1.增加拦截器实例化的判断，#36。

2.httpClient-4.x-plugin，全面支持4.0版本。完成4.2和4.3差异化API测试。

skywalking-api/src/main/java/com/ai/cloud/skywalking/plugin/interceptor/EnhanceClazz4Interceptor.java

@@ -50,7 +50,7 @@ public class EnhanceClazz4Interceptor {
 
 	private void enhance0(String interceptorDefineClassName)
 			throws InstantiationException, IllegalAccessException,
-			ClassNotFoundException {
+			ClassNotFoundException, EnhanceException {
 		logger.debug("prepare to enhance class by {}.",
 				interceptorDefineClassName);
 		InterceptorDefine define = (InterceptorDefine) Class.forName(
@@ -94,6 +94,9 @@ public class EnhanceClazz4Interceptor {
 		 * required by interceptorDefineClass. <br/>
 		 */
 		IAroundInterceptor interceptor = define.instance();
+		if(interceptor == null){
+			throw new EnhanceException("no IAroundInterceptor instance. "); 
+		}
 
 		DynamicType.Builder<?> newClassBuilder = new ByteBuddy().subclass(
 				originClass, ConstructorStrategy.Default.IMITATE_SUPER_CLASS);

skywalking-api/src/main/java/com/ai/cloud/skywalking/plugin/interceptor/EnhanceException.java

+package com.ai.cloud.skywalking.plugin.interceptor;
+
+public class EnhanceException extends Exception {
+	private static final long serialVersionUID = -2234782755784217255L;
+
+	public EnhanceException(String message) {
+        super(message);
+    }
+
+    public EnhanceException(String message, Throwable cause) {
+        super(message, cause);
+    }
+}

skywalking-sdk-plugin/httpClient-4.x-plugin/pom.xml

@@ -23,12 +23,21 @@
 			<version>1.0-SNAPSHOT</version>
 		</dependency>
 		
+		
 		<dependency>
 			<groupId>org.apache.httpcomponents</groupId>
 			<artifactId>httpclient</artifactId>
 			<version>4.3</version>
 			<scope>test</scope>
 		</dependency>
+		<!-- 
+		<dependency>
+			<groupId>org.apache.httpcomponents</groupId>
+			<artifactId>httpclient</artifactId>
+			<version>4.2</version>
+			<scope>test</scope>
+		</dependency>
+		-->
 		
 		<dependency>
 			<groupId>org.apache.logging.log4j</groupId>

skywalking-sdk-plugin/httpClient-4.x-plugin/src/main/java/org/skywalking/httpClient/v4/plugin/HttpClientExecuteInterceptor.java

@@ -12,9 +12,9 @@ import com.ai.cloud.skywalking.plugin.interceptor.MethodInvokeContext;
 
 public class HttpClientExecuteInterceptor implements IAroundInterceptor {
 	/**
-	 * TODO: need laod from config
+	 * default headname of sky walking context<br/>
 	 */
-	public static String traceHearName = "";
+	public static String TRACE_HEAD_NAME = "SkyWalking-TRACING-NAME";
 
 	private static RPCBuriedPointSender sender = new RPCBuriedPointSender();
 
@@ -35,7 +35,7 @@ public class HttpClientExecuteInterceptor implements IAroundInterceptor {
 		HttpRequest httpRequest = (HttpRequest) allArguments[1];
 		httpRequest
 				.setHeader(
-						traceHearName,
+						TRACE_HEAD_NAME,
 						"ContextData="
 								+ sender.beforeSend(
 										Identification

skywalking-sdk-plugin/httpClient-4.x-plugin/src/main/java/org/skywalking/httpClient/v4/plugin/define/AbstractHttpClientPluginDefine.java

 package org.skywalking.httpClient.v4.plugin.define;
 
-import io.netty.handler.codec.http.HttpRequest;
-
-import javax.xml.ws.spi.http.HttpContext;
-
-import org.apache.http.HttpHost;
-
 import com.ai.cloud.skywalking.plugin.interceptor.InterceptPoint;
 
 public class AbstractHttpClientPluginDefine extends HttpClientPluginDefine {
@@ -20,13 +14,10 @@ public class AbstractHttpClientPluginDefine extends HttpClientPluginDefine {
 	 * public final HttpResponse execute(HttpHost target, HttpRequest request,
 	 * HttpContext context)<br/>
 	 * 
-	 * since version 4.3，intercept method: doExecute<br/>
 	 */
 	@Override
 	public InterceptPoint[] getBeInterceptedMethods() {
 		return new InterceptPoint[] {
-				new InterceptPoint("doExecute"),
-				new InterceptPoint("execute", HttpHost.class,
-						HttpRequest.class, HttpContext.class) };
+				new InterceptPoint("doExecute")};
 	}
 }

skywalking-sdk-plugin/httpClient-4.x-plugin/src/main/java/org/skywalking/httpClient/v4/plugin/define/DefaultRequestDirectorPluginDefine.java

+package org.skywalking.httpClient.v4.plugin.define;
+
+import com.ai.cloud.skywalking.plugin.interceptor.InterceptPoint;
+
+public class DefaultRequestDirectorPluginDefine extends HttpClientPluginDefine {
+	/**
+	 * DefaultRequestDirector is default implement.<br/>
+	 * usually use in version 4.0-4.2<br/>
+	 * since 4.3, this class is Deprecated.
+	 */
+	@Override
+	public String getBeInterceptedClassName() {
+		return "org.apache.http.impl.client.DefaultRequestDirector";
+	}
+
+	@Override
+	public InterceptPoint[] getBeInterceptedMethods() {
+		return new InterceptPoint[] {
+				new InterceptPoint("execute")};
+	}
+
+}

skywalking-sdk-plugin/httpClient-4.x-plugin/src/main/resources/skywalking-plugin.def

 org.skywalking.httpClient.v4.plugin.define.AbstractHttpClientPluginDefine
 org.skywalking.httpClient.v4.plugin.define.InternalHttpClientPluginDefine
-org.skywalking.httpClient.v4.plugin.define.MinimalHttpClientPluginDefine
\ No newline at end of file
+org.skywalking.httpClient.v4.plugin.define.MinimalHttpClientPluginDefine
+org.skywalking.httpClient.v4.plugin.define.DefaultRequestDirectorPluginDefine
\ No newline at end of file

skywalking-sdk-plugin/httpClient-4.x-plugin/src/test/java/org/skywalking/httpClient/v4/plugin/TestHttpClientV42.java

+package org.skywalking.httpClient.v4.plugin;
+
+import java.io.BufferedReader;
+import java.io.IOException;
+import java.io.InputStream;
+import java.io.InputStreamReader;
+import java.lang.reflect.InvocationTargetException;
+import java.sql.SQLException;
+
+import org.apache.http.HttpEntity;
+import org.apache.http.HttpResponse;
+import org.apache.http.client.ClientProtocolException;
+import org.apache.http.client.HttpClient;
+import org.apache.http.client.methods.HttpGet;
+import org.apache.http.impl.client.DefaultHttpClient;
+import org.junit.Test;
+
+import com.ai.cloud.skywalking.plugin.TracingBootstrap;
+
+public class TestHttpClientV42 {
+	@Test
+	public void testsql() throws IllegalAccessException,
+			IllegalArgumentException, InvocationTargetException,
+			NoSuchMethodException, SecurityException, ClassNotFoundException {
+		TracingBootstrap
+				.main(new String[] { "org.skywalking.httpClient.v4.plugin.TestHttpClientV42" });
+	}
+
+	public static void main(String[] args) throws ClassNotFoundException,
+			SQLException, InterruptedException, ClientProtocolException, IOException {
+		 // 默认的client类。  
+        HttpClient client = new DefaultHttpClient();  
+        // 设置为get取连接的方式.  
+        HttpGet get = new HttpGet("http://www.baidu.com");  
+        // 得到返回的response.  
+        HttpResponse response = client.execute(get);  
+        // 得到返回的client里面的实体对象信息.  
+        HttpEntity entity = response.getEntity();  
+        if (entity != null) {  
+            System.out.println("内容编码是：" + entity.getContentEncoding());  
+            System.out.println("内容类型是：" + entity.getContentType());  
+            // 得到返回的主体内容.  
+            InputStream instream = entity.getContent();  
+            try {  
+                BufferedReader reader = new BufferedReader(  
+                        new InputStreamReader(instream, "UTF-8"));  
+                System.out.println(reader.readLine());  
+            } catch (Exception e) {  
+                e.printStackTrace();  
+            } finally {  
+                instream.close();  
+            }  
+        }  
+  
+        // 关闭连接.  
+        client.getConnectionManager().shutdown();  
+        
+        Thread.sleep(5*1000);
+	}
+}