5.Dubbo Principle Analysis-agent's javassist bytecode technology generation agent (GO)

Reprinted from The Fall of the column http://blog.csdn.net/quhongwei_zhanqiu/article/details/41597219

Javassistproxyfactory: Using bytecode technology to create objects

 public <T> T getproxy (invoker<t> invoker,class<?>[] interfaces) {       return  (T) Proxy.getproxy (interfaces). newinstance (New Invokerinvocationhandler (Invoker));}

Like the JDK generation proxy, the proxy class here is not the class that comes with the build proxy object in the JDK:

　　Com.alibaba.dubbo.common.bytecode.Proxy.

This proxy class is written by Dubbo itself, using the Javassist tool to generate proxy code with the interface to be proxied.

Get Invoker Object

     Public<T> invoker<t> Getinvoker (T proxy, class<t>type, url url) {        FinalWrapper Wrapper = Wrapper.getwrapper (Proxy.getclass (). GetName (). IndexOf (' $ ') < 0?proxy.getclass (): type); return NewAbstractproxyinvoker<t>(proxy, type, URL) {protectedObject Doinvoke (T proxy, String methodName, Class<?>[] parametertypes, object[] arguments)throwsThrowable {returnWrapper.invokemethod (proxy, MethodName, parametertypes, arguments);    }        }; }

Creates a wrapper object for an incoming proxy object based on its class information wrapper

Returns an instance of the Invoker object that can be invoker based on the name of the method contained in the incoming invocation object.

Method parameter to call the proxy object to return the result of the call

Com.alibaba.dubbo.common.bytecode.Proxy tool class for generating proxy objects

1. Iterate through all the entry interfaces to; Split the connection, with it as key to map for cache lookup If there is, the proxy object has been created to return

2. Using Atomiclong object self-increment gets a long array to be used as the suffix of the production class to prevent conflicts

3. The traversal interface gets all the defined methods, added to a set set<string> worked, used to weigh,

Gets the index of method y should be in the methods array subscript IX

Gets the parameter type of the method and the return type

Build method Body return ret= Handler.invoke (this, Methods[ix], args);

The method call here is actually delegated to the Invokerinvocationhandler instance object, to invoke the real instance method into the methods array .

4. Create a proxy instance object proxyinstance

The class name is Pkg + ". POxy" +id = package name + ". POxy" + self-increment value

Add static field method[] methods;

Add an Instance object Invokerinvocationhandler Hanler

The Add constructor parameter is Invokerinvocationhandler

Add parameterless constructor

Generate corresponding bytecode using the tool class Classgenerator

5. Create a proxy object whose newinstance (handler) method is used to create a proxy based on our interface

　　

Proxy object name proxy + ID

Inherit from proxy, so to implement the Newinstance method

Add a default constructor

Implementation method newinstance code, new PCN (Hadler) Here PCN is the previously generated proxy object class name

Use the tool class Classgenerator to generate bytecode and instantiate objects to return

5.Dubbo Principle Analysis-agent's javassist bytecode technology generation agent (GO)