Android 开发相关注意点

关于Intent实例调用：

1，调用外部程序：

   参数1：Process Name

   参数2：Application Class

try{
            Intent eth = new Intent();
            eth.setClassName("com.android.settings", "com.android.settings.EthernetSettings");
            startActivity(eth);
          }catch(ActivityNotFoundException e)
          {
              //deal error code
              return ;
          }

2，调用SDK自带的

startActivity(new Intent(Settings.ACTION_WIFI_SETTINGS));

3，调用自己写的实例

startActivity(new Intent(this, timecheck.class));

关于添加单击事件处理代码：

声明时需要调用接口：public class ITester extends Activity implements OnClickListener{...}

并添加单击事件:     public void onClick(View v)

View dateTimeBtn = findViewById(R.id.btn_time_chk); dateTimeBtn.setOnClickListener(this);

如果需要获得单击的具体对象，需要用到方法：   v.getId();

例如：

public void onClick(View v)
{
   switch(v.getId())
      {
         case R.id.btn_time_chk:
            startActivity(new Intent(this, timecheck.class));
            break;
        }
 }

其他代码实例：

1，或者内部eMMC容量大小

File path = Environment.getDataDirectory();   
              StatFs stat = new StatFs(path.getPath());   
              
              long blockSize = stat.getBlockSize();   
              long totalBlocks = stat.getBlockCount(); 
              long aBlocks = stat.getAvailableBlocks(); 
              
              float Tsize = (float)blockSize * totalBlocks/(1024*1024*1024);
              float Asize = (float)blockSize * aBlocks/(1024*1024*1024);

2，获取系统当前时间：

import android.graphics.Color;
import android.os.Bundle;
import android.os.Handler;
import android.text.format.Time;
import android.widget.TextView;


public class timecheck extends ITester{
    
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.timecheck);
        
        handler.postDelayed(runnable, 1000);  //delay 1000ms=1s
        
    }
    
    Handler handler=new Handler();
    Runnable runnable=new Runnable(){
       @Override
       public void run() {
        // TODO Auto-generated method stub
            TextView timeV = (TextView)findViewById(R.id.timeView);
            Time tm = new Time();

            tm.setToNow();  //Get local time

            int year = tm.year;
            int mon = tm.month + 1;
            int day = tm.monthDay;
            int hour = tm.hour;
            int min = tm.minute;
            int sec = tm.second;
            
            timeV.setTextSize(39);
            timeV.setTextColor(Color.BLUE);
            timeV.setText("Now Time is: \n    "+ year + "-" + mon + "-" 
                            + day + " " + hour + ":" + min + ":" + sec);        
            handler.postDelayed(this, 500); //delay 500ms=0.5s
       }
    };
}

3，文件读写实例：

File f = new File("/sdcard/sdt.txt");
          
      f.createNewFile();
          FileOutputStream wf = new FileOutputStream(f);
          wf.write("\nSD_Test_String_from_iTester\nWritten By Tody \n(c) 2011 T-ware Inc.\n".getBytes()); // write string to file...
          wf.flush();
          wf.close();File f = new File("/proc/meminfo");
          BufferedReader r = new BufferedReader(new InputStreamReader( new FileInputStream( f )),32);
    String line = r.readLine();

4，对话框弹出实例：                new AlertDialog.Builder(this).setMessage("请按电源按钮选择休眠（S3）测试").show();

5，振动器实例：

private Vibrator iVibrator;
                        iVibrator = (Vibrator)getSystemService(VIBRATOR_SERVICE);
      iVibrator.vibrate(100);
      vibrateBtn.setBackgroundColor(Color.GREEN);

6，取消对话框实例：

new AlertDialog.Builder (this)
    .setTitle ("Alerting Message")
    .setMessage ("eek!")
    .setNegativeButton ("Close", new DialogInterface.OnClickListener() {   
        @Override
        public void onClick(DialogInterface dialog, int which) {
            //do nothing - it will close on its own
        }
     })
   .show ();

7，确定对话框实例：

AlertDialog.Builder builder = new AlertDialog.Builder(MainDialog.this);
            builder.setIcon(R.drawable.icon);
            builder.setTitle("你确定要离开吗？");
            builder.setPositiveButton("确定", new DialogInterface.OnClickListener() {
                public void onClick(DialogInterface dialog, int whichButton) {
                    //这里添加点击确定后的逻辑
                    showDialog("你选择了确定");
                }
            });

AndroidManifest.xml：定义权限及程序配置等：

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
      package="org.example.itester"
      android:versionCode="1"
      android:versionName="1.0">
    <uses-sdk android:minSdkVersion="8" />

    <uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE"/>
    <uses-permission android:name="android.permission.MOUNT_UNMOUNT_FILESYSTEMS"/>
    <uses-permission android:name="android.permission.VIBRATE"/>
    
    <application android:icon="@drawable/icon" android:label="@string/app_name">

        <activity android:name=".ITester"
                  android:label="@string/app_name"
                  android:configChanges="orientation">
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />
                <category android:name="android.intent.category.LAUNCHER" />
                <category android:name="android.intent.catetory.DEFAULT" />
            </intent-filter>
        </activity>
        <activity android:name=".about"
                  android:label="@string/about_title">
        </activity>

        <activity android:name=".timecheck"
                  android:label="@string/now_time_title"
                  android:theme="@android:style/Theme.Dialog">
        </activity>

        <activity android:name=".sdcard"
                  android:label="@string/sd_title"
                  android:theme="@android:style/Theme.Dialog">
                <uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE"/>
        </activity>

        <activity android:name=".meminfo"
                  android:label="@string/mem_info_title"
                  android:theme="@android:style/Theme.Dialog">
        </activity>

        <activity android:name=".rgbchk"
                  android:label="@string/rgb_chk">
        </activity>

    </application>
</manifest>