How to do URL decoding in Java?

In Java, I want to convert this:

https%3A%2F%2Fmywebsite%2Fdocs%2Fenglish%2Fsite%2Fmybook.do%3Frequest_type

To this:

https://mywebsite/docs/english/site/mybook.do&request_type

This is what I have so far:

class StringUTF 
{
	public static void main(String[] args) 
	{
	    try{
			String url = 
               "https%3A%2F%2Fmywebsite%2Fdocs%2Fenglish%2Fsite%2Fmybook.do" +
               "%3Frequest_type%3D%26type%3Dprivate";

			System.out.println(url+"Hello World!------->" +
                new String(url.getBytes("UTF-8"),"ASCII"));
		}
		catch(Exception E){
		}
	}
}

But it doesn't work right. What are these %3A and %2F formats called and how do I convert them?

This does not have anything to do with character encodings such as UTF-8 or ASCII. The string you have there is URL encoded. This kind of encoding is something entirely different than character encoding.

Try something like this:

try {
    String result = java.net.URLDecoder.decode(url, StandardCharsets.UTF_8.name());
} catch (UnsupportedEncodingException e) {
    // not going to happen - value came from JDK's own StandardCharsets
}

Java 10 added direct support for Charset to the API, meaning there's no need to catch UnsupportedEncodingException:

String result = java.net.URLDecoder.decode(url, StandardCharsets.UTF_8);

Note that a character encoding (such as UTF-8 or ASCII) is what determines the mapping of characters to raw bytes. For a good intro to character encodings, see this article.

The string you've got is in application/x-www-form-urlencoded encoding.

Use URLDecoder to convert it to Java String.

URLDecoder.decode( url, "UTF-8" );

This has been answered before (although this question was first!):

> "You should use java.net.URI to do this, as the URLDecoder class does x-www-form-urlencoded decoding which is wrong (despite the name, it's for form data)."

As URL class documentation states: > The recommended way to manage the encoding and decoding of URLs is to > use URI, and to convert between these two classes using toURI() and > URI.toURL(). > > The URLEncoder and URLDecoder classes can also be used, but only for > HTML form encoding, which is not the same as the encoding scheme > defined in RFC2396.

Basically:

String url = "https%3A%2F%2Fmywebsite%2Fdocs%2Fenglish%2Fsite%2Fmybook.do%3Frequest_type";
System.out.println(new java.net.URI(url).getPath());

will give you:

https://mywebsite/docs/english/site/mybook.do?request_type

%3A and %2F are URL encoded characters. Use this java code to convert them back into : and /

String decoded = java.net.URLDecoder.decode(url, "UTF-8");

 try {
		String result = URLDecoder.decode(urlString, "UTF-8");
	} catch (UnsupportedEncodingException e) {
		// TODO Auto-generated catch block
		e.printStackTrace();
	}

public String decodeString(String URL)
    {

	String urlString="";
    try {
        urlString = URLDecoder.decode(URL,"UTF-8");
        } catch (UnsupportedEncodingException e) {
            // TODO Auto-generated catch block
           
        }

        return urlString;

    }

I use [apache commons][1]

String decodedUrl = new URLCodec().decode(url);

The default charset is UTF-8 [1]: http://commons.apache.org/proper/commons-codec/apidocs/org/apache/commons/codec/net/URLCodec.html#decode(java.lang.String)

import java.io.UnsupportedEncodingException;
import java.net.URISyntaxException;

public class URLDecoding { 

	String decoded = "";
	
	public String decodeMethod(String url) throws UnsupportedEncodingException
	{
		decoded = java.net.URLDecoder.decode(url, "UTF-8");	
		return  decoded;
//"You should use java.net.URI to do this, as the URLDecoder class does x-www-form-urlencoded decoding which is wrong (despite the name, it's for form data)."
	}
	
	public String getPathMethod(String url) throws URISyntaxException 
	{
		decoded = new java.net.URI(url).getPath();	
		return  decoded; 
	}
	
	public static void main(String[] args) throws UnsupportedEncodingException, URISyntaxException 
	{
		System.out.println(" Here is your Decoded url with decode method : "+ new URLDecoding().decodeMethod("https%3A%2F%2Fmywebsite%2Fdocs%2Fenglish%2Fsite%2Fmybook.do%3Frequest_type")); 
		System.out.println("Here is your Decoded url with getPath method : "+ new URLDecoding().getPathMethod("https%3A%2F%2Fmywebsite%2Fdocs%2Fenglish%2Fsite%2Fmybook.do%3Frequest")); 
		
	} 

}

You can select your method wisely :)

If it is integer value, we have to catch NumberFormatException also.

try {
        Integer result = Integer.valueOf(URLDecoder.decode(urlNumber, "UTF-8"));
    } catch (NumberFormatException | UnsupportedEncodingException e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
    }

Using java.net.URI class:

public String getDecodedURL(String encodedUrl) {
    try {
        URI uri = new URI(encodedUrl);
        return uri.getScheme() + ":" + uri.getSchemeSpecificPart();
    } catch (Exception e) {
        return "";
    }
}

Please note that exception handling can be better, but it's not much relevant for this example.