Android服务器和客户端连接

Question

我一直在尝试开发一个 android 应用程序，它可以向其他设备(如带有 wi-fi 模块的指示器)发送命令，如“S”、“A”或“B”。因此，我正在尝试使用 wi-fi 在我的 android 设备和 wi-fi 模块之间建立这种连接。

我在 android 开发者网站上搜索了一些信息。我不知道为什么在服务器边缘，我只需要提供“端口”的信息。而在客户端端，我必须提供“端口”和“地址”的信息。

Answer 1

您好，我可以提供一些代码来简单连接到在 java 中运行的服务器，仅使用控制台和使用套接字连接连接到服务器的基本 android 应用程序。它只是在模拟器(例如来自 Eclipse 的模拟器)上运行的示例代码。真的希望它有所帮助。将通过一些步骤很快提供一个更好的例子。只要手机使用的是 android，当然还有 sdk 版本 14 及更高版本。代码不是很干净，稍后我也会这样做。

Android 端使用 AsyncTask 的 MainActivity.java

    public class MainActivity extends Activity {

    Socket socket = null;
    DataOutputStream output;
    DataInputStream input;
    ObjectInputStream objectInput;
    Button buttonConnect;
    Button createTest;
    TextView textResponse;

    EditText subjectInput, gradeInput, testNameInput;
    String curSubject, curGrade, curName;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        buttonConnect = (Button) findViewById(R.id.buttonConnect);
        createTest = (Button) findViewById(R.id.createTest);
        textResponse = (TextView) findViewById(R.id.textResponse);

        buttonConnect.setOnClickListener(new OnClickListener() {
            @Override
            public void onClick(View v) {
                // TODO Auto-generated method stub
                new ConnectThread().execute("Connect");
                buttonConnect.setText("Connected");
            }
        });
        createTest.setOnClickListener(new OnClickListener() {
            @Override
            public void onClick(View v) {
                // TODO Auto-generated method stub
                subjectInput = (EditText) findViewById(R.id.editText1);
                gradeInput = (EditText) findViewById(R.id.editText2);
                testNameInput = (EditText) findViewById(R.id.editText3);
                ConnectThread thread = new ConnectThread(subjectInput.getText()
                        .toString(), gradeInput.getText().toString(),
                        testNameInput.getText().toString());
                thread.execute("createOpen");
            }
        });
    }

    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        // Inflate the menu; this adds items to the action bar if it is present.
        getMenuInflater().inflate(R.menu.main, menu);
        return true;
    }

    @Override
    public boolean onOptionsItemSelected(MenuItem item) {
        // Handle action bar item clicks here. The action bar will
        // automatically handle clicks on the Home/Up button, so long
        // as you specify a parent activity in AndroidManifest.xml.
        int id = item.getItemId();
        if (id == R.id.action_settings) {
            return true;
        }
        return super.onOptionsItemSelected(item);
    }

    public class ConnectThread extends AsyncTask<String, String, String> {
        String response = "Nothing yet";
        String subject, grade, name;

        public ConnectThread() {
        }

        public ConnectThread(String subject, String grade, String name) {
            this.subject = subject;
            this.grade = grade;
            this.name = name;
        }

        @Override
        protected String doInBackground(String... params) {
            if (params[0].equals("Connect")) {
                connect();
            }
            if (params[0].equals("createOpen")) {
                createOpen();
            }
            return null;
        }

        @Override
        protected void onPostExecute(String result) {
            textResponse.setText(response);
            super.onPostExecute(result);
        }

        public void createOpen() {
            try {
                output.writeUTF("createOpen");
                output.writeUTF(subject);
                output.writeUTF(grade);
                output.writeUTF(name);
                String command = input.readUTF();
                if (command.equals("null")) {
                    try {
                        Object object = objectInput.readObject();
                        ArrayList<String> curTest = (ArrayList<String>) object;
                        curName = curTest.get(0);
                        curGrade = curTest.get(1);
                        curSubject = curTest.get(2);
                        response = "New Test Created: " + curName;
                    } catch (ClassNotFoundException e) {
                        e.printStackTrace();
                    }
                }
                if (command.equals("exists")) {
                    try {
                        Object object = objectInput.readObject();
                        ArrayList<String> curTest = (ArrayList<String>) object;
                        curName = curTest.get(0);
                        curGrade = curTest.get(1);
                        curSubject = curTest.get(2);
                        response = "Test already exists: " + curName;
                    } catch (ClassNotFoundException e) {
                        e.printStackTrace();
                    }
                }
            } catch (IOException e) {
                e.printStackTrace();
            }
        }

        public void connect() {
            try {
                socket = new Socket("10.0.0.16", 500);
                output = new DataOutputStream(socket.getOutputStream());
                input = new DataInputStream(socket.getInputStream());
                objectInput = new ObjectInputStream(socket.getInputStream());
                String command = input.readUTF();
                response = command;
            } catch (UnknownHostException e) {
                e.printStackTrace();
                Log.d("fail", e.toString());
                response = "UnknownHostException: " + e.toString();
            } catch (IOException e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
                Log.d("fail", e.toString());
                response = "IOException: " + e.toString();
            }
        }

        public void disconnect() {
            if (socket != null) {
                try {
                    socket.close();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
        }
    }
}

Java 的服务器类，它为客户端线程创建套接字

public class Server {
    DataOutputStream os;
    DataInputStream is;
    ArrayList<Test> tests;

    public static void main(String[] args) {
        new Server();
    }

    public void postSystemMessage(String message) {
        System.out.println(message);
    }

    public Server() {
        try {
            tests = new ArrayList<Test>();
            // initial data set up
            System.out.println("Starting server");
            ServerSocket server = new ServerSocket(500, 100);
            System.out.println("Server started");
            System.out.println("----------------------------------");
            while (true) {
                System.out.println("Waiting for connection");
                Socket socket = server.accept();
                ServerThread connection = new ServerThread(socket, this);
                System.out.println("New client connected");
                System.out.println("----------------------------------");
                connection.start();
            }
        } catch (IOException ex) {
            Logger.getLogger(Server.class.getName())
                    .log(Level.SEVERE, null, ex);
        }
    }

    public synchronized Test checkifexists(String subject, String grade,
            String name) {
        for (Test test : tests) {
            if (test.getTestName().equals(name)) {
                if (test.getGrade().equals(grade)) {
                    if (test.getSubject().equals(subject)) {
                        return test;
                    }
                }
            }
        }
        return null;
    }

    public synchronized Test createTest(String subject, String grade,
            String name) {
        Test test = new Test(subject, grade, name);
        tests.add(test);
        return test;
    }

    public synchronized void addToTests(Test in) {
        tests.add(in);
    }
}

为多客户端连接设置的服务器线程类

public class ServerThread extends Thread {
    private Socket socket;
    private DataInputStream in;
    private DataOutputStream out;
    private ObjectOutputStream objectOutput;
    private Server server;

    public ServerThread(Socket socket, Server server) {
        this.server = server;
        this.socket = socket;
    }

    @Override
    public void run() {
        try {
            in = new DataInputStream(socket.getInputStream());
            out = new DataOutputStream(socket.getOutputStream());
            objectOutput = new ObjectOutputStream(socket.getOutputStream());
            out.writeUTF("connection successful");
            String command = "";
            while (!command.equals("quit")) {
                command = in.readUTF();
                if (command.equals("createOpen")) {
                    createOpen();
                } else if (command.equals("getFile")) {
                } else if (command.equals("saveFile")) {
                } else if (command.equals("quit")) {
                    System.out.println("A client has left");
                }
            }
        } catch (IOException e2) {
            System.out.println("Connection dropped");
            e2.printStackTrace();
        } finally {
            try {
                if (in != null)
                    in.close();
                if (out != null)
                    out.close();
                socket.close();
            } catch (IOException e1) {
                e1.printStackTrace();
            }
        }
    }

    public void createOpen() {
        try {
            String subject = in.readUTF();
            String grade = in.readUTF();
            String name = in.readUTF();
            Test curTest = server.checkifexists(subject, grade, name);
            if (curTest == null) {
                Test test = server.createTest(subject, grade, name);
                server.addToTests(test);
                ArrayList<String> toSendTest = new ArrayList<String>();
                toSendTest.add(subject);
                toSendTest.add(grade);
                toSendTest.add(name);
                out.writeUTF("null");
                System.out.println("sending object");
                objectOutput.writeObject(toSendTest);
                objectOutput.flush();
                System.out.println("object sent");
            } else {
                ArrayList<String> toSendTest = new ArrayList<String>();
                toSendTest.add(subject);
                toSendTest.add(grade);
                toSendTest.add(name);
                out.writeUTF("exists");
                System.out.println("sending object");
                objectOutput.writeObject(toSendTest);
                objectOutput.flush();
                System.out.println("object sent");
            }
        } catch (IOException e) {
            e.printStackTrace();
        }

    }
}