diff --git a/webmagic-core/src/main/java/us/codecraft/webmagic/processor/example/GithubRepoPageProcesser.java b/webmagic-core/src/main/java/us/codecraft/webmagic/processor/example/GithubRepoPageProcesser.java
new file mode 100644
index 00000000..0e7e3b92
--- /dev/null
+++ b/webmagic-core/src/main/java/us/codecraft/webmagic/processor/example/GithubRepoPageProcesser.java
@@ -0,0 +1,36 @@
+package us.codecraft.webmagic.processor.example;
+
+import us.codecraft.webmagic.Page;
+import us.codecraft.webmagic.Site;
+import us.codecraft.webmagic.Spider;
+import us.codecraft.webmagic.processor.PageProcessor;
+
+/**
+ * @author code4crafter@gmail.com <br>
+ * @since 0.3.2
+ */
+public class GithubRepoPageProcesser implements PageProcessor {
+
+    private Site site = Site.me().addStartUrl("https://github.com/code4craft").setRetryTimes(3).setSleepTime(100);
+
+    @Override
+    public void process(Page page) {
+        page.addTargetRequests(page.getHtml().links().regex("(https://github\\.com/\\w+/\\w+)").all());
+        page.putField("author", page.getUrl().regex("https://github\\.com/(\\w+)/.*").toString());
+        page.putField("name", page.getHtml().xpath("//h1[@class='entry-title public']/strong/a/text()").toString());
+        if (page.getResultItems().get("name")==null){
+            //skip this page
+            page.setSkip(true);
+        }
+        page.putField("readme", page.getHtml().xpath("//div[@id='readme']/tidyText()"));
+    }
+
+    @Override
+    public Site getSite() {
+        return site;
+    }
+
+    public static void main(String[] args) {
+        Spider.create(new GithubRepoPageProcesser()).thread(5).run();
+    }
+}
diff --git a/webmagic-core/src/main/java/us/codecraft/webmagic/processor/example/OschinaBlogPageProcesser.java b/webmagic-core/src/main/java/us/codecraft/webmagic/processor/example/OschinaBlogPageProcesser.java
new file mode 100644
index 00000000..fa8dab6d
--- /dev/null
+++ b/webmagic-core/src/main/java/us/codecraft/webmagic/processor/example/OschinaBlogPageProcesser.java
@@ -0,0 +1,39 @@
+package us.codecraft.webmagic.processor.example;
+
+import us.codecraft.webmagic.Page;
+import us.codecraft.webmagic.Site;
+import us.codecraft.webmagic.Spider;
+import us.codecraft.webmagic.processor.PageProcessor;
+
+import java.util.List;
+
+/**
+ * @author code4crafter@gmail.com <br>
+ */
+public class OschinaBlogPageProcesser implements PageProcessor {
+
+    private Site site = Site.me().setDomain("my.oschina.net").addStartUrl("http://my.oschina.net/flashsword/blog");
+
+    @Override
+    public void process(Page page) {
+        List<String> links = page.getHtml().links().regex("http://my\\.oschina\\.net/flashsword/blog/\\d+").all();
+        page.addTargetRequests(links);
+        page.putField("title", page.getHtml().xpath("//div[@class='BlogEntity']/div[@class='BlogTitle']/h1/text()").toString());
+        if (page.getResultItems().get("title") == null) {
+            //skip this page
+            page.setSkip(true);
+        }
+        page.putField("content", page.getHtml().xpath("//div[@class='BlogContent']/tidyText()").toString());
+        page.putField("tags", page.getHtml().xpath("//div[@class='BlogTags']/a/text()").all());
+    }
+
+    @Override
+    public Site getSite() {
+        return site;
+
+    }
+
+    public static void main(String[] args) {
+        Spider.create(new OschinaBlogPageProcesser()).thread(2).run();
+    }
+}
diff --git a/webmagic-extension/src/main/java/us/codecraft/webmagic/example/GithubRepo.java b/webmagic-extension/src/main/java/us/codecraft/webmagic/example/GithubRepo.java
index d9501154..58441cbc 100644
--- a/webmagic-extension/src/main/java/us/codecraft/webmagic/example/GithubRepo.java
+++ b/webmagic-extension/src/main/java/us/codecraft/webmagic/example/GithubRepo.java
@@ -1,6 +1,9 @@
 package us.codecraft.webmagic.example;
 
+import us.codecraft.webmagic.Site;
+import us.codecraft.webmagic.model.ConsolePageModelPipeline;
 import us.codecraft.webmagic.model.HasKey;
+import us.codecraft.webmagic.model.OOSpider;
 import us.codecraft.webmagic.model.annotation.ExtractBy;
 import us.codecraft.webmagic.model.annotation.ExtractByUrl;
 import us.codecraft.webmagic.model.annotation.HelpUrl;
@@ -10,6 +13,7 @@ import java.util.List;
 
 /**
  * @author code4crafter@gmail.com <br>
+ * @since 0.3.2
  */
 @TargetUrl("https://github.com/\\w+/\\w+")
 @HelpUrl({"https://github.com/\\w+\\?tab=repositories", "https://github.com/\\w+", "https://github.com/explore/*"})
@@ -27,15 +31,20 @@ public class GithubRepo implements HasKey {
     @ExtractBy(value = "//div[@class='repository-lang-stats']//li//span[@class='lang']/text()", multi = true)
     private List<String> language;
 
-    @ExtractBy("//ul[@class='pagehead-actions']/li[2]//a[@class='social-count js-social-count']/text()")
+    @ExtractBy("//ul[@class='pagehead-actions']/li[1]//a[@class='social-count js-social-count']/text()")
     private int star;
 
-    @ExtractBy("//ul[@class='pagehead-actions']/li[3]//a[@class='social-count']/text()")
+    @ExtractBy("//ul[@class='pagehead-actions']/li[2]//a[@class='social-count']/text()")
     private int fork;
 
     @ExtractByUrl
     private String url;
 
+    public static void main(String[] args) {
+        OOSpider.create(Site.me().addStartUrl("https://github.com/code4craft").setSleepTime(100)
+                , new ConsolePageModelPipeline(), GithubRepo.class).thread(10).run();
+    }
+
     @Override
     public String key() {
         return author + ":" + name;
diff --git a/webmagic-extension/src/main/java/us/codecraft/webmagic/example/OschinaBlog.java b/webmagic-extension/src/main/java/us/codecraft/webmagic/example/OschinaBlog.java
index 703d6a4f..1545f885 100644
--- a/webmagic-extension/src/main/java/us/codecraft/webmagic/example/OschinaBlog.java
+++ b/webmagic-extension/src/main/java/us/codecraft/webmagic/example/OschinaBlog.java
@@ -1,38 +1,38 @@
 package us.codecraft.webmagic.example;
 
-import us.codecraft.webmagic.Page;
 import us.codecraft.webmagic.Site;
-import us.codecraft.webmagic.model.AfterExtractor;
 import us.codecraft.webmagic.model.OOSpider;
 import us.codecraft.webmagic.model.annotation.ExtractBy;
 import us.codecraft.webmagic.model.annotation.Formatter;
 import us.codecraft.webmagic.model.annotation.TargetUrl;
 import us.codecraft.webmagic.pipeline.JsonFilePageModelPipeline;
 
+import java.util.Date;
 import java.util.List;
 
 /**
  * @author code4crafter@gmail.com <br>
+ * @since 0.3.2
  */
 @TargetUrl("http://my.oschina.net/flashsword/blog/\\d+")
-public class OschinaBlog implements AfterExtractor{
+public class OschinaBlog {
 
     @ExtractBy("//title/text()")
     private String title;
 
-    @ExtractBy(value = "div.BlogContent",type = ExtractBy.Type.Css)
+    @ExtractBy(value = "div.BlogContent", type = ExtractBy.Type.Css)
     private String content;
 
     @ExtractBy(value = "//div[@class='BlogTags']/a/text()", multi = true)
     private List<String> tags;
 
-    @Formatter("YYYY-MM-dd HH:mm")
+    @Formatter("yyyy-MM-dd HH:mm")
     @ExtractBy("//div[@class='BlogStat']/regex('\\d+-\\d+-\\d+\\s+\\d+:\\d+')")
-    private String date;
+    private Date date;
 
     public static void main(String[] args) {
         OOSpider.create(Site.me().addStartUrl("http://my.oschina.net/flashsword/blog")
-                ,new JsonFilePageModelPipeline("/data/webmagic/"), OschinaBlog.class).run();
+                , new JsonFilePageModelPipeline("/data/webmagic/"), OschinaBlog.class).run();
     }
 
     public String getTitle() {
@@ -47,13 +47,8 @@ public class OschinaBlog implements AfterExtractor{
         return tags;
     }
 
-//    public Date getDate() {
-//        return date;
-//    }
-
-    @Override
-    public void afterProcess(Page page) {
-        System.out.println(date);
-        System.out.println(title);
+    public Date getDate() {
+        return date;
     }
+
 }
diff --git a/webmagic-extension/src/main/java/us/codecraft/webmagic/model/PageModelExtractor.java b/webmagic-extension/src/main/java/us/codecraft/webmagic/model/PageModelExtractor.java
index cd3e72b4..c78bd31e 100644
--- a/webmagic-extension/src/main/java/us/codecraft/webmagic/model/PageModelExtractor.java
+++ b/webmagic-extension/src/main/java/us/codecraft/webmagic/model/PageModelExtractor.java
@@ -105,7 +105,8 @@ class PageModelExtractor {
         Formatter formatter = field.getAnnotation(Formatter.class);
         if (formatter != null) {
             if (!formatter.formatter().equals(ObjectFormatter.class)) {
-                return initFormatter(formatter.formatter());
+                ObjectFormatter objectFormatter = initFormatter(formatter.formatter());
+                objectFormatter.initParam(formatter.value());
             }
         }
         return initFormatter(ObjectFormatters.get(fieldClazz));
@@ -311,6 +312,9 @@ class PageModelExtractor {
                     }
                     if (fieldExtractor.getObjectFormatter() != null) {
                         Object converted = convert(value, fieldExtractor.getObjectFormatter());
+                        if (converted == null && fieldExtractor.isNotNull()) {
+                            return null;
+                        }
                         setField(o, fieldExtractor, converted);
                     } else {
                         setField(o, fieldExtractor, value);
@@ -332,7 +336,11 @@ class PageModelExtractor {
 
     private Object convert(String value, ObjectFormatter objectFormatter) {
         try {
-            return objectFormatter.format(value);
+            Object format = objectFormatter.format(value);
+            if (logger.isDebugEnabled()) {
+                logger.debug("String " + value + " is converted to " + format);
+            }
+            return format;
         } catch (Exception e) {
             logger.error("convert " + value + " to " + objectFormatter.clazz() + " error!", e);
         }
@@ -351,6 +359,9 @@ class PageModelExtractor {
     }
 
     private void setField(Object o, FieldExtractor fieldExtractor, Object value) throws IllegalAccessException, InvocationTargetException {
+        if (value==null){
+            return;
+        }
         if (fieldExtractor.getSetterMethod() != null) {
             fieldExtractor.getSetterMethod().invoke(o, value);
         }
diff --git a/webmagic-extension/src/main/java/us/codecraft/webmagic/model/formatter/DateFormatter.java b/webmagic-extension/src/main/java/us/codecraft/webmagic/model/formatter/DateFormatter.java
index 0ad0302b..b0f6e771 100644
--- a/webmagic-extension/src/main/java/us/codecraft/webmagic/model/formatter/DateFormatter.java
+++ b/webmagic-extension/src/main/java/us/codecraft/webmagic/model/formatter/DateFormatter.java
@@ -10,7 +10,7 @@ import java.util.Date;
  */
 public class DateFormatter implements ObjectFormatter<Date> {
 
-    private String[] datePatterns = new String[]{"YYYY-MM-dd HH:mm"};
+    private String[] datePatterns = new String[]{"yyyy-MM-dd HH:mm"};
 
     @Override
     public Date format(String raw) throws Exception {
diff --git a/webmagic-extension/src/test/java/us/codecraft/webmagic/formatter/DateFormatterTest.java b/webmagic-extension/src/test/java/us/codecraft/webmagic/formatter/DateFormatterTest.java
new file mode 100644
index 00000000..a621e2dc
--- /dev/null
+++ b/webmagic-extension/src/test/java/us/codecraft/webmagic/formatter/DateFormatterTest.java
@@ -0,0 +1,20 @@
+package us.codecraft.webmagic.formatter;
+
+import org.junit.Test;
+import us.codecraft.webmagic.model.formatter.DateFormatter;
+
+import java.util.Date;
+
+/**
+ * @author code4crafter@gmail.com
+ */
+public class DateFormatterTest {
+
+    @Test
+    public void testDateFormatter() throws Exception {
+        DateFormatter dateFormatter = new DateFormatter();
+        dateFormatter.initParam(new String[]{"yyyy-MM-dd HH:mm"});
+        Date format = dateFormatter.format("2013-09-10 22:11");
+        System.out.println(format);
+    }
+}
diff --git a/webmagic-extension/src/test/resouces/log4j.xml b/webmagic-extension/src/test/resouces/log4j.xml
new file mode 100644
index 00000000..a58e889b
--- /dev/null
+++ b/webmagic-extension/src/test/resouces/log4j.xml
@@ -0,0 +1,31 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<!DOCTYPE log4j:configuration SYSTEM "log4j.dtd">
+<log4j:configuration xmlns:log4j="http://jakarta.apache.org/log4j/">
+
+    <appender name="stdout" class="org.apache.log4j.ConsoleAppender">
+        <layout class="org.apache.log4j.PatternLayout">
+            <param name="ConversionPattern" value="%d{yy-MM-dd HH:mm:ss,SSS} %-5p %c(%F:%L) ## %m%n" />
+        </layout>
+    </appender>
+
+    <logger name="org.springframework" additivity="false">
+        <level value="warn" />
+        <appender-ref ref="stdout" />
+    </logger>
+
+    <logger name="org.apache" additivity="false">
+        <level value="warn" />
+        <appender-ref ref="stdout" />
+    </logger>
+
+    <logger name="net.sf.ehcache" additivity="false">
+        <level value="warn" />
+        <appender-ref ref="stdout" />
+    </logger>
+
+    <root>
+        <level value="debug" />
+        <appender-ref ref="stdout" />
+    </root>
+
+</log4j:configuration>