byte数组和文件之间的相互转换,string转文件流输出

/**
 * 根据byte数组，生成文件
 * @param bfile 文件数组
 * @param filePath 文件存放路径
 * @param fileName 文件名称
 */
public static void byte2File(byte[] byte,String filePath,String fileName){
    BufferedOutputStream bos=null;
    FileOutputStream fos=null;
    File file=null;
    try{
        File dir=new File(filePath);
        if(!dir.exists() && !dir.isDirectory()){//判断文件目录是否存在
            dir.mkdirs();
        }
        file=new File(filePath+fileName);
        fos=new FileOutputStream(file);
        bos=new BufferedOutputStream(fos);
        bos.write(byte);
    }
    catch(Exception e){
        System.out.println(e.getMessage());
        e.printStackTrace();
    }
    finally{
        try{
            if(bos != null){
                bos.close();
            }
            if(fos != null){
                fos.close();
            }
        }
        catch(Exception e){
            System.out.println(e.getMessage());
            e.printStackTrace();
        }
    }
}
/**
 * 获得指定文件的byte数组
 * @param filePath 文件绝对路径
 * @return
 */
public static byte[] file2Byte(String filePath){
    ByteArrayOutputStream bos=null;
    BufferedInputStream in=null;
    try{
        File file=new File(filePath);
        if(!file.exists()){
            throw new FileNotFoundException("file not exists");
        }
        bos=new ByteArrayOutputStream((int)file.length());
        in=new BufferedInputStream(new FileInputStream(file));
        int buf_size=1024;
        byte[] buffer=new byte[buf_size];
        int len=0;
        while(-1 != (len=in.read(buffer,0,buf_size))){
            bos.write(buffer,0,len);
        }
        return bos.toByteArray();
    }
    catch(Exception e){
        System.out.println(e.getMessage());
        e.printStackTrace();
        return null;
    }
    finally{
        try{
            if(in!=null){
                in.close();
            }
            if(bos!=null){
                bos.close();
            }
        }
        catch(Exception e){
            System.out.println(e.getMessage());
            e.printStackTrace();
        }
    }
}

//字符串转换成数组
public static byte[] toByteArray(String hexString) {
    hexString = hexString.toLowerCase();
    final byte[] byteArray = new byte[hexString.length() / 2];
    int k = 0;
    for (int i = 0; i < byteArray.length; i++) {// 因为是16进制，最多只会占用4位，转换成字节需要两个16进制的字符，高位在先
        byte high = (byte) (Character.digit(hexString.charAt(k), 16) & 0xff);
        byte low = (byte) (Character.digit(hexString.charAt(k + 1), 16) & 0xff);
        byteArray[i] = (byte) (high << 4 | low);
        k += 2;
    }
    return byteArray;
}

/**
 * 字符串转换成字节流并输出
 * 
 */
public void file(HttpServletResponse response,String xx){

    byte[] bytes = CommonUtil.toByteArray(xx);
    OutputStream os = null;
    try {
        os = response.getOutputStream();
        response.addHeader("Content-Type", "image/jpeg");
        os.write(bytes);
        os.flush();
    }catch (Exception e){
        e.printStackTrace();
    }finally {
        if (os != null) {
            try {
                os.close();
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
    }
}