Java扩展/包装内置类的常见方式

我是Java语言的新手,我试图编写我的第一个相对复杂的程序.在我写了几个课程之后,我意识到我几乎没有直接使用内置类(比如BigInteger,MessageDigest,ByteBuffer),因为它们并不完全符合我的需求.相反,我编写自己的类,在类中使用内置类作为属性.
例：

public class SHA1 {
    public static final int SHA_DIGEST_LENGTH = 20;

    private MessageDigest md;

    public SHA1() {
        try {
            md = MessageDigest.getInstance("SHA-1");
        } catch (NoSuchAlgorithmException e) {
            e.printStackTrace();
        }
    }

    public void update(byte[] data) {
        md.update(data);
    }

    public void update(BigNumber bn) {
        md.update(bn.asByteArray());
    }

    public void update(String data) {
        md.update(data.getBytes());
    }

    public byte[] digest() {
        return md.digest();
    }
}

使用以下简单类我不必在使用SHA1时使用try catch,我可以将自定义BigNumber类作为参数,我也可以将String作为参数来更新函数.

以下BigNumber类包含我需要的所有函数以及我需要它们的具体方式.

public class BigNumber {
    private BigInteger m_bn;

    public BigNumber() {
        m_bn = new BigInteger("0");
    }

    public BigNumber(BigInteger bn) {
        m_bn = bn;
    }

    public BigNumber(String hex) {
        setHexStr(hex);
    }

    //reversed no minsize
    public byte[] asByteArray() {
        return asByteArray(0, true);
    }

    //reversed with minsize
    public byte[] asByteArray(int minSize) {
        return asByteArray(minSize, true);
    }

    public byte[] asByteArray(int minSize, boolean rev) {
        byte[] mag = m_bn.toByteArray();

        //delete sign bit
        //there is always a sign bit! so if bitNum % 8 is zero then
        //the sign bit created a new byte (0th)
        if(getNumBits() % 8 == 0) {
            byte[] tmp = new byte[mag.length-1];
            System.arraycopy(mag, 1, tmp, 0, mag.length-1);
            mag = tmp;
        }

        //extend the byte array if needed
        int byteSize = (minSize >= getNumBytes()) ? minSize : getNumBytes();
        byte[] tmp = new byte[byteSize]; 

        //if tmp's length smaller then byteSize then we keep 0x00-s from left
        System.arraycopy(mag, 0, tmp, byteSize-mag.length, mag.length);

        if(rev) ByteManip.reverse(tmp);

        return tmp;
    }

    public String asHexStr() {
        return ByteManip.byteArrayToHexStr(asByteArray(0, false));
    }

    public void setHexStr(String hex) {
        m_bn = new BigInteger(hex, 16);
    }

    public void setBinary(byte[] data) {
        //reverse = true
        ByteManip.reverse(data);
        //set as hex (binary set has some bug with the sign bit...)
        m_bn = new BigInteger(ByteManip.byteArrayToHexStr(data), 16);
    }

    public void setRand(int byteSize) {
        byte[] tmp = new byte[byteSize];
        new Random().nextBytes(tmp);
        //reversing byte order, but it doesn't really matter since it is a random
        //number
        setBinary(tmp);
    }

    public int getNumBytes() {
        return (m_bn.bitLength() % 8 == 0) ? (m_bn.bitLength() / 8) : (m_bn.bitLength() / 8 + 1);
    }

    public int getNumBits() {
        return m_bn.bitLength();
    }

    public boolean isZero() {
        return m_bn.equals(BigInteger.ZERO);
    }

    //operations
    public BigNumber modExp(BigNumber exp, BigNumber mod) {
        return new BigNumber(m_bn.modPow(exp.m_bn, mod.m_bn));
    }

    public BigNumber mod(BigNumber m) {
        return new BigNumber(m_bn.mod(m.m_bn));
    }

    public BigNumber add(BigNumber bn) {
        return new BigNumber(m_bn.add(bn.m_bn));
    }

    public BigNumber subtract(BigNumber bn) {
        return new BigNumber(m_bn.subtract(bn.m_bn));
    }

    public BigNumber multiply(BigNumber bn) {
        return new BigNumber(m_bn.multiply(bn.m_bn));
    }   
}

我的问题是Java语言中使用这些类而不是内置类有多常见？它是否使我的代码对其他程序员来说不可读(与使用内置类实现所有内容相比)？

我已经读过新的C程序员拼命想要编写他们用C编写的代码,因此C的好处对他们来说仍然是隐藏的.
我担心我会在Java中做类似的事情：尝试自己实现所有内容而不是直接使用内置类.
这是否发生(例如在BigNumber类中)？

谢谢你的意见！

解决方法:

通过这样做来添加一些值时,包装类是有意义的.如果要添加小功能,则可以使用Utility类而不是包装现有类.

标签：java,coding-style,built-in,class
来源： https://codeday.me/bug/20190613/1231318.html