基于 TCP 协议的 Socket 通信

2023-04-18
四川
本文字数：9739 字
阅读完需：约 32 分钟

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，相信大家对 Socket 已经有了初步的掌握。本节我们学习使用 Socket 来实现大文件的断点续传！在这里我们以他人的案例进行讲解，这是别人写好的一个 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();    }}

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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;         }         }   }

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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);
    }
}

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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>

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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) {
    }}

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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()});    }}

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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();    }
}

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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"/>

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原文链接:【http://xie.infoq.cn/article/4dd693f9b81d6a61e47f3353a】。文章转载请联系作者。