[分享]Java中byte[]与基础类型之间的转换

Posted 2022-12-14 Qiujuer

========================================================
作者：qiujuer
博客：blog.csdn.net/qiujuer
网站：www.qiujuer.net
开源库：github.com/qiujuer/Genius-Android
开源库：github.com/qiujuer/Blink
转载请注明出处：http://blog.csdn.net/qiujuer/article/details/45152189
------学之开源，用于开源；初学者的心态，与君共勉！

========================================================

很久没有写博客了，有些生疏了；一直忙着做 Blink 框架去了。
在这里打个广告，Blink是一款Socket协议跨平台框架，现在提供有Java、android、C#的版本；通过Blink能实现对Socket传输的异步封装，能直接发送或接受数据，现能直接发送 byte ，String，File 等类型，可在不改动框架情况下直接扩展所需类型。

Blink开源框架链接

因为在Socket的传输中都是 Bytes 的传输，所以涉及到 Java 基本类型（char、short、int、long）与byte[] 的转化，自己总结了一下，简单的写了一个类。

/**
 * Bit Converter
 */
public class BitConverter 

    /**
     * Convert char to byte[]
     *
     * @param x char
     * @return bytes
     */
    public static byte[] toBytes(char x) 
        return toBytes(x, new byte[2], 0);
    

    /**
     * Convert char to byte[]
     *
     * @param x       char
     * @param bytes   Dest bytes
     * @param bytePos Dest pos
     * @return bytes
     */
    public static byte[] toBytes(char x, byte[] bytes, int bytePos) 
        bytes[bytePos++] = (byte) (x);
        bytes[bytePos] = (byte) (x >> 8);
        return bytes;
    


    /**
     * Convert short to byte[]
     *
     * @param x Short
     * @return bytes
     */
    public static byte[] toBytes(short x) 
        return toBytes(x, new byte[2], 0);
    

    /**
     * Convert short to byte[]
     *
     * @param x       Short
     * @param bytes   Dest bytes
     * @param bytePos Dest pos
     * @return bytes
     */
    public static byte[] toBytes(short x, byte[] bytes, int bytePos) 
        bytes[bytePos++] = (byte) (x);
        bytes[bytePos] = (byte) (x >> 8);
        return bytes;
    

    /**
     * Convert int to byte[]
     *
     * @param x int
     * @return bytes
     */
    public static byte[] toBytes(int x) 
        return toBytes(x, new byte[4], 0);
    

    /**
     * Convert int to byte[]
     *
     * @param x       int
     * @param bytes   Dest bytes
     * @param bytePos Dest pos
     * @return bytes
     */
    public static byte[] toBytes(int x, byte[] bytes, int bytePos) 
        bytes[bytePos++] = (byte) (x);
        bytes[bytePos++] = (byte) (x >> 8);
        bytes[bytePos++] = (byte) (x >> 16);
        bytes[bytePos] = (byte) (x >> 24);
        return bytes;
    

    /**
     * Convert long to byte[]
     *
     * @param x long
     * @return bytes
     */
    public static byte[] toBytes(long x) 
        return toBytes(x, new byte[8], 0);
    

    /**
     * Convert long to byte[]
     *
     * @param x       long
     * @param bytes   Dest bytes
     * @param bytePos Dest pos
     * @return bytes
     */
    public static byte[] toBytes(long x, byte[] bytes, int bytePos) 
        bytes[bytePos++] = (byte) (x);
        bytes[bytePos++] = (byte) (x >> 8);
        bytes[bytePos++] = (byte) (x >> 16);
        bytes[bytePos++] = (byte) (x >> 24);
        bytes[bytePos++] = (byte) (x >> 32);
        bytes[bytePos++] = (byte) (x >> 40);
        bytes[bytePos++] = (byte) (x >> 48);
        bytes[bytePos] = (byte) (x >> 56);
        return bytes;
    

    /**
     * Convert byte[] to char
     *
     * @param bytes bytes
     * @return char
     */
    public static char toChar(byte[] bytes) 
        return toChar(bytes, 0);
    

    /**
     * Convert byte[] to char
     *
     * @param bytes bytes
     * @param index byte start index
     * @return char
     */
    public static char toChar(byte[] bytes, int index) 
        return (char) ((bytes[index + 1] << 8) | (bytes[index] & 0xff));
    

    /**
     * Convert byte[] to short
     *
     * @param bytes bytes
     * @return short
     */
    public static short toShort(byte[] bytes) 
        return toShort(bytes, 0);
    

    /**
     * Convert byte[] to short
     *
     * @param bytes bytes
     * @param index byte start index
     * @return short
     */
    public static short toShort(byte[] bytes, int index) 
        return (short) ((bytes[index + 1] << 8) | (bytes[index] & 0xff));
    

    /**
     * Convert byte[] to int
     *
     * @param bytes bytes
     * @return int
     */
    public static int toInt(byte[] bytes) 
        return toInt(bytes, 0);
    

    /**
     * Convert byte[] to int
     *
     * @param bytes bytes
     * @param index bytes start index
     * @return int
     */
    public static int toInt(byte[] bytes, int index) 
        return (((bytes[index + 3]) << 24) |
                ((bytes[index + 2] & 0xff) << 16) |
                ((bytes[index + 1] & 0xff) << 8) |
                ((bytes[index] & 0xff)));
    

    /**
     * Convert byte[] to long
     *
     * @param bytes bytes
     * @return long
     */
    public static long toLong(byte[] bytes) 
        return toLong(bytes, 0);
    

    /**
     * Convert byte[] to long
     *
     * @param bytes bytes
     * @param index bytes start index
     * @return long
     */
    public static long toLong(byte[] bytes, int index) 
        return ((((long) bytes[index + 7]) << 56) |
                (((long) bytes[index + 6] & 0xff) << 48) |
                (((long) bytes[index + 5] & 0xff) << 40) |
                (((long) bytes[index + 4] & 0xff) << 32) |
                (((long) bytes[index + 3] & 0xff) << 24) |
                (((long) bytes[index + 2] & 0xff) << 16) |
                (((long) bytes[index + 1] & 0xff) << 8) |
                (((long) bytes[index] & 0xff)));
    

需要注意的是：无论是从基本类型转换为 byte[] 还是 byte[] 转换为基本类型， 都是采用的低位在前高位在后的形式；这个与C#的默认模式是一致的，如果你的需求是高位在前的情况则需要自己更改一下顺序了。

========================================================
作者：qiujuer
博客：blog.csdn.net/qiujuer
网站：www.qiujuer.net
开源库：github.com/qiujuer/Genius-Android
开源库：github.com/qiujuer/Blink
转载请注明出处：http://blog.csdn.net/qiujuer/article/details/45152189
------学之开源，用于开源；初学者的心态，与君共勉！

========================================================