我的Java独立应用程序从用户那里获得一个URL(指向一个文件)，我需要点击它并下载它。我面临的问题是，我不能正确编码HTTP URL地址…
例子:
URL: http://search.barnesandnoble.com/booksearch/first book.pdf
java.net.URLEncoder.encode(url.toString(), "ISO-8859-1");
回报我。
http%3A%2F%2Fsearch.barnesandnoble.com%2Fbooksearch%2Ffirst+book.pdf
但是，我想要的是
http://search.barnesandnoble.com/booksearch/first%20book.pdf
(空格替换为%20)
我猜URLEncoder不是为编码HTTP url设计的…JavaDoc说“HTML表单编码的实用程序类”…还有别的办法吗?
当前回答
你也可以使用GUAVA和路径逃脱器: UrlEscapers.urlFragmentEscaper () .escape (relativePath)
其他回答
我创建了一个新项目来帮助构建HTTP url。库将自动URL编码路径段和查询参数。
您可以在https://github.com/Widen/urlbuilder上查看源代码并下载二进制文件
这个问题中的URL示例:
new UrlBuilder("search.barnesandnoble.com", "booksearch/first book.pdf").toString()
生产
http://search.barnesandnoble.com/booksearch/first%20book.pdf
请注意，上面的大部分答案都是不正确的。
URLEncoder类，不管它的名字，不是这里需要的。不幸的是，Sun给这个类命名得如此烦人。URLEncoder用于作为参数传递数据，而不是用于对URL本身进行编码。
换句话说，“http://search.barnesandnoble.com/booksearch/first book.pdf”是URL。参数可以是，例如，“http://search.barnesandnoble.com/booksearch/first book.pdf?parameter1=this¶m2=that”。参数是你使用URLEncoder的目的。
下面两个例子强调了两者之间的区别。
根据HTTP标准，下面会产生错误的参数。注意&号(&)和加号(+)编码错误。
uri = new URI("http", null, "www.google.com", 80,
"/help/me/book name+me/", "MY CRZY QUERY! +&+ :)", null);
// URI: http://www.google.com:80/help/me/book%20name+me/?MY%20CRZY%20QUERY!%20+&+%20:)
下面的代码将生成正确的参数，并对查询进行正确编码。注意空格、&号和加号。
uri = new URI("http", null, "www.google.com", 80, "/help/me/book name+me/", URLEncoder.encode("MY CRZY QUERY! +&+ :)", "UTF-8"), null);
// URI: http://www.google.com:80/help/me/book%20name+me/?MY+CRZY+QUERY%2521+%252B%2526%252B+%253A%2529
如果任何人不想向他们的项目添加依赖项，这些函数可能会有帮助。
我们将URL的path部分传递到这里。您可能不想将完整的URL作为参数传递进来(查询字符串需要不同的转义，等等)。
/**
* Percent-encodes a string so it's suitable for use in a URL Path (not a query string / form encode, which uses + for spaces, etc)
*/
public static String percentEncode(String encodeMe) {
if (encodeMe == null) {
return "";
}
String encoded = encodeMe.replace("%", "%25");
encoded = encoded.replace(" ", "%20");
encoded = encoded.replace("!", "%21");
encoded = encoded.replace("#", "%23");
encoded = encoded.replace("$", "%24");
encoded = encoded.replace("&", "%26");
encoded = encoded.replace("'", "%27");
encoded = encoded.replace("(", "%28");
encoded = encoded.replace(")", "%29");
encoded = encoded.replace("*", "%2A");
encoded = encoded.replace("+", "%2B");
encoded = encoded.replace(",", "%2C");
encoded = encoded.replace("/", "%2F");
encoded = encoded.replace(":", "%3A");
encoded = encoded.replace(";", "%3B");
encoded = encoded.replace("=", "%3D");
encoded = encoded.replace("?", "%3F");
encoded = encoded.replace("@", "%40");
encoded = encoded.replace("[", "%5B");
encoded = encoded.replace("]", "%5D");
return encoded;
}
/**
* Percent-decodes a string, such as used in a URL Path (not a query string / form encode, which uses + for spaces, etc)
*/
public static String percentDecode(String encodeMe) {
if (encodeMe == null) {
return "";
}
String decoded = encodeMe.replace("%21", "!");
decoded = decoded.replace("%20", " ");
decoded = decoded.replace("%23", "#");
decoded = decoded.replace("%24", "$");
decoded = decoded.replace("%26", "&");
decoded = decoded.replace("%27", "'");
decoded = decoded.replace("%28", "(");
decoded = decoded.replace("%29", ")");
decoded = decoded.replace("%2A", "*");
decoded = decoded.replace("%2B", "+");
decoded = decoded.replace("%2C", ",");
decoded = decoded.replace("%2F", "/");
decoded = decoded.replace("%3A", ":");
decoded = decoded.replace("%3B", ";");
decoded = decoded.replace("%3D", "=");
decoded = decoded.replace("%3F", "?");
decoded = decoded.replace("%40", "@");
decoded = decoded.replace("%5B", "[");
decoded = decoded.replace("%5D", "]");
decoded = decoded.replace("%25", "%");
return decoded;
}
和测试:
@Test
public void testPercentEncode_Decode() {
assertEquals("", percentDecode(percentEncode(null)));
assertEquals("", percentDecode(percentEncode("")));
assertEquals("!", percentDecode(percentEncode("!")));
assertEquals("#", percentDecode(percentEncode("#")));
assertEquals("$", percentDecode(percentEncode("$")));
assertEquals("@", percentDecode(percentEncode("@")));
assertEquals("&", percentDecode(percentEncode("&")));
assertEquals("'", percentDecode(percentEncode("'")));
assertEquals("(", percentDecode(percentEncode("(")));
assertEquals(")", percentDecode(percentEncode(")")));
assertEquals("*", percentDecode(percentEncode("*")));
assertEquals("+", percentDecode(percentEncode("+")));
assertEquals(",", percentDecode(percentEncode(",")));
assertEquals("/", percentDecode(percentEncode("/")));
assertEquals(":", percentDecode(percentEncode(":")));
assertEquals(";", percentDecode(percentEncode(";")));
assertEquals("=", percentDecode(percentEncode("=")));
assertEquals("?", percentDecode(percentEncode("?")));
assertEquals("@", percentDecode(percentEncode("@")));
assertEquals("[", percentDecode(percentEncode("[")));
assertEquals("]", percentDecode(percentEncode("]")));
assertEquals(" ", percentDecode(percentEncode(" ")));
// Get a little complex
assertEquals("[]]", percentDecode(percentEncode("[]]")));
assertEquals("a=d%*", percentDecode(percentEncode("a=d%*")));
assertEquals(") (", percentDecode(percentEncode(") (")));
assertEquals("%21%20%2A%20%27%20%28%20%25%20%29%20%3B%20%3A%20%40%20%26%20%3D%20%2B%20%24%20%2C%20%2F%20%3F%20%23%20%5B%20%5D%20%25",
percentEncode("! * ' ( % ) ; : @ & = + $ , / ? # [ ] %"));
assertEquals("! * ' ( % ) ; : @ & = + $ , / ? # [ ] %", percentDecode(
"%21%20%2A%20%27%20%28%20%25%20%29%20%3B%20%3A%20%40%20%26%20%3D%20%2B%20%24%20%2C%20%2F%20%3F%20%23%20%5B%20%5D%20%25"));
assertEquals("%23456", percentDecode(percentEncode("%23456")));
}
如果你有一个URL，你可以将URL . tostring()传递给这个方法。首先解码，以避免双重编码(例如，编码空格会得到%20，编码百分号会得到%25，因此双重编码将把空格变成%2520)。然后，像上面解释的那样使用URI，添加URL的所有部分(这样就不会删除查询参数)。
public URL convertToURLEscapingIllegalCharacters(String string){
try {
String decodedURL = URLDecoder.decode(string, "UTF-8");
URL url = new URL(decodedURL);
URI uri = new URI(url.getProtocol(), url.getUserInfo(), url.getHost(), url.getPort(), url.getPath(), url.getQuery(), url.getRef());
return uri.toURL();
} catch (Exception ex) {
ex.printStackTrace();
return null;
}
}
我阅读了以前的答案，写我自己的方法，因为我不能有一些正确的工作使用以前的答案的解决方案，它看起来对我很好，但如果你能找到不与此工作的URL，请让我知道。
public static URL convertToURLEscapingIllegalCharacters(String toEscape) throws MalformedURLException, URISyntaxException {
URL url = new URL(toEscape);
URI uri = new URI(url.getProtocol(), url.getUserInfo(), url.getHost(), url.getPort(), url.getPath(), url.getQuery(), url.getRef());
//if a % is included in the toEscape string, it will be re-encoded to %25 and we don't want re-encoding, just encoding
return new URL(uri.toString().replace("%25", "%"));
}
