这几天在做一个与PLC交互的系统，PLC会传过来一些指令，这些指令是二进制的格式，要转为4位十进制的指令来读，下面是代码部分：

public class BytesChange {
    /**
     * 二进制转十六进制方法
     * @param bString
     * @return
     */
    public static String bytes2hex(String bString){
        if(bString == null || bString.equals("") || bString.length() % 4 != 0){
            return null;
        }
        int beginIndex = 0;
        int length = 16;
        String instructions = "";
        while(true){
            if((beginIndex+length)>bString.length()){
                break;
            }
            String instruction = bString.substring(beginIndex, beginIndex + length);
            String result = bytes2hex0f(instruction);
            instructions += result + " ";
            if("00ca".equals(result)){
                break;
            }
            beginIndex += 16;
        }
        return instructions;
    }

    public static String bytes2hex0f(String bString){
        StringBuffer sb = new StringBuffer();
        int tmp = 0;
        for(int i=0; i<bString.length(); i+=4){
            tmp = 0;
            for(int j=0;j<4;j++){
                tmp += Integer.parseInt(bString.substring(i+j, i+j+1)) << (4-j-1);
            }
            sb.append(Integer.toHexString(tmp));
        }
        return sb.toString();
    }

    /**
     * 十六进制转十进制
     * @param strHex
     * @return
     */
    public static String hexToInt(String strHex){
        int in = Integer.parseInt(strHex,16);
        String result = "";
        if(in < 10){
            result = "0" + Integer.toString(in);
        }else{
            result = Integer.toString(in);
        }
        return result;
    }

    /**
     * 测试
     * @param args
     */
    public static void main(String[] args) {
        String message = "1010110000000000000000000000000100000000000000010000000000000001000000000000000100000000000000010000000011001010";
        BytesChange bc = new BytesChange();
        System.out.println(bc.bytes2hex(message));
        String str = "0001";
        System.out.println(bc.hexToInt(str));
    }

}