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;
 20 
/**
 * 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;
    }
    
    
}