android中一些文件的操作方法

1.创建文件

File Directory=mContext.getDir("mydir", Context.MODE_PRIVATE);File dest = new File(Directory, filename);

2.读取图片文件

public static Drawable loadImageFromFilesystem(Context context,            String filename, int originalDensity) {             File Directory = context.getDir("mydir", Context.MODE_PRIVATE);        File f = new File( Directory , filename );        InputStream is = null;        try {            is = new FileInputStream(f);        } catch (FileNotFoundException e) {            e.printStackTrace();        }                 Bitmap bmp = BitmapFactory.decodeStream(is );               Drawable drawable = new BitmapDrawable(bmp);  ;         return drawable;    }

3.读取文本文件

public static String read( Context context, String fileName ) {try {FileInputStream in = context.openFileInput(fileName);return readInStream(in);} catch (Exception e) {e.printStackTrace();}return "";} private static String readInStream(FileInputStream inStream){try {   ByteArrayOutputStream outStream = new ByteArrayOutputStream();   byte[] buffer = new byte[512];   int length = -1;   while((length = inStream.read(buffer)) != -1 )   {   outStream.write(buffer, 0, length);   }      outStream.close();   inStream.close();   return outStream.toString();} catch (IOException e){   Log.i("FileTest", e.getMessage()); }return null;}

4.删除文件（目录）

public static void delFolder(String folderPath) {        try {            delAllFile(folderPath); // 删除完里面所有内容            String filePath = folderPath;            filePath = filePath.toString();            java.io.File myFilePath = new java.io.File(filePath);            myFilePath.delete(); // 删除空文件夹        } catch (Exception e) {            System.out.println("删除文件夹操作出错");            e.printStackTrace();        }    }         public static void delAllFile(String path) {        File file = new File(path);        if (!file.exists()) {            return;        }        if (!file.isDirectory()) {            return;        }        String[] tempList = file.list();        File temp = null;        for (int i = 0; i < tempList.length; i++) {            if (path.endsWith(File.separator)) {                temp = new File(path + tempList[i]);            } else {                temp = new File(path + File.separator + tempList[i]);            }            if (temp.isFile()) {                temp.delete();            }            if (temp.isDirectory()) {                delAllFile(path + "/" + tempList[i]);// 先删除文件夹里面的文件                delFolder(path + "/" + tempList[i]);// 再删除空文件夹            }        }    }

5.计算SD卡的剩余空间

public static long getFreeDiskSpace() {String status = Environment.getExternalStorageState();long freeSpace = 0;if (status.equals(Environment.MEDIA_MOUNTED)) {try {File path = Environment.getExternalStorageDirectory();StatFs stat = new StatFs(path.getPath());long blockSize = stat.getBlockSize();long availableBlocks = stat.getAvailableBlocks();freeSpace = availableBlocks * blockSize / 1024;} catch (Exception e) {e.printStackTrace();}} else {return -1;}return (freeSpace);}

6.向手机写图片

public static boolean writeFile( byte[] buffer, String folder, String fileName ){boolean writeSucc = false;boolean sdCardExist = Environment.getExternalStorageState().equals(android.os.Environment.MEDIA_MOUNTED);String folderPath = "";if( sdCardExist ){folderPath = Environment.getExternalStorageDirectory() + File.separator +  folder + File.separator;}else{writeSucc =false;}File fileDir = new File(folderPath);if(!fileDir.exists()) {fileDir.mkdirs();}  File file = new File( folderPath + fileName );FileOutputStream out = null;try {out = new FileOutputStream( file );out.write(buffer);writeSucc = true;} catch (Exception e) {e.printStackTrace();}finally{try {out.close();} catch (IOException e) {e.printStackTrace();}}return writeSucc;}

7.将输入流转换为字符串

/** * 将输入流转化为字符串 * @param inputStream * @return */public String inStream2string(InputStream inputStream) {ByteArrayOutputStream baos = new ByteArrayOutputStream();byte[] buf = new byte[1024];try {int len = -1;while ((len = inputStream.read(buf)) != -1) {baos.write(buf, 0, len);}} catch (IOException e) {// TODO Auto-generated catch blocke.printStackTrace();}return new String(baos.toByteArray());}