How can I decode Base64 url in Java?
I tried found smt into javadoc but couldn't find solution.
Do I need install any external -jars for this aim?
Snippet of code:
public static void main(String []args){
String url = "aHR0cDovL05jLmtwaS51YS9hdXR1bW4yMDEz";
String decodedUrl = Base64.decode(url);
System.out.println( decodedUrl );
return;
}
How to decode this url?
You do not need any third party library see the below class I have written to encode and decode in Base64. Your URL is http://Nc.kpi.ua/autumn2013
public class Decode {
private static char[] map1 = new char[64];
static {
int i = 0;
for (char c = 'A'; c <= 'Z'; c++) {
map1[i++] = c;
}
for (char c = 'a'; c <= 'z'; c++) {
map1[i++] = c;
}
for (char c = '0'; c <= '9'; c++) {
map1[i++] = c;
}
map1[i++] = '+';
map1[i++] = '/';
}
//Mapping table from Base64 characters to 6-bit nibbles.
private static byte[] map2 = new byte[128];
static {
for (int i = 0; i < map2.length; i++) {
map2[i] = -1;
}
for (int i = 0; i < 64; i++) {
map2[map1[i]] = (byte) i;
}
}
/**
* Encodes a string into Base64 format. No blanks or line breaks are
* inserted.
*
* @param s a String to be encoded.
* @return A String with the Base64 encoded data.
*/
public static String encodeString(String s) {
return new String(encode(s.getBytes()));
}
/**
* Encodes a byte array into Base64 format. No blanks or line breaks are
* inserted.
*
* @param in an array containing the data bytes to be encoded.
* @return A character array with the Base64 encoded data.
*/
public static char[] encode(byte[] in) {
return encode(in, in.length);
}
/**
* Encodes a byte array into Base64 format. No blanks or line breaks are
* inserted.
*
* @param in an array containing the data bytes to be encoded.
* @param iLen number of bytes to process in <code>in</code>.
* @return A character array with the Base64 encoded data.
*/
public static char[] encode(byte[] in, int iLen) {
int oDataLen = (iLen * 4 + 2) / 3; // output length without padding
int oLen = ((iLen + 2) / 3) * 4; // output length including padding
char[] out = new char[oLen];
int ip = 0;
int op = 0;
while (ip < iLen) {
int i0 = in[ip++] & 0xff;
int i1 = ip < iLen ? in[ip++] & 0xff : 0;
int i2 = ip < iLen ? in[ip++] & 0xff : 0;
int o0 = i0 >>> 2;
int o1 = ((i0 & 3) << 4) | (i1 >>> 4);
int o2 = ((i1 & 0xf) << 2) | (i2 >>> 6);
int o3 = i2 & 0x3F;
out[op++] = map1[o0];
out[op++] = map1[o1];
out[op] = op < oDataLen ? map1[o2] : '=';
op++;
out[op] = op < oDataLen ? map1[o3] : '=';
op++;
}
return out;
}
/**
* Decodes a string from Base64 format.
*
* @param s a Base64 String to be decoded.
* @return A String containing the decoded data.
* @throws IllegalArgumentException if the input is not valid Base64 encoded
* data.
*/
public static String decodeString(String s) {
return new String(decode(s));
}
/**
* Decodes a byte array from Base64 format.
*
* @param s a Base64 String to be decoded.
* @return An array containing the decoded data bytes.
* @throws IllegalArgumentException if the input is not valid Base64 encoded
* data.
*/
public static byte[] decode(String s) {
return decode(s.toCharArray());
}
/**
* Decodes a byte array from Base64 format. No blanks or line breaks are
* allowed within the Base64 encoded data.
*
* @param in a character array containing the Base64 encoded data.
* @return An array containing the decoded data bytes.
* @throws IllegalArgumentException if the input is not valid Base64 encoded
* data.
*/
public static byte[] decode(char[] in) {
int iLen = in.length;
if (iLen % 4 != 0) {
throw new IllegalArgumentException("Length of Base64 encoded input string is not a multiple of 4.");
}
while (iLen > 0 && in[iLen - 1] == '=') {
iLen--;
}
int oLen = (iLen * 3) / 4;
byte[] out = new byte[oLen];
int ip = 0;
int op = 0;
while (ip < iLen) {
int i0 = in[ip++];
int i1 = in[ip++];
int i2 = ip < iLen ? in[ip++] : 'A';
int i3 = ip < iLen ? in[ip++] : 'A';
if (i0 > 127 || i1 > 127 || i2 > 127 || i3 > 127) {
throw new IllegalArgumentException("Illegal character in Base64 encoded data.");
}
int b0 = map2[i0];
int b1 = map2[i1];
int b2 = map2[i2];
int b3 = map2[i3];
if (b0 < 0 || b1 < 0 || b2 < 0 || b3 < 0) {
throw new IllegalArgumentException("Illegal character in Base64 encoded data.");
}
int o0 = (b0 << 2) | (b1 >>> 4);
int o1 = ((b1 & 0xf) << 4) | (b2 >>> 2);
int o2 = ((b2 & 3) << 6) | b3;
out[op++] = (byte) o0;
if (op < oLen) {
out[op++] = (byte) o1;
}
if (op < oLen) {
out[op++] = (byte) o2;
}
}
return out;
}
//Dummy constructor.
public Decode() {
}
/**
* @param args the command line arguments
*/
public static void main(String[] args) {
String test = "aHR0cDovL05jLmtwaS51YS9hdXR1bW4yMDEz";
System.out.println(Decode.decodeString(test));
}
}
You can use this both to Encode and decode. Hope this Helps.
No need for external jars, use Java SE javax.xml.bind.DatatypeConverter.parseBase64Binary(String lexicalXSDBase64Binary)
Java-8 provides java.util.Base64 class for Base64 encodings. It supports URL encoding/decoding by its static getUrlEncoder() and getUrlDecoder() methods.
You can use org.apache.commons.codec.binary.Base64 package available in Java for the same.
Sample code(not tested though) :
Base64 decoder = new Base64();
String url = "aHR0cDovL05jLmtwaS51YS9hdXR1bW4yMDEz";
byte[] decoded = Base64.decodeBase64(url);
System.out.println(new String(decoded, "UTF-8") + "\n");
org.apache.commons.codec.binary.Base64? But eclipse couldn't import this one.Apache Commons-Codec has a base64 decoder
http://commons.apache.org/proper/commons-codec/apidocs/org/apache/commons/codec/binary/Base64.html
I use org.apache.ws.commons.util.Base64 and simply do:
String encoded = Base64.encode( "whatever" );
byte[] decoded = Base64.decode( encoded );
