包含对操作文件及访问的SD卡一些方法和关于bitmap压缩

public class FileUtil {
private final static String TAG = “FileUtil”;

public static boolean checkSD() {    return Environment.getExternalStorageState().equals(android.os.Environment.MEDIA_MOUNTED);}/** * 获取SD卡根目录路径 * @return 表示根目录路径字符串（末尾不带“/”，如"/sdcard"),若SD卡未安装，则返回null */public static String getSDRootPath() {    if(!checkSD()) {        return null;    } else {        return Environment.getExternalStorageDirectory().getPath();    }}/** * 创建目录 * @param dirPath 目录路径（末尾不带“/”，如"/sdcard"） * @return true - 创建成功，false - 创建失败 */public static boolean makeDir(String dirPath) {    boolean isSuccessful = true;    File dir = new File(dirPath);    if(!dir.exists()) {        isSuccessful = dir.mkdirs();    }    return isSuccessful;}/** * 以jpg格式保存Bitmap * @param filePath 完整的文件路径（含路径、扩展名） * @param bitmap * @return true - 保存成功， false - 保存失败 */public static boolean saveBitmapInJPG(String filePath, Bitmap bitmap) {    File f = new File(filePath);    if(f.exists()) {        return true;    }    try {        f.createNewFile();        FileOutputStream fOut = null;        fOut = new FileOutputStream(f);        bitmap.compress(Bitmap.CompressFormat.JPEG, 90, fOut);        fOut.flush();        fOut.close();    } catch (FileNotFoundException e) {        e.printStackTrace();        return false;    } catch (IOException e) {        e.printStackTrace();        return false;    }    return true;}static class CompratorByLastModified implements Comparator<File> {    public int compare(File f1, File f2) {        long diff = f1.lastModified() - f2.lastModified();        if (diff > 0) {            return -1;        } else if (diff == 0) {            return 0;        } else {            return 1;        }    }}/** * 获取图片缩略图 * @param path 图片的完整路径 * @param width 缩略图宽，单位：像素 * @param height 缩略图高，单位：像素 * @return 图片缩略图的Bitmap，若出现异常，返回null */public static Bitmap getThumbnail(String path, int width, int height) {    Bitmap bitmap = null;    Bitmap thumbnail = null;    try {        BitmapFactory.Options options = new BitmapFactory.Options();        options.inSampleSize = 8;        bitmap = BitmapFactory.decodeFile(path, options);        thumbnail = ThumbnailUtils.extractThumbnail(bitmap, width, height);        bitmap.recycle();    } catch (Exception e) {        e.printStackTrace();        return null;    }    return thumbnail;}/** * 删除指定路径下的所有文件 * @param path 指定的路径 */public static void delFiles(String path) {    File file = new File(path);    if(!file.exists()) { return; }    File[] files = file.listFiles();    for(int i = 0; i < files.length; i++) {        files[i].delete();    }}public static boolean isFileExist(String path) {    File file = new File(path);    if(file.exists()) {        return true;    }    else{        return false;    }}

}