
67. }
69. @Override
70. public void run() {
71. try {
72. System.out.println("accepted connenction from "
73. + socket.getInetAddress() + " @ " + socket.getPort());
74. PushbackInputStream inStream = new PushbackInputStream(
75. socket.getInputStream());
76. // 得到客戶端發來的第一行協議數據：Content-Length=143253434;filename=xxx.3gp;sourceid=
77. // 如果用戶初次上傳文件，sourceid的值為空。
78. String head = StreamTool.readLine(inStream);
79. System.out.println(head);
80. if (head != null) {
81. // 下面從協議數據中讀取各種參數值
82. String[] items = head.split(";");
83. String filelength = items[0].substring(items[0].indexOf("=") + 1);
84. String filename = items[1].substring(items[1].indexOf("=") + 1);
85. String sourceid = items[2].substring(items[2].indexOf("=") + 1);
86. Long id = System.currentTimeMillis();
87. FileLog log = null;
88. if (null != sourceid && !"".equals(sourceid)) {
89. id = Long.valueOf(sourceid);
90. log = find(id);//查找上傳的文件是否存在上傳記錄
91. }
92. File file = null;
93. int position = 0;
94. if(log==null){//如果上傳的文件不存在上傳記錄,為文件添加跟蹤記錄
95. String path = new SimpleDateFormat("yyyy/MM/dd/HH/mm").format(new Date());
96. File dir = new File(uploadPath+ path);
97. if(!dir.exists()) dir.mkdirs();
98. file = new File(dir, filename);
99. if(file.exists()){//如果上傳的文件發生重名，然後進行改名
100. filename = filename.substring(0, filename.indexOf(".")-1)+ dir.listFiles().length+ filename.substring(filename.indexOf("."));
101. file = new File(dir, filename);
102. }
103. save(id, file);
104. }else{// 如果上傳的文件存在上傳記錄,讀取上次的斷點位置
105. file = new File(log.getPath());//從上傳記錄中得到文件的路徑
106. if(file.exists()){
107. File logFile = new File(file.getParentFile(), file.getName()+".log");
108. if(logFile.exists()){
109. Properties properties = new Properties();
110. properties.load(new FileInputStream(logFile));
111. position = Integer.valueOf(properties.getProperty("length"));//讀取斷點位置
112. }
113. }
114. }
116. OutputStream outStream = socket.getOutputStream();
117. String response = "sourceid="+ id+ ";position="+ position+ "\r\n";
118. //服務器收到客戶端的請求信息後，給客戶端返回響應信息：sourceid=1274773833264;position=0
119. //sourceid由服務生成，唯一標識上傳的文件，position指示客戶端從文件的什麽位置開始上傳
120. outStream.write(response.getBytes());
122. RandomAccessFile fileOutStream = new RandomAccessFile(file, "rwd");
123. if(position==0) fileOutStream.setLength(Integer.valueOf(filelength));//設置文件長度
124. fileOutStream.seek(position);//移動文件指定的位置開始寫入數據
125. byte[] buffer = new byte[1024];
126. int len = -1;
127. int length = position;
128. while( (len=inStream.read(buffer)) != -1){//從輸入流中讀取數據寫入到文件中
129. fileOutStream.write(buffer, 0, len);
130. length += len;
131. Properties properties = new Properties();
132. properties.put("length", String.valueOf(length));
133. FileOutputStream logFile = new FileOutputStream(new File(file.getParentFile(), file.getName()+".log"));
134. properties.store(logFile, null);//實時記錄文件的最後保存位置
135. logFile.close();
136. }
137. if(length==fileOutStream.length()) delete(id);
138. fileOutStream.close();
139. inStream.close();
140. outStream.close();
141. file = null;
142. }
143. } catch (Exception e) {
144. e.printStackTrace();
145. } finally {
146. try {
147. if(socket != null && !socket.isClosed()) socket.close();
148. } catch (IOException e) {}
149. }
150. }
152. }
154. public FileLog find(Long sourceid) {
155. return datas.get(sourceid);
156. }
158. // 保存上傳記錄
159. public void save(Long id, File saveFile) {
160. // 日後可以改成通過數據庫存放
161. datas.put(id, new FileLog(id, saveFile.getAbsolutePath()));
162. }
164. // 當文件上傳完畢，刪除記錄
165. public void delete(long sourceid) {
166. if (datas.containsKey(sourceid))
167. datas.remove(sourceid);
168. }
170. private class FileLog {
171. private Long id;
172. private String path;
174. public FileLog(Long id, String path) {
175. super();
176. this.id = id;
177. this.path = path;
178. }
180. public Long getId() {
181. return id;
182. }
184. public void setId(Long id) {
185. this.id = id;
186. }
188. public String getPath() {
189. return path;
190. }
192. public void setPath(String path) {
193. this.path = path;
194. }
196. }
197. }
198. ServerWindow.javapackage com.android.socket.server;
200. import java.awt.BorderLayout;
201. import java.awt.Frame;
202. import java.awt.Label;
203. import java.awt.event.WindowEvent;
204. import java.awt.event.WindowListener;
206. public class ServerWindow extends Frame{
207. private SocketServer server;
208. private Label label;
210. public ServerWindow(String title){
211. super(title);
212. server = new SocketServer(7878);
213. label = new Label();
214. add(label, BorderLayout.PAGE_START);
215. label.setText("服務器已經啟動");
216. this.addWindowListener(new WindowListener() {
217. @Override
218. public void windowOpened(WindowEvent e) {
219. new Thread(new Runnable() {
220. @Override
221. public void run() {
222. try {
223. server.start();
224. } catch (Exception e) {
225. e.printStackTrace();
226. }
227. }
228. }).start();
229. }
231. @Override
232. public void windowIconified(WindowEvent e) {
233. }
235. @Override
236. public void windowDeiconified(WindowEvent e) {
237. }
239. @Override
240. public void windowDeactivated(WindowEvent e) {
241. }
243. @Override
244. public void windowClosing(WindowEvent e) {
245. server.quit();
246. System.exit(0);
247. }
249. @Override
250. public void windowClosed(WindowEvent e) {
251. }
253. @Override
254. public void windowActivated(WindowEvent e) {
255. }
256. });
257. }
258. /**
259. * @param args
260. */
261. public static void main(String[] args) {
262. ServerWindow window = new ServerWindow("文件上傳服務端");
263. window.setSize(300, 300);
264. window.setVisible(true);
265. }
267. }
268. StreamTool.javapackage com.android.socket.utils;
270. import java.io.ByteArrayOutputStream;
271. import java.io.File;
272. import java.io.FileOutputStream;
273. import java.io.IOException;
274. import java.io.InputStream;
275. import java.io.PushbackInputStream;
277. public class StreamTool {
279. public static void save(File file, byte[] data) throws Exception {
280. FileOutputStream outStream = new FileOutputStream(file);
281. outStream.write(data);
282. outStream.close();
283. }
285. public static String readLine(PushbackInputStream in) throws IOException {
286. char buf[] = new char[128];
287. int room = buf.length;
288. int offset = 0;
289. int c;
290. loop: while (true) {
291. switch (c = in.read()) {
292. case -1:
293. case ‘\n‘:
294. break loop;
295. case ‘\r‘:
296. int c2 = in.read();
297. if ((c2 != ‘\n‘) && (c2 != -1)) in.unread(c2);
298. break loop;
299. default:
300. if (--room < 0) {
301. char[] lineBuffer = buf;
302. buf = new char[offset + 128];
303. room = buf.length - offset - 1;
304. System.arraycopy(lineBuffer, 0, buf, 0, offset);
306. }
307. buf[offset++] = (char) c;
308. break;
309. }
310. }
311. if ((c == -1) && (offset == 0)) return null;
312. return String.copyValueOf(buf, 0, offset);
313. }
315. /**
316. * 讀取流
317. * @param inStream
318. * @return 字節數組
319. * @throws Exception
320. */
321. public static byte[] readStream(InputStream inStream) throws Exception{
322. ByteArrayOutputStream outSteam = new ByteArrayOutputStream();
323. byte[] buffer = new byte[1024];
324. int len = -1;
325. while( (len=inStream.read(buffer)) != -1){
326. outSteam.write(buffer, 0, len);
327. }
328. outSteam.close();
329. inStream.close();
330. return outSteam.toByteArray();
331. }
333. }

運行效果如下:
android前端控制:

後臺監控日誌:

下載後的文件路徑:

源碼下載地址

Android中Socket大文件斷點上傳