import java.io.File;
import java.io.FileOutputStream;
import java.io.IOException;

import android.content.Context;
import android.graphics.Bitmap;
import android.graphics.Bitmap.CompressFormat;
import android.graphics.BitmapFactory;
import android.os.Environment;

public class FileUtils {
 /**
  * sd卡的根目錄
  */
 private static String mSdRootPath = Environment.getExternalStorageDirectory().getPath();
 /**
  * 手機的快取根目錄
  */
 private static String mDataRootPath = null;
 /**
  * 儲存Image的目錄名
  */
 private final static String FOLDER_NAME = "/tea/image";

 public FileUtils(Context context) {
  mDataRootPath = context.getCacheDir().getPath();
 }

 /**
  * 獲取儲存Image的目錄
  *
  * @return
  */
 private String getStorageDirectory() {
  return Environment.getExternalStorageState().equals(Environment.MEDIA_MOUNTED) ? mSdRootPath + FOLDER_NAME : mDataRootPath + FOLDER_NAME;
 }

 /**
  * 儲存Image的方法，有sd卡儲存到sd卡，沒有就儲存到手機目錄
  *
  * @param fileName
  * @param bitmap
  * @throws IOException
  */
 public void savaBitmap(String url, Bitmap bitmap) throws IOException {
  if (bitmap == null) {
   return;
  }
  String path = getStorageDirectory();
  File folderFile = new File(path);
  if (!folderFile.exists()) {
   folderFile.mkdirs();
  }
  File file = new File(path + File.separator + getFileName(url));
  file.createNewFile();
  FileOutputStream fos = new FileOutputStream(file);
  bitmap.compress(CompressFormat.JPEG, 100, fos);
  fos.flush();
  fos.close();
 }

 /**
  * 從手機或者sd卡獲取Bitmap
  *
  * @param fileName
  * @return
  */
 public Bitmap getBitmap(String url) {
  return BitmapFactory.decodeFile(getStorageDirectory() + File.separator + getFileName(url));
 }

 /**
  * 判斷檔案是否存在
  *
  * @param fileName
  * @return
  */
 public boolean isFileExists(String fileName) {
  return new File(getStorageDirectory() + File.separator + getFileName(fileName)).exists();
 }

 /**
  * 獲取檔案的大小
  *
  * @param fileName
  * @return
  */
 public long getFileSize(String url) {
  return new File(getStorageDirectory() + File.separator + getFileName(url)).length();
 }

 /**
  * 刪除SD卡或者手機的快取圖片和目錄
  */
 public void deleteFile() {
  File dirFile = new File(getStorageDirectory());
  if (!dirFile.exists()) {
   return;
  }
  if (dirFile.isDirectory()) {
   String[] children = dirFile.list();
   for (int i = 0; i < children.length; i++) {
    new File(dirFile, children[i]).delete();
   }
  }

  dirFile.delete();
 }

 /**
  *
  * @Title: getFileName
  * @說 明: 根據url擷取檔名
  * @參 數: @param url
  * @參 數: @return
  * @return String 返回型別
  * @throws
  */
 public String getFileName(String url) {
  return url.substring(url.lastIndexOf("/") + 1);
 }

}
-------------------------------------------下載工具類-------------------------------------------------------------------

package com.qianfeng.android.utils;

import java.io.IOException;

import org.apache.http.HttpEntity;
import org.apache.http.HttpResponse;
import org.apache.http.HttpStatus;
import org.apache.http.client.ClientProtocolException;
import org.apache.http.client.HttpClient;
import org.apache.http.client.methods.HttpGet;
import org.apache.http.client.params.HttpClientParams;
import org.apache.http.impl.client.DefaultHttpClient;
import org.apache.http.params.BasicHttpParams;
import org.apache.http.params.HttpConnectionParams;
import org.apache.http.params.HttpParams;
import org.apache.http.params.HttpProtocolParams;
import org.apache.http.util.EntityUtils;

import android.graphics.Bitmap;
import android.graphics.BitmapFactory;



public class HttpUtils {
 /**
  *
  * @Title: getBitmapFormUrl
  * @說 明:從伺服器獲取Bitmap
  * @參 數: @param url
  * @參 數: @return
  * @return Bitmap 返回型別
  * @throws
  */
 public static Bitmap getBitmapFormUrl(String url) {
  Bitmap bitmap = null;
  HttpClient httpClient = new DefaultHttpClient();
  // 設定超時時間
  HttpConnectionParams.setConnectionTimeout(new BasicHttpParams(), 6 * 1000);
  HttpGet get = new HttpGet(url);
  try {
   HttpResponse response = httpClient.execute(get);
   if (response.getStatusLine().getStatusCode() == HttpStatus.SC_OK) {
    HttpEntity entity = response.getEntity();
    bitmap = BitmapFactory.decodeStream(entity.getContent());
   }
  } catch (ClientProtocolException e) {
   e.printStackTrace();
  } catch (IOException e) {
   e.printStackTrace();
  }
  return bitmap;
 }

 public static String getJsonFromServer(String url) {

  HttpClient httpClient = getHttpClient();
  HttpGet get = new HttpGet(url);

  try {
   HttpResponse response = httpClient.execute(get);
   if (response.getStatusLine().getStatusCode() == HttpStatus.SC_OK) {
    HttpEntity entity = response.getEntity();
    return EntityUtils.toString(entity);
   }
  } catch (ClientProtocolException e) {
   e.printStackTrace();
  } catch (IOException e) {
   e.printStackTrace();
  } finally {
   if (get != null) {
    get.abort();
   }
  }
  return null;

 }

 /**
  *
  * @Title: getHttpClient
  * @說 明:設定httpClient的一些引數
  * @參 數: @return
  * @return HttpClient 返回型別
  * @throws
  */
 private static HttpClient getHttpClient() {
  // 建立 HttpParams 以用來設定 HTTP 引數（這一部分不是必需的）
  HttpParams httpParams = new BasicHttpParams();
  // 設定連線超時和 Socket 超時，以及 Socket 快取大小
  HttpConnectionParams.setConnectionTimeout(httpParams, 20 * 1000);
  HttpConnectionParams.setSoTimeout(httpParams, 20 * 1000);
  HttpConnectionParams.setSocketBufferSize(httpParams, 8192);
  // 設定重定向，預設為 true
  HttpClientParams.setRedirecting(httpParams, true);
  // 設定 user agent
  String userAgent = "Mozilla/5.0 (Windows; U; Windows NT 5.1; zh-CN; rv:1.9.2) Gecko/20100115 Firefox/3.6";
  HttpProtocolParams.setUserAgent(httpParams, userAgent);
  // 建立一個 HttpClient 例項
  // 注意 HttpClient httpClient = new HttpClient(); 是Commons HttpClient
  // 中的用法，在 Android 1.5 中我們需要使用 Apache 的預設實現 DefaultHttpClient
  HttpClient httpClient = new DefaultHttpClient(httpParams);
  return httpClient;
 }
}