Added append parameters to URL method

src/main/java/org/scribe/utils/URLUtils.java

@@ -7,8 +7,8 @@ import java.util.*;
 import org.scribe.exceptions.*;
 
 /**
- * Utils to deal with URL and url-encodings 
- * 
+ * Utils to deal with URL and url-encodings
+ *
  * @author Pablo Fernandez
  */
 public class URLUtils
@@ -17,6 +17,7 @@ public class URLUtils
   private static final String UTF_8 = "UTF-8";
   private static final char PAIR_SEPARATOR = '=';
   private static final char PARAM_SEPARATOR = '&';
+  private static final char QUERY_STRING_SEPARATOR = '?';
 
   private static final String ERROR_MSG = String.format("Cannot find specified encoding: %s", UTF_8);
 
@@ -100,6 +101,25 @@ public class URLUtils
     }
   }
 
+  /**
+   * Append given parameters to the query string of the url
+   *
+   * @param url the url to append parameters to
+   * @param params any map
+   * @return new url with parameters on query string
+   */
+  public static String appendParametersToQueryString(String url, Map<String, String> params)
+  {
+    Preconditions.checkNotNull(url, "Cannot append to null URL");
+    String queryString = URLUtils.formURLEncodeMap(params);
+    if (queryString.isEmpty()) return url;
+
+    // Check if there are parameters in the url already and use '&' instead of '?'
+    url += url.indexOf(QUERY_STRING_SEPARATOR) != -1 ? PARAM_SEPARATOR : QUERY_STRING_SEPARATOR;
+    url += queryString;
+    return url;
+  }
+
   private static final class EncodingRule
   {
     private final String ch;

src/test/java/org/scribe/utils/URLUtilsTest.java

@@ -82,4 +82,49 @@ public class URLUtilsTest
     URLUtils.percentDecode(toDecode);
   }
 
+  @Test(expected = IllegalArgumentException.class)
+  public void shouldThrowExceptionWhenAppendingNullMapToQuerystring()
+  {
+    String url = "http://www.example.com";
+    Map<String, String> nullMap = null;
+    URLUtils.appendParametersToQueryString(url, nullMap);
+  }
+
+  @Test
+  public void shouldAppendNothingToQuerystringIfGivenEmptyMap()
+  {
+    String url = "http://www.example.com";
+    Map<String, String> emptyMap = new HashMap<String, String>();
+    String newUrl = URLUtils.appendParametersToQueryString(url, emptyMap);
+    Assert.assertEquals(url, newUrl);
+  }
+
+  @Test
+  public void shouldAppendParametersToSimpleUrl()
+  {
+    String url = "http://www.example.com";
+    String expectedUrl = "http://www.example.com?param1=value1&param2=value%20with%20spaces";
+
+    Map<String, String> params = new HashMap<String, String>();
+    params.put("param1", "value1");
+    params.put("param2", "value with spaces");
+
+    url = URLUtils.appendParametersToQueryString(url, params);
+    Assert.assertEquals(url, expectedUrl);
+  }
+
+  @Test
+  public void shouldAppendParametersToUrlWithQuerystring()
+  {
+    String url = "http://www.example.com?already=present";
+    String expectedUrl = "http://www.example.com?already=present&param1=value1&param2=value%20with%20spaces";
+
+    Map<String, String> params = new HashMap<String, String>();
+    params.put("param1", "value1");
+    params.put("param2", "value with spaces");
+
+    url = URLUtils.appendParametersToQueryString(url, params);
+    Assert.assertEquals(url, expectedUrl);
+  }
+
 }