http://stackoverflow.com/questions/26199515/callback-closure-with-jnr-taking-a-pointer-argument
import jnr.ffi.Memory;
import jnr.ffi.Pointer;
import jnr.ffi.Runtime;

@Test
public void testMetaUtf8() throws UnsupportedEncodingException {
    Pointer ptr = Runtime.getRuntime(c).getMemoryManager().allocate(5000);
    int size = c.snprintf(ptr, 5000, "%s", UTF8Encoding.class, "\u7684");
    Assert.assertEquals(3, size);
    String result = ptr.getString(0, size, Charset.forName("UTF-8"));
    String expected = new String("\u7684".getBytes("UTF-8"), "UTF-8");
    Assert.assertEquals(expected, result);
}