android 笔记

1.  安装apk：

    public static void installApk(Context context, String apkPath) {
        File apkfile = new File(apkPath);
        if (!apkfile.exists()) {
            return;
        }
        Intent i = new Intent(android.content.Intent.ACTION_VIEW);
        i.addFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
        i.setDataAndType(Uri.fromFile(apkfile),
                "application/vnd.android.package-archive");
        context.startActivity(i);
    }

2.  设置ContextMenu标题颜色：

    <item name="android:alertDialogTheme">@style/alert_dialog_theme</item>


    <style name="alert_dialog_theme" parent="@android:style/Theme.Holo.Light.Dialog">
        <item name="android:windowTitleStyle">@style/DialogWindowTitle</item>
    </style>


    <style name="DialogWindowTitle">
        <item name="android:maxLines">1</item>
        <item name="android:scrollHorizontally">true</item>
        <item name="android:textAppearance">@style/MyTextAppearance</item>
    </style>


    <style name="MyTextAppearance">
        <item name="android:textSize">22sp</item>
        <item name="android:textColor">@android:color/holo_red_light</item>
    </style>

3.  拷贝文件：

    public static void copyFile(File src, File dst) throws IOException {
        FileChannel in = new FileInputStream(src).getChannel();
        FileChannel out = new FileOutputStream(dst).getChannel();
        try {
            in.transferTo(0, in.size(), out);
        } catch (IOException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        } finally {
            if (in != null) {
                in.close();
            }
            if (out != null) {
                out.close();
            }
        }
    }

4.  检测网络是否可用：

    public static boolean networkIsAvailable(Context ctx) {
        ConnectivityManager cManager = (ConnectivityManager) ctx
                .getSystemService(Context.CONNECTIVITY_SERVICE);
        NetworkInfo info = cManager.getActiveNetworkInfo();
        return info != null && info.isAvailable() && info.isConnected();
    }

5.  检测GPS是否打开：

    public static boolean gpsIsOpend(Context ctx) {
        LocationManager lm = (LocationManager) ctx
                .getSystemService(Context.LOCATION_SERVICE);
        return lm
                .isProviderEnabled(android.location.LocationManager.GPS_PROVIDER);
    }

 

6.  TextView跑马灯效果：

    android:ellipsize="marquee"
    android:focusable="true"
    android:focusableInTouchMode="true"
    android:marqueeRepeatLimit="marquee_forever"
    android:singleLine="true"

以上属性缺一不可或在Java代码中设置对应属性值。

 

7.  进入应用自动弹出软键盘：

    @Override
    protected void onResume() {
        // TODO Auto-generated method stub
        new Handler().postDelayed(new Runnable() {
            @Override
            public void run() {
                // TODO Auto-generated method stub
                mEditText.requestFocus();
                showInputMethod(mEditText);
            }
        }, 100);
        super.onResume();
    }

    private void showInputMethod(View view) {
        if (view instanceof EditText) {
            InputMethodManager inputMethodManager = (InputMethodManager) getSystemService(Context.INPUT_METHOD_SERVICE);
            inputMethodManager.showSoftInput(view, 0);
        }
    }

8.  4.0之后隐藏 虚拟键：

public class MainActivity extends Activity implements OnClickListener {

    private View mMainView;

    /** Called when the activity is first created. */
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);

        mMainView = findViewById(R.id.main);
        mMainView.setOnClickListener(this);
    }

    @Override
    public void onClick(View v) {
        // TODO Auto-generated method stub
        int i = mMainView.getSystemUiVisibility();
        if (i == View.SYSTEM_UI_FLAG_HIDE_NAVIGATION) {
            mMainView.setSystemUiVisibility(View.SYSTEM_UI_FLAG_VISIBLE);
        } else if (i == View.SYSTEM_UI_FLAG_VISIBLE) {
            mMainView.setSystemUiVisibility(View.SYSTEM_UI_FLAG_LOW_PROFILE);
        } else if (i == View.SYSTEM_UI_FLAG_LOW_PROFILE) {
            mMainView.setSystemUiVisibility(View.SYSTEM_UI_FLAG_HIDE_NAVIGATION);
        }
    }

}

 

9.  获得app版本：

    // 获得 AndroidManifest.xml android:versionName 字段
    public static String getVersionName(Context ctx) {
        PackageManager pManager = ctx.getPackageManager();
        String version = null;
        try {
            version = pManager.getPackageInfo(ctx.getPackageName(), 0).versionName;
        } catch (NameNotFoundException e) {
            // TODO: handle exception
            e.printStackTrace();
        } finally {
            return version;
        }
    }

    // 获得 AndroidManifest.xml android:versionCode 字段
    public static int getVersionCode(Context ctx) {
        PackageManager pManager = ctx.getPackageManager();
        int versionCode = 0;
        try {
            versionCode = pManager.getPackageInfo(ctx.getPackageName(), 0).versionCode;
        } catch (NameNotFoundException e) {
            // TODO: handle exception
            e.printStackTrace();
        } finally {
            return versionCode;
        }
    }

 

10.  dip与px互转：

    public static int dip2px(Context context, float dipValue) {
        final float scale = context.getResources().getDisplayMetrics().density;
        return (int) (dipValue * scale + 0.5f);
    }

    public static int px2dip(Context context, float pxValue) {
        final float scale = context.getResources().getDisplayMetrics().density;
        return (int) (pxValue / scale + 0.5f);
    }

 

11.  Bitmap与字节流互转：

    public byte[] serialize(Bitmap bitmap) {
        if (bitmap == null) {
            return null;
        }
        ByteArrayOutputStream baos = new ByteArrayOutputStream();
        // 将bitmap压缩成PNG编码，质量为100%存储
        bitmap.compress(Bitmap.CompressFormat.PNG, 100, baos);
        return baos.toByteArray();

    }

    public Bitmap unserialize(byte[] bizdata) {
        return BitmapFactory.decodeByteArray(bizdata, 0, bizdata.length, null);
    }

12.  跳到指定联系人收件箱：

    startActivity(new Intent(Intent.ACTION_SENDTO, Uri.fromParts("sms", number, null)));



13.Ubuntu（Linux）下下载的mp3文件名乱码：
    写个脚本：
    #!/bin/bash

    convmv -r -f utf8 -t iso88591 $1 --notest --nosmart && convmv -r -f gbk -t utf8 $1 --notest --nosmart
    # $1 第一个参数---一个目录