FileUtil

import java.io.ByteArrayOutputStream;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;


import android.os.Environment;


public class FileUtil {


private String SDCardRoot;


public FileUtil() {
//得到当前外部存储设备目录
SDCardRoot = Environment.getExternalStorageDirectory().getAbsolutePath() + File.separator;
}

/**
* 在SDCard上创建文件
* */
public File createFileInSDCard(String fileName, String dir) throws Exception {
File file = new File(SDCardRoot + dir + File.separator + fileName);
System.out.println("file-->" + file);
file.createNewFile();
return file;
}

/**
* 在SDCard上创建目录
* */
public File createSDDir(String dir) {
File file = new File(SDCardRoot + dir + File.separator);
System.out.println(file.mkdirs());
return file;
}

/**
* 判断SDCard上的文件是否存在
* */
public boolean isFileExist(String fileName, String path) {
File file = new File(SDCardRoot + path + File.separator + fileName);
return file.exists();
}

/**
* 获取文件
* 
* @param fileName
* @param path
* @return
*/
public File getFile(String fileName, String path) {
File file = new File(SDCardRoot + path + File.separator + fileName);
return file;
}

/**
* 删除文件
* 
* @param fileName
* @param path
*/
public void deleteFile(String fileName, String path) {
System.out.println("delete");
File file = new File(SDCardRoot + path + File.separator + fileName);
file.delete();
}

/**
* 将一个InputStream写入SDCard
* */
public File writeToSDCardFromInput(String path, String fileName, InputStream inputStream) {
File file = null;
OutputStream  outputStream = null;

try {
createSDDir(path);
file = createFileInSDCard(fileName, path);

outputStream = new FileOutputStream(file);
byte data[] = new byte[4*1024];
int tmp;
while((tmp = inputStream.read(data)) !=-1) {
outputStream.write(data, 0, tmp);
}
outputStream.flush();
} catch (Exception e) {
e.printStackTrace();
} finally {
try {
outputStream.close();
} catch (Exception e) {
e.printStackTrace();
}
}
return file;
}

    /**
     * @param file
     * @return
     */
    public byte[] getBytesFromFile(File file) {
        if (file == null) {
            return null;
        }
        try {
            FileInputStream stream = new FileInputStream(file);
            ByteArrayOutputStream out = new ByteArrayOutputStream(1000);
            byte[] b = new byte[1000];
            int n;
            while ((n = stream.read(b)) != -1) {
            out.write(b, 0, n);
            }
            
            stream.close();
            out.close();
            return out.toByteArray();
    } catch (IOException e) {
   
    }
        return null;
    }
    
    
}