与字节数组相关的IO操作

总结一下与字节数组相关的IO操作。

关于 把十六进制的位串转化为byte数组,请参阅 http://hw1287789687.iteye.com/blog/1882644

 

(1)从InputStream 读取字节数组

方式一:

/***
	 * Has been tested
	 * 
	 * @param in
	 * @return
	 * @throws IOException
	 */
	public static byte[] readBytes3(InputStream in) throws IOException {
		BufferedInputStream bufin = new BufferedInputStream(in);
		int buffSize = BUFFSIZE_1024;
		ByteArrayOutputStream out = new ByteArrayOutputStream(buffSize);

		// System.out.println("Available bytes:" + in.available());

		byte[] temp = new byte[4096];
		int size = 0;
		while ((size = bufin.read(temp)) != -1) {
			out.write(temp, 0, size);
		}
		bufin.close();
		in.close();
		byte[] content = out.toByteArray();
		return content;
	}

 说明:先把inputstream的字节读到ByteArrayOutputStream中,读完之后再调用toByteArray() 转化为字节数组。

 

方式二:

/***
	 * Has been tested
	 * 
	 * @param in
	 * @return
	 * @throws IOException
	 */
	public static byte[] readBytes(InputStream in) throws IOException {
		byte[] temp = new byte[in.available()];
		byte[] result = new byte[0];
		int size = 0;
		while ((size = in.read(temp)) != -1) {
			byte[] readBytes = new byte[size];
			System.arraycopy(temp, 0, readBytes, 0, size);
			result = mergeArray(result, readBytes);
		}
		return result;
	}
/***
	 * 合并字节数组
	 * 
	 * @param a
	 * @return
	 */
	public static byte[] mergeArray(byte[]... a) {
		// 合并完之后数组的总长度
		int index = 0;
		int sum = 0;
		for (int i = 0; i < a.length; i++) {
			sum = sum + a[i].length;
		}
		byte[] result = new byte[sum];
		for (int i = 0; i < a.length; i++) {
			int lengthOne = a[i].length;
			if (lengthOne == 0) {
				continue;
			}
			// 拷贝数组
			System.arraycopy(a[i], 0, result, index, lengthOne);
			index = index + lengthOne;
		}
		return result;
	}

 

 

(2)把字节数组写入文件

/***
	 * write byte[] to file
	 * 
	 * @param bytes
	 * @param destFile
	 * @throws IOException
	 */
	public static void writeBytesToFile(byte[] bytes, File destFile)
			throws IOException {
		FileOutputStream out = new FileOutputStream(destFile);
		write2File(bytes, out);
	}
/***
	 * 
	 * @param bytes
	 * @param out
	 * @throws IOException
	 */
	public static void write2File(byte[] bytes, FileOutputStream out)
			throws IOException {
		out.write(bytes);
		out.close();
	}

 

 

(3)在已有字节数组基础上追加一个字节

/***
	 * append a byte.
	 * 
	 * @param a
	 * @param b
	 * @return
	 */
	public static byte[] appandByte(byte[] a, byte b) {
		int length = a.length;
		byte[] resultBytes = new byte[length + 1];
		System.arraycopy(a, 0, resultBytes, 0, length);
		resultBytes[length] = b;
		return resultBytes;
	}

 

(4)比较两个字节数组是否相同

/***
	 * Compare two byte arrays whether are the same.
	 * 
	 * @param a
	 * @param b
	 * @return
	 */
	public static boolean arrayIsEqual(byte[] a, byte[] b) {
		if(a==null&&b==null){
			return true;
		}
		
		if (a != null && b != null) {
			if (a.length != b.length) {
				return false;
			} else {
				for (int i = 0; i < a.length; i++) {
					if (a[i] != b[i]) {
						return false;
					}
				}
			}
		}else {//one is null, the other is not null
			return false;
		}
		return true;
	}

 

(5)查找指定字节findTarget在指定字节数组source中的位置

/***
	 * 
	 * @param source
	 * @param findTarget
	 *            :key word
	 * @param pos
	 *            :where start from
	 * @return index
	 */
	public static int findBytes(byte[] source, byte[] findTarget, int pos) {
		int i, j, k = 0;
		i = pos;
		j = 0;
		while (i < source.length && j < findTarget.length) {
			if (source[i] == findTarget[j]) {
				++i;
				++j;
				if (j == findTarget.length) {
					k = k + 1;// k++
					break;
					// j = 0;
				}
			} else {
				i = i - j + 1;
				j = 0;
			}
		}
		return k == 0 ? -1 : i - j;
	}

 

 

测试代码:

 @Test
    public void test_arrayIsEqual2(){
    	System.out.println("test_filterFrontBytes");
		byte[] a = new byte[] { 1, 2, 3, 4 };
		byte[] b = new byte[] { 1, 2, 3 };
		System.out.println( arrayIsEqual(a, b));
}
@Test
	public void test_appandByte(){
		byte[]bytes=new byte[]{1,2,3};
		byte[]resultBytes=appandByte(bytes, (byte)32);
		arrayIsEqual(resultBytes, new byte[]{1, 2, 3, 32});
	}

 

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