Java –如何连接和分割字节数组byte []

系统管理员 2023-02-15 01:28 103阅读 0赞

在此示例中，我们将向您展示如何使用`ByteBuffer`和`System.arraycopy`连接和拆分字节数组。

`ByteBuffer`

public static byte[] joinByteArray(byte[] byte1, byte[] byte2) {
    
        return ByteBuffer.allocate(byte1.length + byte2.length)
                .put(byte1)
                .put(byte2)
                .array();
    
    }
    
    public static void splitByteArray(byte[] input) {
    
        ByteBuffer bb = ByteBuffer.wrap(input);
    
        byte[] cipher = new byte[8];
        byte[] nonce = new byte[4];
        byte[] extra = new byte[2];
        bb.get(cipher, 0, cipher.length);
        bb.get(nonce, 0, nonce.length);
        bb.get(extra, 0, extra.length);
    
    }

`System.arraycopy`

public static byte[] joinByteArray(byte[] byte1, byte[] byte2) {
    
        byte[] result = new byte[byte1.length + byte2.length];
    
        System.arraycopy(byte1, 0, result, 0, byte1.length);
        System.arraycopy(byte2, 0, result, byte1.length, byte2.length);
    
        return result;
    
    }
    
    public static void splitByteArray(byte[] input) {
    
        byte[] cipher = new byte[8];
        byte[] nonce = new byte[4];
        byte[] extra = new byte[2];
        System.arraycopy(input, 0, cipher, 0, cipher.length);
        System.arraycopy(input, cipher.length, nonce, 0, nonce.length);
        System.arraycopy(input, cipher.length + nonce.length, extra, 0, extra.length);
    
    }

## 1.连接字节数组 ##

此Java示例使用`ByteBuffer`或`System.arraycopy`来连接或连接两个字节数组。

JoinByteArrayExample.java

package com.mkyong.nio;
    
    import java.nio.ByteBuffer;
    
    public class JoinByteArrayExample {
    
        public static void main(String[] args) {
    
            String str1 = "Hello World ";
            String str2 = "Java";
    
            byte[] bytes = joinByteArray(str1.getBytes(), str2.getBytes());
            byte[] bytes2 = joinByteArray2(str1.getBytes(), str2.getBytes());
    
            // byte[] to String
            System.out.println("Result       : " + new String(bytes));
            System.out.println("Result (Hex) : " + convertBytesToHex(bytes));
    
            System.out.println("Result2      : " + new String(bytes2));
            System.out.println("Result2 (Hex): " + convertBytesToHex(bytes2));
    
        }
    
        public static byte[] joinByteArray(byte[] byte1, byte[] byte2) {
    
            return ByteBuffer.allocate(byte1.length + byte2.length)
                    .put(byte1)
                    .put(byte2)
                    .array();
    
        }
    
        public static byte[] joinByteArray2(byte[] byte1, byte[] byte2) {
    
            byte[] result = new byte[byte1.length + byte2.length];
    
            System.arraycopy(byte1, 0, result, 0, byte1.length);
            System.arraycopy(byte2, 0, result, byte1.length, byte2.length);
    
            return result;
    
        }
    
        public static String convertBytesToHex(byte[] bytes) {
            StringBuilder result = new StringBuilder();
            for (byte temp : bytes) {
                result.append(String.format("%02x", temp));
            }
            return result.toString();
        }
    
    }

输出量

Terminal

Result       : Hello World Java
    Result (Hex) : 48656c6c6f20576f726c64204a617661
    Result2      : Hello World Java
    Result2 (Hex): 48656c6c6f20576f726c64204a617661

## 2.分割字节数组 ##

在Java中，我们可以使用`ByteBuffer`或`System.arraycopy`将单个字节数组拆分为多个字节数组。

例如，此`000102030a0b0c0d1a1b1c1d2f2f`以十六进制表示`000102030a0b0c0d1a1b1c1d2f2f`是一个字节数组（14个字节），它是密码（8个字节）+随机数（4个字节）+额外（2个字节）的组合。

000102030a0b0c0d | 1a1b1c1d | 2f2f
    cipher | nonce | extra

SplitByteArrayExample.java

package com.mkyong.nio;
    
    import java.nio.ByteBuffer;
    
    public class SplitByteArrayExample {
    
        public static void main(String[] args) {
    
            byte[] input = {0x00, 0x01, 0x02, 0x03, 0x0a, 0x0b, 0x0c, 0x0d, 0x1a, 0x1b, 0x1c, 0x1d, 0x2f, 0x2f};
    
            if (input.length != 14) {
                throw new IllegalArgumentException("input must be 14 bytes.");
            }
    
            ByteBuffer bb = ByteBuffer.wrap(input);
    
            byte[] cipher = new byte[8];
            byte[] nonce = new byte[4];
            byte[] extra = new byte[2];
            bb.get(cipher, 0, cipher.length);
            bb.get(nonce, 0, nonce.length);
            bb.get(extra, 0, extra.length);
    
            System.out.println("Input (Hex)    : " + convertBytesToHex(input));
    
            System.out.println("\n--- ByteBuffer ---");
            System.out.println("Cipher(Hex)    : " + convertBytesToHex(cipher));
            System.out.println("Nonce (Hex)    : " + convertBytesToHex(nonce));
            System.out.println("Nonce (Hex)    : " + convertBytesToHex(extra));
    
            byte[] cipher2 = new byte[8];
            byte[] nonce2 = new byte[4];
            byte[] extra2 = new byte[2];
            System.arraycopy(input, 0, cipher2, 0, cipher2.length);
            System.arraycopy(input, cipher2.length, nonce2, 0, nonce2.length);
            System.arraycopy(input, cipher2.length + nonce2.length, extra2, 0, extra2.length);
    
            System.out.println("\n--- System.arraycopy ---");
            System.out.println("Cipher2 (Hex)  : " + convertBytesToHex(cipher2));
            System.out.println("Nonce2  (Hex)  : " + convertBytesToHex(nonce2));
            System.out.println("Nonce2  (Hex)  : " + convertBytesToHex(extra2));
    
        }
    
        public static String convertBytesToHex(byte[] bytes) {
            StringBuilder result = new StringBuilder();
            for (byte temp : bytes) {
                result.append(String.format("%02x", temp));
            }
            return result.toString();
        }
    
    }

输出量

Terminal

Input (Hex)    : 000102030a0b0c0d1a1b1c1d2f2f
    
    --- ByteBuffer ---
    Cipher(Hex)    : 000102030a0b0c0d
    Nonce (Hex)    : 1a1b1c1d
    Nonce (Hex)    : 2f2f
    
    --- System.arraycopy ---
    Cipher2 (Hex)  : 000102030a0b0c0d
    Nonce2  (Hex)  : 1a1b1c1d
    Nonce2  (Hex)  : 2f2f

## 参考文献 ##

*  Java –将字节数组转换为int，反之亦然
 *  Java –将字节转换为无符号字节
 *  [字节缓冲区JavaDoc][JavaDoc]
 *  [System.arraycopy JavaDoc][]

标签： [字节][Link 1] [字节数组][Link 2] [ByteBuffer][] [复制数组][Link 3] [Java][] [联接][Link 4]

> 翻译自: [https://mkyong.com/java/java-how-to-join-and-split-byte-arrays-byte/][https_mkyong.com_java_java-how-to-join-and-split-byte-arrays-byte]

[JavaDoc]: https://docs.oracle.com/javase/7/docs/api/java/nio/ByteBuffer.html
[System.arraycopy JavaDoc]: https://docs.oracle.com/javase/7/docs/api/java/lang/System.html#arraycopy%28java.lang.Object,%20int,%20java.lang.Object,%20int,%20int%29
[Link 1]: https://mkyong.com/tag/byte/
[Link 2]: https://mkyong.com/tag/byte-array/
[ByteBuffer]: https://mkyong.com/tag/bytebuffer/
[Link 3]: https://mkyong.com/tag/copy-array/
[Java]: https://mkyong.com/tag/java/
[Link 4]: https://mkyong.com/tag/join/
[https_mkyong.com_java_java-how-to-join-and-split-byte-arrays-byte]: https://mkyong.com/java/java-how-to-join-and-split-byte-arrays-byte/