diff --git a/webmagic-core/src/main/java/us/codecraft/webmagic/Spider.java b/webmagic-core/src/main/java/us/codecraft/webmagic/Spider.java
index a25fd02..2717b66 100644
--- a/webmagic-core/src/main/java/us/codecraft/webmagic/Spider.java
+++ b/webmagic-core/src/main/java/us/codecraft/webmagic/Spider.java
@@ -2,6 +2,7 @@ package us.codecraft.webmagic;
 
 import org.apache.commons.collections.CollectionUtils;
 import org.apache.log4j.Logger;
+import us.codecraft.webmagic.annotation.ObjectPageProcessor;
 import us.codecraft.webmagic.downloader.Destroyable;
 import us.codecraft.webmagic.downloader.Downloader;
 import us.codecraft.webmagic.downloader.HttpClientDownloader;
@@ -89,6 +90,10 @@ public class Spider implements Runnable, Task {
         return new Spider(pageProcessor);
     }
 
+    public static Spider create(Site site,Class... pageModels) {
+        return new Spider(ObjectPageProcessor.create(site,pageModels));
+    }
+
     /**
      * 重新设置startUrls，会覆盖Site本身的startUrls。
      *
diff --git a/webmagic-core/src/main/java/us/codecraft/webmagic/annotation/ExtractBy.java b/webmagic-core/src/main/java/us/codecraft/webmagic/annotation/ExtractBy.java
index 7c749b3..4c791fd 100644
--- a/webmagic-core/src/main/java/us/codecraft/webmagic/annotation/ExtractBy.java
+++ b/webmagic-core/src/main/java/us/codecraft/webmagic/annotation/ExtractBy.java
@@ -18,4 +18,6 @@ public @interface ExtractBy {
     public enum Type {XPath, Regex, Css};
 
     Type type() default Type.XPath;
+
+    boolean notNull() default true;
 }
diff --git a/webmagic-core/src/main/java/us/codecraft/webmagic/annotation/ExtractByUrl.java b/webmagic-core/src/main/java/us/codecraft/webmagic/annotation/ExtractByUrl.java
index 3ecb451..57747f5 100644
--- a/webmagic-core/src/main/java/us/codecraft/webmagic/annotation/ExtractByUrl.java
+++ b/webmagic-core/src/main/java/us/codecraft/webmagic/annotation/ExtractByUrl.java
@@ -11,8 +11,10 @@ import java.lang.annotation.Target;
  */
 @Retention(java.lang.annotation.RetentionPolicy.RUNTIME)
 @Target({ElementType.FIELD})
-public @interface ExtractByUrl {
+public @interface ExtractByUrl{
 
     String value() default "";
 
+    boolean notNull() default true;
+
 }
diff --git a/webmagic-core/src/main/java/us/codecraft/webmagic/annotation/FieldExtractor.java b/webmagic-core/src/main/java/us/codecraft/webmagic/annotation/FieldExtractor.java
index d241c8d..f415cb8 100644
--- a/webmagic-core/src/main/java/us/codecraft/webmagic/annotation/FieldExtractor.java
+++ b/webmagic-core/src/main/java/us/codecraft/webmagic/annotation/FieldExtractor.java
@@ -20,18 +20,15 @@ class FieldExtractor {
 
     private Method setterMethod;
 
+    private final boolean notNull;
+
     static enum Source {Html, Url}
 
-    public FieldExtractor(Field field, Selector selector) {
-        this.field = field;
-        this.selector = selector;
-        this.source = Source.Html;
-    }
-
-    public FieldExtractor(Field field, Selector selector, Source source) {
+    public FieldExtractor(Field field, Selector selector, Source source, boolean notNull) {
         this.field = field;
         this.selector = selector;
         this.source = source;
+        this.notNull = notNull;
     }
 
     Field getField() {
@@ -53,4 +50,8 @@ class FieldExtractor {
     Method getSetterMethod() {
         return setterMethod;
     }
+
+    boolean isNotNull() {
+        return notNull;
+    }
 }
diff --git a/webmagic-core/src/main/java/us/codecraft/webmagic/annotation/HelpUrl.java b/webmagic-core/src/main/java/us/codecraft/webmagic/annotation/HelpUrl.java
new file mode 100644
index 0000000..3020817
--- /dev/null
+++ b/webmagic-core/src/main/java/us/codecraft/webmagic/annotation/HelpUrl.java
@@ -0,0 +1,17 @@
+package us.codecraft.webmagic.annotation;
+
+import java.lang.annotation.ElementType;
+import java.lang.annotation.Retention;
+import java.lang.annotation.Target;
+
+/**
+ * @author yihua.huang@dianping.com <br>
+ * @date: 13-8-1 <br>
+ * Time: 下午8:40 <br>
+ */
+@Retention(java.lang.annotation.RetentionPolicy.RUNTIME)
+@Target({ElementType.TYPE})
+public @interface HelpUrl {
+
+    String[] value();
+}
diff --git a/webmagic-core/src/main/java/us/codecraft/webmagic/annotation/ObjectPageProcessor.java b/webmagic-core/src/main/java/us/codecraft/webmagic/annotation/ObjectPageProcessor.java
index ae3131e..ad8297e 100644
--- a/webmagic-core/src/main/java/us/codecraft/webmagic/annotation/ObjectPageProcessor.java
+++ b/webmagic-core/src/main/java/us/codecraft/webmagic/annotation/ObjectPageProcessor.java
@@ -40,6 +40,7 @@ public class ObjectPageProcessor implements PageProcessor {
         targetUrlPatterns = new HashSet<Pattern>();
         for (PageModelExtractor pageModelExtractor : pageModelExtractorList) {
             targetUrlPatterns.addAll(pageModelExtractor.getTargetUrlPatterns());
+            targetUrlPatterns.addAll(pageModelExtractor.getHelpUrlPatterns());
         }
     }
 
@@ -47,6 +48,9 @@ public class ObjectPageProcessor implements PageProcessor {
     public void process(Page page) {
         for (PageModelExtractor pageModelExtractor : pageModelExtractorList) {
             Object process = pageModelExtractor.process(page);
+            if (process==null){
+                page.getResultItems().setSkip(true);
+            }
             postProcessPageModel(pageModelExtractor.getClazz(), process);
             page.putField(pageModelExtractor.getClazz().getCanonicalName(), process);
         }
diff --git a/webmagic-core/src/main/java/us/codecraft/webmagic/annotation/PageModelExtractor.java b/webmagic-core/src/main/java/us/codecraft/webmagic/annotation/PageModelExtractor.java
index 7d0d4f2..41f635c 100644
--- a/webmagic-core/src/main/java/us/codecraft/webmagic/annotation/PageModelExtractor.java
+++ b/webmagic-core/src/main/java/us/codecraft/webmagic/annotation/PageModelExtractor.java
@@ -24,6 +24,8 @@ class PageModelExtractor {
 
     private List<Pattern> targetUrlPatterns;
 
+    private List<Pattern> helpUrlPatterns;
+
     private Class clazz;
 
     private List<FieldExtractor> fieldExtractors;
@@ -57,7 +59,7 @@ class PageModelExtractor {
                     default:
                         selector = new XpathSelector(value);
                 }
-                FieldExtractor fieldExtractor = new FieldExtractor(field, selector);
+                FieldExtractor fieldExtractor = new FieldExtractor(field, selector, FieldExtractor.Source.Html, extractBy.notNull());
                 Method setterMethod = getSetterMethod(clazz, field);
                 if (setterMethod != null) {
                     fieldExtractor.setSetterMethod(setterMethod);
@@ -70,7 +72,7 @@ class PageModelExtractor {
                 if (regexPattern.trim().equals("")) {
                     regexPattern = ".*";
                 }
-                FieldExtractor fieldExtractor = new FieldExtractor(field, new RegexSelector(regexPattern), FieldExtractor.Source.Url);
+                FieldExtractor fieldExtractor = new FieldExtractor(field, new RegexSelector(regexPattern), FieldExtractor.Source.Url, extractByUrl.notNull());
                 Method setterMethod = getSetterMethod(clazz, field);
                 if (setterMethod != null) {
                     fieldExtractor.setSetterMethod(setterMethod);
@@ -102,6 +104,14 @@ class PageModelExtractor {
                 targetUrlPatterns.add(Pattern.compile(s.replace(".", "\\.").replace("*", "[^\"'#]*")));
             }
         }
+        helpUrlPatterns = new ArrayList<Pattern>();
+        annotation = clazz.getAnnotation(HelpUrl.class);
+        if (annotation != null) {
+            String[] value = ((HelpUrl) annotation).value();
+            for (String s : value) {
+                helpUrlPatterns.add(Pattern.compile(s.replace(".", "\\.").replace("*", "[^\"'#]*")));
+            }
+        }
     }
 
     public Object process(Page page) {
@@ -129,7 +139,10 @@ class PageModelExtractor {
                     default:
                         value = fieldExtractor.getSelector().select(page.getHtml().toString());
                 }
-                setField(o,fieldExtractor,value);
+                if (value==null&&fieldExtractor.isNotNull()){
+                    page.getResultItems().setSkip(true);
+                }
+                setField(o, fieldExtractor, value);
             }
         } catch (InstantiationException e) {
             e.printStackTrace();
@@ -142,8 +155,8 @@ class PageModelExtractor {
     }
 
     private void setField(Object o, FieldExtractor fieldExtractor, String value) throws IllegalAccessException, InvocationTargetException {
-        if (fieldExtractor.getSetterMethod()!=null){
-            fieldExtractor.getSetterMethod().invoke(o,value);
+        if (fieldExtractor.getSetterMethod() != null) {
+            fieldExtractor.getSetterMethod().invoke(o, value);
         }
         fieldExtractor.getField().set(o, value);
     }
@@ -155,4 +168,8 @@ class PageModelExtractor {
     List<Pattern> getTargetUrlPatterns() {
         return targetUrlPatterns;
     }
+
+    List<Pattern> getHelpUrlPatterns() {
+        return helpUrlPatterns;
+    }
 }
diff --git a/webmagic-samples/src/main/java/us/codecraft/webmagic/annotation/samples/IteyeBlog.java b/webmagic-samples/src/main/java/us/codecraft/webmagic/annotation/samples/IteyeBlog.java
new file mode 100644
index 0000000..8fbf089
--- /dev/null
+++ b/webmagic-samples/src/main/java/us/codecraft/webmagic/annotation/samples/IteyeBlog.java
@@ -0,0 +1,34 @@
+package us.codecraft.webmagic.annotation.samples;
+
+import us.codecraft.webmagic.Site;
+import us.codecraft.webmagic.Spider;
+import us.codecraft.webmagic.annotation.ExtractBy;
+import us.codecraft.webmagic.annotation.TargetUrl;
+
+/**
+ * @author yihua.huang@dianping.com <br>
+ * @date: 13-8-2 <br>
+ * Time: 上午7:52 <br>
+ */
+@TargetUrl("http://dengminhui.iteye.com/blog/*")
+public class IteyeBlog {
+
+    @ExtractBy("//title")
+    private String title;
+
+    @ExtractBy(value = "div#blog_content",type = ExtractBy.Type.Css)
+    private String content;
+
+    @Override
+    public String toString() {
+        return "IteyeBlog{" +
+                "title='" + title + '\'' +
+                ", content='" + content + '\'' +
+                '}';
+    }
+
+    public static void main(String[] args) {
+        Spider.create(Site.me().addStartUrl("http://dengminhui.iteye.com/blog"),IteyeBlog.class).run();
+    }
+
+}