diff --git a/webmagic-core/src/main/java/us/codecraft/webmagic/Page.java b/webmagic-core/src/main/java/us/codecraft/webmagic/Page.java
index c11df693c..ea875e43f 100644
--- a/webmagic-core/src/main/java/us/codecraft/webmagic/Page.java
+++ b/webmagic-core/src/main/java/us/codecraft/webmagic/Page.java
@@ -108,6 +108,7 @@ public Json getJson() {
      * @deprecated since 0.4.0
      * The html is parse just when first time of calling {@link #getHtml()}, so use {@link #setRawText(String)} instead.
      */
+    @Deprecated
     public void setHtml(Html html) {
         this.html = html;
     }
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 5940e738d..8bede01bf 100644
--- a/webmagic-core/src/main/java/us/codecraft/webmagic/Spider.java
+++ b/webmagic-core/src/main/java/us/codecraft/webmagic/Spider.java
@@ -86,11 +86,11 @@ public class Spider implements Runnable, Task {
 
     protected boolean exitWhenComplete = true;
 
-    protected final static int STAT_INIT = 0;
+    protected static final int STAT_INIT = 0;
 
-    protected final static int STAT_RUNNING = 1;
+    protected static final int STAT_RUNNING = 1;
 
-    protected final static int STAT_STOPPED = 2;
+    protected static final int STAT_STOPPED = 2;
 
     protected boolean spawnUrl = true;
 
@@ -171,6 +171,7 @@ public Spider setUUID(String uuid) {
      * set scheduler for Spider
      *
      * @param scheduler scheduler
+     * @deprecated since 0.4.0
      * @return this
      * @see #setScheduler(us.codecraft.webmagic.scheduler.Scheduler)
      */
@@ -543,9 +544,9 @@ protected CollectorPipeline getCollectorPipeline() {
 
     public <T> T get(String url) {
         List<String> urls = WMCollections.newArrayList(url);
-        List<T> resultItemses = getAll(urls);
-        if (resultItemses != null && resultItemses.size() > 0) {
-            return resultItemses.get(0);
+        List<T> singleResultItems = getAll(urls);
+        if (singleResultItems != null && !singleResultItems.isEmpty()) {
+            return singleResultItems.get(0);
         } else {
             return null;
         }
@@ -677,7 +678,7 @@ public Status getStatus() {
 
 
     public enum Status {
-        Init(0), Running(1), Stopped(2);
+        INIT(0), RUNNING(1), STOPPED(2);
 
         private Status(int value) {
             this.value = value;
@@ -696,7 +697,7 @@ public static Status fromValue(int value) {
                 }
             }
             //default value
-            return Init;
+            return INIT;
         }
     }
 
diff --git a/webmagic-core/src/main/java/us/codecraft/webmagic/downloader/HttpClientGenerator.java b/webmagic-core/src/main/java/us/codecraft/webmagic/downloader/HttpClientGenerator.java
index 80e0f1085..75f899925 100644
--- a/webmagic-core/src/main/java/us/codecraft/webmagic/downloader/HttpClientGenerator.java
+++ b/webmagic-core/src/main/java/us/codecraft/webmagic/downloader/HttpClientGenerator.java
@@ -69,9 +69,7 @@ private SSLConnectionSocketFactory buildSSLConnectionSocketFactory() {
             return new SSLConnectionSocketFactory(sslContext, supportedProtocols,
                     null,
                     new DefaultHostnameVerifier()); // 优先绕过安全证书
-        } catch (KeyManagementException e) {
-            logger.error("ssl connection fail", e);
-        } catch (NoSuchAlgorithmException e) {
+        } catch (KeyManagementException | NoSuchAlgorithmException e) {
             logger.error("ssl connection fail", e);
         }
         return SSLConnectionSocketFactory.getSocketFactory();
@@ -91,7 +89,7 @@ public void checkServerTrusted(X509Certificate[] chain, String authType) throws
 
             @Override
             public X509Certificate[] getAcceptedIssuers() {
-                return null;
+            	return new X509Certificate[0];
             }
 
         };
diff --git a/webmagic-core/src/main/java/us/codecraft/webmagic/model/HttpRequestBody.java b/webmagic-core/src/main/java/us/codecraft/webmagic/model/HttpRequestBody.java
index 7d3b30785..5ae8126f4 100644
--- a/webmagic-core/src/main/java/us/codecraft/webmagic/model/HttpRequestBody.java
+++ b/webmagic-core/src/main/java/us/codecraft/webmagic/model/HttpRequestBody.java
@@ -17,8 +17,10 @@
 public class HttpRequestBody implements Serializable {
 
     private static final long serialVersionUID = 5659170945717023595L;
+    
+    private static final String ENCODING_ERROR ="illegal encoding "; 
 
-    public static abstract class ContentType {
+    public abstract static class ContentType {
 
         public static final String JSON = "application/json";
 
@@ -68,7 +70,7 @@ public static HttpRequestBody json(String json, String encoding) {
         try {
             return new HttpRequestBody(json.getBytes(encoding), ContentType.JSON, encoding);
         } catch (UnsupportedEncodingException e) {
-            throw new IllegalArgumentException("illegal encoding " + encoding, e);
+            throw new IllegalArgumentException(ENCODING_ERROR+ encoding, e);
         }
     }
 
@@ -76,7 +78,7 @@ public static HttpRequestBody xml(String xml, String encoding) {
         try {
             return new HttpRequestBody(xml.getBytes(encoding), ContentType.XML, encoding);
         } catch (UnsupportedEncodingException e) {
-            throw new IllegalArgumentException("illegal encoding " + encoding, e);
+            throw new IllegalArgumentException(ENCODING_ERROR + encoding, e);
         }
     }
 
@@ -92,7 +94,7 @@ public static HttpRequestBody form(Map<String,Object> params, String encoding){
         try {
             return new HttpRequestBody(URLEncodedUtils.format(nameValuePairs, encoding).getBytes(encoding), ContentType.FORM, encoding);
         } catch (UnsupportedEncodingException e) {
-            throw new IllegalArgumentException("illegal encoding " + encoding, e);
+            throw new IllegalArgumentException(ENCODING_ERROR + encoding, e);
         }
     }
 
diff --git a/webmagic-core/src/main/java/us/codecraft/webmagic/processor/example/BaiduBaikePageProcessor.java b/webmagic-core/src/main/java/us/codecraft/webmagic/processor/example/BaiduBaikePageProcessor.java
index f6ad87e05..070db4803 100644
--- a/webmagic-core/src/main/java/us/codecraft/webmagic/processor/example/BaiduBaikePageProcessor.java
+++ b/webmagic-core/src/main/java/us/codecraft/webmagic/processor/example/BaiduBaikePageProcessor.java
@@ -42,9 +42,9 @@ public static void main(String[] args) {
         list.add(String.format(urlTemplate,"太阳能"));
         list.add(String.format(urlTemplate,"地热发电"));
         list.add(String.format(urlTemplate,"地热发电"));
-        List<ResultItems> resultItemses = spider.<ResultItems>getAll(list);
-        for (ResultItems resultItemse : resultItemses) {
-            System.out.println(resultItemse.getAll());
+        List<ResultItems> multiResultItems = spider.<ResultItems>getAll(list);
+        for (ResultItems singleResultItems : multiResultItems) {
+            System.out.println(singleResultItems.getAll());
         }
         spider.close();
     }
diff --git a/webmagic-core/src/main/java/us/codecraft/webmagic/scheduler/component/DuplicateRemover.java b/webmagic-core/src/main/java/us/codecraft/webmagic/scheduler/component/DuplicateRemover.java
index 4139f27fd..8c879ba61 100644
--- a/webmagic-core/src/main/java/us/codecraft/webmagic/scheduler/component/DuplicateRemover.java
+++ b/webmagic-core/src/main/java/us/codecraft/webmagic/scheduler/component/DuplicateRemover.java
@@ -4,7 +4,7 @@
 import us.codecraft.webmagic.Task;
 
 /**
- * Remove duplicate requests.
+ * Remove duplicate requests.</br>
  * @author code4crafer@gmail.com
  * @since 0.5.1
  */
diff --git a/webmagic-core/src/main/java/us/codecraft/webmagic/selector/AbstractSelectable.java b/webmagic-core/src/main/java/us/codecraft/webmagic/selector/AbstractSelectable.java
index e2bb55215..5e868ebb8 100644
--- a/webmagic-core/src/main/java/us/codecraft/webmagic/selector/AbstractSelectable.java
+++ b/webmagic-core/src/main/java/us/codecraft/webmagic/selector/AbstractSelectable.java
@@ -91,7 +91,7 @@ public Selectable replace(String regex, String replacement) {
     }
 
     public String getFirstSourceText() {
-        if (getSourceTexts() != null && getSourceTexts().size() > 0) {
+        if (getSourceTexts() != null && !getSourceTexts().isEmpty()) {
             return getSourceTexts().get(0);
         }
         return null;
@@ -104,6 +104,6 @@ public String toString() {
 
     @Override
     public boolean match() {
-        return getSourceTexts() != null && getSourceTexts().size() > 0;
+        return getSourceTexts() != null && !getSourceTexts().isEmpty();
     }
 }
diff --git a/webmagic-core/src/main/java/us/codecraft/webmagic/selector/AndSelector.java b/webmagic-core/src/main/java/us/codecraft/webmagic/selector/AndSelector.java
index 135442dc6..d51e29824 100644
--- a/webmagic-core/src/main/java/us/codecraft/webmagic/selector/AndSelector.java
+++ b/webmagic-core/src/main/java/us/codecraft/webmagic/selector/AndSelector.java
@@ -48,7 +48,7 @@ public List<String> selectList(String text) {
                     resultsTemp.addAll(selector.selectList(result));
                 }
                 results = resultsTemp;
-                if (results == null || results.size() == 0) {
+                if (results.size() == 0) {
                     return results;
                 }
             }
diff --git a/webmagic-core/src/main/java/us/codecraft/webmagic/selector/BaseElementSelector.java b/webmagic-core/src/main/java/us/codecraft/webmagic/selector/BaseElementSelector.java
index bbc7217ab..64c7ef621 100644
--- a/webmagic-core/src/main/java/us/codecraft/webmagic/selector/BaseElementSelector.java
+++ b/webmagic-core/src/main/java/us/codecraft/webmagic/selector/BaseElementSelector.java
@@ -7,6 +7,8 @@
 import java.util.List;
 
 /**
+ * Base selector for html elements.
+ * 
  * @author code4crafter@gmail.com
  * @since 0.3.0
  */
diff --git a/webmagic-core/src/main/java/us/codecraft/webmagic/selector/JsonPathSelector.java b/webmagic-core/src/main/java/us/codecraft/webmagic/selector/JsonPathSelector.java
index f5c0baeb5..de1e68c64 100644
--- a/webmagic-core/src/main/java/us/codecraft/webmagic/selector/JsonPathSelector.java
+++ b/webmagic-core/src/main/java/us/codecraft/webmagic/selector/JsonPathSelector.java
@@ -33,7 +33,7 @@ public String select(String text) {
         }
         if (object instanceof List) {
             List list = (List) object;
-            if (list != null && list.size() > 0) {
+            if (list.size() > 0) {
                 return toString(list.iterator().next());
             }
         }
diff --git a/webmagic-core/src/main/java/us/codecraft/webmagic/selector/SmartContentSelector.java b/webmagic-core/src/main/java/us/codecraft/webmagic/selector/SmartContentSelector.java
index ff8e26998..df798e81e 100644
--- a/webmagic-core/src/main/java/us/codecraft/webmagic/selector/SmartContentSelector.java
+++ b/webmagic-core/src/main/java/us/codecraft/webmagic/selector/SmartContentSelector.java
@@ -51,22 +51,21 @@ public String select(String html) {
         text.setLength(0);
 
         for (int i = 0; i < indexDistribution.size() - 1; i++) {
-            if (indexDistribution.get(i) > threshold && ! boolstart) {
-                if (indexDistribution.get(i+1).intValue() != 0
-                        || indexDistribution.get(i+2).intValue() != 0
-                        || indexDistribution.get(i+3).intValue() != 0) {
+            if (indexDistribution.get(i) > threshold && ! boolstart
+            	&& !isAnyIndexDistributionZero(indexDistribution,i+1,i+2,i+3)){
                     boolstart = true;
                     start = i;
                     continue;
                 }
-            }
-            if (boolstart) {
-                if (indexDistribution.get(i).intValue() == 0
-                        || indexDistribution.get(i+1).intValue() == 0) {
+            
+            if (boolstart && isAnyIndexDistributionZero (indexDistribution,i,i+1,0)) {
+               
                     end = i;
                     boolend = true;
-                }
+                
             }
+            
+          		
             StringBuilder tmp = new StringBuilder();
             if (boolend) {
                 //System.out.println(start+1 + "\t\t" + end+1);
@@ -83,9 +82,25 @@ public String select(String html) {
         }
         return text.toString();
     }
-
+    
+   
     @Override
     public List<String> selectList(String text) {
         throw new UnsupportedOperationException();
     }
+    
+    private static boolean isAnyIndexDistributionZero( ArrayList <Integer> indexDistribution, int index, int successorIndex, int afterSuccessorIndex) {
+        
+    	
+    	if (afterSuccessorIndex != 0) {
+    		return (indexDistribution.get(index).intValue() == 0
+                    && indexDistribution.get(successorIndex).intValue() == 0
+                    && indexDistribution.get(afterSuccessorIndex).intValue() == 0 );
+    	}else {
+    		return (indexDistribution.get(index).intValue() == 0
+                    || indexDistribution.get(successorIndex).intValue() == 0);
+    	}
+    	
+    }        
+
 }
diff --git a/webmagic-core/src/main/java/us/codecraft/webmagic/utils/HttpConstant.java b/webmagic-core/src/main/java/us/codecraft/webmagic/utils/HttpConstant.java
index 2d6b8fe2a..7459e7327 100644
--- a/webmagic-core/src/main/java/us/codecraft/webmagic/utils/HttpConstant.java
+++ b/webmagic-core/src/main/java/us/codecraft/webmagic/utils/HttpConstant.java
@@ -7,7 +7,7 @@
  */
 public abstract class HttpConstant {
 
-    public static abstract class Method {
+    public abstract static class Method {
 
         public static final String GET = "GET";
 
@@ -25,13 +25,13 @@ public static abstract class Method {
 
     }
 
-    public static abstract class StatusCode {
+    public abstract static class StatusCode {
 
         public static final int CODE_200 = 200;
 
     }
 
-    public static abstract class Header {
+    public abstract static class Header {
 
         public static final String REFERER = "Referer";
 
diff --git a/webmagic-core/src/main/java/us/codecraft/webmagic/utils/NumberUtils.java b/webmagic-core/src/main/java/us/codecraft/webmagic/utils/NumberUtils.java
index 55e185105..e73d1d9a8 100644
--- a/webmagic-core/src/main/java/us/codecraft/webmagic/utils/NumberUtils.java
+++ b/webmagic-core/src/main/java/us/codecraft/webmagic/utils/NumberUtils.java
@@ -1,6 +1,8 @@
 package us.codecraft.webmagic.utils;
 
 /**
+ * Numbers comparison utilility for schedule priority
+ * 
  * @author yihua.huang@dianping.com
  */
 public abstract class NumberUtils {
diff --git a/webmagic-core/src/main/java/us/codecraft/webmagic/utils/ProxyUtils.java b/webmagic-core/src/main/java/us/codecraft/webmagic/utils/ProxyUtils.java
index 9b734c73c..5661d3846 100644
--- a/webmagic-core/src/main/java/us/codecraft/webmagic/utils/ProxyUtils.java
+++ b/webmagic-core/src/main/java/us/codecraft/webmagic/utils/ProxyUtils.java
@@ -30,13 +30,12 @@ public static boolean validateProxy(Proxy p) {
 			logger.warn("FAILRE - CAN not connect!  remote: " + p);
 			return false;
 		} finally {
-			if (socket != null) {
-				try {
+    		    try {
 					socket.close();
 				} catch (IOException e) {
 					logger.warn("Error occurred while closing socket of validating proxy", e);
 				}
-			}
+			
 		}
 
 	}
diff --git a/webmagic-core/src/main/java/us/codecraft/webmagic/utils/WMCollections.java b/webmagic-core/src/main/java/us/codecraft/webmagic/utils/WMCollections.java
index 23e1644ce..5fbe37d0d 100644
--- a/webmagic-core/src/main/java/us/codecraft/webmagic/utils/WMCollections.java
+++ b/webmagic-core/src/main/java/us/codecraft/webmagic/utils/WMCollections.java
@@ -6,6 +6,8 @@
 import java.util.Set;
 
 /**
+ * WebMagic collections builders
+ * 
  * @author code4crafter@gmail.com
  *         Date: 16/12/18
  *         Time: 上午10:16
diff --git a/webmagic-extension/src/main/java/us/codecraft/webmagic/downloader/PhantomJSDownloader.java b/webmagic-extension/src/main/java/us/codecraft/webmagic/downloader/PhantomJSDownloader.java
index 6055bdb0f..5fd7f66a1 100644
--- a/webmagic-extension/src/main/java/us/codecraft/webmagic/downloader/PhantomJSDownloader.java
+++ b/webmagic-extension/src/main/java/us/codecraft/webmagic/downloader/PhantomJSDownloader.java
@@ -20,6 +20,7 @@ public class PhantomJSDownloader extends AbstractDownloader {
     private static Logger logger = LoggerFactory.getLogger(PhantomJSDownloader.class);
     private static String crawlJsPath;
     private static String phantomJsCommand = "phantomjs"; // default
+    private static final String HTTP_REQUEST_ERROR = "HTTP request failed";
 
     private int retryNum;
     private int threadNum;
@@ -91,14 +92,14 @@ public Page download(Request request, Task task) {
             logger.info("downloading page: " + request.getUrl());
         }
         String content = getPage(request);
-        if (content.contains("HTTP request failed")) {
+        if (content.contains(HTTP_REQUEST_ERROR)) {
             for (int i = 1; i <= getRetryNum(); i++) {
                 content = getPage(request);
-                if (!content.contains("HTTP request failed")) {
+                if (!content.contains(HTTP_REQUEST_ERROR)) {
                     break;
                 }
             }
-            if (content.contains("HTTP request failed")) {
+            if (content.contains(HTTP_REQUEST_ERROR)) {
                 //when failed
                 Page page = new Page();
                 page.setRequest(request);
diff --git a/webmagic-extension/src/main/java/us/codecraft/webmagic/example/BaiduBaike.java b/webmagic-extension/src/main/java/us/codecraft/webmagic/example/BaiduBaike.java
index 003c5730d..e830bbb09 100644
--- a/webmagic-extension/src/main/java/us/codecraft/webmagic/example/BaiduBaike.java
+++ b/webmagic-extension/src/main/java/us/codecraft/webmagic/example/BaiduBaike.java
@@ -40,9 +40,9 @@ public static void main(String[] args) {
         list.add(String.format(urlTemplate,"太阳能"));
         list.add(String.format(urlTemplate,"地热发电"));
         list.add(String.format(urlTemplate,"地热发电"));
-        List<BaiduBaike> resultItemses = ooSpider.<BaiduBaike>getAll(list);
-        for (BaiduBaike resultItemse : resultItemses) {
-            System.out.println(resultItemse);
+        List<BaiduBaike> multiResultItems = ooSpider.<BaiduBaike>getAll(list);
+        for (BaiduBaike singleResultItems : multiResultItems) {
+            System.out.println(singleResultItems);
         }
         ooSpider.close();
     }
diff --git a/webmagic-extension/src/main/java/us/codecraft/webmagic/handler/PatternProcessor.java b/webmagic-extension/src/main/java/us/codecraft/webmagic/handler/PatternProcessor.java
index f9ef286b2..4f428851b 100644
--- a/webmagic-extension/src/main/java/us/codecraft/webmagic/handler/PatternProcessor.java
+++ b/webmagic-extension/src/main/java/us/codecraft/webmagic/handler/PatternProcessor.java
@@ -7,7 +7,7 @@ public abstract class PatternProcessor extends PatternRequestMatcher implements
     /**
      * @param pattern url pattern to handle
      */
-    public PatternProcessor(String pattern) {
+    protected PatternProcessor(String pattern) {
         super(pattern);
     }
 }
diff --git a/webmagic-extension/src/main/java/us/codecraft/webmagic/handler/PatternRequestMatcher.java b/webmagic-extension/src/main/java/us/codecraft/webmagic/handler/PatternRequestMatcher.java
index 1be61a8f3..59559ed23 100644
--- a/webmagic-extension/src/main/java/us/codecraft/webmagic/handler/PatternRequestMatcher.java
+++ b/webmagic-extension/src/main/java/us/codecraft/webmagic/handler/PatternRequestMatcher.java
@@ -25,7 +25,7 @@ public abstract class PatternRequestMatcher implements RequestMatcher {
     /**
      * @param pattern url pattern to handle
      */
-    public PatternRequestMatcher(String pattern) {
+    protected PatternRequestMatcher(String pattern) {
         this.pattern = pattern;
         this.patternCompiled = Pattern.compile(pattern);
     }
diff --git a/webmagic-extension/src/main/java/us/codecraft/webmagic/model/FieldExtractor.java b/webmagic-extension/src/main/java/us/codecraft/webmagic/model/FieldExtractor.java
index a2cba1332..fa9d45244 100644
--- a/webmagic-extension/src/main/java/us/codecraft/webmagic/model/FieldExtractor.java
+++ b/webmagic-extension/src/main/java/us/codecraft/webmagic/model/FieldExtractor.java
@@ -27,11 +27,13 @@ public FieldExtractor(Field field, Selector selector, Source source, boolean not
     Field getField() {
         return field;
     }
-
+    
+    @Override
     Selector getSelector() {
         return selector;
     }
-
+    
+    @Override
     Source getSource() {
         return source;
     }
@@ -44,6 +46,7 @@ Method getSetterMethod() {
         return setterMethod;
     }
 
+    @Override
     boolean isNotNull() {
         return notNull;
     }
diff --git a/webmagic-extension/src/main/java/us/codecraft/webmagic/utils/MultiKeyMapBase.java b/webmagic-extension/src/main/java/us/codecraft/webmagic/utils/MultiKeyMapBase.java
index d0537163c..1f6f859c8 100755
--- a/webmagic-extension/src/main/java/us/codecraft/webmagic/utils/MultiKeyMapBase.java
+++ b/webmagic-extension/src/main/java/us/codecraft/webmagic/utils/MultiKeyMapBase.java
@@ -18,11 +18,11 @@ public abstract class MultiKeyMapBase {
     @SuppressWarnings("rawtypes")
     private Class<? extends Map> protoMapClass = DEFAULT_CLAZZ;
 
-    public MultiKeyMapBase() {
+    protected MultiKeyMapBase() {
     }
 
     @SuppressWarnings("rawtypes")
-    public MultiKeyMapBase(Class<? extends Map> protoMapClass) {
+    protected MultiKeyMapBase(Class<? extends Map> protoMapClass) {
         this.protoMapClass = protoMapClass;
     }