Android开发 文件操作

Android的文件、文件夹操作是比较常见的应用，文件操作涉及到拷贝、文件夹拷贝、文件转字节数组、字节数组转文件等。

public class FileUtil {

	/**
	 * 复制文件
	 * @param fromFile 源文件
	 * @param toFile 目标文件
	 * @param rewrite 是否覆盖
	 */
	public static void copyfile(File fromFile, File toFile,Boolean rewrite)
	{
		if (!fromFile.exists()) {
			return;
		}
		if (!fromFile.isFile()) {
			return ;
		}
		if (!fromFile.canRead()) {
			return ;
		}
		if (!toFile.getParentFile().exists()) {
			toFile.getParentFile().mkdirs();
		}
		if (toFile.exists() && rewrite) {
			toFile.delete();
		}
		try {
			java.io.FileInputStream fosfrom = new java.io.FileInputStream(fromFile);
			java.io.FileOutputStream fosto = new FileOutputStream(toFile);
			byte bt[] = new byte[1024];
			int c;
			while ((c = fosfrom.read(bt)) > 0) {
				fosto.write(bt, 0, c); //将内容写到新文件当中
			}
			fosfrom.close();
			fosto.close();
		} catch (Exception ex) {
			MyLog.e(FileUtil.class, ex.getMessage());
		}
	}
	/** 
	 * 复制整个文件夹内容 
	 * @param oldPath String 原文件路径 如：c:/fqf 
	 * @param newPath String 复制后路径 如：f:/fqf/ff 
	 * @return boolean 
	 */ 
	public void copyFolder(String oldPath, String newPath) { 

		try { 
			(new File(newPath)).mkdirs(); //如果文件夹不存在 则建立新文件夹 
			File a=new File(oldPath); 
			String[] file=a.list(); 
			File temp=null; 
			for (int i = 0; i < file.length; i++) { 
				if(oldPath.endsWith(File.separator)){ 
					temp=new File(oldPath+file[i]); 
				} 
				else{ 
					temp=new File(oldPath+File.separator+file[i]); 
				} 

				if(temp.isFile()){ 
					FileInputStream input = new FileInputStream(temp); 
					FileOutputStream output = new FileOutputStream(newPath + "/" + 
							(temp.getName()).toString()); 
					byte[] b = new byte[1024 * 5]; 
					int len; 
					while ( (len = input.read(b)) != -1) { 
						output.write(b, 0, len); 
					} 
					output.flush(); 
					output.close(); 
					input.close(); 
				} 
				if(temp.isDirectory()){//如果是子文件夹 
					copyFolder(oldPath+"/"+file[i],newPath+"/"+file[i]); 
				} 
			} 
		} 
		catch (Exception e) { 
			MyLog.e(FileUtil.class, e==null?"":e.getMessage());
		} 
	}
	public static void CopyAssets(Context context,String assetDir, String dir) {
		String[] files;
		try {
			files = context.getResources().getAssets().list(assetDir);
		} catch (IOException e1) {
			MyLog.e(FileUtil.class, "cannot get assets.");
			return;
		}
		File mWorkingPath = new File(dir);
		// if this directory does not exists, make one.
		if (!mWorkingPath.exists()) {
			if (!mWorkingPath.mkdirs()) {
				MyLog.e(FileUtil.class, "cannot create directory.");
			}
		}

		for (int i = 0; i < files.length; i++) {
			try {
				String fileName = files[i];
				// we make sure file name not contains '.' to be a folder.
				if (!fileName.contains(".")) {
					if (0 == assetDir.length()) { 
						CopyAssets(context,fileName, dir + fileName + "/");
					} else {
						CopyAssets(context,assetDir + "/" + fileName, dir + fileName
								+ "/");
					}
					continue;
				}
				File outFile = new File(mWorkingPath, fileName);
				if (outFile.exists())
					outFile.delete();
				InputStream in = null;
				if (0 != assetDir.length())
					in = context.getAssets().open(assetDir + "/" + fileName);
				else
					in = context.getAssets().open(fileName);
				OutputStream out = new FileOutputStream(outFile);

				// Transfer bytes from in to out
				byte[] buf = new byte[1024];
				int len;
				while ((len = in.read(buf)) > 0) {
					out.write(buf, 0, len);
				}
				in.close();
				out.close();
			} catch (FileNotFoundException e) {
				e.printStackTrace();
			} catch (IOException e) {
				e.printStackTrace();
			}
		}
	}
	public static boolean fileIsExists(String filePath){

		File f=new File(filePath);
		if(!f.exists()){
			return false;
		}
		return true;
	}

	/**
	 * 获得指定文件的byte数组
	 * @param filePath
	 * @return
	 */
	public static byte[] getBytes(String filePath,String fileName){  
		byte[] buffer = null;  
		try {  
			File file = new File(filePath+"\\"+fileName);  
			FileInputStream fis = new FileInputStream(file);  
			ByteArrayOutputStream bos = new ByteArrayOutputStream(1024*1024);  
			byte[] b = new byte[1000];  
			int n;  
			while ((n = fis.read(b)) != -1) {  
				bos.write(b, 0, n);  
			}  
			fis.close();  
			bos.close();  
			buffer = bos.toByteArray();  
		} catch (FileNotFoundException e) {  
			e.printStackTrace();  
		} catch (IOException e) {  
			e.printStackTrace();  
		}  
		return buffer;  
	}  

	/**
	 * 根据byte数组，生成文件
	 * @param bfile
	 * @param filePath
	 * @param fileName
	 */
	public static void getFile(byte[] bfile, String filePath,String fileName) {  
        BufferedOutputStream bos = null;  
        FileOutputStream fos = null;  
        File file = null;  
        try {  
            File dir = new File(filePath);  
            if(!dir.exists()&&dir.isDirectory()){//判断文件目录是否存在  
                dir.mkdirs();  
            }  
            file = new File(filePath+"\\"+fileName);  
            fos = new FileOutputStream(file);  
            bos = new BufferedOutputStream(fos);  
            bos.write(bfile);  
        } catch (Exception e) {  
            e.printStackTrace();  
        } finally {  
            if (bos != null) {  
                try {  
                    bos.close();  
                } catch (IOException e1) {  
                    e1.printStackTrace();  
                }  
            }  
            if (fos != null) {  
                try {  
                    fos.close();  
                } catch (IOException e1) {  
                    e1.printStackTrace();  
                }  
            }  
        }  
    }  
}