SDCard助手类

 package com.zyh.sdcardHelper;

 import java.io.BufferedInputStream;
 import java.io.BufferedOutputStream;
 import java.io.ByteArrayOutputStream;
 import java.io.File;
 import java.io.FileInputStream;
 import java.io.FileOutputStream;
 import java.io.IOException;

 import android.content.Context;
 import android.graphics.Bitmap;
 import android.graphics.BitmapFactory;
 import android.os.Environment;
 import android.os.StatFs;
 import android.text.format.Formatter;

 public class SDCardHelper {
     //判断SD卡是否被挂载
     public static boolean isSDCardMounted(){
         return Environment.getExternalStorageState().equals(Environment.MEDIA_MOUNTED);
     }

     //获取SDCard的绝对路径目录
     public static String getSDCardBaseDir(){
         if(isSDCardMounted()){
             return Environment.getExternalStorageDirectory().getAbsolutePath();
         }
         return null;
     }

     //获取SDCard总大小
     public static String getSDCardTotalSize(Context context){
         if(isSDCardMounted()){
             StatFs fs = new StatFs(getSDCardBaseDir());
             long blockSize = fs.getBlockSize();
             long totalBlocks = fs.getBlockCount();
             long totalSize = blockSize * totalBlocks;
             return Formatter.formatFileSize(context, totalSize);
         }
         return null;
     }

     //获取sd卡的剩余空间
     public static String getSDCardFreeSize(Context context){
         if(isSDCardMounted()){
             StatFs fs = new StatFs(getSDCardBaseDir());
             long blockSize = fs.getBlockSize();
             long freeBlocks = fs.getFreeBlocks();
             long freeSize = blockSize * freeBlocks;
             return Formatter.formatFileSize(context, freeSize);
         }
         return null;
     }

     //获取sd卡的可用空间
     public static String getSDCardAvailableSize(Context context){
         if(isSDCardMounted()){
             StatFs fs = new StatFs(getSDCardBaseDir());
             long blockSize = fs.getBlockSize();
             long availableBlocks = fs.getFreeBlocks();
             long availableSize = blockSize * availableBlocks;
             return Formatter.formatFileSize(context, availableSize);
         }
         return null;
     }

     //往sd卡的公有目录下保存数据进文件
     public static boolean saveFileToSDCardPublicDir(byte[] data, String type, String fileName){
         BufferedOutputStream bos = null;
         if(isSDCardMounted()){
             try {
                 File file = Environment.getExternalStoragePublicDirectory(type);
                 bos = new BufferedOutputStream(new FileOutputStream(new File(file,fileName)));
                 bos.write(data);
                 bos.flush();
                 return true;
             } catch (Exception e) {
                 // TODO Auto-generated catch block
                 e.printStackTrace();
             }finally{
                 try {
                     bos.close();
                 } catch (IOException e) {
                     // TODO Auto-generated catch block
                     e.printStackTrace();
                 }
             }
         }
         return false;
     }

     //往sd卡用户自定义目录中保存数据进文件
     public static boolean savaFileToSDCardCustomDir(byte[] data, String dir, String fileName){
         BufferedOutputStream bos = null;
         if(isSDCardMounted()){
             try {
                 File file = new File(getSDCardBaseDir() + File.separator + dir);
                 if(!file.exists()){
                     file.mkdirs();//递归创建自定义目录
                 }
                 bos = new BufferedOutputStream(new FileOutputStream(new File(file,fileName)));
                 bos.write(data);
                 bos.flush();
                 return true;
             } catch (Exception e) {
                 // TODO Auto-generated catch block
                 e.printStackTrace();
             }finally{
                 try {
                     bos.close();
                 } catch (IOException e) {
                     // TODO Auto-generated catch block
                     e.printStackTrace();
                 }
             }
         }
         return false;
     }

     //往sd卡私有Files目录下保存数据进文件
     //注意如果不加<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE"/>这个权限，则报空指针异常
     //type可用为null
     public static boolean saveFileToSDCardPrivateFilesDir(byte[] data, String type, String fileName, Context context){
         BufferedOutputStream bos = null;
         if(isSDCardMounted()){
             try {
                 File file = context.getExternalFilesDir(type);
                 bos = new BufferedOutputStream(new FileOutputStream(new File(file,fileName)));
                 bos.write(data);
                 bos.flush();
                 return true;
             } catch (Exception e) {
                 // TODO Auto-generated catch block
                 e.printStackTrace();
             }finally{
                 try {
                     bos.close();
                 } catch (IOException e) {
                     // TODO Auto-generated catch block
                     e.printStackTrace();
                 }
             }
         }
         return false;
     }

     //往sd卡的私有Cache目录下保存数据进文件
     //cache目录和files目录是同一级的
     public static boolean saveFileToSDCardPrivateCacheDir(byte[] data, String fileName, Context context){
         BufferedOutputStream bos = null;
         if(isSDCardMounted()){
             try {
                 File file = context.getExternalCacheDir();
                 bos = new BufferedOutputStream(new FileOutputStream(new File(file,fileName)));
                 bos.write(data);
                 bos.flush();
                 return true;
             } catch (Exception e) {
                 // TODO Auto-generated catch block
                 e.printStackTrace();
             }finally{
                 try {
                     bos.close();
                 } catch (IOException e) {
                     // TODO Auto-generated catch block
                     e.printStackTrace();
                 }
             }
         }
         return false;
     }

     //把bitmap保存在sd卡的私有cache目录中
     public static boolean saveBitmapToSDCardPrivateCacheDir(Bitmap bitmap,String fileName, Context context){
         if(isSDCardMounted()){
             BufferedOutputStream bos = null;
             File file = context.getExternalCacheDir();
             try {
                 bos = new BufferedOutputStream(new FileOutputStream(new File(file,fileName)));
                 //100表示压缩率为0
                 if(fileName != null && (fileName.endsWith(".png") || fileName.endsWith(".PNG"))){
                     bitmap.compress(Bitmap.CompressFormat.PNG, 100, bos);
                 }else{
                     bitmap.compress(Bitmap.CompressFormat.JPEG, 100, bos);
                 }
                 bos.flush();
             } catch (Exception e) {
                 // TODO Auto-generated catch block
                 e.printStackTrace();
             }finally{
                 if(bos != null){
                     try {
                         bos.close();
                     } catch (IOException e) {
                         // TODO Auto-generated catch block
                         e.printStackTrace();
                     }
                 }
             }
             return true;
         }
         return false;
     }

     //从sd卡的路径中获取文件的内容
     public static byte[] readFileFromSDCard(String filePath){
         BufferedInputStream bis = null;
         ByteArrayOutputStream baos = new ByteArrayOutputStream();
         try {
             bis = new BufferedInputStream(new FileInputStream(new File(filePath)));
             byte[] buffer = new byte[8 * 1024];
             int hasRead = 0;
             while((hasRead = bis.read(buffer)) != -1){
                 baos.write(buffer, 0, hasRead);
                 baos.flush();
             }
             return baos.toByteArray();
         } catch (Exception e) {
             // TODO Auto-generated catch block
             e.printStackTrace();
         }finally{
             try {
                 baos.close();
                 bis.close();
             } catch (IOException e) {
                 // TODO Auto-generated catch block
                 e.printStackTrace();
             }
         }
         return null;
     }

     //从sd卡中获取Bitmap文件
     public static Bitmap loadBitmapFromSDCard(String filePath){
         byte[] data = readFileFromSDCard(filePath);
         if(data != null){
             Bitmap bitmap = BitmapFactory.decodeByteArray(data, 0, data.length);
             if(bitmap != null){
                 return bitmap;
             }
         }
         return null;
     }

     //获取sd卡的公有目录路径
     public static String getSDCardPublicDir(String type){
         return Environment.getExternalStoragePublicDirectory(type).toString();

     }

     //获取sd卡私有cache目录路径
     public static String getSDCardPrivateCacheDir(Context context){
         return context.getExternalCacheDir().getAbsolutePath();
     }

     //sd卡私有files目录下的路径
     public static String getSDCardPrivateFilesDir(Context context, String type){
         return context.getExternalFilesDir(type).getAbsolutePath();
     }

     //从sd卡中删除文件
     public static boolean removeFileFromSDCard(String filePath){
         File file = new File(filePath);
         if(file.exists()){
             try {
                 file.delete();
                 return true;
             } catch (Exception e) {
                 return false;
             }
         }
         return false;
     }

 }

参考:http://www.androidchina.net/4106.html