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1. arthas安装启动
1.1 安装
arthas.aliyun.com/doc/install…
1.2 启动
运行java -jar arthas-boot.jar 需要进入到arthas的解压目录中运行(否则会报错没有权限运行该jar),可以通过命令:
find / -name arthas-boot.jar查找安装路径,如:/Users/**/.arthas/lib/3.4.0/arthas
2. 查看扩展接口适配器类的源码
[arthas@11050]$ jad org.apache.dubbo.rpc.Protocol$Adaptive
Affect(row-cnt:0) cost in 14 ms.
No class found for: org
[arthas@11050]$ jad org.apache.dubbo.rpc.Protocol$Adaptive
ClassLoader:
+-sun.misc.Launcher$AppClassLoader@18b4aac2
+-sun.misc.Launcher$ExtClassLoader@3541cb24
Location:
/Users/haoshaofei/IdeaProjects/dubbo-3.0/dubbo-demo/dubbo-demo-xml/dubbo-demo-xml-provider/target/classes/
/*
* Decompiled with CFR.
*
* Could not load the following classes:
* org.apache.dubbo.common.URL
* org.apache.dubbo.common.extension.ExtensionLoader
* org.apache.dubbo.rpc.Exporter
* org.apache.dubbo.rpc.Invoker
* org.apache.dubbo.rpc.Protocol
* org.apache.dubbo.rpc.RpcException
*/
package org.apache.dubbo.rpc;
import java.util.List;
import org.apache.dubbo.common.URL;
import org.apache.dubbo.common.extension.ExtensionLoader;
import org.apache.dubbo.rpc.Exporter;
import org.apache.dubbo.rpc.Invoker;
import org.apache.dubbo.rpc.Protocol;
import org.apache.dubbo.rpc.RpcException;
public class Protocol$Adaptive
implements Protocol {
public Exporter export(Invoker arg0) throws RpcException {
String extName;
/*31*/ if (arg0 == null) {
throw new IllegalArgumentException("org.apache.dubbo.rpc.Invoker argument == null");
}
/*32*/ if (arg0.getUrl() == null) {
throw new IllegalArgumentException("org.apache.dubbo.rpc.Invoker argument getUrl() == null");
}
URL url = arg0.getUrl();
/*35*/ String string = extName = url.getProtocol() == null ? "dubbo" : url.getProtocol();
/*36*/ if (extName == null) {
throw new IllegalStateException("Failed to get extension (org.apache.dubbo.rpc.Protocol) name from url (" + url.toString() + ") use keys([protocol])");
}
/*38*/ Protocol extension = (Protocol)ExtensionLoader.getExtensionLoader(Protocol.class).getExtension(extName);
/*39*/ return extension.export(arg0);
}
public List getServers() {
throw new UnsupportedOperationException("The method public default java.util.List org.apache.dubbo.rpc.Protocol.getServers() of interface org.apache.dubbo.rpc.Protocol is not adaptive method!");
}
public void destroy() {
throw new UnsupportedOperationException("The method public abstract void org.apache.dubbo.rpc.Protocol.destroy() of interface org.apache.dubbo.rpc.Protocol is not adaptive method!");
}
public int getDefaultPort() {
throw new UnsupportedOperationException("The method public abstract int org.apache.dubbo.rpc.Protocol.getDefaultPort() of interface org.apache.dubbo.rpc.Protocol is not adaptive method!");
}
public Invoker refer(Class arg0, URL arg1) throws RpcException {
String extName;
/*19*/ if (arg1 == null) {
throw new IllegalArgumentException("url == null");
}
/*20*/ URL url = arg1;
/*21*/ String string = extName = url.getProtocol() == null ? "dubbo" : url.getProtocol();
/*22*/ if (extName == null) {
throw new IllegalStateException("Failed to get extension (org.apache.dubbo.rpc.Protocol) name from url (" + url.toString() + ") use keys([protocol])");
}
/*24*/ Protocol extension = (Protocol)ExtensionLoader.getExtensionLoader(Protocol.class).getExtension(extName);
/*27*/ return extension.refer(arg0, arg1);
}
}
Affect(row-cnt:1) cost in 601 ms.
3. 查看服务提供端 Wrapper 类的源码
Dubbo 会给每个服务提供者的实现生成一个 Wrapper 类，在这个 Wrapper 类里最终是调用服务提供者的接口实现类， Wrapper 类的存在是为了减少反射的调用。那么我们可以使用 jad 命令方便地查看被包装后的某一个服务实现类，以便探究它是如何工作的。
为此，在启动 Dubbo 服务提供端和 Arthas 后，在 Arthas 的控制台执行下面的命令即可：
[arthas@11050]$ sc *Wrapper*
com.google.gson.internal.bind.TypeAdapterRuntimeTypeWrapper
com.sun.org.apache.xerces.internal.util.EntityResolverWrapper
com.sun.org.apache.xerces.internal.util.ErrorHandlerWrapper
com.taobao.arthas.core.shell.handlers.term.CloseHandlerWrapper
org.apache.dubbo.common.bytecode.Wrapper
org.apache.dubbo.common.bytecode.Wrapper$$Lambda$145/1473981203
org.apache.dubbo.common.bytecode.Wrapper$$Lambda$146/1552326679
org.apache.dubbo.common.bytecode.Wrapper$$Lambda$147/1383519982
org.apache.dubbo.common.bytecode.Wrapper$1
org.apache.dubbo.common.bytecode.Wrapper0
org.apache.dubbo.common.bytecode.Wrapper1
org.apache.dubbo.common.bytecode.Wrapper2
org.apache.dubbo.common.bytecode.Wrapper3
org.apache.dubbo.common.extension.Wrapper
org.apache.dubbo.common.extension.support.WrapperComparator
org.apache.dubbo.common.extension.support.WrapperComparator$OrderInfo
...
[arthas@11050]$ jad org.apache.dubbo.common.bytecode.Wrapper1
ClassLoader:
+-sun.misc.Launcher$AppClassLoader@18b4aac2
+-sun.misc.Launcher$ExtClassLoader@3541cb24
Location:
/Users/haoshaofei/IdeaProjects/dubbo-3.0/dubbo-common/target/classes/
/*
* Decompiled with CFR.
*
* Could not load the following classes:
* org.apache.dubbo.common.bytecode.ClassGenerator$DC
* org.apache.dubbo.common.bytecode.NoSuchMethodException
* org.apache.dubbo.common.bytecode.NoSuchPropertyException
* org.apache.dubbo.common.bytecode.Wrapper
* org.apache.dubbo.demo.provider.GreetingServiceImpl
*/
package org.apache.dubbo.common.bytecode;
import java.lang.reflect.InvocationTargetException;
import java.util.Map;
import org.apache.dubbo.common.bytecode.ClassGenerator;
import org.apache.dubbo.common.bytecode.NoSuchMethodException;
import org.apache.dubbo.common.bytecode.NoSuchPropertyException;
import org.apache.dubbo.common.bytecode.Wrapper;
import org.apache.dubbo.demo.provider.GreetingServiceImpl;
public class Wrapper1
extends Wrapper
implements ClassGenerator.DC {
public static String[] pns;
public static Map pts;
public static String[] mns;
public static String[] dmns;
public static Class[] mts0;
public Object invokeMethod(Object object, String string, Class[] classArray, Object[] objectArray) throws InvocationTargetException {
GreetingServiceImpl greetingServiceImpl;
try {
greetingServiceImpl = (GreetingServiceImpl)object;
}
catch (Throwable throwable) {
throw new IllegalArgumentException(throwable);
}
try {
if ("hello".equals(string) && classArray.length == 0) {
return greetingServiceImpl.hello();
}
}
catch (Throwable throwable) {
throw new InvocationTargetException(throwable);
}
throw new NoSuchMethodException(new StringBuffer().append("Not found method \"").append(string).append("\" in class org.apache.dubbo.demo.provider.GreetingServiceImpl.").toString());
}
public Class getPropertyType(String string) {
return (Class)pts.get(string);
}
public String[] getPropertyNames() {
return pns;
}
public Object getPropertyValue(Object object, String string) {
try {
GreetingServiceImpl greetingServiceImpl = (GreetingServiceImpl)object;
}
catch (Throwable throwable) {
throw new IllegalArgumentException(throwable);
}
throw new NoSuchPropertyException(new StringBuffer().append("Not found property \"").append(string).append("\" field or getter method in class org.apache.dubbo.demo.provider.GreetingServiceImpl.").toString());
}
public void setPropertyValue(Object object, String string, Object object2) {
try {
GreetingServiceImpl greetingServiceImpl = (GreetingServiceImpl)object;
}
catch (Throwable throwable) {
throw new IllegalArgumentException(throwable);
}
throw new NoSuchPropertyException(new StringBuffer().append("Not found property \"").append(string).append("\" field or setter method in class org.apache.dubbo.demo.provider.GreetingServiceImpl.").toString());
}
public String[] getMethodNames() {
return mns;
}
public String[] getDeclaredMethodNames() {
return dmns;
}
public boolean hasProperty(String string) {
return pts.containsKey(string);
}
}
Affect(row-cnt:1) cost in 231 ms.
[arthas@11050]$
参考文章
Dubbo3.0源码注释github地址
深度剖析Apache Dubbo核心技术内幕
dubbo源码系列
dubbo源码分析专栏
