我選擇在 Android 上加入 HTTP 服務器，這樣只要把域名或地址接通，便能在瀏覽器上輸入地址，透過互聯網直接連線。到時在家中的路由器按埠號把數據分發到紅米就行了。利用瀏覽器的好處是不同平台都有，不用安裝特別程式。
我不懂 Android 編程，所以這次試驗遇到不同問題。首先是 NanoHTTPD 有很多版本，網上的教學也有很多版本，通通都不適用最新的版本。public Response serve(IHTTPSession session) 就是新版本的格式。既然不能照抄，那只好參考舊版的編寫方式，加上自己的思考去做。好不容易改好了，畫面也出現了，瀏覽器卻連不上。找了很久，原來是舊版不用 server.start()，新版要。好了，成功連上了，但想連線是在畫面顯示當刻時間，發現那時要更新介面，不如 iOS 般簡單、直接、容易。又找了一會，成功以 Handler 來達成。今回學到不少。下一步就是加入 OTG + Arduino 連線。這樣基本的硬件功能便已齊全。
//========================================================================================
// AMIGO Camera
//----------------------------------------------------------------------------------------
// Created by Pacess on 2014-07-30
// Copyright (c) 2014 Sita Technology Company. All rights reserved.
//========================================================================================
//----------------------------------------------------------------------------------------
// 0 1 2 3 4 5 6 7 8 9
// 56789012345678901234567890123456789012345678901234567890123456789012345678901234567890
package com.pacess.amigocamera;
import android.widget.TextView;
import android.app.Activity;
import android.app.Fragment;
import android.os.Message;
import android.os.Handler;
import android.os.Bundle;
import android.net.wifi.WifiManager;
import android.util.Log;
import android.view.LayoutInflater;
import android.view.ViewGroup;
import android.view.MenuItem;
import android.view.Menu;
import android.view.View;
import java.text.SimpleDateFormat;
import java.io.IOException;
import java.lang.Runnable;
import java.util.Date;
//========================================================================================
public class MainActivity extends Activity {
//----------------------------------------------------------------------------------------
// Defines
private static final int PORT = 8080;
//----------------------------------------------------------------------------------------
// Class variables
private TextView statusTextView;
private HTTPServer httpServer;
//----------------------------------------------------------------------------------------
Handler handler = new Handler() {
@Override public void handleMessage(Message message) {
if (statusTextView == null) {return;}
String timeStamp = (String)message.obj;
StringBuilder stringBuilder = new StringBuilder();
stringBuilder.append("Last request: ");
stringBuilder.append(timeStamp);
statusTextView.setText(stringBuilder.toString());
}
};
//----------------------------------------------------------------------------------------
@Override protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
Log.d("MainActivity", "onCreate");
if (savedInstanceState != null) {return;}
getFragmentManager().beginTransaction().add(R.id.container, new PlaceholderFragment()).commit();
}
//----------------------------------------------------------------------------------------
@Override protected void onResume() {
super.onResume();
Log.d("MainActivity", "onResume");
SimpleDateFormat dateFormat = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
String timeString = dateFormat.format(new Date());
statusTextView = (TextView)findViewById(R.id.status);
if (statusTextView == null) {
Log.d("MainActivity", "### statusTextView is null...");
} else {
statusTextView.setText("Time stamp: "+timeString);
}
WifiManager wifiManager = (WifiManager)getSystemService(WIFI_SERVICE);
int ipAddress = wifiManager.getConnectionInfo().getIpAddress();
final String ipString = String.format("%d.%d.%d.%d", (ipAddress & 0xff), (ipAddress >> 8 & 0xff), (ipAddress >> 16 & 0xff), (ipAddress >> 24 & 0xff));
TextView textView = (TextView)findViewById(R.id.ipAddress);
textView.setText("http://"+ipString+":"+PORT);
try {
httpServer = new HTTPServer();
httpServer.start();
Log.d("MainActivity", "HTTP server started...");
} catch (IOException e) {
e.printStackTrace();
}
}
//----------------------------------------------------------------------------------------
@Override protected void onPause() {
super.onPause();
Log.d("MainActivity", "onPause");
if (httpServer == null) {return;}
httpServer.stop();
Log.d("MainActivity", "HTTP server stopped");
}
//----------------------------------------------------------------------------------------
@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);
}
//========================================================================================
// A placeholder fragment containing a simple view.
public static class PlaceholderFragment extends Fragment {
//----------------------------------------------------------------------------------------
public PlaceholderFragment() {
}
//----------------------------------------------------------------------------------------
@Override public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
View rootView = inflater.inflate(R.layout.fragment_main, container, false);
return rootView;
}
}
//========================================================================================
public class HTTPServer extends NanoHTTPD {
//----------------------------------------------------------------------------------------
public HTTPServer() throws IOException {
super(PORT);
Log.d("HTTPServer", "Server start "+PORT);
}
//----------------------------------------------------------------------------------------
@Override public Response serve(IHTTPSession session) {
Log.d("HTTPServer", "Server response");
SimpleDateFormat dateFormat = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
final String timeString = dateFormat.format(new Date());
//----------------------------------------------------------------------------------------
// Use handler to update user interface
Thread thread = new Thread(new Runnable() {
@Override public void run() {
Message message = handler.obtainMessage();
message.obj = timeString;
message.sendToTarget();
}
});
thread.start();
//----------------------------------------------------------------------------------------
// Create response HTML
StringBuilder stringBuilder = new StringBuilder();
stringBuilder.append("<html>");
stringBuilder.append("<body>");
stringBuilder.append("<b>AMIGO Camera - ").append(timeString).append("</b><hr>");
stringBuilder.append("<b>Headers</b> = ").append(String.valueOf(session.getHeaders())).append("<br>");
stringBuilder.append("<b>Method</b> = ").append(String.valueOf(session.getMethod())).append("<br>");
stringBuilder.append("<b>URI</b> = ").append(String.valueOf(session.getUri())).append("<br>");
stringBuilder.append("<b>Parameters</b> = ").append(String.valueOf(session.getParms())).append("<br>");
stringBuilder.append("</body>");
stringBuilder.append("</html>");
return new NanoHTTPD.Response(stringBuilder.toString());
}
}
}
