对手机SD卡的一些操作

首先要导入外包 log4j-1.2.16.jar

代码如下：

 package com.car273.util;

 import java.io.BufferedReader;
 import java.io.File;
 import java.io.FileInputStream;
 import java.io.FileNotFoundException;
 import java.io.FileOutputStream;
 import java.io.FileReader;
 import java.io.IOException;
 import java.io.OutputStream;

 import org.apache.log4j.Logger;

 import android.os.Environment;
 import android.os.StatFs;

 /**
  * 关于SD卡上的操作方法集
  *
  * @author Administrator
  *
  */
 public class SDcardUtil {
     /** log4j对象 */
     private static final Logger logger = Logger.getLogger(SDcardUtil.class);

     /**
      * 判断SD卡是否可用
      *
      * @return 有sd卡返回true，无sd卡返回false
      */
     public static boolean isSDcardCanUse() {
         try {
             return Environment.getExternalStorageState().equals(
                     Environment.MEDIA_MOUNTED);
         } catch (Exception e) {
             e.printStackTrace();
         }
         return false;
     }

     /** 获取SD卡路径 **/
     public static String getSDcardPath() {
         File sdDir = null;
         boolean sdCardExist = Environment.getExternalStorageState().equals(
                 android.os.Environment.MEDIA_MOUNTED); // 判断sd卡是否存在
         if (sdCardExist) {
             sdDir = Environment.getExternalStorageDirectory();// 获取跟目录
         }
         if(sdDir ==null){
             return "/mnt/sdcard";
         }
         return sdDir.toString();
     }

     /**
      * 外部存储空间信息
      *
      * @return 当前可用的存储空间大小
      */
     public static long getExternalStorageSize() {
         if (isSDcardCanUse()) {
             // 判断外部存储空间
             File path = Environment.getExternalStorageDirectory();
             StatFs stat = new StatFs(path.getPath());
             long blockSize = stat.getBlockSize();
             long availableBlocks = stat.getAvailableBlocks();
             availableBlocks *= blockSize;
             if (availableBlocks >= GlobalData.MIN_SPACE_SIZE)
                 return availableBlocks;
         }
         return 0;
     }

     /**
      * 获得文件大小
      *
      * @return 文件大小 -1表示文件不存在
      * @throws FileNotFoundException
      * @throws IOException
      */
     @SuppressWarnings("resource")
     public static int getFileSize(File file) throws FileNotFoundException,
             IOException {
         if (isFileExisted(file))
             return (new FileInputStream(file)).available();
         else
             return -1;
     }

     /**
      * 判断文件是否存在
      *
      * @return
      */
     public static boolean isFileExisted(File file) {
         return file.exists();
     }

     /**
      * @param bytes
      *            字节数组
      * @param flag
      *            是否追加形式写入文件
      * @param dirPath
      *            文件目录(目录不存在则创建目录）
      * @param fileName
      *            文件名
      * @return 1:成功 0:写入过程中失败 -1:流关闭失败
      * @throws IOException
      */
     public static int writeSDCardByBytes(byte[] bytes, boolean flag,
             String dirPath, String fileName) throws IOException {
         OutputStream output = null;
         try {
             createDirInSDCard(dirPath);
             output = new FileOutputStream(new File(dirPath + File.separator
                     + fileName), flag);
             output.write(bytes);
             output.flush();
         } catch (IOException e) {
             e.printStackTrace();
             logger.error(Car273Util.dumpThrowable(e));
             throw e;
         } finally {
             try {
                 if (output != null)
                     output.close();
             } catch (IOException e) {
                 logger.error(Car273Util.dumpThrowable(e));
                 e.printStackTrace();
                 return -1;
             }
         }
         return 1;
     }

     /**
      * 根据路径dir创建文件目录
      *
      * @param dir
      * @return
      */
     private static File createDirInSDCard(String dir) {
         File fileDir = new File(dir);
         fileDir.mkdir();
         return fileDir;
     }

     /**
      * 读取文件
      * @param f 要读取的文件
      * @return 文件信息字符串
      * @throws IOException 读取异常
      */
     public static String loadFileToString(File f) throws IOException {
         // long beginTime = System.currentTimeMillis();
         BufferedReader br = null;
         String ret = null;
         try {
             br = new BufferedReader(new FileReader(f));
             String line = null;
             StringBuffer sb = new StringBuffer();
             while ((line = br.readLine()) != null) {
                 sb.append(line);
             }
             ret = sb.toString();
         } finally {
             if (br != null) {
                 try {
                     br.close();
                 } catch (Exception e) {
                 }
             }
         }
         return ret;
     }

 }