Added a getContentLength() method to URLConnection

This is particularly important if you want to get the number of bytes of a
resource loaded by the class loader:
  getClass().getResource("myFile").openConnection().getContentLength()

classpath/java/net/URL.java

@@ -100,6 +100,10 @@ public final class URL {
       super(url);
     }
 
+    public int getContentLength() {
+      return ResourceInputStream.getContentLength(url.getFile());
+    }
+
     public InputStream getInputStream() throws IOException {
       return new ResourceInputStream(url.getFile());
     }
@@ -116,6 +120,8 @@ public final class URL {
       }
     }
 
+    private static native int getContentLength(String path);
+
     private static native long open(String path) throws IOException;
 
     private static native int read(long peer, int position) throws IOException;

classpath/java/net/URLConnection.java

@@ -25,6 +25,10 @@ public abstract class URLConnection {
     return getInputStream();
   }
 
+  public int getContentLength() {
+    return -1;
+  }
+
   public InputStream getInputStream() throws IOException {
     throw new UnknownServiceException();
   }

src/builtin.cpp

@@ -741,6 +741,26 @@ Java_java_lang_Thread_enumerate(Thread* t, jclass, jobjectArray array)
   return count;
 }
 
+extern "C" JNIEXPORT jint JNICALL
+Java_java_net_URL_00024ResourceInputStream_getContentLength
+(Thread* t, jclass, jstring path)
+{
+  ENTER(t, Thread::ActiveState);
+
+  if (LIKELY(path)) {
+    char p[stringLength(t, *path) + 1];
+    stringChars(t, *path, p);
+
+    System::Region* r = t->m->finder->find(p);
+    if (r) {
+      jint rSize = r->length();
+      r->dispose();
+      return rSize;
+    }
+  }
+  return -1;
+}
+
 extern "C" JNIEXPORT jlong JNICALL
 Java_java_net_URL_00024ResourceInputStream_open
 (Thread* t, jclass, jstring path)