本节引言：

上节中我们给大家接触了Socket的一些基本概念以及使用方法，然后写了一个小猪简易聊天室的 Demo，相信大家对Socket有了初步的掌握，本节我们来学习下使用Socket来实现大文件的断点续传！ 这里讲解的是别人写好的一个Socket上传大文件的例子，不要求我们自己可以写出来，需要的时候会用 就好！

1.运行效果图：

1.先把我们编写好的Socket服务端运行起来：

2.将一个音频文件放到SD卡根目录下：

3.运行我们的客户端：

4.上传成功后可以看到我们的服务端的项目下生成一个file的文件夹，我们可以在这里找到上传的文件： .log那个是我们的日志文件

2.实现流程图：

3.代码示例：

先编写一个服务端和客户端都会用到的流解析类：

StreamTool.java：

public class StreamTool {

    public static void save(File file, byte[] data) throws Exception {
        FileOutputStream outStream = new FileOutputStream(file);
        outStream.write(data);
        outStream.close();
    }

    public static String readLine(PushbackInputStream in) throws IOException {
        char buf[] = new char[128];
        int room = buf.length;
        int offset = 0;
        int c;
        loop:       while (true) {
            switch (c = in.read()) {
                case -1:
                case '\n':
                    break loop;
                case '\r':
                    int c2 = in.read();
                    if ((c2 != '\n') && (c2 != -1)) in.unread(c2);
                    break loop;
                default:
                    if (--room < 0) {
                        char[] lineBuffer = buf;
                        buf = new char[offset + 128];
                        room = buf.length - offset - 1;
                        System.arraycopy(lineBuffer, 0, buf, 0, offset);

                    }
                    buf[offset++] = (char) c;
                    break;
            }
        }
        if ((c == -1) && (offset == 0)) return null;
        return String.copyValueOf(buf, 0, offset);
    }

    /**
     * 读取流
     * @param inStream
     * @return 字节数组
     * @throws Exception
     */
    public static byte[] readStream(InputStream inStream) throws Exception{
        ByteArrayOutputStream outSteam = new ByteArrayOutputStream();
        byte[] buffer = new byte[1024];
        int len = -1;
        while( (len=inStream.read(buffer)) != -1){
            outSteam.write(buffer, 0, len);
        }
        outSteam.close();
        inStream.close();
        return outSteam.toByteArray();
    }
} 

1）服务端的实现：

socket管理与多线程管理类：

FileServer.java：

public class FileServer {  
    
    private ExecutorService executorService;//线程池  
    private int port;//监听端口  
    private boolean quit = false;//退出  
    private ServerSocket server;  
    private Map<Long, FileLog> datas = new HashMap<Long, FileLog>();//存放断点数据  
      
    public FileServer(int port){  
        this.port = port;  
        //创建线程池，池中具有(cpu个数*50)条线程  
        executorService = Executors.newFixedThreadPool(Runtime.getRuntime().availableProcessors() * 50);  
    }  
    /** 
     * 退出 
     */  
    public void quit(){  
       this.quit = true;  
       try {  
           server.close();  
       } catch (IOException e) {  
       }  
    }  
    /** 
     * 启动服务 
     * @throws Exception 
     */  
    public void start() throws Exception{  
        server = new ServerSocket(port);  
        while(!quit){  
            try {  
              Socket socket = server.accept();  
              //为支持多用户并发访问，采用线程池管理每一个用户的连接请求  
              executorService.execute(new SocketTask(socket));  
            } catch (Exception e) {  
              //  e.printStackTrace();  
            }  
        }  
    }  
      
    private final class SocketTask implements Runnable{  
       private Socket socket = null;  
       public SocketTask(Socket socket) {  
           this.socket = socket;  
       }  
         
       public void run() {  
           try {  
               System.out.println("accepted connection "+ socket.getInetAddress()+ ":"+ socket.getPort());  
               PushbackInputStream inStream = new PushbackInputStream(socket.getInputStream());  
               //得到客户端发来的第一行协议数据：Content-Length=143253434;filename=xxx.3gp;sourceid=  
               //如果用户初次上传文件，sourceid的值为空。  
               String head = StreamTool.readLine(inStream);  
               System.out.println(head);  
               if(head!=null){  
                   //下面从协议数据中提取各项参数值  
                   String[] items = head.split(";");  
                   String filelength = items[0].substring(items[0].indexOf("=")+1);  
                   String filename = items[1].substring(items[1].indexOf("=")+1);  
                   String sourceid = items[2].substring(items[2].indexOf("=")+1);        
                   long id = System.currentTimeMillis();//生产资源id，如果需要唯一性，可以采用UUID  
                   FileLog log = null;  
                   if(sourceid!=null && !"".equals(sourceid)){  
                       id = Long.valueOf(sourceid);  
                       log = find(id);//查找上传的文件是否存在上传记录  
                   }  
                   File file = null;  
                   int position = 0;  
                   if(log==null){//如果不存在上传记录,为文件添加跟踪记录  
                       String path = new SimpleDateFormat("yyyy/MM/dd/HH/mm").format(new Date());  
                       File dir = new File("file/"+ path);  
                       if(!dir.exists()) dir.mkdirs();  
                       file = new File(dir, filename);  
                       if(file.exists()){//如果上传的文件发生重名，然后进行改名  
                           filename = filename.substring(0, filename.indexOf(".")-1)+ dir.listFiles().length+ filename.substring(filename.indexOf("."));  
                           file = new File(dir, filename);  
                       }  
                       save(id, file);  
                   }else{// 如果存在上传记录,读取已经上传的数据长度  
                       file = new File(log.getPath());//从上传记录中得到文件的路径  
                       if(file.exists()){  
                           File logFile = new File(file.getParentFile(), file.getName()+".log");  
                           if(logFile.exists()){  
                               Properties properties = new Properties();  
                               properties.load(new FileInputStream(logFile));  
                               position = Integer.valueOf(properties.getProperty("length"));//读取已经上传的数据长度  
                           }  
                       }  
                   }  
                     
                   OutputStream outStream = socket.getOutputStream();  
                   String response = "sourceid="+ id+ ";position="+ position+ "\r\n";  
                   //服务器收到客户端的请求信息后，给客户端返回响应信息：sourceid=1274773833264;position=0  
                   //sourceid由服务器端生成，唯一标识上传的文件，position指示客户端从文件的什么位置开始上传  
                   outStream.write(response.getBytes());  
                     
                   RandomAccessFile fileOutStream = new RandomAccessFile(file, "rwd");  
                   if(position==0) fileOutStream.setLength(Integer.valueOf(filelength));//设置文件长度  
                   fileOutStream.seek(position);//指定从文件的特定位置开始写入数据  
                   byte[] buffer = new byte[1024];  
                   int len = -1;  
                   int length = position;  
                   while( (len=inStream.read(buffer)) != -1){//从输入流中读取数据写入到文件中  
                       fileOutStream.write(buffer, 0, len);  
                       length += len;  
                       Properties properties = new Properties();  
                       properties.put("length", String.valueOf(length));  
                       FileOutputStream logFile = new FileOutputStream(new File(file.getParentFile(), file.getName()+".log"));  
                       properties.store(logFile, null);//实时记录已经接收的文件长度  
                       logFile.close();  
                   }  
                   if(length==fileOutStream.length()) delete(id);  
                   fileOutStream.close();                    
                   inStream.close();  
                   outStream.close();  
                   file = null;  
                     
               }  
           } catch (Exception e) {  
               e.printStackTrace();  
           }finally{  
               try {  
                   if(socket!=null && !socket.isClosed()) socket.close();  
               } catch (IOException e) {}  
           }  
       }  
    }  
      
    public FileLog find(Long sourceid){  
        return datas.get(sourceid);  
    }  
    //保存上传记录  
    public void save(Long id, File saveFile){  
        //日后可以改成通过数据库存放  
        datas.put(id, new FileLog(id, saveFile.getAbsolutePath()));  
    }  
    //当文件上传完毕，删除记录  
    public void delete(long sourceid){  
        if(datas.containsKey(sourceid)) datas.remove(sourceid);  
    }  
      
    private class FileLog{  
       private Long id;  
       private String path;  
       public Long getId() {  
           return id;  
       }  
       public void setId(Long id) {  
           this.id = id;  
       }  
       public String getPath() {  
           return path;  
       }  
       public void setPath(String path) {  
           this.path = path;  
       }  
       public FileLog(Long id, String path) {  
           this.id = id;  
           this.path = path;  
       }     
    }  
 
}  

服务端界面类:ServerWindow.java：

public class ServerWindow extends Frame {
    private FileServer s = new FileServer(12345);
    private Label label;

    public ServerWindow(String title) {
        super(title);
        label = new Label();
        add(label, BorderLayout.PAGE_START);
        label.setText("服务器已经启动");
        this.addWindowListener(new WindowListener() {
            public void windowOpened(WindowEvent e) {
                new Thread(new Runnable() {
                    public void run() {
                        try {
                            s.start();
                        } catch (Exception e) {
                            // e.printStackTrace();
                        }
                    }
                }).start();
            }

            public void windowIconified(WindowEvent e) {
            }

            public void windowDeiconified(WindowEvent e) {
            }

            public void windowDeactivated(WindowEvent e) {
            }

            public void windowClosing(WindowEvent e) {
                s.quit();
                System.exit(0);
            }

            public void windowClosed(WindowEvent e) {
            }

            public void windowActivated(WindowEvent e) {
            }
        });
    }

    /**
     * @param args
     */
    public static void main(String[] args) throws IOException {
        InetAddress address = InetAddress.getLocalHost();
        ServerWindow window = new ServerWindow("文件上传服务端：" + address.getHostAddress());
        window.setSize(400, 300);
        window.setVisible(true);

    }

}

2）客户端(Android端)

首先是布局文件：activity_main.xml：

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent"
    android:orientation="vertical"
    android:padding="5dp">

    <TextView
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:text="文件名"
        android:textSize="18sp" />

    <EditText
        android:id="@+id/edit_fname"
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:text="Nikki Jamal - Priceless.mp3" />

    <Button
        android:id="@+id/btn_upload"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="上传" />

    <Button
        android:id="@+id/btn_stop"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="停止" />

    <ProgressBar
        android:id="@+id/pgbar"
        style="@android:style/Widget.ProgressBar.Horizontal"
        android:layout_width="fill_parent"
        android:layout_height="40px" />

    <TextView
        android:id="@+id/txt_result"
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:gravity="center" />
</LinearLayout> 

因为断点续传，我们需要保存上传的进度，我们需要用到数据库，这里我们定义一个数据库 管理类：DBOpenHelper.java：：

/**
 * Created by Jay on 2015/9/17 0017.
 */
public class DBOpenHelper extends SQLiteOpenHelper {

    public DBOpenHelper(Context context) {
        super(context, "jay.db", null, 1);
    }

    @Override
    public void onCreate(SQLiteDatabase db) {
        db.execSQL("CREATE TABLE IF NOT EXISTS uploadlog (_id integer primary key autoincrement, path varchar(20), sourceid varchar(20))");
    }

    @Override
    public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {

    }
}

然后是数据库操作类：UploadHelper.java：

/**
 * Created by Jay on 2015/9/17 0017.
 */
public class UploadHelper {
    private DBOpenHelper dbOpenHelper;

    public UploadHelper(Context context) {
        dbOpenHelper = new DBOpenHelper(context);
    }

    public String getBindId(File file) {
        SQLiteDatabase db = dbOpenHelper.getReadableDatabase();
        Cursor cursor = db.rawQuery("select sourceid from uploadlog where path=?", new String[]{file.getAbsolutePath()});
        if (cursor.moveToFirst()) {
            return cursor.getString(0);
        }
        return null;
    }

    public void save(String sourceid, File file) {
        SQLiteDatabase db = dbOpenHelper.getWritableDatabase();
        db.execSQL("insert into uploadlog(path,sourceid) values(?,?)",
                new Object[]{file.getAbsolutePath(), sourceid});
    }

    public void delete(File file) {
        SQLiteDatabase db = dbOpenHelper.getWritableDatabase();
        db.execSQL("delete from uploadlog where path=?", new Object[]{file.getAbsolutePath()});
    }
}

对了，别忘了客户端也要贴上那个流解析类哦，最后就是我们的MainActivity.java了：

public class MainActivity extends AppCompatActivity implements View.OnClickListener {

    private EditText edit_fname;
    private Button btn_upload;
    private Button btn_stop;
    private ProgressBar pgbar;
    private TextView txt_result;

    private UploadHelper upHelper;
    private boolean flag = true;


    private Handler handler = new Handler() {
        @Override
        public void handleMessage(Message msg) {
            pgbar.setProgress(msg.getData().getInt("length"));
            float num = (float) pgbar.getProgress() / (float) pgbar.getMax();
            int result = (int) (num * 100);
            txt_result.setText(result + "%");
            if (pgbar.getProgress() == pgbar.getMax()) {
                Toast.makeText(MainActivity.this, "上传成功", Toast.LENGTH_SHORT).show();
            }
        }
    };

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        bindViews();
        upHelper = new UploadHelper(this);
    }

    private void bindViews() {
        edit_fname = (EditText) findViewById(R.id.edit_fname);
        btn_upload = (Button) findViewById(R.id.btn_upload);
        btn_stop = (Button) findViewById(R.id.btn_stop);
        pgbar = (ProgressBar) findViewById(R.id.pgbar);
        txt_result = (TextView) findViewById(R.id.txt_result);

        btn_upload.setOnClickListener(this);
        btn_stop.setOnClickListener(this);
    }

    @Override
    public void onClick(View v) {
        switch (v.getId()) {
            case R.id.btn_upload:
                String filename = edit_fname.getText().toString();
                flag = true;
                if (Environment.getExternalStorageState().equals(Environment.MEDIA_MOUNTED)) {
                    File file = new File(Environment.getExternalStorageDirectory(), filename);
                    if (file.exists()) {
                        pgbar.setMax((int) file.length());
                        uploadFile(file);
                    } else {
                        Toast.makeText(MainActivity.this, "文件并不存在~", Toast.LENGTH_SHORT).show();
                    }
                } else {
                    Toast.makeText(MainActivity.this, "SD卡不存在或者不可用", Toast.LENGTH_SHORT).show();
                }
                break;
            case R.id.btn_stop:
                flag = false;
                break;
        }
    }

    private void uploadFile(final File file) {
        new Thread(new Runnable() {
            public void run() {
                try {
                    String sourceid = upHelper.getBindId(file);
                    Socket socket = new Socket("172.16.2.54", 12345);
                    OutputStream outStream = socket.getOutputStream();
                    String head = "Content-Length=" + file.length() + ";filename=" + file.getName()
                            + ";sourceid=" + (sourceid != null ? sourceid : "") + "\r\n";
                    outStream.write(head.getBytes());

                    PushbackInputStream inStream = new PushbackInputStream(socket.getInputStream());
                    String response = StreamTool.readLine(inStream);
                    String[] items = response.split(";");
                    String responseSourceid = items[0].substring(items[0].indexOf("=") + 1);
                    String position = items[1].substring(items[1].indexOf("=") + 1);
                    if (sourceid == null) {//如果是第一次上传文件，在数据库中不存在该文件所绑定的资源id
                        upHelper.save(responseSourceid, file);
                    }
                    RandomAccessFile fileOutStream = new RandomAccessFile(file, "r");
                    fileOutStream.seek(Integer.valueOf(position));
                    byte[] buffer = new byte[1024];
                    int len = -1;
                    int length = Integer.valueOf(position);
                    while (flag && (len = fileOutStream.read(buffer)) != -1) {
                        outStream.write(buffer, 0, len);
                        length += len;//累加已经上传的数据长度
                        Message msg = new Message();
                        msg.getData().putInt("length", length);
                        handler.sendMessage(msg);
                    }
                    if (length == file.length()) upHelper.delete(file);
                    fileOutStream.close();
                    outStream.close();
                    inStream.close();
                    socket.close();
                } catch (Exception e) {
                    Toast.makeText(MainActivity.this, "上传异常~", Toast.LENGTH_SHORT).show();
                }
            }
        }).start();
    }

}

最后，还有，记得往**AndroidManifest.xml**中写入这些权限哦！

<!-- 在SDCard中创建与删除文件权限 -->
<uses-permission android:name="android.permission.MOUNT_UNMOUNT_FILESYSTEMS"/>
<!-- 往SDCard写入数据权限 -->
<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE"/>
<!-- 访问internet权限 -->
<uses-permission android:name="android.permission.INTERNET"/>

4.代码下载：

Socket上传大文件demo

5.本节小结：

本节给大家介绍了基于TCP协议的Socket的另一个实例：使用Socket完成大文件的续传， 相信大家对Socket的了解更进一步，嗯，下一节再写一个例子吧，两个处于同一Wifi 下的手机相互传递数据的实例吧！就说这么多，谢谢~