测试代码已经上传到github上了
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以上为spring实例化列的方法路径，之前会有很多预处理操作
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融合注入属性
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初始方法 和销毁方法
private LifecycleMetadata buildLifecycleMetadata(final Class<?> clazz) {
final boolean debug = logger.isDebugEnabled();
LinkedList<LifecycleElement> initMethods = new LinkedList<LifecycleElement>();
LinkedList<LifecycleElement> destroyMethods = new LinkedList<LifecycleElement>();
Class<?> targetClass = clazz;
do {
final LinkedList<LifecycleElement> currInitMethods = new LinkedList<LifecycleElement>();
final LinkedList<LifecycleElement> currDestroyMethods = new LinkedList<LifecycleElement>();
ReflectionUtils.doWithLocalMethods(targetClass, new ReflectionUtils.MethodCallback() {
@Override
public void doWith(Method method) throws IllegalArgumentException, IllegalAccessException {
if (initAnnotationType != null) {
if (method.getAnnotation(initAnnotationType) != null) {
LifecycleElement element = new LifecycleElement(method);
currInitMethods.add(element);
if (debug) {
logger.debug("Found init method on class [" + clazz.getName() + "]: " + method);
}
}
}
if (destroyAnnotationType != null) {
if (method.getAnnotation(destroyAnnotationType) != null) {
currDestroyMethods.add(new LifecycleElement(method));
if (debug) {
logger.debug("Found destroy method on class [" + clazz.getName() + "]: " + method);
}
}
}
}
});
initMethods.addAll(0, currInitMethods);
destroyMethods.addAll(currDestroyMethods);
targetClass = targetClass.getSuperclass();
}
while (targetClass != null && targetClass != Object.class);
return new LifecycleMetadata(clazz, initMethods, destroyMethods);
}
一个回调模式设计比较好的例子
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ServiceConfig
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连接池
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心跳更新
附带心跳例子
public class ScheduledThreadPoolTest {
public static void main(String[] args) {
LinkedBlockingDeque<String> workQueue = new LinkedBlockingDeque<String>();
ScheduledExecutorService scheduledExecutorService
= Executors.newScheduledThreadPool(
8);
for (int i = 0; i < 10; i++) {
workQueue.add(""+i);
}
ScheduledFuture scheduledFuture = scheduledExecutorService.scheduleAtFixedRate(
new Runnable() {
@Override
public void run() {
System.out.println(Thread.currentThread().getName()+":"+workQueue.poll());
}
},
1000,
1000,
TimeUnit.MICROSECONDS
);
for (int i = 10; i < 200; i++) {
workQueue.add(""+i);
}
// scheduledExecutorService.schedule(new Callable<String>() {
// @Override
// public String call() throws Exception {
// String message = workQueue.poll();
//
// System.out.println(Thread.currentThread().getName()+":"+message);
// return Thread.currentThread().getName()+"";
// }
// },500, TimeUnit.MICROSECONDS);
}
}
dubbo中HeaderExchageServer的启动源码
private void startHeatbeatTimer() {
stopHeartbeatTimer();
if (heartbeat > 0) {
// 采用固定延迟心跳方式
heatbeatTimer = scheduled.scheduleWithFixedDelay(
new HeartBeatTask( new HeartBeatTask.ChannelProvider() {
public Collection<Channel> getChannels() {
return Collections.unmodifiableCollection(
HeaderExchangeServer.this.getChannels() );
}
}, heartbeat, heartbeatTimeout),
heartbeat, heartbeat,TimeUnit.MILLISECONDS);
}
}
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注册zk
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启动接口配置
接口代理主要的几个类：
ReferenceBean
ReferenceConfig
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创建接口代理的入口代码
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ClassHelper.getCallerClassLoader(.class)
dubbo 接口代理高潮部分：
com.alibaba.dubbo.common.bytecode.Proxy.getProxy
public static Proxy getProxy(ClassLoader cl, Class<?>... ics)
{
if( ics.length > 65535 )
throw new IllegalArgumentException("interface limit exceeded");
StringBuilder sb = new StringBuilder();
for(int i=0;i<ics.length;i++)
{
String itf = ics[i].getName();
if( !ics[i].isInterface() )
throw new RuntimeException(itf + " is not a interface.");
Class<?> tmp = null;
try
{
tmp = Class.forName(itf, false, cl);
}
catch(ClassNotFoundException e)
{}
if( tmp != ics[i] )
throw new IllegalArgumentException(ics[i] + " is not visible from class loader");
sb.append(itf).append(';');
}
// use interface class name list as key.
String key = sb.toString();
// get cache by class loader.
Map<String, Object> cache;
synchronized( ProxyCacheMap )
{
cache = ProxyCacheMap.get(cl);
if( cache == null )
{
cache = new HashMap<String, Object>();
ProxyCacheMap.put(cl, cache);
}
}
Proxy proxy = null;
synchronized( cache )
{
do
{
Object value = cache.get(key);
if( value instanceof Reference<?> )
{
proxy = (Proxy)((Reference<?>)value).get();
if( proxy != null )
return proxy;
}
if( value == PendingGenerationMarker )
{
try{ cache.wait(); }catch(InterruptedException e){}
}
else
{
cache.put(key, PendingGenerationMarker);
break;
}
}
while( true );
}
long id = PROXY_CLASS_COUNTER.getAndIncrement();
String pkg = null;
ClassGenerator ccp = null, ccm = null;
try
{
ccp = ClassGenerator.newInstance(cl);
Set<String> worked = new HashSet<String>();
List<Method> methods = new ArrayList<Method>();
for(int i=0;i<ics.length;i++)
{
if( !Modifier.isPublic(ics[i].getModifiers()) )
{
String npkg = ics[i].getPackage().getName();
if( pkg == null )
{
pkg = npkg;
}
else
{
if( !pkg.equals(npkg) )
throw new IllegalArgumentException("non-public interfaces from different packages");
}
}
ccp.addInterface(ics[i]);
for( Method method : ics[i].getMethods() )
{
String desc = ReflectUtils.getDesc(method);
if( worked.contains(desc) )
continue;
worked.add(desc);
int ix = methods.size();
Class<?> rt = method.getReturnType();
Class<?>[] pts = method.getParameterTypes();
StringBuilder code = new StringBuilder("Object[] args = new Object[").append(pts.length).append("];");
for(int j=0;j<pts.length;j++)
code.append(" args[").append(j).append("] = ($w)$").append(j+1).append(";");
code.append(" Object ret = handler.invoke(this, methods[" + ix + "], args);");
if( !Void.TYPE.equals(rt) )
code.append(" return ").append(asArgument(rt, "ret")).append(";");
methods.add(method);
ccp.addMethod(method.getName(), method.getModifiers(), rt, pts, method.getExceptionTypes(), code.toString());
}
}
if( pkg == null )
pkg = PACKAGE_NAME;
// create ProxyInstance class.
String pcn = pkg + ".proxy" + id;
ccp.setClassName(pcn);
ccp.addField("public static java.lang.reflect.Method[] methods;");
ccp.addField("private " + InvocationHandler.class.getName() + " handler;");
ccp.addConstructor(Modifier.PUBLIC, new Class<?>[]{ InvocationHandler.class }, new Class<?>[0], "handler=$1;");
ccp.addDefaultConstructor();
Class<?> clazz = ccp.toClass();
clazz.getField("methods").set(null, methods.toArray(new Method[0]));
// create Proxy class.
String fcn = Proxy.class.getName() + id;
ccm = ClassGenerator.newInstance(cl);
ccm.setClassName(fcn);
ccm.addDefaultConstructor();
ccm.setSuperClass(Proxy.class);
ccm.addMethod("public Object newInstance(" + InvocationHandler.class.getName() + " h){ return new " + pcn + "($1); }");
Class<?> pc = ccm.toClass();
proxy = (Proxy)pc.newInstance();
}
catch(RuntimeException e)
{
throw e;
}
catch(Exception e)
{
throw new RuntimeException(e.getMessage(), e);
}
finally
{
// release ClassGenerator
if( ccp != null )
ccp.release();
if( ccm != null )
ccm.release();
synchronized( cache )
{
if( proxy == null )
cache.remove(key);
else
cache.put(key, new WeakReference<Proxy>(proxy));
cache.notifyAll();
}
}
return proxy;
}
在做以上步骤的时候，首先需要通过zookeeper验证下，是否已经注册与之对应的服务，当然也可以将接口配置成check="false"，这样启动时不检查，而是通过心跳方式检查。
接下来我们梳理步骤
首先引入两个类，在本例中，我的消费接口为
interface cn.wd.easyx.service.api.QueryAdapter 自定义
interface com.alibaba.dubbo.rpc.service.EchoService dubbo定义的一个空接口。
第一步：确保都在同一个classloader中
第二步：将所有的接口加载类加载器为键的 Map中
第三步：根据classloader创建ClassGenerator dubbo基于javassist二进制的字节码生成器
第四步：遍历两个接口中的所有方法，将接口中的所有方法注册到ClassGenerator中，然后生成一个以com.alibaba.dubbo.common.bytecode.proxy0为Class.name的class实例
第五步：再创建一个基于cl加载器的ClassGenerator的实例，设置同名为com.alibaba.dubbo.common.bytecode.proxy0，继承Proxy.class,添加实例化方法，生成实例化proxy
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为了更加直观看到dubbo中的ClassGenerator到底做了哪些东西，我们做一个实验：
在自己的项目中引入dubbo 依赖
<dependency>
<groupId>com.alibaba</groupId>
<artifactId>dubbo</artifactId>
<version>2.5.3</version>
</dependency>
模仿dubbo中的EchoService接口
public interface EchoService {
Object $eche(Object obj);
}
自定义接口：
public interface Interface1 {
String getName();
String setName(String name);
}
拷贝Proxy类，将类名给为MyProxy，
String pcn = pkg + ".proxy" + id;
ccp.setClassName(pcn);
ccp.addField("public static java.lang.reflect.Method[] methods;");
ccp.addField("private " + InvocationHandler.class.getName() + " handler;");
ccp.addConstructor(Modifier.PUBLIC, new Class<?>[]{ InvocationHandler.class }, new Class<?>[0], "handler=$1;");
ccp.addDefaultConstructor();
Class<?> clazz = ccp.toClass();
//把生成的class文件写入文件
byte[] byteArr = ccp.getCtClass(clazz).toBytecode();
FileOutputStream fos = new FileOutputStream(new File("Proxy.class"));
fos.write(byteArr);
fos.close();
clazz.getField("methods").set(null, methods.toArray(new Method[0]));
// create Proxy class.
String fcn = MyProxy.class.getName() + id;
ccm = MyClassGenerator.newInstance(cl);
ccm.setClassName(fcn);
ccm.addDefaultConstructor();
ccm.setSuperClass(MyProxy.class);
ccm.addMethod("public Object newInstance(" + InvocationHandler.class.getName() + " h){ return new " + pcn + "($1); }");
Class<?> pc = ccm.toClass();
//把生成的class文件写入文件
byte[] byteArr2 = ccm.getCtClass(pc).toBytecode();
FileOutputStream fos2 = new FileOutputStream(new File("Proxy2.class"));
fos2.write(byteArr2);
fos2.close();
拷贝ClassGenerator类，改名为MyClassGenerator，将getCtClass方法改成public
public CtClass getCtClass(Class<?> c) throws NotFoundException
{
return mPool.get(c.getName());
}
运行代码
public static void main(String[] args) {
Class<?>[] interfaces = new Class[]{Interface1.class,EchoService.class};
MyProxy.getProxy(interfaces).newInstance(new InvocationHandler() {
@Override
public Object invoke(Object proxy, Method method, Object[] args) throws Throwable {
return null;
}
});
}
动态生成的字节码
public class proxy0 implements DC, EchoService, Interface1 {
public static Method[] methods;
private InvocationHandler handler;
public String getName() {
Object[] var1 = new Object[0];
Object var2 = this.handler.invoke(this, methods[0], var1);
return (String)var2;
}
public String setName(String var1) {
Object[] var2 = new Object[]{var1};
Object var3 = this.handler.invoke(this, methods[1], var2);
return (String)var3;
}
public Object $eche(Object var1) {
Object[] var2 = new Object[]{var1};
Object var3 = this.handler.invoke(this, methods[2], var2);
return (Object)var3;
}
public proxy0() {
}
public proxy0(InvocationHandler var1) {
this.handler = var1;
}
}
public class MyProxy0 extends MyProxy implements DC {
public Object newInstance(InvocationHandler var1) {
return new proxy0(var1);
}
public MyProxy0() {
}
}
