code: @Test public void createEntryUrl() throws Exception {
    URL url=new URL(this.jarFile.getUrl(),"1.dat");
    assertThat(url.toString(),equalTo("jar:" + this.rootJarFile.toURI() + "!/1.dat"));
    JarURLConnection jarURLConnection=(JarURLConnection)url.openConnection();
    assertThat(jarURLConnection.getJarFile(),sameInstance(this.jarFile));
    assertThat(jarURLConnection.getJarEntry(),sameInstance(this.jarFile.getJarEntry("1.dat")));
    assertThat(jarURLConnection.getContentLength(),equalTo(1));
    assertThat(jarURLConnection.getContent(),instanceOf(InputStream.class));
    assertThat(jarURLConnection.getContentType(),equalTo("content/unknown"));
  }
  