jdk8：Aop的代理研究

版权声明：本文为博主原创文章，未经博主允许不得转载。 https://blog.csdn.net/u012998254/article/details/82534036

Spring AOP两种实现机制是什么？

1. 如果是有接口声明的类进行AOP 时，spring调用的是java.lang.reflection.Proxy 类来做处理
2. 如果是没有接口声明的类时， spring通过cglib包和内部类来实现

在AOP，权限控制，事务管理等方面都有动态代理的实现。JDK本身有实现动态代理技术，但是略有限制，即被代理的类必须实现某个接口，否则无法使用
JDK自带的动态代理，因此，如果不满足条件，就只能使用另一种更加灵活，功能更加强大的动态代理技术—— CGLIB。Spring里会自动在JDK的代理和CGLIB之间切换，同时我们也可以强制Spring使用CGLIB。

Spring AOP应用场景:性能检测，访问控制，日志管理，事务等。
默认的策略是如果目标类实现接口，则使用JDK动态代理技术，如果目标对象没有实现接口，则默认会采用CGLIB代理

配置了这句话的话就会强制使用cglib代理。 默认就是false。

jdk代理

使用

public interface IBookService {

    public void readBook();
}

public class BookService implements IBookService {

    @Override
    public void readBook() {

        System.out.println("----- read book!");
    }
}

public class BookInvocationHandler implements InvocationHandler {

    private Object target;

    public BookInvocationHandler(Object target) {
        super();
        this.target = target;
    }

    @Override
    public Object invoke(Object proxy, Method method, Object[] args) throws Throwable {
        return method.invoke(target, args);
    }

    public Object getProxy() {
        return Proxy.newProxyInstance(Thread.currentThread().getContextClassLoader(),
                target.getClass().getInterfaces(), this);
    }
}

JDK动态生成代理类的字节

newProxyInstance，返回一个指定接口的代理类实例，该接口可以将方法调用指派到指定的调用处理程序

   public static Object newProxyInstance(ClassLoader loader,
                                          Class<?>[] interfaces,
                                          InvocationHandler h)
        throws IllegalArgumentException
    {
        Objects.requireNonNull(h);

        final Class<?>[] intfs = interfaces.clone();
        final SecurityManager sm = System.getSecurityManager();
        if (sm != null) {
            checkProxyAccess(Reflection.getCallerClass(), loader, intfs);
        }

        /*
         * Look up or generate the designated proxy class.
         */
        Class<?> cl = getProxyClass0(loader, intfs);

        /*
         * Invoke its constructor with the designated invocation handler.
         */
        try {
            if (sm != null) {
                checkNewProxyPermission(Reflection.getCallerClass(), cl);
            }

            final Constructor<?> cons = cl.getConstructor(constructorParams);
            final InvocationHandler ih = h;
            if (!Modifier.isPublic(cl.getModifiers())) {
                AccessController.doPrivileged(new PrivilegedAction<Void>() {
                    public Void run() {
                        cons.setAccessible(true);
                        return null;
                    }
                });
            }
            return cons.newInstance(new Object[]{h});
        } catch (IllegalAccessException|InstantiationException e) {
            throw new InternalError(e.toString(), e);
        } catch (InvocationTargetException e) {
            Throwable t = e.getCause();
            if (t instanceof RuntimeException) {
                throw (RuntimeException) t;
            } else {
                throw new InternalError(t.toString(), t);
            }
        } catch (NoSuchMethodException e) {
            throw new InternalError(e.toString(), e);
        }
    }

getProxyClass0代码

   private static Class<?> getProxyClass0(ClassLoader loader,
                                           Class<?>... interfaces) {
        if (interfaces.length > 65535) {
            throw new IllegalArgumentException("interface limit exceeded");
        }

        // If the proxy class defined by the given loader implementing
        // the given interfaces exists, this will simply return the cached copy;
        // otherwise, it will create the proxy class via the ProxyClassFactory
        return proxyClassCache.get(loader, interfaces);
    }

ProxyClassFactory

 private static final class ProxyClassFactory
        implements BiFunction<ClassLoader, Class<?>[], Class<?>>
    {
        // prefix for all proxy class names
        private static final String proxyClassNamePrefix = "$Proxy";

        // next number to use for generation of unique proxy class names
        private static final AtomicLong nextUniqueNumber = new AtomicLong();

        @Override
        public Class<?> apply(ClassLoader loader, Class<?>[] interfaces) {

            Map<Class<?>, Boolean> interfaceSet = new IdentityHashMap<>(interfaces.length);
            for (Class<?> intf : interfaces) {
                /*
                 * Verify that the class loader resolves the name of this
                 * interface to the same Class object.
                 */
                Class<?> interfaceClass = null;
                try {
                    interfaceClass = Class.forName(intf.getName(), false, loader);
                } catch (ClassNotFoundException e) {
                }
                if (interfaceClass != intf) {
                    throw new IllegalArgumentException(
                        intf + " is not visible from class loader");
                }
                /*
                 * Verify that the Class object actually represents an
                 * interface.
                 */
                if (!interfaceClass.isInterface()) {
                    throw new IllegalArgumentException(
                        interfaceClass.getName() + " is not an interface");
                }
                /*
                 * Verify that this interface is not a duplicate.
                 */
                if (interfaceSet.put(interfaceClass, Boolean.TRUE) != null) {
                    throw new IllegalArgumentException(
                        "repeated interface: " + interfaceClass.getName());
                }
            }

            String proxyPkg = null;     // package to define proxy class in
            int accessFlags = Modifier.PUBLIC | Modifier.FINAL;

            /*
             * Record the package of a non-public proxy interface so that the
             * proxy class will be defined in the same package.  Verify that
             * all non-public proxy interfaces are in the same package.
             */
            for (Class<?> intf : interfaces) {
                int flags = intf.getModifiers();
                if (!Modifier.isPublic(flags)) {
                    accessFlags = Modifier.FINAL;
                    String name = intf.getName();
                    int n = name.lastIndexOf('.');
                    String pkg = ((n == -1) ? "" : name.substring(0, n + 1));
                    if (proxyPkg == null) {
                        proxyPkg = pkg;
                    } else if (!pkg.equals(proxyPkg)) {
                        throw new IllegalArgumentException(
                            "non-public interfaces from different packages");
                    }
                }
            }

            if (proxyPkg == null) {
                // if no non-public proxy interfaces, use com.sun.proxy package
                proxyPkg = ReflectUtil.PROXY_PACKAGE + ".";
            }

            /*
             * Choose a name for the proxy class to generate.
             */
            long num = nextUniqueNumber.getAndIncrement();
            String proxyName = proxyPkg + proxyClassNamePrefix + num;

            /*
             * Generate the specified proxy class.
             */
            byte[] proxyClassFile = ProxyGenerator.generateProxyClass(
                proxyName, interfaces, accessFlags);
            try {
                return defineClass0(loader, proxyName,
                                    proxyClassFile, 0, proxyClassFile.length);
            } catch (ClassFormatError e) {
                /*
                 * A ClassFormatError here means that (barring bugs in the
                 * proxy class generation code) there was some other
                 * invalid aspect of the arguments supplied to the proxy
                 * class creation (such as virtual machine limitations
                 * exceeded).
                 */
                throw new IllegalArgumentException(e.toString());
            }
        }
    }

jdk怎么调用生产的字节码

public class ProxyGeneratorUtils {

    /**
     * 把代理类的字节码写到硬盘上
     * @param path 保存路径
     */
    public static void writeProxyClassToHardDisk(String path) {

        // 第二种方法

        // 获取代理类的字节码
        byte[] classFile = ProxyGenerator.generateProxyClass("$Proxy11", BookService.class.getInterfaces());

        FileOutputStream out = null;

        try {
            out = new FileOutputStream(path);
            out.write(classFile);
            out.flush();
        } catch (Exception e) {
            e.printStackTrace();
        } finally {
            try {
                out.close();
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
    }

    public static void main(String[] args) {

        ProxyGeneratorUtils.writeProxyClassToHardDisk("./tmp/Proxy11.class");

    }

}

proxy11.class文件

import com.own.learn.aop.jdk.IBookService;
import java.lang.reflect.InvocationHandler;
import java.lang.reflect.Method;
import java.lang.reflect.Proxy;
import java.lang.reflect.UndeclaredThrowableException;

public final class $Proxy11 extends Proxy implements IBookService {
    //m1,m2,m3,m4，在static中加载了
    private static Method m1;
    private static Method m3;
    private static Method m2;
    private static Method m0;

    public $Proxy11(InvocationHandler var1) throws  {
        super(var1);
    }

    public final boolean equals(Object var1) throws  {
        try {
            return (Boolean)super.h.invoke(this, m1, new Object[]{var1});
        } catch (RuntimeException | Error var3) {
            throw var3;
        } catch (Throwable var4) {
            throw new UndeclaredThrowableException(var4);
        }
    }

    public final void readBook() throws  {
        try {
            // 实际上就是调用MyInvocationHandler的public Object invoke(Object proxy, Method method, Object[] args)方法
            super.h.invoke(this, m3, (Object[])null);
        } catch (RuntimeException | Error var2) {
            throw var2;
        } catch (Throwable var3) {
            throw new UndeclaredThrowableException(var3);
        }
    }

    public final String toString() throws  {
        try {
            return (String)super.h.invoke(this, m2, (Object[])null);
        } catch (RuntimeException | Error var2) {
            throw var2;
        } catch (Throwable var3) {
            throw new UndeclaredThrowableException(var3);
        }
    }

    public final int hashCode() throws  {
        try {
            return (Integer)super.h.invoke(this, m0, (Object[])null);
        } catch (RuntimeException | Error var2) {
            throw var2;
        } catch (Throwable var3) {
            throw new UndeclaredThrowableException(var3);
        }
    }

    static {
        try {
            m1 = Class.forName("java.lang.Object").getMethod("equals", Class.forName("java.lang.Object"));
            m3 = Class.forName("com.own.learn.aop.jdk.IBookService").getMethod("readBook");
            m2 = Class.forName("java.lang.Object").getMethod("toString");
            m0 = Class.forName("java.lang.Object").getMethod("hashCode");
        } catch (NoSuchMethodException var2) {
            throw new NoSuchMethodError(var2.getMessage());
        } catch (ClassNotFoundException var3) {
            throw new NoClassDefFoundError(var3.getMessage());
        }
    }
}

cglib动态代理

使用

public class PeopleDao {

    public void update() {
        System.out.println("PeopleDao.update()");
    }

    public void select() {
        System.out.println("PeopleDao.select()");
    }
}

import net.sf.cglib.proxy.MethodInterceptor;
import net.sf.cglib.proxy.MethodProxy;

import java.lang.reflect.Method;

public class DaoProxy implements MethodInterceptor {

    @Override
    public Object intercept(Object object, Method method, Object[] objects,
                            MethodProxy methodProxy) throws Throwable {


        System.out.println("Before Method Invoke");
        methodProxy.invokeSuper(object, objects);
        System.out.println("After Method Invoke");

        return object;
    }
}

public class CglibTest {


    public static void main(String[] args) {

        PeopleDao lastPeopleDao = null;
        System.setProperty(DebuggingClassWriter.DEBUG_LOCATION_PROPERTY, "./tmp");
        DaoProxy daoProxy = new DaoProxy();

        Enhancer enhancer = new Enhancer();
        enhancer.setSuperclass(PeopleDao.class);
        enhancer.setCallback(daoProxy);
        PeopleDao peopleDao = (PeopleDao) enhancer.create();
        System.out.println(peopleDao == lastPeopleDao);

    }
}

生成代理类

import java.lang.reflect.Method;
import net.sf.cglib.core.ReflectUtils;
import net.sf.cglib.core.Signature;
import net.sf.cglib.proxy.Callback;
import net.sf.cglib.proxy.Factory;
import net.sf.cglib.proxy.MethodInterceptor;
import net.sf.cglib.proxy.MethodProxy;

public class PeopleDao$$EnhancerByCGLIB$$4c0e359d extends PeopleDao implements Factory {
    private boolean CGLIB$BOUND;
    public static Object CGLIB$FACTORY_DATA;
    private static final ThreadLocal CGLIB$THREAD_CALLBACKS;
    private static final Callback[] CGLIB$STATIC_CALLBACKS;
    private MethodInterceptor CGLIB$CALLBACK_0;//代理类
    private static Object CGLIB$CALLBACK_FILTER;
    private static final Method CGLIB$update$0$Method;/被代理方法
    private static final MethodProxy CGLIB$update$0$Proxy;//代理方法
    private static final Object[] CGLIB$emptyArgs;
    private static final Method CGLIB$select$1$Method;/被代理方法
    private static final MethodProxy CGLIB$select$1$Proxy;//代理方法
    private static final Method CGLIB$equals$2$Method;
    private static final MethodProxy CGLIB$equals$2$Proxy;
    private static final Method CGLIB$toString$3$Method;
    private static final MethodProxy CGLIB$toString$3$Proxy;
    private static final Method CGLIB$hashCode$4$Method;
    private static final MethodProxy CGLIB$hashCode$4$Proxy;
    private static final Method CGLIB$clone$5$Method;
    private static final MethodProxy CGLIB$clone$5$Proxy;

    static void CGLIB$STATICHOOK1() {
        CGLIB$THREAD_CALLBACKS = new ThreadLocal();
        CGLIB$emptyArgs = new Object[0];
        Class var0 = Class.forName("com.own.learn.aop.cglib.PeopleDao$$EnhancerByCGLIB$$4c0e359d");//代理类

        Class var1;//被代理类的生成
        Method[] var10000 = ReflectUtils.findMethods(new String[]{"equals", "(Ljava/lang/Object;)Z", "toString", "()Ljava/lang/String;", "hashCode", "()I", "clone", "()Ljava/lang/Object;"}, (var1 = Class.forName("java.lang.Object")).getDeclaredMethods());
        CGLIB$equals$2$Method = var10000[0];
        CGLIB$equals$2$Proxy = MethodProxy.create(var1, var0, "(Ljava/lang/Object;)Z", "equals", "CGLIB$equals$2");
        CGLIB$toString$3$Method = var10000[1];
        CGLIB$toString$3$Proxy = MethodProxy.create(var1, var0, "()Ljava/lang/String;", "toString", "CGLIB$toString$3");
        CGLIB$hashCode$4$Method = var10000[2];
        CGLIB$hashCode$4$Proxy = MethodProxy.create(var1, var0, "()I", "hashCode", "CGLIB$hashCode$4");
        CGLIB$clone$5$Method = var10000[3];
        CGLIB$clone$5$Proxy = MethodProxy.create(var1, var0, "()Ljava/lang/Object;", "clone", "CGLIB$clone$5");
        var10000 = ReflectUtils.findMethods(new String[]{"update", "()V", "select", "()V"}, (var1 = Class.forName("com.own.learn.aop.cglib.PeopleDao")).getDeclaredMethods());
        CGLIB$update$0$Method = var10000[0];
        CGLIB$update$0$Proxy = MethodProxy.create(var1, var0, "()V", "update", "CGLIB$update$0");
        CGLIB$select$1$Method = var10000[1];
        CGLIB$select$1$Proxy = MethodProxy.create(var1, var0, "()V", "select", "CGLIB$select$1");
    }

    final void CGLIB$update$0() {
        super.update();
    }

    public final void update() {
        MethodInterceptor var10000 = this.CGLIB$CALLBACK_0;
        if (this.CGLIB$CALLBACK_0 == null) {
            CGLIB$BIND_CALLBACKS(this);
            var10000 = this.CGLIB$CALLBACK_0;
        }

        if (var10000 != null) {
            var10000.intercept(this, CGLIB$update$0$Method, CGLIB$emptyArgs, CGLIB$update$0$Proxy);
        } else {
            super.update();
        }
    }

    final void CGLIB$select$1() {
        super.select();
    }

    public final void select() {
        MethodInterceptor var10000 = this.CGLIB$CALLBACK_0;
        if (this.CGLIB$CALLBACK_0 == null) {
            CGLIB$BIND_CALLBACKS(this);
            var10000 = this.CGLIB$CALLBACK_0;
        }

        if (var10000 != null) {
            var10000.intercept(this, CGLIB$select$1$Method, CGLIB$emptyArgs, CGLIB$select$1$Proxy);
        } else {
            super.select();
        }
    }

    final boolean CGLIB$equals$2(Object var1) {
        return super.equals(var1);
    }

    public final boolean equals(Object var1) {
        MethodInterceptor var10000 = this.CGLIB$CALLBACK_0;
        if (this.CGLIB$CALLBACK_0 == null) {
            CGLIB$BIND_CALLBACKS(this);
            var10000 = this.CGLIB$CALLBACK_0;
        }

        if (var10000 != null) {
            Object var2 = var10000.intercept(this, CGLIB$equals$2$Method, new Object[]{var1}, CGLIB$equals$2$Proxy);
            return var2 == null ? false : (Boolean)var2;
        } else {
            return super.equals(var1);
        }
    }

    final String CGLIB$toString$3() {
        return super.toString();
    }

    public final String toString() {
        MethodInterceptor var10000 = this.CGLIB$CALLBACK_0;
        if (this.CGLIB$CALLBACK_0 == null) {
            CGLIB$BIND_CALLBACKS(this);
            var10000 = this.CGLIB$CALLBACK_0;
        }

        return var10000 != null ? (String)var10000.intercept(this, CGLIB$toString$3$Method, CGLIB$emptyArgs, CGLIB$toString$3$Proxy) : super.toString();
    }

    final int CGLIB$hashCode$4() {
        return super.hashCode();
    }

    public final int hashCode() {
        MethodInterceptor var10000 = this.CGLIB$CALLBACK_0;
        if (this.CGLIB$CALLBACK_0 == null) {
            CGLIB$BIND_CALLBACKS(this);
            var10000 = this.CGLIB$CALLBACK_0;
        }

        if (var10000 != null) {
            Object var1 = var10000.intercept(this, CGLIB$hashCode$4$Method, CGLIB$emptyArgs, CGLIB$hashCode$4$Proxy);
            return var1 == null ? 0 : ((Number)var1).intValue();
        } else {
            return super.hashCode();
        }
    }

    final Object CGLIB$clone$5() throws CloneNotSupportedException {
        return super.clone();
    }

    protected final Object clone() throws CloneNotSupportedException {
        MethodInterceptor var10000 = this.CGLIB$CALLBACK_0;
        if (this.CGLIB$CALLBACK_0 == null) {
            CGLIB$BIND_CALLBACKS(this);
            var10000 = this.CGLIB$CALLBACK_0;
        }

        return var10000 != null ? var10000.intercept(this, CGLIB$clone$5$Method, CGLIB$emptyArgs, CGLIB$clone$5$Proxy) : super.clone();
    }

    public static MethodProxy CGLIB$findMethodProxy(Signature var0) {
        String var10000 = var0.toString();
        switch(var10000.hashCode()) {
        case -1949253108:
            if (var10000.equals("update()V")) {
                return CGLIB$update$0$Proxy;
            }
            break;
        case -1716030215:
            if (var10000.equals("select()V")) {
                return CGLIB$select$1$Proxy;
            }
            break;
        case -508378822:
            if (var10000.equals("clone()Ljava/lang/Object;")) {
                return CGLIB$clone$5$Proxy;
            }
            break;
        case 1826985398:
            if (var10000.equals("equals(Ljava/lang/Object;)Z")) {
                return CGLIB$equals$2$Proxy;
            }
            break;
        case 1913648695:
            if (var10000.equals("toString()Ljava/lang/String;")) {
                return CGLIB$toString$3$Proxy;
            }
            break;
        case 1984935277:
            if (var10000.equals("hashCode()I")) {
                return CGLIB$hashCode$4$Proxy;
            }
        }

        return null;
    }

    public PeopleDao$$EnhancerByCGLIB$$4c0e359d() {
        CGLIB$BIND_CALLBACKS(this);
    }

    public static void CGLIB$SET_THREAD_CALLBACKS(Callback[] var0) {
        CGLIB$THREAD_CALLBACKS.set(var0);
    }

    public static void CGLIB$SET_STATIC_CALLBACKS(Callback[] var0) {
        CGLIB$STATIC_CALLBACKS = var0;
    }

    private static final void CGLIB$BIND_CALLBACKS(Object var0) {
        PeopleDao$$EnhancerByCGLIB$$4c0e359d var1 = (PeopleDao$$EnhancerByCGLIB$$4c0e359d)var0;
        if (!var1.CGLIB$BOUND) {
            var1.CGLIB$BOUND = true;
            Object var10000 = CGLIB$THREAD_CALLBACKS.get();
            if (var10000 == null) {
                var10000 = CGLIB$STATIC_CALLBACKS;
                if (CGLIB$STATIC_CALLBACKS == null) {
                    return;
                }
            }

            var1.CGLIB$CALLBACK_0 = (MethodInterceptor)((Callback[])var10000)[0];
        }

    }

    public Object newInstance(Callback[] var1) {
        CGLIB$SET_THREAD_CALLBACKS(var1);
        PeopleDao$$EnhancerByCGLIB$$4c0e359d var10000 = new PeopleDao$$EnhancerByCGLIB$$4c0e359d();
        CGLIB$SET_THREAD_CALLBACKS((Callback[])null);
        return var10000;
    }

    public Object newInstance(Callback var1) {
        CGLIB$SET_THREAD_CALLBACKS(new Callback[]{var1});
        PeopleDao$$EnhancerByCGLIB$$4c0e359d var10000 = new PeopleDao$$EnhancerByCGLIB$$4c0e359d();
        CGLIB$SET_THREAD_CALLBACKS((Callback[])null);
        return var10000;
    }

    public Object newInstance(Class[] var1, Object[] var2, Callback[] var3) {
        CGLIB$SET_THREAD_CALLBACKS(var3);
        PeopleDao$$EnhancerByCGLIB$$4c0e359d var10000 = new PeopleDao$$EnhancerByCGLIB$$4c0e359d;
        switch(var1.length) {
        case 0:
            var10000.<init>();
            CGLIB$SET_THREAD_CALLBACKS((Callback[])null);
            return var10000;
        default:
            throw new IllegalArgumentException("Constructor not found");
        }
    }

    public Callback getCallback(int var1) {
        CGLIB$BIND_CALLBACKS(this);
        MethodInterceptor var10000;
        switch(var1) {
        case 0:
            var10000 = this.CGLIB$CALLBACK_0;
            break;
        default:
            var10000 = null;
        }

        return var10000;
    }

    public void setCallback(int var1, Callback var2) {
        switch(var1) {
        case 0:
            this.CGLIB$CALLBACK_0 = (MethodInterceptor)var2;
        default:
        }
    }

    public Callback[] getCallbacks() {
        CGLIB$BIND_CALLBACKS(this);
        return new Callback[]{this.CGLIB$CALLBACK_0};
    }

    public void setCallbacks(Callback[] var1) {
        this.CGLIB$CALLBACK_0 = (MethodInterceptor)var1[0];
    }

    static {
        CGLIB$STATICHOOK1();
    }
}

调用过程

调用过程：代理对象调用this.select方法->调用拦截器->methodProxy.invokeSuper->CGLIB$select$0->被代理对象select方法

MethodProxy

public class MethodProxy {
    private Signature sig1;
    private Signature sig2;
    private MethodProxy.CreateInfo createInfo;
    private final Object initLock = new Object();
    private volatile MethodProxy.FastClassInfo fastClassInfo;
    //c1:被代理对象Class
    //c2:代理对象Class
    //desc：入参类型
    //name1:被代理方法名
    //name2:代理方法名
    public static MethodProxy create(Class c1, Class c2, String desc, String name1, String name2) {
        MethodProxy proxy = new MethodProxy();
        proxy.sig1 = new Signature(name1, desc);//被代理方法签名
        proxy.sig2 = new Signature(name2, desc);//代理方法签名
        proxy.createInfo = new MethodProxy.CreateInfo(c1, c2);
        return proxy;
    }

private static class CreateInfo {
    Class c1;
    Class c2;
    NamingPolicy namingPolicy;
    GeneratorStrategy strategy;
    boolean attemptLoad;

    public CreateInfo(Class c1, Class c2) {
        this.c1 = c1;
        this.c2 = c2;
        AbstractClassGenerator fromEnhancer = AbstractClassGenerator.getCurrent();
        if(fromEnhancer != null) {
            this.namingPolicy = fromEnhancer.getNamingPolicy();
            this.strategy = fromEnhancer.getStrategy();
            this.attemptLoad = fromEnhancer.getAttemptLoad();
        }

    }
}

invokeSuper调用

public Object invokeSuper(Object obj, Object[] args) throws Throwable {
        try {
            this.init();
            MethodProxy.FastClassInfo fci = this.fastClassInfo;
            return fci.f2.invoke(fci.i2, obj, args);
        } catch (InvocationTargetException var4) {
            throw var4.getTargetException();
        }
    }

private static class FastClassInfo {
    FastClass f1;//被代理类FastClass
    FastClass f2;//代理类FastClass
    int i1; //被代理类的方法签名(index)
    int i2;//代理类的方法签名

    private FastClassInfo() {
    }
}

FastClass机制
Cglib动态代理执行代理方法效率之所以比JDK的高是因为Cglib采用了FastClass机制，它的原理简单来说就是：为代理类和被代理类各生成一个Class，这个Class会为代理类或被代理类的方法分配一个index(int类型)

比较

最后我们总结一下JDK动态代理和Gglib动态代理的区别：
1.JDK动态代理是实现了被代理对象的接口，Cglib是继承了被代理对象。
2.JDK和Cglib都是在运行期生成字节码，JDK是直接写Class字节码，Cglib使用ASM框架写Class字节码，Cglib代理实现更复杂，生成代理类比JDK效率低。
3.JDK调用代理方法，是通过反射机制调用，Cglib是通过FastClass机制直接调用方法，Cglib执行效率更高。

动态代理实现原理
Cglib实现动态代理