Android 开发中的一些小技巧

dip转px

    public int convertDipOrPx(int dip) {        float scale = MarketApplication.getMarketApplicationContext()                .getResources().getDisplayMetrics().density;        return (int) (dip * scale + 0.5f * (dip >= 0 ? 1 : -1));    }

获取当前窗体,并添加自定义view:

getWindowManager()                .addView(                        overlay,                        new WindowManager.LayoutParams(                                LayoutParams.WRAP_CONTENT,                                LayoutParams.WRAP_CONTENT,                                WindowManager.LayoutParams.TYPE_APPLICATION,                                WindowManager.LayoutParams.FLAG_NOT_FOCUSABLE                                        | WindowManager.LayoutParams.FLAG_NOT_TOUCHABLE,                                PixelFormat.TRANSLUCENT));

自定义fastScrollBar图片样式：

        try {            Field f = AbsListView.class.getDeclaredField("mFastScroller");            f.setAccessible(true);            Object o = f.get(listView);            f = f.getType().getDeclaredField("mThumbDrawable");            f.setAccessible(true);            Drawable drawable = (Drawable) f.get(o);            drawable = getResources().getDrawable(R.drawable.ic_launcher);            f.set(o, drawable);            Toast.makeText(this, f.getType().getName(), 1000).show();        } catch (Exception e) {            throw new RuntimeException(e);        }

=网络==================================

判断网络是否可用：

/** * 网络是否可用 *  * @param context * @return */public static boolean isNetworkAvailable(Context context) {ConnectivityManager mgr = (ConnectivityManager) context.getSystemService(Context.CONNECTIVITY_SERVICE);NetworkInfo[] info = mgr.getAllNetworkInfo();    if (info != null) {    for (int i = 0; i < info.length; i++) {    if (info[i].getState() == NetworkInfo.State.CONNECTED) {    return true;    }    }    }return false;}

方法二：

    /*     * 判断网络连接是否已开 2012-08-20true 已打开 false 未打开     */    public static boolean isConn(Context context) {        boolean bisConnFlag = false;        ConnectivityManager conManager = (ConnectivityManager) context                .getSystemService(Context.CONNECTIVITY_SERVICE);        NetworkInfo network = conManager.getActiveNetworkInfo();        if (network != null) {            bisConnFlag = conManager.getActiveNetworkInfo().isAvailable();        }        return bisConnFlag;    }

判断是不是Wifi连接：

    public static boolean isWifiActive(Context icontext) {        Context context = icontext.getApplicationContext();        ConnectivityManager connectivity = (ConnectivityManager) context                .getSystemService(Context.CONNECTIVITY_SERVICE);        NetworkInfo[] info;        if (connectivity != null) {            info = connectivity.getAllNetworkInfo();            if (info != null) {                for (int i = 0; i < info.length; i++) {                    if (info[i].getTypeName().equals("WIFI")                            && info[i].isConnected()) {                        return true;                    }                }            }        }        return false;    }

判断当前网络类型

/** * 网络方式检查 */private static int netCheck(Context context) {ConnectivityManager conMan = (ConnectivityManager) context.getSystemService(Context.CONNECTIVITY_SERVICE);State mobile = conMan.getNetworkInfo(ConnectivityManager.TYPE_MOBILE).getState();State wifi = conMan.getNetworkInfo(ConnectivityManager.TYPE_WIFI).getState();if (wifi.equals(State.CONNECTED)) {return DO_WIFI;} else if (mobile.equals(State.CONNECTED)) {return DO_3G;} else {return NO_CONNECTION;}}

获取下载文件的真实名字

    public String getReallyFileName(String url) {        StrictMode.setThreadPolicy(new StrictMode.ThreadPolicy.Builder()                .detectDiskReads().detectDiskWrites().detectNetwork() // 这里可以替换为detectAll()                                                                      // 就包括了磁盘读写和网络I/O                .penaltyLog() // 打印logcat，当然也可以定位到dropbox，通过文件保存相应的log                .build());        StrictMode.setVmPolicy(new StrictMode.VmPolicy.Builder()                .detectLeakedSqlLiteObjects() // 探测SQLite数据库操作                .penaltyLog() // 打印logcat                .penaltyDeath().build());        String filename = "";        URL myURL;        HttpURLConnection conn = null;        if (url == null || url.length() < 1) {            return null;        }        try {            myURL = new URL(url);            conn = (HttpURLConnection) myURL.openConnection();            conn.connect();            conn.getResponseCode();            URL absUrl = conn.getURL();// 获得真实Url            // 打印输出服务器Header信息            // Map<String, List<String>> map = conn.getHeaderFields();            // for (String str : map.keySet()) {            // if (str != null) {            // Log.e("H3c", str + map.get(str));            // }            // }            filename = conn.getHeaderField("Content-Disposition");// 通过Content-Disposition获取文件名，这点跟服务器有关，需要灵活变通            if (filename == null || filename.length() < 1) {                filename = URLDecoder.decode(absUrl.getFile(), "UTF-8");            }        } catch (MalformedURLException e) {            e.printStackTrace();        } catch (IOException e) {            e.printStackTrace();        } finally {            if (conn != null) {                conn.disconnect();                conn = null;            }        }        return filename;    }

=图片==========================

bitmap转Byte数组(微信分享就需要用到)

public byte[] bmpToByteArray(final Bitmap bmp, final boolean needRecycle) {        ByteArrayOutputStream output = new ByteArrayOutputStream();        bmp.compress(CompressFormat.PNG, 100, output);        if (needRecycle) {            bmp.recycle();        }        byte[] result = output.toByteArray();        try {            output.close();        } catch (Exception e) {            e.printStackTrace();        }        return result;    }

Resources转Bitmap

public Bitmap loadBitmap(Resources res, int id) {        BitmapFactory.Options opt = new BitmapFactory.Options();        opt.inPreferredConfig = Bitmap.Config.RGB_565;        opt.inPurgeable = true;        opt.inInputShareable = true;        InputStream is = res.openRawResource(id);// 获取资源图片        return BitmapFactory.decodeStream(is, null, opt);    }

保存图片到SD卡

public void saveBitmapToFile(String url, String filePath) {        File iconFile = new File(filePath);        if (!iconFile.getParentFile().exists()) {            iconFile.getParentFile().mkdirs();        }        if (iconFile.exists() && iconFile.length() > 0) {            return;        }        FileOutputStream fos = null;        InputStream is = null;        try {            fos = new FileOutputStream(filePath);            is = new URL(url).openStream();            int data = is.read();            while (data != -1) {                fos.write(data);                data = is.read();            }        } catch (IOException e) {            e.printStackTrace();        } finally {            try {                if (is != null) {                    is.close();                }                if (fos != null) {                    fos.close();                }            } catch (IOException e) {                e.printStackTrace();            }        }    }

=系统==============================

根据包名打开一个应用程序

    public boolean openApp(String packageName) {        PackageInfo pi = null;        try {            pi = mPM.getPackageInfo(packageName, 0);        } catch (NameNotFoundException e) {            e.printStackTrace();            return false;        }        if (pi == null) {            return false;        }        Intent resolveIntent = new Intent(Intent.ACTION_MAIN, null);        resolveIntent.addCategory(Intent.CATEGORY_LAUNCHER);        resolveIntent.setPackage(pi.packageName);        List<ResolveInfo> apps = mPM.queryIntentActivities(resolveIntent, 0);        ResolveInfo ri = null;        try {            ri = apps.iterator().next();        } catch (Exception e) {            return true;        }        if (ri != null) {            String tmpPackageName = ri.activityInfo.packageName;            String className = ri.activityInfo.name;            Intent intent = new Intent(Intent.ACTION_MAIN);            intent.addCategory(Intent.CATEGORY_LAUNCHER);            ComponentName cn = new ComponentName(tmpPackageName, className);            intent.setComponent(cn);            intent.setFlags(Intent.FLAG_ACTIVITY_NEW_TASK);            MarketApplication.getMarketApplicationContext().startActivity(                    intent);        } else {            return false;        }        return true;    }

判断是否APK是否安装过

public boolean checkApkExist(Context context, String packageName) {        if (packageName == null || "".equals(packageName))            return false;        try {            ApplicationInfo info = context.getPackageManager()                    .getApplicationInfo(packageName,                            PackageManager.GET_UNINSTALLED_PACKAGES);            return true;        } catch (NameNotFoundException e) {            return false;        } catch (NullPointerException e) {            return false;        }    }

安装APK

    public void installApk(Context context, String strFileAllName) {        File file = new File(strFileAllName);        Intent intent = new Intent();        intent.addFlags(Intent.FLAG_ACTIVITY_NEW_TASK);        intent.setAction(Intent.ACTION_VIEW);        String type = "application/vnd.android.package-archive";        intent.setDataAndType(Uri.fromFile(file), type);        context.startActivity(intent);    }

卸载APK

    public void UninstallApk(Context context, String strPackageName) {        Uri packageURI = Uri.parse("package:" + strPackageName);        Intent uninstallIntent = new Intent(Intent.ACTION_DELETE, packageURI);        context.startActivity(uninstallIntent);    }

判断SD卡是否可用

    public boolean CheckSD() {        if (android.os.Environment.getExternalStorageState().equals(                android.os.Environment.MEDIA_MOUNTED)) {            return true;        } else {            return false;        }    }

创建快捷方式：

    public void createShortCut(Context contxt) {        // if (isInstallShortcut()) {// 如果已经创建了一次就不会再创建了        // return;        // }        Intent sIntent = new Intent(Intent.ACTION_MAIN);        sIntent.addCategory(Intent.CATEGORY_LAUNCHER);// 加入action,和category之后，程序卸载的时候才会主动将该快捷方式也卸载        sIntent.setClass(contxt, Login.class);        Intent installer = new Intent();        installer.putExtra("duplicate", false);        installer.putExtra("android.intent.extra.shortcut.INTENT", sIntent);        installer.putExtra("android.intent.extra.shortcut.NAME", "名字");        installer.putExtra("android.intent.extra.shortcut.ICON_RESOURCE",                Intent.ShortcutIconResource                        .fromContext(contxt, R.drawable.icon));        installer.setAction("com.android.launcher.action.INSTALL_SHORTCUT");        contxt.sendBroadcast(installer);    }

判断快捷方式是否创建：

private boolean isInstallShortcut() {        boolean isInstallShortcut = false;        final ContentResolver cr = MarketApplication                .getMarketApplicationContext().getContentResolver();        String AUTHORITY = "com.android.launcher.settings";        Uri CONTENT_URI = Uri.parse("content://" + AUTHORITY                + "/favorites?notify=true");        Cursor c = cr.query(CONTENT_URI,                new String[] { "title", "iconResource" }, "title=?",                new String[] { "名字" }, null);        if (c != null && c.getCount() > 0) {            isInstallShortcut = true;        }        if (c != null) {            c.close();        }        if (isInstallShortcut) {            return isInstallShortcut;        }        AUTHORITY = "com.android.launcher2.settings";        CONTENT_URI = Uri.parse("content://" + AUTHORITY                + "/favorites?notify=true");        c = cr.query(CONTENT_URI, new String[] { "title", "iconResource" },                "title=?", new String[] { "名字" }, null);        if (c != null && c.getCount() > 0) {            isInstallShortcut = true;        }        if (c != null) {            c.close();        }        AUTHORITY = "com.baidu.launcher";        CONTENT_URI = Uri.parse("content://" + AUTHORITY                + "/favorites?notify=true");        c = cr.query(CONTENT_URI, new String[] { "title", "iconResource" },                "title=?", new String[] { "名字" }, null);        if (c != null && c.getCount() > 0) {            isInstallShortcut = true;        }        if (c != null) {            c.close();        }        return isInstallShortcut;    }

过滤特殊字符：

    private String StringFilter(String str) throws PatternSyntaxException {        // 只允许字母和数字        // String regEx = "[^a-zA-Z0-9]";        // 清除掉所有特殊字符        String regEx = "[`~!@#$%^&*()+=|{}':;',//[//].<>/?~！@#￥%……&*（）——+|{}【】‘；：”“’。，、？]";        Pattern p = Pattern.compile(regEx);        Matcher m = p.matcher(str);        return m.replaceAll("").trim();    }

执行shell语句：

    public int execRootCmdSilent(String cmd) {        int result = -1;        DataOutputStream dos = null;        try {            Process p = Runtime.getRuntime().exec("su");            dos = new DataOutputStream(p.getOutputStream());            dos.writeBytes(cmd + "\n");            dos.flush();            dos.writeBytes("exit\n");            dos.flush();            p.waitFor();            result = p.exitValue();        } catch (Exception e) {            e.printStackTrace();        } finally {            if (dos != null) {                try {                    dos.close();                } catch (IOException e) {                    e.printStackTrace();                }            }        }        return result;    }

获得文件MD5值：

    public String getFileMD5(File file) {        if (!file.isFile()) {            return null;        }        MessageDigest digest = null;        FileInputStream in = null;        byte buffer[] = new byte[1024];        int len;        try {            digest = MessageDigest.getInstance("MD5");            in = new FileInputStream(file);            while ((len = in.read(buffer, 0, 1024)) != -1) {                digest.update(buffer, 0, len);            }        } catch (Exception e) {            e.printStackTrace();            return null;        } finally {            if (in != null) {                try {                    in.close();                } catch (IOException e) {                    e.printStackTrace();                }            }        }        BigInteger bigInt = new BigInteger(1, digest.digest());        return bigInt.toString(16);    }