URI Encode for Java

I always forget and struggling about the behavior of Java methods and classes for encoding uri. To clear my heads I will post small test codes.

import java.net.URI;
import java.net.URLEncoder;
import java.util.BitSet;

import org.apache.commons.httpclient.util.URIUtil;

public class URIEncodeExample {

    // hehe using Japanese :p
    private static final String INPUT = "あいうえお/";

    public static void main(String[] args) throws Exception {

        // java.net.URI
        // slash is not encoded because it is detected as a path separator 
        // %E3%81%82%E3%81%84%E3%81%86%E3%81%88%E3%81%8A/
        System.out.println(URI.create(INPUT).toASCIIString());

        // java.net.URI + relativize
        // slash is not encoded because it is detected as a path separator 
        // %E3%81%82%E3%81%84%E3%81%86%E3%81%88%E3%81%8A/
        URI root = new URI("http", "dummy.com", null, null);
        URI uri = new URI("http", "dummy.com", "/"+INPUT, null);
        System.out.println(root.relativize(uri).toASCIIString());
        
        // java.net.URLEncoder
        // encode entire string including slash
        // %E3%81%82%E3%81%84%E3%81%86%E3%81%88%E3%81%8A%2F
        System.out.println(URLEncoder.encode(INPUT, "utf-8"));
        
        // org.apache.commons.httpclient.util.URIUtil
        // %E3%81%82%E3%81%84%E3%81%86%E3%81%88%E3%81%8A%2F
        System.out.println(URIUtil.encode(INPUT, new BitSet()));
        
        // org.apache.commons.httpclient.util.URIUtil
        // you can specify which is already encoded character by BitSet
        // here slash is skipped to be encoded
        // %E3%81%82%E3%81%84%E3%81%86%E3%81%88%E3%81%8A/
        BitSet allowed = new BitSet();
        allowed.set('/', true);
        System.out.println(URIUtil.encode(INPUT, allowed));
    }
}

You might also want to check:

• org.springframework.web.util.UriUtils
• com.google.gwt.safehtml.shared.UriUtils