Java 等效于 JavaScript 的 encodeURIComponent，产生相同的输出？

我一直在尝试使用各种 Java 代码，试图编码一个包含引号、空格和“奇特的”Unicode 字符的字符串，并产生与 JavaScript 的 EncodeURIComponent函数相同的输出。

我的酷刑测试字符串是: “ A”B ±

如果我在 Firebug 中输入以下 JavaScript 语句:

encodeURIComponent('"A" B ± "');

然后我得到:

"%22A%22%20B%20%C2%B1%20%22"

这是我的小测试 Java 程序:

import java.io.UnsupportedEncodingException;
import java.net.URLEncoder;


public class EncodingTest
{
public static void main(String[] args) throws UnsupportedEncodingException
{
String s = "\"A\" B ± \"";
System.out.println("URLEncoder.encode returns "
+ URLEncoder.encode(s, "UTF-8"));


System.out.println("getBytes returns "
+ new String(s.getBytes("UTF-8"), "ISO-8859-1"));
}
}

这个程序输出:

URLEncoder.encode returns %22A%22+B+%C2%B1+%22
getBytes returns "A" B ± "

差不多，但是没有雪茄！使用 Java 编码 UTF-8字符串以使其产生与 JavaScript 的 encodeURIComponent相同的输出的最佳方法是什么？

编辑: 我即将使用 Java 1.4迁移到 Java 5。

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小开

Using the javascript engine that is shipped with Java 6:


import javax.script.ScriptEngine;
import javax.script.ScriptEngineManager;


public class Wow
{
public static void main(String[] args) throws Exception
{
ScriptEngineManager factory = new ScriptEngineManager();
ScriptEngine engine = factory.getEngineByName("JavaScript");
engine.eval("print(encodeURIComponent('\"A\" B ± \"'))");
}
}

Output: %22A%22%20B%20%c2%b1%20%22

The case is different but it's closer to what you want.

小开
最佳答案

Looking at the implementation differences, I see that:

MDC on encodeURIComponent():

  • literal characters (regex representation): [-a-zA-Z0-9._*~'()!]

Java 1.5.0 documentation on URLEncoder:

  • literal characters (regex representation): [-a-zA-Z0-9._*]
  • the space character " " is converted into a plus sign "+".

So basically, to get the desired result, use URLEncoder.encode(s, "UTF-8") and then do some post-processing:

  • replace all occurrences of "+" with "%20"
  • replace all occurrences of "%xx" representing any of [~'()!] back to their literal counter-parts
小开

This is the class I came up with in the end:

import java.io.UnsupportedEncodingException;
import java.net.URLDecoder;
import java.net.URLEncoder;


/**
* Utility class for JavaScript compatible UTF-8 encoding and decoding.
*
* @see http://stackoverflow.com/questions/607176/java-equivalent-to-javascripts-encodeuricomponent-that-produces-identical-output
* @author John Topley
*/
public class EncodingUtil
{
/**
* Decodes the passed UTF-8 String using an algorithm that's compatible with
* JavaScript's <code>decodeURIComponent</code> function. Returns
* <code>null</code> if the String is <code>null</code>.
*
* @param s The UTF-8 encoded String to be decoded
* @return the decoded String
*/
public static String decodeURIComponent(String s)
{
if (s == null)
{
return null;
}


String result = null;


try
{
result = URLDecoder.decode(s, "UTF-8");
}


// This exception should never occur.
catch (UnsupportedEncodingException e)
{
result = s;
}


return result;
}


/**
* Encodes the passed String as UTF-8 using an algorithm that's compatible
* with JavaScript's <code>encodeURIComponent</code> function. Returns
* <code>null</code> if the String is <code>null</code>.
*
* @param s The String to be encoded
* @return the encoded String
*/
public static String encodeURIComponent(String s)
{
String result = null;


try
{
result = URLEncoder.encode(s, "UTF-8")
.replaceAll("\\+", "%20")
.replaceAll("\\%21", "!")
.replaceAll("\\%27", "'")
.replaceAll("\\%28", "(")
.replaceAll("\\%29", ")")
.replaceAll("\\%7E", "~");
}


// This exception should never occur.
catch (UnsupportedEncodingException e)
{
result = s;
}


return result;
}


/**
* Private constructor to prevent this class from being instantiated.
*/
private EncodingUtil()
{
super();
}
}
小开

I came up with another implementation documented at, http://blog.sangupta.com/2010/05/encodeuricomponent-and.html. The implementation can also handle Unicode bytes.

小开

I came up with my own version of the encodeURIComponent, because the posted solution has one problem, if there was a + present in the String, which should be encoded, it will converted to a space.

So here is my class:

import java.io.UnsupportedEncodingException;
import java.util.BitSet;


public final class EscapeUtils
{
/** used for the encodeURIComponent function */
private static final BitSet dontNeedEncoding;


static
{
dontNeedEncoding = new BitSet(256);


// a-z
for (int i = 97; i <= 122; ++i)
{
dontNeedEncoding.set(i);
}
// A-Z
for (int i = 65; i <= 90; ++i)
{
dontNeedEncoding.set(i);
}
// 0-9
for (int i = 48; i <= 57; ++i)
{
dontNeedEncoding.set(i);
}


// '()*
for (int i = 39; i <= 42; ++i)
{
dontNeedEncoding.set(i);
}
dontNeedEncoding.set(33); // !
dontNeedEncoding.set(45); // -
dontNeedEncoding.set(46); // .
dontNeedEncoding.set(95); // _
dontNeedEncoding.set(126); // ~
}


/**
* A Utility class should not be instantiated.
*/
private EscapeUtils()
{


}


/**
* Escapes all characters except the following: alphabetic, decimal digits, - _ . ! ~ * ' ( )
*
* @param input
*            A component of a URI
* @return the escaped URI component
*/
public static String encodeURIComponent(String input)
{
if (input == null)
{
return input;
}


StringBuilder filtered = new StringBuilder(input.length());
char c;
for (int i = 0; i < input.length(); ++i)
{
c = input.charAt(i);
if (dontNeedEncoding.get(c))
{
filtered.append(c);
}
else
{
final byte[] b = charToBytesUTF(c);


for (int j = 0; j < b.length; ++j)
{
filtered.append('%');
filtered.append("0123456789ABCDEF".charAt(b[j] >> 4 & 0xF));
filtered.append("0123456789ABCDEF".charAt(b[j] & 0xF));
}
}
}
return filtered.toString();
}


private static byte[] charToBytesUTF(char c)
{
try
{
return new String(new char[] { c }).getBytes("UTF-8");
}
catch (UnsupportedEncodingException e)
{
return new byte[] { (byte) c };
}
}
}
小开

I have found PercentEscaper class from google-http-java-client library, that can be used to implement encodeURIComponent quite easily.

PercentEscaper from google-http-java-client javadoc google-http-java-client home

小开

I have successfully used the java.net.URI class like so:

public static String uriEncode(String string) {
String result = string;
if (null != string) {
try {
String scheme = null;
String ssp = string;
int es = string.indexOf(':');
if (es > 0) {
scheme = string.substring(0, es);
ssp = string.substring(es + 1);
}
result = (new URI(scheme, ssp, null)).toString();
} catch (URISyntaxException usex) {
// ignore and use string that has syntax error
}
}
return result;
}
小开

I use java.net.URI#getRawPath(), e.g.

String s = "a+b c.html";
String fixed = new URI(null, null, s, null).getRawPath();

The value of fixed will be a+b%20c.html, which is what you want.

Post-processing the output of URLEncoder.encode() will obliterate any pluses that are supposed to be in the URI. For example

URLEncoder.encode("a+b c.html").replaceAll("\\+", "%20");

will give you a%20b%20c.html, which will be interpreted as a b c.html.

小开

Guava library has PercentEscaper:

Escaper percentEscaper = new PercentEscaper("-_.*", false);

"-_.*" are safe characters

false says PercentEscaper to escape space with '%20', not '+'

小开

This is a straightforward example Ravi Wallau's solution:

public String buildSafeURL(String partialURL, String documentName)
throws ScriptException {
ScriptEngineManager scriptEngineManager = new ScriptEngineManager();
ScriptEngine scriptEngine = scriptEngineManager
.getEngineByName("JavaScript");


String urlSafeDocumentName = String.valueOf(scriptEngine
.eval("encodeURIComponent('" + documentName + "')"));
String safeURL = partialURL + urlSafeDocumentName;


return safeURL;
}


public static void main(String[] args) {
EncodeURIComponentDemo demo = new EncodeURIComponentDemo();
String partialURL = "https://www.website.com/document/";
String documentName = "Tom & Jerry Manuscript.pdf";


try {
System.out.println(demo.buildSafeURL(partialURL, documentName));
} catch (ScriptException se) {
se.printStackTrace();
}
}

Output: https://www.website.com/document/Tom%20%26%20Jerry%20Manuscript.pdf

It also answers the hanging question in the comments by Loren Shqipognja on how to pass a String variable to encodeURIComponent(). The method scriptEngine.eval() returns an Object, so it can converted to String via String.valueOf() among other methods.

小开

for me this worked:

import org.apache.http.client.utils.URIBuilder;


String encodedString = new URIBuilder()
.setParameter("i", stringToEncode)
.build()
.getRawQuery() // output: i=encodedString
.substring(2);

or with a different UriBuilder

import javax.ws.rs.core.UriBuilder;


String encodedString = UriBuilder.fromPath("")
.queryParam("i", stringToEncode)
.toString()   // output: ?i=encodedString
.substring(3);

In my opinion using a standard library is a better idea rather than post processing manually. Also @Chris answer looked good, but it doesn't work for urls, like "http://a+b c.html"

小开

This is what I'm using:

private static final String HEX = "0123456789ABCDEF";


public static String encodeURIComponent(String str) {
if (str == null) return null;


byte[] bytes = str.getBytes(StandardCharsets.UTF_8);
StringBuilder builder = new StringBuilder(bytes.length);


for (byte c : bytes) {
if (c >= 'a' ? c <= 'z' || c == '~' :
c >= 'A' ? c <= 'Z' || c == '_' :
c >= '0' ? c <= '9' :  c == '-' || c == '.')
builder.append((char)c);
else
builder.append('%')
.append(HEX.charAt(c >> 4 & 0xf))
.append(HEX.charAt(c & 0xf));
}


return builder.toString();
}

It goes beyond Javascript's by percent-encoding every character that is not an unreserved character according to RFC 3986.

This is the oposite conversion:

public static String decodeURIComponent(String str) {
if (str == null) return null;


int length = str.length();
byte[] bytes = new byte[length / 3];
StringBuilder builder = new StringBuilder(length);


for (int i = 0; i < length; ) {
char c = str.charAt(i);
if (c != '%') {
builder.append(c);
i += 1;
} else {
int j = 0;
do {
char h = str.charAt(i + 1);
char l = str.charAt(i + 2);
i += 3;


h -= '0';
if (h >= 10) {
h |= ' ';
h -= 'a' - '0';
if (h >= 6) throw new IllegalArgumentException();
h += 10;
}


l -= '0';
if (l >= 10) {
l |= ' ';
l -= 'a' - '0';
if (l >= 6) throw new IllegalArgumentException();
l += 10;
}


bytes[j++] = (byte)(h << 4 | l);
if (i >= length) break;
c = str.charAt(i);
} while (c == '%');
builder.append(new String(bytes, 0, j, UTF_8));
}
}


return builder.toString();
}
小开

I used String encodedUrl = new URI(null, url, null).toASCIIString(); to encode urls. To add parameters after the existing ones in the url I use UriComponentsBuilder


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