比较常用的文件处理类

package com.aijia.util;
/**
 * 一些文件处理
 */


import java.io.File;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.net.HttpURLConnection;






import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.graphics.drawable.BitmapDrawable;
import android.graphics.drawable.Drawable;
import android.util.Log;
import android.widget.ImageView;


public class FileUtil {
	/**
	 * 显示图片的缩略图
	 * 
	 * @param uri  图片路径
	 * @param size图片比例
	 * @return
	 */
	public static Bitmap getOpBitmap(String uri, int size) {
		BitmapFactory.Options options = new BitmapFactory.Options();
		options.inJustDecodeBounds = true;


		Bitmap bitmap = BitmapFactory.decodeFile(uri, options);


		options.inJustDecodeBounds = false;


		int be = (int) (options.outHeight / (float) size);


		if (be <= 0)
			be = 1;
		options.inSampleSize = be;
		options.inPreferredConfig = Bitmap.Config.RGB_565;
		File file = new File(uri);
		InputStream in = null;
		try {
			in = new FileInputStream(file);


		} catch (FileNotFoundException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}
		if (in != null) {
			bitmap = BitmapFactory.decodeStream(in, null, options);
			try {
				in.close();
			} catch (IOException e) {


				e.printStackTrace();
			}
		}


		// bitmap = BitmapFactory.decodeFile(uri, options);
		return bitmap;
	}


	/**
	 * 删除文件夹
	 * 
	 * @param folderPath
	 */
	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();


		}
	}
	/**
	 * 删除所有文件
	 * @param path
	 */


	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
			}
		}
	}


	/**
	 * 判断指定路徑的文件是否存在
	 * 
	 * @param path
	 * @return
	 */
	public static boolean existFile(String path) {
		File file = new File(path);
		if (file.exists()) {
			return true;
		} else {
			return false;
		}


	}


	/**
	 * 如果给定路径不存在这个文件夹，创建文件夹
	 * 
	 * @param path
	 */
	public static void createFolder(String path) {
		File file = new File(path);
		if (!file.exists()) {
			file.mkdirs();
		}


	}
/**
 * 如果給定路徑存在這個文件，刪除這個文件
 * @param path
 */
	public static void deleteFile(String path) {
		File file = new File(path);
		if (file.exists()) {
			file.delete();
		}


	}


	


	/**
	 * 下载图片到本地
	 * 
	 * @param urlPath
	 * @param savePath
	 * @throws Exception
	 */
	public static void downloadImg(String urlPath, String savePath)
			throws Exception {// 获取图片
		if (!existFile(savePath)) {//如果不存在这个文件


			String folderpath = savePath
					.substring(0, savePath.lastIndexOf("/"));
			createFolder(folderpath);//创建相应的文件夹


			String str = java.net.URLEncoder.encode(urlPath, "UTF-8");
			str = str.replaceAll("%2F", "/");// 需要把网址的特殊字符转过来
			str = str.replaceAll("%3A", ":");


			URL url = new URL(str);
			HttpURLConnection conn = (HttpURLConnection) url.openConnection();
			conn.setConnectTimeout(3 * 1000);
			if (conn.getResponseCode() == 200) {
				InputStream inSream = conn.getInputStream();
				File file = new File(savePath);


				FileOutputStream outStream = new FileOutputStream(file);
				byte[] buffer = new byte[1024];
				int len = -1;
				while ((len = inSream.read(buffer)) != -1) {
					outStream.write(buffer, 0, len);
				}
				outStream.close();
				inSream.close();


			}


		}


	}
}