StringUtils – common utility methods for Java

StringUtils.java

import com.google.common.base.Charsets;
import com.google.common.base.Joiner;
import com.google.common.base.Splitter;
import com.google.common.base.Strings;
import com.google.common.collect.Lists;
import com.google.common.collect.Maps;

import java.io.UnsupportedEncodingException;
import java.net.URLDecoder;
import java.net.URLEncoder;
import java.util.Collections;
import java.util.List;
import java.util.Map;

/**
 * @author Joni Karppinen
 * Licence: WTFPL, http://www.wtfpl.net/txt/copying/
 */
public class StringUtils {
  
    public static String encodeUrlParameters(Map<String, String> parameters) {
        if (parameters == null || parameters.isEmpty()) {
            return "";
        }

        List<String> nameValuePairs = Lists.newArrayList();
        for (Map.Entry<String, String> entry : parameters.entrySet()) {
            nameValuePairs.add(entry.getKey() + "=" + urlEncode(entry.getValue()));
        }
        return "?" + Joiner.on("&").join(nameValuePairs);
    }

    public static Map<String, String> decodeUrlParameters(String paramString) {
        if (Strings.isNullOrEmpty(paramString)) {
            return Collections.emptyMap();
        }

        if (paramString.startsWith("?")) {
            paramString = paramString.substring(1);
        }

        Map<String, String> result = Maps.newLinkedHashMap();
        for (String nameValue : Splitter.on("&").trimResults().split(paramString)) {
            String[] parts = nameValue.split("=");
            result.put(parts[0], urlDecode(parts[1]));
        }

        return result;
    }
    
    public static String urlEncode(String string) {
        try {
            return URLEncoder.encode(string, Charsets.UTF_8.name());
        }
        catch (UnsupportedEncodingException e) { // UTF-8 should always be supported
            throw new RuntimeException("URLEncoder.encode() failed");
        }
    }

    public static String urlDecode(String string) {
        try {
            return URLDecoder.decode(string, Charsets.UTF_8.name());
        }
        catch (UnsupportedEncodingException e) { // UTF-8 should always be supported
            throw new RuntimeException("URLDecoder.decode() failed");
        }
    }
    
}