JAVA byte数组转化为16进制字符串输出

最简单的方法：

利用javax.xml.bind包下的DatatypeConverter

printHexBinary

public static java.lang.String printHexBinary(byte[] val)

Converts an array of bytes into a string.

Parameters:

val - An array of bytes

Returns:

A string containing a lexical representation of xsd:hexBinary

Throws:

IllegalArgumentException - if  val is null.

import javax.xml.bind.DatatypeConverter;
import java.io.UnsupportedEncodingException;
public class test {
    public static void main(String[] args) throws UnsupportedEncodingException{
 		//print hex string version of HELLO WORLD
		byte[] helloBytes = "HELLO WORLD".getBytes();
		String helloHex = DatatypeConverter.printHexBinary(helloBytes);
		System.out.printf("Hello hex: 0x%s\n", helloHex);
 
		//convert hex-encoded string back to original string
		byte[] decodedHex = DatatypeConverter.parseHexBinary(helloHex);
		String decodedString = new String(decodedHex, "UTF-8");
		System.out.printf("Hello decoded : %s\n", decodedString);	
    }
}

或者使用 stackoverflow提供的方法，貌似最快

final protected static char[] hexArray = "0123456789ABCDEF".toCharArray();
public static String bytesToHex(byte[] bytes) {
    char[] hexChars = new char[bytes.length * 2];
    for ( int j = 0; j < bytes.length; j++ ) {
        int v = bytes[j] & 0xFF;
        hexChars[j * 2] = hexArray[v >>> 4];
        hexChars[j * 2 + 1] = hexArray[v & 0x0F];
    }
    return new String(hexChars);
}

又或者使用java源码：

D:\JAVA\jdk1.8.0_65\src\javax\xml\bind\DatatypeConverterImpl.java

private static final char[] hexCode = "0123456789ABCDEF".toCharArray();

    public String printHexBinary(byte[] data) {
        StringBuilder r = new StringBuilder(data.length * 2);
        for (byte b : data) {
            r.append(hexCode[(b >> 4) & 0xF]);
            r.append(hexCode[(b & 0xF)]);
        }
        return r.toString();
    }