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：
  1 package com.car273.util;
  2 
  3 
  4 
  5 import java.io.BufferedReader;
  6 import java.io.File;
  7 import java.io.FileInputStream;
  8 import java.io.FileNotFoundException;
  9 import java.io.FileOutputStream;
 10 import java.io.FileReader;
 11 import java.io.IOException;
 12 import java.io.OutputStream;
 13 
 14 import org.apache.log4j.Logger;
 15 
 16 import android.os.Environment;
 17 import android.os.StatFs;
 18  20 
 21 /**
 22  * 关于SD卡上的操作方法集
 23  * 
 24  * @author Administrator
 25  * 
 26  */
 27 public class SDcardUtil {
 28     /** log4j对象 */
 29     private static final Logger logger = Logger.getLogger(SDcardUtil.class);
 30 
 31     /**
 32      * 判断SD卡是否可用
 33      * 
 34      * @return 有sd卡返回true，无sd卡返回false
 35      */
 36     public static boolean isSDcardCanUse() {
 37         try {
 38             return Environment.getExternalStorageState().equals(
 39                     Environment.MEDIA_MOUNTED);
 40         } catch (Exception e) {
 41             e.printStackTrace();
 42         }
 43         return false;
 44     }
 45 
 46     /** 获取SD卡路径 **/
 47     public static String getSDcardPath() {
 48         File sdDir = null;
 49         boolean sdCardExist = Environment.getExternalStorageState().equals(
 50                 android.os.Environment.MEDIA_MOUNTED); // 判断sd卡是否存在
 51         if (sdCardExist) {
 52             sdDir = Environment.getExternalStorageDirectory();// 获取跟目录
 53         }
 54         if(sdDir ==null){
 55             return "/mnt/sdcard";
 56         }
 57         return sdDir.toString();
 58     }
 59 
 60     /**
 61      * 外部存储空间信息
 62      * 
 63      * @return 当前可用的存储空间大小
 64      */
 65     public static long getExternalStorageSize() {
 66         if (isSDcardCanUse()) {
 67             // 判断外部存储空间
 68             File path = Environment.getExternalStorageDirectory();
 69             StatFs stat = new StatFs(path.getPath());
 70             long blockSize = stat.getBlockSize();
 71             long availableBlocks = stat.getAvailableBlocks();
 72             availableBlocks *= blockSize;
 73             if (availableBlocks >= GlobalData.MIN_SPACE_SIZE)
 74                 return availableBlocks;
 75         }
 76         return 0;
 77     }
 78 
 79     /**
 80      * 获得文件大小
 81      * 
 82      * @return 文件大小 -1表示文件不存在
 83      * @throws FileNotFoundException
 84      * @throws IOException
 85      */
 86     @SuppressWarnings("resource")
 87     public static int getFileSize(File file) throws FileNotFoundException,
 88             IOException {
 89         if (isFileExisted(file))
 90             return (new FileInputStream(file)).available();
 91         else
 92             return -1;
 93     }
 94 
 95     /**
 96      * 判断文件是否存在
 97      * 
 98      * @return
 99      */
100     public static boolean isFileExisted(File file) {
101         return file.exists();
102     }
103 
104     /**
105      * @param bytes
106      *            字节数组
107      * @param flag
108      *            是否追加形式写入文件
109      * @param dirPath
110      *            文件目录(目录不存在则创建目录）
111      * @param fileName
112      *            文件名
113      * @return 1:成功 0:写入过程中失败 -1:流关闭失败
114      * @throws IOException
115      */
116     public static int writeSDCardByBytes(byte[] bytes, boolean flag,
117             String dirPath, String fileName) throws IOException {
118         OutputStream output = null;
119         try {
120             createDirInSDCard(dirPath);
121             output = new FileOutputStream(new File(dirPath + File.separator
122                     + fileName), flag);
123             output.write(bytes);
124             output.flush();
125         } catch (IOException e) {
126             e.printStackTrace();
127             logger.error(Car273Util.dumpThrowable(e));
128             throw e;
129         } finally {
130             try {
131                 if (output != null)
132                     output.close();
133             } catch (IOException e) {
134                 logger.error(Car273Util.dumpThrowable(e));
135                 e.printStackTrace();
136                 return -1;
137             }
138         }
139         return 1;
140     }
141 
142     /**
143      * 根据路径dir创建文件目录
144      * 
145      * @param dir
146      * @return
147      */
148     private static File createDirInSDCard(String dir) {
149         File fileDir = new File(dir);
150         fileDir.mkdir();
151         return fileDir;
152     }
153     
154     /**
155      * 读取文件
156      * @param f 要读取的文件
157      * @return 文件信息字符串
158      * @throws IOException 读取异常
159      */
160     public static String loadFileToString(File f) throws IOException {
161         // long beginTime = System.currentTimeMillis();
162         BufferedReader br = null;
163         String ret = null;
164         try {
165             br = new BufferedReader(new FileReader(f));
166             String line = null;
167             StringBuffer sb = new StringBuffer();
168             while ((line = br.readLine()) != null) {
169                 sb.append(line);
170             }
171             ret = sb.toString();
172         } finally {
173             if (br != null) {
174                 try {
175                     br.close();
176                 } catch (Exception e) {
177                 }
178             }
179         }
180         return ret;
181     }
182     
183     
184 }