Encode a URI vs URLEncoder in Java and Javascript

Encoding URLs in Java is quite trivial. However, too often I see people using the URLEncoder class for this. This is WRONG.

The URLEncoder class is used for encoding form data into xxx-form-urlencoded -format. Even though very poorly named, it does say this in the Javadocs ;)

The proper class for URL encoding is the URI class.

Lets assume we have an URL such as http://www.somedomain.com/shop/Awesome Sauces

If you encode this with the URLEncoder class, you get:

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http%3A%2F%2Fwww.somedomain.com%2FAwesome+Sauces

Unreadable and incorrectly encoded. Reserved characters such as : and / should not be encoded. Also, the URLEncoder encodes empty spaces as a “+” even though it should be encoded as “%20”.

Which makes it really annoying and doesn’t end up matching up with what you would expect if you used javascript’s

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encodeURI

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encodeURIComponent()

With the URI class, you get:

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http://www.somedomain.com/Awesome%20Sauces

which is much better and correct.

To construct as simple URL like the example above with the URI class:

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URI myURI = new URI("http", "www.somedomain.com", "/Awesome Sauces");

And to get the URL in an encoded format:

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String url = myURI.toASCIIString();

If you want to do something like encode the functionality found in

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encodeURIComponent()

Here’s a bit of a dodgy work around.

    private String getEncodedFileName(String filename) {
        try {
            def filelink = new URI("file","//", filename)
            return filelink.toASCIIString().replace("file://#",'')
        }catch (Exception e){
            return  filename!=null? filename:"";
        }
    }