公共方法总结

1、 判断是否为快速点击

    /** 判断是否是快速点击 */
    private static long lastClickTime;

    public static boolean isFastDoubleClick() {
        long time = System.currentTimeMillis();
        long timeD = time - lastClickTime;
        if (0 < timeD && timeD < 500) {

            return true;
        }
        lastClickTime = time;
        return false;
    }

2、日志工具类 Log.java

public class L  
{  
    private L()  
    {  
        /* 不可被实例化 */  
        throw new UnsupportedOperationException("Cannot be instantiated!");  
    }  
    // 是否需要打印bug，可以在application的onCreate函数里面初始化  
    public static boolean isDebug = true; 
    private static final String TAG = "DefaultTag";  

    // 下面四个是默认tag的函数  
    public static void i(String msg)  
    {  
        if (isDebug)  
            Log.i(TAG, msg);  
    }  

    public static void d(String msg)  
    {  
        if (isDebug)  
            Log.d(TAG, msg);  
    }  

    public static void e(String msg)  
    {  
        if (isDebug)  
            Log.e(TAG, msg);  
    }  

    public static void v(String msg)  
    {  
        if (isDebug)  
            Log.v(TAG, msg);  
    }  

    // 下面是传入自定义tag的函数  
    public static void i(String tag, String msg)  
    {  
        if (isDebug)  
            Log.i(tag, msg);  
    }  

    public static void d(String tag, String msg)  
    {  
        if (isDebug)  
            Log.i(tag, msg);  
    }  

    public static void e(String tag, String msg)  
    {  
        if (isDebug)  
            Log.i(tag, msg);  
    }  

    public static void v(String tag, String msg)  
    {  
        if (isDebug)  
            Log.i(tag, msg);  
    }  
}

3、DensityUtils  

public class DensityUtils  
{  
    private DensityUtils()  
    {  
        /* cannot be instantiated */  
        throw new UnsupportedOperationException("cannot be instantiated");  
    }  

    /** 
     * dp转px 
     *  
     * @param context 
     * @param val 
     * @return 
     */  
    public static int dp2px(Context context, float dpVal)  
    {  
        return (int) TypedValue.applyDimension(TypedValue.COMPLEX_UNIT_DIP,  
                dpVal, context.getResources().getDisplayMetrics());  
    }  

    /** 
     * sp转px 
     *  
     * @param context 
     * @param val 
     * @return 
     */  
    public static int sp2px(Context context, float spVal)  
    {  
        return (int) TypedValue.applyDimension(TypedValue.COMPLEX_UNIT_SP,  
                spVal, context.getResources().getDisplayMetrics());  
    }  

    /** 
     * px转dp 
     *  
     * @param context 
     * @param pxVal 
     * @return 
     */  
    public static float px2dp(Context context, float pxVal)  
    {  
        final float scale = context.getResources().getDisplayMetrics().density;  
        return (pxVal / scale);  
    }  

    /** 
     * px转sp 
     *  
     * @param fontScale 
     * @param pxVal 
     * @return 
     */  
    public static float px2sp(Context context, float pxVal)  
    {  
        return (pxVal / context.getResources().getDisplayMetrics().scaledDensity);  
    }  

}

4、SD卡相关辅助类 SDCardUtils.java

public class SDCardUtils  
{  
    private SDCardUtils()  
    {  
        /* cannot be instantiated */  
        throw new UnsupportedOperationException("cannot be instantiated");  
    }  

    /** 
     * 判断SDCard是否可用 
     *  
     * @return 
     */  
    public static boolean isSDCardEnable()  
    {  
        return Environment.getExternalStorageState().equals(  
                Environment.MEDIA_MOUNTED);  

    }  

    /** 
     * 获取SD卡路径 
     *  
     * @return 
     */  
    public static String getSDCardPath()  
    {  
        return Environment.getExternalStorageDirectory().getAbsolutePath()  
                + File.separator;  
    }  

    /** 
     * 获取SD卡的剩余容量 单位byte 
     *  
     * @return 
     */  
    public static long getSDCardAllSize()  
    {  
        if (isSDCardEnable())  
        {  
            StatFs stat = new StatFs(getSDCardPath());  
            // 获取空闲的数据块的数量  
            long availableBlocks = (long) stat.getAvailableBlocks() - 4;  
            // 获取单个数据块的大小（byte）  
            long freeBlocks = stat.getAvailableBlocks();  
            return freeBlocks * availableBlocks;  
        }  
        return 0;  
    }  

    /** 
     * 获取指定路径所在空间的剩余可用容量字节数，单位byte 
     *  
     * @param filePath 
     * @return 容量字节 SDCard可用空间，内部存储可用空间 
     */  
    public static long getFreeBytes(String filePath)  
    {  
        // 如果是sd卡的下的路径，则获取sd卡可用容量  
        if (filePath.startsWith(getSDCardPath()))  
        {  
            filePath = getSDCardPath();  
        } else  
        {// 如果是内部存储的路径，则获取内存存储的可用容量  
            filePath = Environment.getDataDirectory().getAbsolutePath();  
        }  
        StatFs stat = new StatFs(filePath);  
        long availableBlocks = (long) stat.getAvailableBlocks() - 4;  
        return stat.getBlockSize() * availableBlocks;  
    }  

    /** 
     * 获取系统存储路径 
     *  
     * @return 
     */  
    public static String getRootDirectoryPath()  
    {  
        return Environment.getRootDirectory().getAbsolutePath();  
    }  

}

5、屏幕相关辅助类 ScreenUtils.java

public class ScreenUtils  
{  
    private ScreenUtils()  
    {  
        /* cannot be instantiated */  
        throw new UnsupportedOperationException("cannot be instantiated");  
    }  

    /** 
     * 获得屏幕高度 
     *  
     * @param context 
     * @return 
     */  
    public static int getScreenWidth(Context context)  
    {  
        WindowManager wm = (WindowManager) context  
                .getSystemService(Context.WINDOW_SERVICE);  
        DisplayMetrics outMetrics = new DisplayMetrics();  
        wm.getDefaultDisplay().getMetrics(outMetrics);  
        return outMetrics.widthPixels;  
    }  

    /** 
     * 获得屏幕宽度 
     *  
     * @param context 
     * @return 
     */  
    public static int getScreenHeight(Context context)  
    {  
        WindowManager wm = (WindowManager) context  
                .getSystemService(Context.WINDOW_SERVICE);  
        DisplayMetrics outMetrics = new DisplayMetrics();  
        wm.getDefaultDisplay().getMetrics(outMetrics);  
        return outMetrics.heightPixels;  
    }  

    /** 
     * 获得状态栏的高度 
     *  
     * @param context 
     * @return 
     */  
    public static int getStatusHeight(Context context)  
    {  

        int statusHeight = -1;  
        try  
        {  
            Class<?> clazz = Class.forName("com.android.internal.R$dimen");  
            Object object = clazz.newInstance();  
            int height = Integer.parseInt(clazz.getField("status_bar_height")  
                    .get(object).toString());  
            statusHeight = context.getResources().getDimensionPixelSize(height);  
        } catch (Exception e)  
        {  
            e.printStackTrace();  
        }  
        return statusHeight;  
    }  

    /** 
     * 获取当前屏幕截图，包含状态栏 
     *  
     * @param activity 
     * @return 
     */  
    public static Bitmap snapShotWithStatusBar(Activity activity)  
    {  
        View view = activity.getWindow().getDecorView();  
        view.setDrawingCacheEnabled(true);  
        view.buildDrawingCache();  
        Bitmap bmp = view.getDrawingCache();  
        int width = getScreenWidth(activity);  
        int height = getScreenHeight(activity);  
        Bitmap bp = null;  
        bp = Bitmap.createBitmap(bmp, 0, 0, width, height);  
        view.destroyDrawingCache();  
        return bp;  

    }  

    /** 
     * 获取当前屏幕截图，不包含状态栏 
     *  
     * @param activity 
     * @return 
     */  
    public static Bitmap snapShotWithoutStatusBar(Activity activity)  
    {  
        View view = activity.getWindow().getDecorView();  
        view.setDrawingCacheEnabled(true);  
        view.buildDrawingCache();  
        Bitmap bmp = view.getDrawingCache();  
        Rect frame = new Rect();  
        activity.getWindow().getDecorView().getWindowVisibleDisplayFrame(frame);  
        int statusBarHeight = frame.top;  

        int width = getScreenWidth(activity);  
        int height = getScreenHeight(activity);  
        Bitmap bp = null;  
        bp = Bitmap.createBitmap(bmp, 0, statusBarHeight, width, height  
                - statusBarHeight);  
        view.destroyDrawingCache();  
        return bp;  

    }  

}

6、文件工具类 FileUtils.java

public class FileUtils {

    public final static String FILE_EXTENSION_SEPARATOR = ".";

    private FileUtils() {
        throw new AssertionError();
    }

    /**
     * read file
     * 
     * @param filePath
     * @param charsetName The name of a supported {@link java.nio.charset.Charset </code>charset<code>}
     * @return if file not exist, return null, else return content of file
     * @throws RuntimeException if an error occurs while operator BufferedReader
     */
    public static StringBuilder readFile(String filePath, String charsetName) {
        File file = new File(filePath);
        StringBuilder fileContent = new StringBuilder("");
        if (file == null || !file.isFile()) {
            return null;
        }

        BufferedReader reader = null;
        try {
            InputStreamReader is = new InputStreamReader(new FileInputStream(file), charsetName);
            reader = new BufferedReader(is);
            String line = null;
            while ((line = reader.readLine()) != null) {
                if (!fileContent.toString().equals("")) {
                    fileContent.append("
");
                }
                fileContent.append(line);
            }
            return fileContent;
        } catch (IOException e) {
            throw new RuntimeException("IOException occurred. ", e);
        } finally {
            IOUtils.close(reader);
        }
    }

    /**
     * write file
     * 
     * @param filePath
     * @param content
     * @param append is append, if true, write to the end of file, else clear content of file and write into it
     * @return return false if content is empty, true otherwise
     * @throws RuntimeException if an error occurs while operator FileWriter
     */
    public static boolean writeFile(String filePath, String content, boolean append) {
        if (StringUtils.isEmpty(content)) {
            return false;
        }

        FileWriter fileWriter = null;
        try {
            makeDirs(filePath);
            fileWriter = new FileWriter(filePath, append);
            fileWriter.write(content);
            return true;
        } catch (IOException e) {
            throw new RuntimeException("IOException occurred. ", e);
        } finally {
            IOUtils.close(fileWriter);
        }
    }

    /**
     * write file
     * 
     * @param filePath
     * @param contentList
     * @param append is append, if true, write to the end of file, else clear content of file and write into it
     * @return return false if contentList is empty, true otherwise
     * @throws RuntimeException if an error occurs while operator FileWriter
     */
    public static boolean writeFile(String filePath, List<String> contentList, boolean append) {
        if (ListUtils.isEmpty(contentList)) {
            return false;
        }

        FileWriter fileWriter = null;
        try {
            makeDirs(filePath);
            fileWriter = new FileWriter(filePath, append);
            int i = 0;
            for (String line : contentList) {
                if (i++ > 0) {
                    fileWriter.write("
");
                }
                fileWriter.write(line);
            }
            return true;
        } catch (IOException e) {
            throw new RuntimeException("IOException occurred. ", e);
        } finally {
            IOUtils.close(fileWriter);
        }
    }

    /**
     * write file, the string will be written to the begin of the file
     * 
     * @param filePath
     * @param content
     * @return
     */
    public static boolean writeFile(String filePath, String content) {
        return writeFile(filePath, content, false);
    }

    /**
     * write file, the string list will be written to the begin of the file
     * 
     * @param filePath
     * @param contentList
     * @return
     */
    public static boolean writeFile(String filePath, List<String> contentList) {
        return writeFile(filePath, contentList, false);
    }

    /**
     * write file, the bytes will be written to the begin of the file
     * 
     * @param filePath
     * @param stream
     * @return
     * @see {@link #writeFile(String, InputStream, boolean)}
     */
    public static boolean writeFile(String filePath, InputStream stream) {
        return writeFile(filePath, stream, false);
    }

    /**
     * write file
     * 
     * @param file the file to be opened for writing.
     * @param stream the input stream
     * @param append if <code>true</code>, then bytes will be written to the end of the file rather than the beginning
     * @return return true
     * @throws RuntimeException if an error occurs while operator FileOutputStream
     */
    public static boolean writeFile(String filePath, InputStream stream, boolean append) {
        return writeFile(filePath != null ? new File(filePath) : null, stream, append);
    }

    /**
     * write file, the bytes will be written to the begin of the file
     * 
     * @param file
     * @param stream
     * @return
     * @see {@link #writeFile(File, InputStream, boolean)}
     */
    public static boolean writeFile(File file, InputStream stream) {
        return writeFile(file, stream, false);
    }

    /**
     * write file
     * 
     * @param file the file to be opened for writing.
     * @param stream the input stream
     * @param append if <code>true</code>, then bytes will be written to the end of the file rather than the beginning
     * @return return true
     * @throws RuntimeException if an error occurs while operator FileOutputStream
     */
    public static boolean writeFile(File file, InputStream stream, boolean append) {
        OutputStream o = null;
        try {
            makeDirs(file.getAbsolutePath());
            o = new FileOutputStream(file, append);
            byte data[] = new byte[1024];
            int length = -1;
            while ((length = stream.read(data)) != -1) {
                o.write(data, 0, length);
            }
            o.flush();
            return true;
        } catch (FileNotFoundException e) {
            throw new RuntimeException("FileNotFoundException occurred. ", e);
        } catch (IOException e) {
            throw new RuntimeException("IOException occurred. ", e);
        } finally {
            IOUtils.close(o);
            IOUtils.close(stream);
        }
    }

    /**
     * move file
     * 
     * @param sourceFilePath
     * @param destFilePath
     */
    public static void moveFile(String sourceFilePath, String destFilePath) {
        if (TextUtils.isEmpty(sourceFilePath) || TextUtils.isEmpty(destFilePath)) {
            throw new RuntimeException("Both sourceFilePath and destFilePath cannot be null.");
        }
        moveFile(new File(sourceFilePath), new File(destFilePath));
    }

    /**
     * move file
     * 
     * @param srcFile
     * @param destFile
     */
    public static void moveFile(File srcFile, File destFile) {
        boolean rename = srcFile.renameTo(destFile);
        if (!rename) {
            copyFile(srcFile.getAbsolutePath(), destFile.getAbsolutePath());
            deleteFile(srcFile.getAbsolutePath());
        }
    }

    /**
     * copy file
     * 
     * @param sourceFilePath
     * @param destFilePath
     * @return
     * @throws RuntimeException if an error occurs while operator FileOutputStream
     */
    public static boolean copyFile(String sourceFilePath, String destFilePath) {
        InputStream inputStream = null;
        try {
            inputStream = new FileInputStream(sourceFilePath);
        } catch (FileNotFoundException e) {
            throw new RuntimeException("FileNotFoundException occurred. ", e);
        }
        return writeFile(destFilePath, inputStream);
    }

    /**
     * read file to string list, a element of list is a line
     * 
     * @param filePath
     * @param charsetName The name of a supported {@link java.nio.charset.Charset </code>charset<code>}
     * @return if file not exist, return null, else return content of file
     * @throws RuntimeException if an error occurs while operator BufferedReader
     */
    public static List<String> readFileToList(String filePath, String charsetName) {
        File file = new File(filePath);
        List<String> fileContent = new ArrayList<String>();
        if (file == null || !file.isFile()) {
            return null;
        }

        BufferedReader reader = null;
        try {
            InputStreamReader is = new InputStreamReader(new FileInputStream(file), charsetName);
            reader = new BufferedReader(is);
            String line = null;
            while ((line = reader.readLine()) != null) {
                fileContent.add(line);
            }
            return fileContent;
        } catch (IOException e) {
            throw new RuntimeException("IOException occurred. ", e);
        } finally {
            IOUtils.close(reader);
        }
    }

    /**
     * get file name from path, not include suffix
     * 
     * <pre>
     *      getFileNameWithoutExtension(null)               =   null
     *      getFileNameWithoutExtension("")                 =   ""
     *      getFileNameWithoutExtension("   ")              =   "   "
     *      getFileNameWithoutExtension("abc")              =   "abc"
     *      getFileNameWithoutExtension("a.mp3")            =   "a"
     *      getFileNameWithoutExtension("a.b.rmvb")         =   "a.b"
     *      getFileNameWithoutExtension("c:\")              =   ""
     *      getFileNameWithoutExtension("c:\a")             =   "a"
     *      getFileNameWithoutExtension("c:\a.b")           =   "a"
     *      getFileNameWithoutExtension("c:a.txt\a")        =   "a"
     *      getFileNameWithoutExtension("/home/admin")      =   "admin"
     *      getFileNameWithoutExtension("/home/admin/a.txt/b.mp3")  =   "b"
     * </pre>
     * 
     * @param filePath
     * @return file name from path, not include suffix
     * @see
     */
    public static String getFileNameWithoutExtension(String filePath) {
        if (StringUtils.isEmpty(filePath)) {
            return filePath;
        }

        int extenPosi = filePath.lastIndexOf(FILE_EXTENSION_SEPARATOR);
        int filePosi = filePath.lastIndexOf(File.separator);
        if (filePosi == -1) {
            return (extenPosi == -1 ? filePath : filePath.substring(0, extenPosi));
        }
        if (extenPosi == -1) {
            return filePath.substring(filePosi + 1);
        }
        return (filePosi < extenPosi ? filePath.substring(filePosi + 1, extenPosi) : filePath.substring(filePosi + 1));
    }

    /**
     * get file name from path, include suffix
     * 
     * <pre>
     *      getFileName(null)               =   null
     *      getFileName("")                 =   ""
     *      getFileName("   ")              =   "   "
     *      getFileName("a.mp3")            =   "a.mp3"
     *      getFileName("a.b.rmvb")         =   "a.b.rmvb"
     *      getFileName("abc")              =   "abc"
     *      getFileName("c:\")              =   ""
     *      getFileName("c:\a")             =   "a"
     *      getFileName("c:\a.b")           =   "a.b"
     *      getFileName("c:a.txt\a")        =   "a"
     *      getFileName("/home/admin")      =   "admin"
     *      getFileName("/home/admin/a.txt/b.mp3")  =   "b.mp3"
     * </pre>
     * 
     * @param filePath
     * @return file name from path, include suffix
     */
    public static String getFileName(String filePath) {
        if (StringUtils.isEmpty(filePath)) {
            return filePath;
        }

        int filePosi = filePath.lastIndexOf(File.separator);
        return (filePosi == -1) ? filePath : filePath.substring(filePosi + 1);
    }

    /**
     * get folder name from path
     * 
     * <pre>
     *      getFolderName(null)               =   null
     *      getFolderName("")                 =   ""
     *      getFolderName("   ")              =   ""
     *      getFolderName("a.mp3")            =   ""
     *      getFolderName("a.b.rmvb")         =   ""
     *      getFolderName("abc")              =   ""
     *      getFolderName("c:\")              =   "c:"
     *      getFolderName("c:\a")             =   "c:"
     *      getFolderName("c:\a.b")           =   "c:"
     *      getFolderName("c:a.txt\a")        =   "c:a.txt"
     *      getFolderName("c:a\b\c\d.txt")    =   "c:a\b\c"
     *      getFolderName("/home/admin")      =   "/home"
     *      getFolderName("/home/admin/a.txt/b.mp3")  =   "/home/admin/a.txt"
     * </pre>
     * 
     * @param filePath
     * @return
     */
    public static String getFolderName(String filePath) {

        if (StringUtils.isEmpty(filePath)) {
            return filePath;
        }

        int filePosi = filePath.lastIndexOf(File.separator);
        return (filePosi == -1) ? "" : filePath.substring(0, filePosi);
    }

    /**
     * get suffix of file from path
     * 
     * <pre>
     *      getFileExtension(null)               =   ""
     *      getFileExtension("")                 =   ""
     *      getFileExtension("   ")              =   "   "
     *      getFileExtension("a.mp3")            =   "mp3"
     *      getFileExtension("a.b.rmvb")         =   "rmvb"
     *      getFileExtension("abc")              =   ""
     *      getFileExtension("c:\")              =   ""
     *      getFileExtension("c:\a")             =   ""
     *      getFileExtension("c:\a.b")           =   "b"
     *      getFileExtension("c:a.txt\a")        =   ""
     *      getFileExtension("/home/admin")      =   ""
     *      getFileExtension("/home/admin/a.txt/b")  =   ""
     *      getFileExtension("/home/admin/a.txt/b.mp3")  =   "mp3"
     * </pre>
     * 
     * @param filePath
     * @return
     */
    public static String getFileExtension(String filePath) {
        if (StringUtils.isBlank(filePath)) {
            return filePath;
        }

        int extenPosi = filePath.lastIndexOf(FILE_EXTENSION_SEPARATOR);
        int filePosi = filePath.lastIndexOf(File.separator);
        if (extenPosi == -1) {
            return "";
        }
        return (filePosi >= extenPosi) ? "" : filePath.substring(extenPosi + 1);
    }

    /**
     * Creates the directory named by the trailing filename of this file, including the complete directory path required
     * to create this directory. <br/>
     * <br/>
     * <ul>
     * <strong>Attentions:</strong>
     * <li>makeDirs("C:\Users\Trinea") can only create users folder</li>
     * <li>makeFolder("C:\Users\Trinea\") can create Trinea folder</li>
     * </ul>
     * 
     * @param filePath
     * @return true if the necessary directories have been created or the target directory already exists, false one of
     *         the directories can not be created.
     *         <ul>
     *         <li>if {@link FileUtils#getFolderName(String)} return null, return false</li>
     *         <li>if target directory already exists, return true</li>
     *         <li>return {@link java.io.File#makeFolder}</li>
     *         </ul>
     */
    public static boolean makeDirs(String filePath) {
        String folderName = getFolderName(filePath);
        if (StringUtils.isEmpty(folderName)) {
            return false;
        }

        File folder = new File(folderName);
        return (folder.exists() && folder.isDirectory()) ? true : folder.mkdirs();
    }

    /**
     * @param filePath
     * @return
     * @see #makeDirs(String)
     */
    public static boolean makeFolders(String filePath) {
        return makeDirs(filePath);
    }

    /**
     * Indicates if this file represents a file on the underlying file system.
     * 
     * @param filePath
     * @return
     */
    public static boolean isFileExist(String filePath) {
        if (StringUtils.isBlank(filePath)) {
            return false;
        }

        File file = new File(filePath);
        return (file.exists() && file.isFile());
    }

    /**
     * Indicates if this file represents a directory on the underlying file system.
     * 
     * @param directoryPath
     * @return
     */
    public static boolean isFolderExist(String directoryPath) {
        if (StringUtils.isBlank(directoryPath)) {
            return false;
        }

        File dire = new File(directoryPath);
        return (dire.exists() && dire.isDirectory());
    }

    /**
     * delete file or directory
     * <ul>
     * <li>if path is null or empty, return true</li>
     * <li>if path not exist, return true</li>
     * <li>if path exist, delete recursion. return true</li>
     * <ul>
     * 
     * @param path
     * @return
     */
    public static boolean deleteFile(String path) {
        if (StringUtils.isBlank(path)) {
            return true;
        }

        File file = new File(path);
        if (!file.exists()) {
            return true;
        }
        if (file.isFile()) {
            return file.delete();
        }
        if (!file.isDirectory()) {
            return false;
        }
        for (File f : file.listFiles()) {
            if (f.isFile()) {
                f.delete();
            } else if (f.isDirectory()) {
                deleteFile(f.getAbsolutePath());
            }
        }
        return file.delete();
    }

    /**
     * get file size
     * <ul>
     * <li>if path is null or empty, return -1</li>
     * <li>if path exist and it is a file, return file size, else return -1</li>
     * <ul>
     * 
     * @param path
     * @return returns the length of this file in bytes. returns -1 if the file does not exist.
     */
    public static long getFileSize(String path) {
        if (StringUtils.isBlank(path)) {
            return -1;
        }

        File file = new File(path);
        return (file.exists() && file.isFile() ? file.length() : -1);
    }
}

7、assets和raw资源工具类 ResourceUtils.java

public class ResourceUtils {

    private ResourceUtils() {
        throw new AssertionError();
    }

    /**
     * get an asset using ACCESS_STREAMING mode. This provides access to files that have been bundled with an
     * application as assets -- that is, files placed in to the "assets" directory.
     * 
     * @param context
     * @param fileName The name of the asset to open. This name can be hierarchical.
     * @return
     */
    public static String geFileFromAssets(Context context, String fileName) {
        if (context == null || StringUtils.isEmpty(fileName)) {
            return null;
        }

        StringBuilder s = new StringBuilder("");
        try {
            InputStreamReader in = new InputStreamReader(context.getResources().getAssets().open(fileName));
            BufferedReader br = new BufferedReader(in);
            String line;
            while ((line = br.readLine()) != null) {
                s.append(line);
            }
            return s.toString();
        } catch (IOException e) {
            e.printStackTrace();
            return null;
        }
    }

    /**
     * get content from a raw resource. This can only be used with resources whose value is the name of an asset files
     * -- that is, it can be used to open drawable, sound, and raw resources; it will fail on string and color
     * resources.
     * 
     * @param context
     * @param resId The resource identifier to open, as generated by the appt tool.
     * @return
     */
    public static String geFileFromRaw(Context context, int resId) {
        if (context == null) {
            return null;
        }

        StringBuilder s = new StringBuilder();
        try {
            InputStreamReader in = new InputStreamReader(context.getResources().openRawResource(resId));
            BufferedReader br = new BufferedReader(in);
            String line;
            while ((line = br.readLine()) != null) {
                s.append(line);
            }
            return s.toString();
        } catch (IOException e) {
            e.printStackTrace();
            return null;
        }
    }

    /**
     * same to {@link ResourceUtils#geFileFromAssets(Context, String)}, but return type is List<String>
     * 
     * @param context
     * @param fileName
     * @return
     */
    public static List<String> geFileToListFromAssets(Context context, String fileName) {
        if (context == null || StringUtils.isEmpty(fileName)) {
            return null;
        }

        List<String> fileContent = new ArrayList<String>();
        try {
            InputStreamReader in = new InputStreamReader(context.getResources().getAssets().open(fileName));
            BufferedReader br = new BufferedReader(in);
            String line;
            while ((line = br.readLine()) != null) {
                fileContent.add(line);
            }
            br.close();
            return fileContent;
        } catch (IOException e) {
            e.printStackTrace();
            return null;
        }
    }

    /**
     * same to {@link ResourceUtils#geFileFromRaw(Context, int)}, but return type is List<String>
     * 
     * @param context
     * @param resId
     * @return
     */
    public static List<String> geFileToListFromRaw(Context context, int resId) {
        if (context == null) {
            return null;
        }

        List<String> fileContent = new ArrayList<String>();
        BufferedReader reader = null;
        try {
            InputStreamReader in = new InputStreamReader(context.getResources().openRawResource(resId));
            reader = new BufferedReader(in);
            String line = null;
            while ((line = reader.readLine()) != null) {
                fileContent.add(line);
            }
            reader.close();
            return fileContent;
        } catch (IOException e) {
            e.printStackTrace();
            return null;
        }
    }
}

8、单例工具类 SingletonUtils.java

public abstract class SingletonUtils<T> {

    private T instance;

    protected abstract T newInstance();

    public final T getInstance() {
        if (instance == null) {
            synchronized (SingletonUtils.class) {
                if (instance == null) {
                    instance = newInstance();
                }
            }
        }
        return instance;
    }
}