[Java]_[初级]_[实用的byte处理类]

标签：java   字节处理   uint8_t   char   byteutils封装类   

场景:

1.  C++可以使用std::string来缓存uint8_t的字节数组,比如在接收socket数据包时, 需要接收完整才可以处理某些数据，这时候就需要先缓存起来再处理。

2.  问题来了，Java的String是存储的UNICODE双字节结构,而且只支持字符,不支持如\0这些字符,并不适合处理字节数据.

先看看Java提供字节处理有哪些类,但是都不具备临时缓存的功能.

1. java.lang.Byte 类: 处理String和byte类型之间的转换,包括支持基数.可惜最大只支持byte 1字节的大小转换.

2. java.lang.System 类的 arraycopy
处理数组之间的复制,对原始类型是值复制,对于对象类型就是调用clone方法(估计).
static void arraycopy(Object src, int srcPos, Object dst, int dstPos, int length)
Copies length elements from the array src, starting at offset srcPos, into the array dst, starting at offset dstPos. 

3. java.util.Arrays 类
static int 	binarySearch(byte[] array, byte value)
Performs a binary search for value in the ascending sorted array array. 

static byte[] 	copyOf(byte[] original, int newLength)
Copies newLength elements from original into a new array. 

static void 	sort(byte[] array)

static String 	toString(byte[] array)
Creates a String representation of the byte[] passed. 

static void 	fill(byte[] array, byte value)
Fills the specified array with the specified element. 


static boolean 	equals(byte[] array1, byte[] array2)
Compares the two arrays. 


static byte[] 	copyOfRange(byte[] original, int start, int end)
Copies elements from original into a new array, from indexes start (inclusive) to end (exclusive). 

static <T> List<T> 	asList(T... array)
Returns a List of the objects in the specified array. 

方案:

1. 封装一个byte[]数组的处理类,参考std::string.

package com.androidassist.util;

import java.util.Arrays;

public class ByteUtils {

	private int size;
	private byte[] buffer;
	
	public byte[] getBuffer() {
		return buffer;
	}

	private final int kBufferSizeIncrease = 512;
	private final int kDefaultBufferSize = 1024;

	public ByteUtils() {
		buffer = new byte[kDefaultBufferSize];
		size = 0;
	}

	public long getSize() {
		return size;
	}

	public void setSize(int size) {
		this.size = size;
	}

	public ByteUtils append(byte[] buf, int length) {

		if (size + length > buffer.length) {
			buffer = Arrays.copyOf(buffer, buffer.length + kBufferSizeIncrease);
		}
		System.arraycopy(buf, 0, buffer, size, length);
		size += length;
		return this;
	}

	public void erase(int begin, int count) {
		if (begin + count > size) {
			size = begin;
		} else {
			int startIndex = begin + count;
			System.arraycopy(buffer, startIndex, buffer, begin, count);
			size -= count;
		}
	}
	
	public void clear()
	{
		buffer = new byte[kDefaultBufferSize];
		size = 0;
	}
	
//	public static void main(String[] args) {
//		ByteUtils bu = new ByteUtils();
//		byte[] buf = new byte[32];
//		Arrays.fill(buf, (byte)1);
//		bu.append(buf,buf.length);
//		buf = new byte[1024];
//		Arrays.fill(buf, (byte)2);
//		bu.append(buf,buf.length);
//		System.out.println(bu.getSize());
//		bu.erase(0, 30);
//		System.out.println(bu.getSize());
//		bu.erase(4, 50);
//		System.out.println(bu.getSize());
//		System.out.println(bu.getBuffer()[2]);
//		System.out.println(bu.getBuffer()[1]);
//	}
}

备注: 最近发现的java.nio.ByteBUffer类也只能设定固定容量,并不能动态增长.

[Java]_[初级]_[实用的byte处理类]

标签：java   字节处理   uint8_t   char   byteutils封装类   

原文地址：http://blog.csdn.net/infoworld/article/details/43925667