应用

/**
 * 利用MD5进行加密
 *
 * @param str 待加密的字符串
 * @return 加密后的字符串
 * @throws NoSuchAlgorithmException     没有这种产生消息摘要的算法
 * @throws UnsupportedEncodingException
 */

public String EncoderByMd5(String str) throws NoSuchAlgorithmException, UnsupportedEncodingException {// 确定计算方法
    MessageDigest md5 = MessageDigest.getInstance("MD5");

    BASE64Encoder base64en = new BASE64Encoder();
    // 加密后的字符串
    String newstr = base64en.encode(md5.digest(str.getBytes("utf-8")));
    return newstr;
}

两个工具类搞定

import java.io.IOException;
import java.io.OutputStream;

public class BASE64Encoder extends CharacterEncoder {private static final char[] pem_array = new char[]{'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', 'I', 'J', 'K', 'L', 'M', 'N', 'O', 'P', 'Q', 'R', 'S', 'T', 'U', 'V', 'W', 'X', 'Y', 'Z', 'a', 'b', 'c', 'd', 'e', 'f', 'g', 'h', 'i', 'j', 'k', 'l', 'm', 'n', 'o', 'p', 'q', 'r', 's', 't', 'u', 'v', 'w', 'x', 'y', 'z', '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', '+', '/'};

    public BASE64Encoder() {}protected int bytesPerAtom() {return 3;
    }protected int bytesPerLine() {return 57;
    }protected void encodeAtom(OutputStream outStream, byte[] data, int offset, int len) throws IOException {byte a;
        if (len == 1) {a = data[offset];
            byte b = 0;
            outStream.write(pem_array[a >>> 2 & 63]);
            outStream.write(pem_array[(a << 4 & 48) + (b >>> 4 & 15)]);
            outStream.write(61);
            outStream.write(61);
        } else {byte b;
            if (len == 2) {a = data[offset];
                b = data[offset + 1];
                byte c = 0;
                outStream.write(pem_array[a >>> 2 & 63]);
                outStream.write(pem_array[(a << 4 & 48) + (b >>> 4 & 15)]);
                outStream.write(pem_array[(b << 2 & 60) + (c >>> 6 & 3)]);
                outStream.write(61);
            } else {a = data[offset];
                b = data[offset + 1];
                byte c = data[offset + 2];
                outStream.write(pem_array[a >>> 2 & 63]);
                outStream.write(pem_array[(a << 4 & 48) + (b >>> 4 & 15)]);
                outStream.write(pem_array[(b << 2 & 60) + (c >>> 6 & 3)]);
                outStream.write(pem_array[c & 63]);
            }}}
}

import java.io.ByteArrayInputStream;
import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.io.PrintStream;
import java.nio.ByteBuffer;

public abstract class CharacterEncoder {protected PrintStream pStream;

    public CharacterEncoder() {}protected abstract int bytesPerAtom();

    protected abstract int bytesPerLine();

    protected void encodeBufferPrefix(OutputStream aStream) throws IOException {this.pStream = new PrintStream(aStream);
    }protected void encodeBufferSuffix(OutputStream aStream) throws IOException {}protected void encodeLinePrefix(OutputStream aStream, int aLength) throws IOException {}protected void encodeLineSuffix(OutputStream aStream) throws IOException {this.pStream.println();
    }protected abstract void encodeAtom(OutputStream var1, byte[] var2, int var3, int var4) throws IOException;

    protected int readFully(InputStream in, byte[] buffer) throws IOException {for(int i = 0; i < buffer.length; ++i) {int q = in.read();
            if (q == -1) {return i;
            }buffer[i] = (byte)q;
        }return buffer.length;
    }public void encode(InputStream inStream, OutputStream outStream) throws IOException {byte[] tmpbuffer = new byte[this.bytesPerLine()];
        this.encodeBufferPrefix(outStream);

        while(true) {int numBytes = this.readFully(inStream, tmpbuffer);
            if (numBytes == 0) {break;
            }this.encodeLinePrefix(outStream, numBytes);

            for(int j = 0; j < numBytes; j += this.bytesPerAtom()) {if (j + this.bytesPerAtom() <= numBytes) {this.encodeAtom(outStream, tmpbuffer, j, this.bytesPerAtom());
                } else {this.encodeAtom(outStream, tmpbuffer, j, numBytes - j);
                }}if (numBytes < this.bytesPerLine()) {break;
            }this.encodeLineSuffix(outStream);
        }this.encodeBufferSuffix(outStream);
    }public void encode(byte[] aBuffer, OutputStream aStream) throws IOException {ByteArrayInputStream inStream = new ByteArrayInputStream(aBuffer);
        this.encode((InputStream)inStream, aStream);
    }public String encode(byte[] aBuffer) {ByteArrayOutputStream outStream = new ByteArrayOutputStream();
        ByteArrayInputStream inStream = new ByteArrayInputStream(aBuffer);
        String retVal = null;

        try {this.encode((InputStream)inStream, outStream);
            retVal = outStream.toString("8859_1");
            return retVal;
        } catch (Exception var6) {throw new Error("CharacterEncoder.encode internal error");
        }}private byte[] getBytes(ByteBuffer bb) {byte[] buf = null;
        if (bb.hasArray()) {byte[] tmp = bb.array();
            if (tmp.length == bb.capacity() && tmp.length == bb.remaining()) {buf = tmp;
                bb.position(bb.limit());
            }}if (buf == null) {buf = new byte[bb.remaining()];
            bb.get(buf);
        }return buf;
    }public void encode(ByteBuffer aBuffer, OutputStream aStream) throws IOException {byte[] buf = this.getBytes(aBuffer);
        this.encode(buf, aStream);
    }public String encode(ByteBuffer aBuffer) {byte[] buf = this.getBytes(aBuffer);
        return this.encode(buf);
    }public void encodeBuffer(InputStream inStream, OutputStream outStream) throws IOException {byte[] tmpbuffer = new byte[this.bytesPerLine()];
        this.encodeBufferPrefix(outStream);

        int numBytes;
        do {numBytes = this.readFully(inStream, tmpbuffer);
            if (numBytes == 0) {break;
            }this.encodeLinePrefix(outStream, numBytes);

            for(int j = 0; j < numBytes; j += this.bytesPerAtom()) {if (j + this.bytesPerAtom() <= numBytes) {this.encodeAtom(outStream, tmpbuffer, j, this.bytesPerAtom());
                } else {this.encodeAtom(outStream, tmpbuffer, j, numBytes - j);
                }}this.encodeLineSuffix(outStream);
        } while(numBytes >= this.bytesPerLine());

        this.encodeBufferSuffix(outStream);
    }public void encodeBuffer(byte[] aBuffer, OutputStream aStream) throws IOException {ByteArrayInputStream inStream = new ByteArrayInputStream(aBuffer);
        this.encodeBuffer((InputStream)inStream, aStream);
    }public String encodeBuffer(byte[] aBuffer) {ByteArrayOutputStream outStream = new ByteArrayOutputStream();
        ByteArrayInputStream inStream = new ByteArrayInputStream(aBuffer);

        try {this.encodeBuffer((InputStream)inStream, outStream);
        } catch (Exception var5) {throw new Error("CharacterEncoder.encodeBuffer internal error");
        }return outStream.toString();
    }public void encodeBuffer(ByteBuffer aBuffer, OutputStream aStream) throws IOException {byte[] buf = this.getBytes(aBuffer);
        this.encodeBuffer(buf, aStream);
    }public String encodeBuffer(ByteBuffer aBuffer) {byte[] buf = this.getBytes(aBuffer);
        return this.encodeBuffer(buf);
    }
}