【ListViewJSON】【com.demo.app.common】【FileUtils】源码分析及其在工程中作用
源码如下：
package com.demo.app.common; import java.io.ByteArrayOutputStream; import java.io.File; import java.io.FileInputStream; import java.io.FileOutputStream; import java.io.IOException; import java.io.InputStream; import android.content.Context; import android.os.Environment; import android.os.StatFs; import android.util.Log; /** * 文件操作工具包 * @version 1.0 * @created 2012-3-21 */ public class FileUtils { /** * 写文本文件 * 在Android系统中，文件保存在 /data/data/PACKAGE_NAME/files 目录下 * @param context * @param msg */ public static void write(Context context, String fileName, String content) { if( content == null ) content = ""; try { FileOutputStream fos = context.openFileOutput(fileName, Context.MODE_PRIVATE); fos.write( content.getBytes() ); fos.close(); } catch (Exception e) { e.printStackTrace(); } } /** * 读取文本文件 * @param context * @param fileName * @return */ 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; } public static File createFile( String folderPath, String fileName ) { File destDir = new File(folderPath); if (!destDir.exists()) { destDir.mkdirs(); } return new File(folderPath, fileName + fileName ); } /** * 向手机写图片 * @param buffer * @param folder * @param fileName * @return */ 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; } /** * 根据文件绝对路径获取文件名 * @param filePath * @return */ public static String getFileName( String filePath ) { if( StringUtils.isEmpty(filePath) ) return ""; return filePath.substring( filePath.lastIndexOf( File.separator )+1 ); } /** * 根据文件的绝对路径获取文件名但不包含扩展名 * @param filePath * @return */ public static String getFileNameNoFormat( String filePath){ if(StringUtils.isEmpty(filePath)){ return ""; } int point = filePath.lastIndexOf('.'); return filePath.substring(filePath.lastIndexOf(File.separator)+1,point); } /** * 获取文件扩展名 * @param fileName * @return */ public static String getFileFormat( String fileName ) { if( StringUtils.isEmpty(fileName) ) return ""; int point = fileName.lastIndexOf( '.' ); return fileName.substring( point+1 ); } /** * 获取文件大小 * @param filePath * @return */ public static long getFileSize( String filePath ) { long size = 0; File file = new File( filePath ); if(file!=null && file.exists()) { size = file.length(); } return size; } /** * 获取文件大小 * @param size 字节 * @return */ public static String getFileSize(long size) { if (size <= 0) return "0"; java.text.DecimalFormat df = new java.text.DecimalFormat("##.##"); float temp = (float)size / 1024; if (temp >= 1024) { return df.format(temp / 1024) + "M"; } else { return df.format(temp) + "K"; } } /** * 转换文件大小 * @param fileS * @return B/KB/MB/GB */ public static String formatFileSize(long fileS) { java.text.DecimalFormat df = new java.text.DecimalFormat("#.00"); String fileSizeString = ""; if (fileS < 1024) { fileSizeString = df.format((double) fileS) + "B"; } else if (fileS < 1048576) { fileSizeString = df.format((double) fileS / 1024) + "KB"; } else if (fileS < 1073741824) { fileSizeString = df.format((double) fileS / 1048576) + "MB"; } else { fileSizeString = df.format((double) fileS / 1073741824) + "G"; } return fileSizeString; } /** * 获取目录文件大小 * @param dir * @return */ public static long getDirSize(File dir) { if (dir == null) { return 0; } if (!dir.isDirectory()) { return 0; } long dirSize = 0; File[] files = dir.listFiles(); for (File file : files) { if (file.isFile()) { dirSize += file.length(); } else if (file.isDirectory()) { dirSize += file.length(); dirSize += getDirSize(file); //递归调用继续统计 } } return dirSize; } /** * 获取目录文件个数 * @param f * @return */ public long getFileList(File dir){ long count = 0; File[] files = dir.listFiles(); count = files.length; for (File file : files) { if (file.isDirectory()) { count = count + getFileList(file);//递归 count--; } } return count; } public static byte[] toBytes(InputStream in) throws IOException { ByteArrayOutputStream out = new ByteArrayOutputStream(); int ch; while ((ch = in.read()) != -1) { out.write(ch); } byte buffer[]=out.toByteArray(); out.close(); return buffer; } /** * 检查文件是否存在 * @param name * @return */ public static boolean checkFileExists(String name) { boolean status; if (!name.equals("")) { File path = Environment.getExternalStorageDirectory(); File newPath = new File(path.toString() + name); status = newPath.exists(); } else { status = false; } return status; } /** * 计算SD卡的剩余空间 * @return 返回-1，说明没有安装sd卡 */ 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); } /** * 新建目录 * @param directoryName * @return */ public static boolean createDirectory(String directoryName) { boolean status; if (!directoryName.equals("")) { File path = Environment.getExternalStorageDirectory(); File newPath = new File(path.toString() + directoryName); status = newPath.mkdir(); status = true; } else status = false; return status; } /** * 检查是否安装SD卡 * @return */ public static boolean checkSaveLocationExists() { String sDCardStatus = Environment.getExternalStorageState(); boolean status; if (sDCardStatus.equals(Environment.MEDIA_MOUNTED)) { status = true; } else status = false; return status; } /** * 删除目录(包括：目录里的所有文件) * @param fileName * @return */ public static boolean deleteDirectory(String fileName) { boolean status; SecurityManager checker = new SecurityManager(); if (!fileName.equals("")) { File path = Environment.getExternalStorageDirectory(); File newPath = new File(path.toString() + fileName); checker.checkDelete(newPath.toString()); if (newPath.isDirectory()) { String[] listfile = newPath.list(); // delete all files within the specified directory and then // delete the directory try { for (int i = 0; i < listfile.length; i++) { File deletedFile = new File(newPath.toString() + "/" + listfile[i].toString()); deletedFile.delete(); } newPath.delete(); Log.i("DirectoryManager deleteDirectory", fileName); status = true; } catch (Exception e) { e.printStackTrace(); status = false; } } else status = false; } else status = false; return status; } /** * 删除文件 * @param fileName * @return */ public static boolean deleteFile(String fileName) { boolean status; SecurityManager checker = new SecurityManager(); if (!fileName.equals("")) { File path = Environment.getExternalStorageDirectory(); File newPath = new File(path.toString() + fileName); checker.checkDelete(newPath.toString()); if (newPath.isFile()) { try { Log.i("DirectoryManager deleteFile", fileName); newPath.delete(); status = true; } catch (SecurityException se) { se.printStackTrace(); status = false; } } else status = false; } else status = false; return status; } }
