13五 / 2010

base64的URL传输

众所周知标准的Base64并不适合直接放在URL里传输，因为URL编码器会把标准Base64中的“/”和“+”字符变为形如“%XX”的形式，而这些“%”号如果在存入数据库时还需要再进行转换。下面提供一个适合URL的改进版本。

调用方法：

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public static String base64Encode(String str) {
	byte[] bytes = UrlBase64.encode(str.getBytes());
	return new String(bytes);
}
 
public static String base64Decode(String str) {
	byte[] bytes = UrlBase64.decode(str.getBytes());
	return new String(bytes);
}

具体的使用方法，例如我的action_19参数的值需要用加密：

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String url = "servlet?action_19="+Tools.base64Encode(num);
url = java.net.URLEncoder.encode(url);

之后访问servlet得到action_19解密即可~这其实也间接解决了GET中含有中文乱码的问题（当然这不是最好的GET中文乱码解决方法）。

以下为具体的类：

UrlBase64Encoder.java

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package com.rizon.apollo.xnjk.util;
 
public class UrlBase64Encoder extends Base64Encoder {
 
	public UrlBase64Encoder() {
		encodingTable[encodingTable.length - 2] = 45;
		encodingTable[encodingTable.length - 1] = 95;
		padding = 46;
		initialiseDecodingTable();
	}
}

UrlBase64.java

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package com.rizon.apollo.xnjk.util;
 
import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.io.OutputStream;
 
//Referenced classes of package org.bouncycastle.util.encoders:
//         UrlBase64Encoder, Encoder
 
public class UrlBase64 {
 
	private static final Encoder encoder = new UrlBase64Encoder();
 
	public UrlBase64() {
	}
 
	public static byte[] encode(byte abyte0[]) {
		ByteArrayOutputStream bytearrayoutputstream = new ByteArrayOutputStream();
		try {
			encoder.encode(abyte0, 0, abyte0.length, bytearrayoutputstream);
		} catch (IOException ioexception) {
			throw new RuntimeException((new StringBuilder()).append(
					"exception encoding URL safe base64 string: ").append(
					ioexception).toString());
		}
		return bytearrayoutputstream.toByteArray();
	}
 
	public static int encode(byte abyte0[], OutputStream outputstream)
			throws IOException {
		return encoder.encode(abyte0, 0, abyte0.length, outputstream);
	}
 
	public static byte[] decode(byte abyte0[]) {
		ByteArrayOutputStream bytearrayoutputstream = new ByteArrayOutputStream();
		try {
			encoder.decode(abyte0, 0, abyte0.length, bytearrayoutputstream);
		} catch (IOException ioexception) {
			throw new RuntimeException((new StringBuilder()).append(
					"exception decoding URL safe base64 string: ").append(
					ioexception).toString());
		}
		return bytearrayoutputstream.toByteArray();
	}
 
	public static int decode(byte abyte0[], OutputStream outputstream)
			throws IOException {
		return encoder.decode(abyte0, 0, abyte0.length, outputstream);
	}
 
	public static byte[] decode(String s) {
		ByteArrayOutputStream bytearrayoutputstream = new ByteArrayOutputStream();
		try {
			encoder.decode(s, bytearrayoutputstream);
		} catch (IOException ioexception) {
			throw new RuntimeException((new StringBuilder()).append(
					"exception decoding URL safe base64 string: ").append(
					ioexception).toString());
		}
		return bytearrayoutputstream.toByteArray();
	}
 
	public static int decode(String s, OutputStream outputstream)
			throws IOException {
		return encoder.decode(s, outputstream);
	}
 
}

Encoder.java

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package com.rizon.apollo.xnjk.util;
 
import java.io.IOException;
import java.io.OutputStream;
 
public interface Encoder {
 
	public abstract int encode(byte abyte0[], int i, int j,
			OutputStream outputstream) throws IOException;
 
	public abstract int decode(byte abyte0[], int i, int j,
			OutputStream outputstream) throws IOException;
 
	public abstract int decode(String s, OutputStream outputstream)
			throws IOException;
}

Base64Encoder.java

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package com.rizon.apollo.xnjk.util;
 
import java.io.IOException;
import java.io.OutputStream;
 
// Referenced classes of package org.bouncycastle.util.encoders:
//            Encoder
 
public class Base64Encoder implements Encoder {
 
	protected final byte encodingTable[] = { 65, 66, 67, 68, 69, 70, 71, 72,
			73, 74, 75, 76, 77, 78, 79, 80, 81, 82, 83, 84, 85, 86, 87, 88, 89,
			90, 97, 98, 99, 100, 101, 102, 103, 104, 105, 106, 107, 108, 109,
			110, 111, 112, 113, 114, 115, 116, 117, 118, 119, 120, 121, 122,
			48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 43, 47 };
	protected byte padding;
	protected final byte decodingTable[] = new byte[128];
 
	protected void initialiseDecodingTable() {
		for (int i = 0; i < encodingTable.length; i++) {
			decodingTable[encodingTable[i]] = (byte) i;
		}
 
	}
 
	public Base64Encoder() {
		padding = 61;
		initialiseDecodingTable();
	}
 
	public int encode(byte abyte0[], int i, int j, OutputStream outputstream)
			throws IOException {
		int k = j % 3;
		int l = j - k;
		for (int l1 = i; l1 < i + l; l1 += 3) {
			int i1 = abyte0[l1] & 0xff;
			int j1 = abyte0[l1 + 1] & 0xff;
			int k1 = abyte0[l1 + 2] & 0xff;
			outputstream.write(encodingTable[i1 >>> 2 & 0x3f]);
			outputstream.write(encodingTable[(i1 << 4 | j1 >>> 4) & 0x3f]);
			outputstream.write(encodingTable[(j1 << 2 | k1 >>> 6) & 0x3f]);
			outputstream.write(encodingTable[k1 & 0x3f]);
		}
 
		switch (k) {
		case 1: // '\001'
			int j3 = abyte0[i + l] & 0xff;
			int i2 = j3 >>> 2 & 0x3f;
			int k2 = j3 << 4 & 0x3f;
			outputstream.write(encodingTable[i2]);
			outputstream.write(encodingTable[k2]);
			outputstream.write(padding);
			outputstream.write(padding);
			break;
 
		case 2: // '\002'
			int k3 = abyte0[i + l] & 0xff;
			int l3 = abyte0[i + l + 1] & 0xff;
			int j2 = k3 >>> 2 & 0x3f;
			int l2 = (k3 << 4 | l3 >>> 4) & 0x3f;
			int i3 = l3 << 2 & 0x3f;
			outputstream.write(encodingTable[j2]);
			outputstream.write(encodingTable[l2]);
			outputstream.write(encodingTable[i3]);
			outputstream.write(padding);
			break;
		}
		return (l / 3) * 4 + (k != 0 ? 4 : 0);
	}
 
	private boolean ignore(char c) {
		return c == '\n' || c == '\r' || c == '\t' || c == ' ';
	}
 
	public int decode(byte abyte0[], int i, int j, OutputStream outputstream)
			throws IOException {
		int k = 0;
		int l;
		for (l = i + j; l > i && ignore((char) abyte0[l - 1]); l--) {
		}
		int i1 = i;
		int j1 = l - 4;
		for (i1 = nextI(abyte0, i1, j1); i1 < j1; i1 = nextI(abyte0, i1, j1)) {
			byte byte0 = decodingTable[abyte0[i1++]];
			i1 = nextI(abyte0, i1, j1);
			byte byte1 = decodingTable[abyte0[i1++]];
			i1 = nextI(abyte0, i1, j1);
			byte byte2 = decodingTable[abyte0[i1++]];
			i1 = nextI(abyte0, i1, j1);
			byte byte3 = decodingTable[abyte0[i1++]];
			outputstream.write(byte0 << 2 | byte1 >> 4);
			outputstream.write(byte1 << 4 | byte2 >> 2);
			outputstream.write(byte2 << 6 | byte3);
			k += 3;
		}
 
		k += decodeLastBlock(outputstream, (char) abyte0[l - 4],
				(char) abyte0[l - 3], (char) abyte0[l - 2],
				(char) abyte0[l - 1]);
		return k;
	}
 
	private int nextI(byte abyte0[], int i, int j) {
		for (; i < j && ignore((char) abyte0[i]); i++) {
		}
		return i;
	}
 
	public int decode(String s, OutputStream outputstream) throws IOException {
		int i = 0;
		int j;
		for (j = s.length(); j > 0 && ignore(s.charAt(j - 1)); j--) {
		}
		int k = 0;
		int l = j - 4;
		for (k = nextI(s, k, l); k < l; k = nextI(s, k, l)) {
			byte byte0 = decodingTable[s.charAt(k++)];
			k = nextI(s, k, l);
			byte byte1 = decodingTable[s.charAt(k++)];
			k = nextI(s, k, l);
			byte byte2 = decodingTable[s.charAt(k++)];
			k = nextI(s, k, l);
			byte byte3 = decodingTable[s.charAt(k++)];
			outputstream.write(byte0 << 2 | byte1 >> 4);
			outputstream.write(byte1 << 4 | byte2 >> 2);
			outputstream.write(byte2 << 6 | byte3);
			i += 3;
		}
 
		i += decodeLastBlock(outputstream, s.charAt(j - 4), s.charAt(j - 3), s
				.charAt(j - 2), s.charAt(j - 1));
		return i;
	}
 
 
	private int decodeLastBlock(OutputStream outputstream, char c, char c1,
			char c2, char c3) throws IOException {
		if (c2 == padding) {
			byte byte0 = decodingTable[c];
			byte byte3 = decodingTable[c1];
			outputstream.write(byte0 << 2 | byte3 >> 4);
			return 1;
		}
		if (c3 == padding) {
			byte byte1 = decodingTable[c];
			byte byte4 = decodingTable[c1];
			byte byte6 = decodingTable[c2];
			outputstream.write(byte1 << 2 | byte4 >> 4);
			outputstream.write(byte4 << 4 | byte6 >> 2);
			return 2;
		} else {
			byte byte2 = decodingTable[c];
			byte byte5 = decodingTable[c1];
			byte byte7 = decodingTable[c2];
			byte byte8 = decodingTable[c3];
			outputstream.write(byte2 << 2 | byte5 >> 4);
			outputstream.write(byte5 << 4 | byte7 >> 2);
			outputstream.write(byte7 << 6 | byte8);
			return 3;
		}
	}
 
	private int nextI(String s, int i, int j) {
		for (; i < j && ignore(s.charAt(i)); i++) {
		}
		return i;
	}
}

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