private static ReentrantLock reentrantLock = new ReentrantLock();
private static int count = 0;
//...
// 多线程 run 如下代码
reentrantLock.lock();
try
{
    count++;
} 
finally
{
    reentrantLock.unlock();
}
//...

/**
 * The synchronization state.
 */
private volatile int state;
/**
 * Returns the current value of synchronization state.
 * This operation has memory semantics of a {@code volatile} read.
 * @return current state value
 */
protected final int getState() {
    return state;
}
// 释放锁
protected final boolean tryRelease(int releases) {
    int c = getState() - releases;
    if (Thread.currentThread() != getExclusiveOwnerThread())
        throw new IllegalMonitorStateException();
    boolean free = false;
    if (c == 0) {
        free = true;
        setExclusiveOwnerThread(null);
    }
    setState(c);// 释放锁的最后，写volatile变量state
    return free;
}
// 获取锁
protected final boolean tryAcquire(int acquires) {
    final Thread current = Thread.currentThread();
    int c = getState();// 获取锁的开始，首先读volatile变量state
    if (c == 0) {
        if (!hasQueuedPredecessors() &&
            compareAndSetState(0, acquires)) {
            setExclusiveOwnerThread(current);
            return true;
        }
    }
    else if (current == getExclusiveOwnerThread()) {
        int nextc = c + acquires;
        if (nextc < 0)
            throw new Error("Maximum lock count exceeded");
        setState(nextc);
        return true;
    }
    return false;
}

private transient volatile Node head;
private transient volatile Node tail;
//The synchronization state.
//在互斥锁中它表示着线程是否已经获取了锁，0未获取，1已经获取了，大于1表示重入数。
private volatile int state;

static final class Node {
    //该等待节点处于共享模式
    static final Node SHARED = new Node();
    //该等待节点处于独占模式
    static final Node EXCLUSIVE = null;
    
    //表示节点的线程是已被取消的
    static final int CANCELLED =  1;
    //表示当前节点的后继节点的线程需要被唤醒
    static final int SIGNAL    = -1;
    //表示线程正在等待某个条件
    static final int CONDITION = -2;
    //表示下一个共享模式的节点应该无条件的传播下去
    static final int PROPAGATE = -3;

    //状态位 ，分别可以使CANCELLED、SINGNAL、CONDITION、PROPAGATE、0 
    volatile int waitStatus;

    volatile Node prev;//前驱节点
    volatile Node next;//后继节点
    volatile Thread thread;//等待锁的线程

    //ConditionObject链表的后继节点或者代表共享模式的节点。
    //因为Condition队列只能在独占模式下被能被访问,我们只需要简单的使用链表队列来链接正在等待条件的节点。
    //然后它们会被转移到同步队列（AQS队列）再次重新获取。
    //由于条件队列只能在独占模式下使用，所以我们要表示共享模式的节点的话只要使用特殊值SHARED来标明即可。
    Node nextWaiter;
    //Returns true if node is waiting in shared mode
    final boolean isShared() {
            return nextWaiter == SHARED;
    }
    .......
}

//忽略中断的（即不手动抛出InterruptedException异常）独占模式下的获取方法。
//该方法在成功返回前至少会调用一次tryAcquire()方法(该方法是子类重写的方法，如果返回true则代表能成功获取).
//否则当前线程会进入队列排队，重复的阻塞和唤醒等待再次成功获取后返回, 
//该方法可以用来实现Lock.lock
public final void acquire(int arg) {
       if (!tryAcquire(arg) &&
            acquireQueued(addWaiter(Node.EXCLUSIVE), arg))
            selfInterrupt();
    }

private Node addWaiter(Node mode) {
        //把当前线程包装为node,设为独占模式
        Node node = new Node(Thread.currentThread(), mode);
        // 尝试快速入队，即无竞争条件下肯定成功。如果失败，则进入enq自旋重试入队
        Node pred = tail;
        if (pred != null) {
            node.prev = pred;
            //CAS替换当前尾部。成功则返回
            if (compareAndSetTail(pred, node)) {
                pred.next = node;
                return node;
            }
        }
        enq(node);
        return node;
    }
//插入节点到队列中，如果队列未初始化则初始化，然后再插入。
private Node enq(final Node node) {
        for (;;) {
            Node t = tail;
            if (t == null) { // Must initialize
                if (compareAndSetHead(new Node()))
                    tail = head;
            } else {
                node.prev = t;
                if (compareAndSetTail(t, node)) {
                    t.next = node;
                    return t;
                }
            }
        }
    }

final boolean acquireQueued(final Node node, int arg) {
        boolean failed = true;
        try {
            boolean interrupted = false;
            for (;;) {
                final Node p = node.predecessor();
                //如果它的前继节点为头结点,尝试获取锁,获取成功则返回           
                if (p == head && tryAcquire(arg)) {
                    setHead(node);
                    p.next = null; // help GC
                    failed = false;
                    return interrupted;
                }
                //判断当前节点的线程是否应该被挂起，如果应该被挂起则挂起。
                //等待release唤醒释放
                if (shouldParkAfterFailedAcquire(p, node) &&
                    parkAndCheckInterrupt())
                    interrupted = true;
            }
        } finally {
            if (failed)
                //在队列中取消当前节点
                cancelAcquire(node);
        }
    }

private static boolean shouldParkAfterFailedAcquire(Node pred, Node node) {
        int ws = pred.waitStatus;
        //该节点如果状态如果为SIGNAL。则返回true，然后park挂起线程
        if (ws == Node.SIGNAL)
            return true;
       //表明该节点已经被取消，向前循环重新调整链表节点
        if (ws > 0) {
            /*
             * Predecessor was cancelled. Skip over predecessors and
             * indicate retry.
             */
            do {
                node.prev = pred = pred.prev;
            } while (pred.waitStatus > 0);
            pred.next = node;
        } else {
            //执行到这里代表节点是0或者PROPAGATE，然后标记他们为SIGNAL，但是
            //还不能park挂起线程。需要重试是否能获取，如果不能，则挂起。
            compareAndSetWaitStatus(pred, ws, Node.SIGNAL);
        }
        return false;
    }
   
//挂起当前线程，且返回线程的中断状态
private final boolean parkAndCheckInterrupt() {
        LockSupport.park(this);
        return Thread.interrupted();
    }

public final boolean release(int arg) {
    if (tryRelease(arg)) {
        Node h = head;
        if (h != null && h.waitStatus != 0)
            unparkSuccessor(h);
        return true;
    }
    return false;
}
//如果node的后继节点不为空且不是作废状态,则唤醒这个后继节点,
//否则从末尾开始寻找合适的节点,如果找到,则唤醒
private void unparkSuccessor(Node node) {
        int ws = node.waitStatus;
        if (ws < 0)
            compareAndSetWaitStatus(node, ws, 0);
        Node s = node.next;
        if (s == null || s.waitStatus > 0) {
            s = null;
            for (Node t = tail; t != null && t != node; t = t.prev)
                if (t.waitStatus <= 0)
                    s = t;
        }
        if (s != null)
            LockSupport.unpark(s.thread);
    }

    /**
     * Performs non-fair tryLock.  tryAcquire is implemented in
     * subclasses, but both need nonfair try for trylock method.
     */
    @ReservedStackAccess
    final boolean nonfairTryAcquire(int acquires) {
        final Thread current = Thread.currentThread();
        int c = getState();
        if (c == 0) {
            if (compareAndSetState(0, acquires)) {
                setExclusiveOwnerThread(current);
                return true;
            }
        }
        else if (current == getExclusiveOwnerThread()) {
            int nextc = c + acquires;
            if (nextc < 0) // overflow
                throw new Error("Maximum lock count exceeded");
            setState(nextc);
            return true;
        }
        return false;
    }

 /**
 * Atomically sets synchronization state to the given updated
 * value if the current state value equals the expected value.
 * This operation has memory semantics of a {@code volatile} read
 * and write.
 *
 * @param expect the expected value
 * @param update the new value
 * @return {@code true} if successful. False return indicates that the actual
 *         value was not equal to the expected value.
 */
protected final boolean compareAndSetState(int expect, int update) {
    return STATE.compareAndSet(this, expect, update);
}

 /**
 * Atomically sets the value of a variable to the {@code newValue} with the
 * memory semantics of {@link #setVolatile} if the variable's current value,
 * referred to as the <em>witness value</em>, {@code ==} the
 * {@code expectedValue}, as accessed with the memory semantics of
 * {@link #getVolatile}.
 *
 * <p>The method signature is of the form {@code (CT1 ct1, ..., CTn ctn, T expectedValue, T newValue)boolean}.
 *
 * <p>The symbolic type descriptor at the call site of {@code
 * compareAndSet} must match the access mode type that is the result of
 * calling {@code accessModeType(VarHandle.AccessMode.COMPARE_AND_SET)} on
 * this VarHandle.
 *
 * @param args the signature-polymorphic parameter list of the form
 * {@code (CT1 ct1, ..., CTn ctn, T expectedValue, T newValue)}
 * , statically represented using varargs.
 * @return {@code true} if successful, otherwise {@code false} if the
 * witness value was not the same as the {@code expectedValue}.
 * @throws UnsupportedOperationException if the access mode is unsupported
 * for this VarHandle.
 * @throws WrongMethodTypeException if the access mode type does not
 * match the caller's symbolic type descriptor.
 * @throws ClassCastException if the access mode type matches the caller's
 * symbolic type descriptor, but a reference cast fails.
 * @see #setVolatile(Object...)
 * @see #getVolatile(Object...)
 */
public final native
@MethodHandle.PolymorphicSignature
@HotSpotIntrinsicCandidate
boolean compareAndSet(Object... args);

public object invoke(Object obj,Method method, Object[] args)

package jiankunking;

/**
 * 需要动态代理的接口
 */
public interface Subject {
    /**
     * 你好
     *
     * @param name
     * @return
     */
    public String SayHello(String name);

    /**
     * 再见
     *
     * @return
     */
    public String SayGoodBye();
}

package jiankunking;

/**
 * 实际对象
 */
public class RealSubject implements Subject {

    /**
     * 你好
     *
     * @param name
     * @return
     */
    @Override
    public String SayHello(String name) {
        return "hello " + name;
    }

    /**
     * 再见
     *
     * @return
     */
    @Override
    public String SayGoodBye() {
        return " good bye ";
    }
}

package jiankunking;

import java.lang.reflect.InvocationHandler;
import java.lang.reflect.Method;


/**
 * 调用处理器实现类
 * 每次生成动态代理类对象时都需要指定一个实现了该接口的调用处理器对象
 */
public class InvocationHandlerImpl implements InvocationHandler {

    /**
     * 这个就是我们要代理的真实对象
     */
    private Object subject;

    /**
     * 构造方法，给我们要代理的真实对象赋初值
     *
     * @param subject
     */
    public InvocationHandlerImpl(Object subject) {
        this.subject = subject;
    }

    /**
     * 该方法负责集中处理动态代理类上的所有方法调用。
     * 调用处理器根据这三个参数进行预处理或分派到委托类实例上反射执行
     *
     * @param proxy  代理类实例
     * @param method 被调用的方法对象
     * @param args   调用参数
     * @return
     * @throws Throwable
     */
    @Override
    public Object invoke(Object proxy, Method method, Object[] args) throws Throwable {
        //在代理真实对象前我们可以添加一些自己的操作
        System.out.println("在调用之前，我要干点啥呢？");
        System.out.println("Method:" + method);
        //当代理对象调用真实对象的方法时，其会自动的跳转到代理对象关联的handler对象的invoke方法来进行调用
        Object returnValue = method.invoke(subject, args);
        //在代理真实对象后我们也可以添加一些自己的操作
        System.out.println("在调用之后，我要干点啥呢？");
        return returnValue;
    }
}

package jiankunking;

import java.lang.reflect.InvocationHandler;
import java.lang.reflect.Proxy;

/**
 * 动态代理演示
 */
public class DynamicProxyDemonstration {
    public static void main(String[] args) {
        //代理的真实对象
        Subject realSubject = new RealSubject();
        /**
         * InvocationHandlerImpl 实现了 InvocationHandler 接口，并能实现方法调用从代理类到委托类的分派转发
         * 其内部通常包含指向委托类实例的引用，用于真正执行分派转发过来的方法调用.
         * 即：要代理哪个真实对象，就将该对象传进去，最后是通过该真实对象来调用其方法
         */
        InvocationHandler handler = new InvocationHandlerImpl(realSubject);

        ClassLoader loader = handler.getClass().getClassLoader();
        Class<?>[] interfaces = realSubject.getClass().getInterfaces();
        /**
         * 该方法用于为指定类装载器、一组接口及调用处理器生成动态代理类实例
         */
        Subject subject = (Subject) Proxy.newProxyInstance(loader, interfaces, handler);

        System.out.println("动态代理对象的类型：" + subject.getClass().getName());

        String hello = subject.SayHello("jiankunking");
        System.out.println(hello);
//        String goodbye = subject.SayGoodBye();
//        System.out.println(goodbye);
    }
}

Subject subject = (Subject) Proxy.newProxyInstance(loader, interfaces, handler);

/**
 * Returns an instance of a proxy class for the specified interfaces
 * that dispatches method invocations to the specified invocation
 * handler.
 *
 * <p>{@code Proxy.newProxyInstance} throws
 * {@code IllegalArgumentException} for the same reasons that
 * {@code Proxy.getProxyClass} does.
 *
 * @param   loader the class loader to define the proxy class
 * @param   interfaces the list of interfaces for the proxy class
 *          to implement
 * @param   h the invocation handler to dispatch method invocations to
 * @return  a proxy instance with the specified invocation handler of a
 *          proxy class that is defined by the specified class loader
 *          and that implements the specified interfaces
 * @throws  IllegalArgumentException if any of the restrictions on the
 *          parameters that may be passed to {@code getProxyClass}
 *          are violated
 * @throws  SecurityException if a security manager, <em>s</em>, is present
 *          and any of the following conditions is met:
 *          <ul>
 *          <li> the given {@code loader} is {@code null} and
 *               the caller's class loader is not {@code null} and the
 *               invocation of {@link SecurityManager#checkPermission
 *               s.checkPermission} with
 *               {@code RuntimePermission("getClassLoader")} permission
 *               denies access;</li>
 *          <li> for each proxy interface, {@code intf},
 *               the caller's class loader is not the same as or an
 *               ancestor of the class loader for {@code intf} and
 *               invocation of {@link SecurityManager#checkPackageAccess
 *               s.checkPackageAccess()} denies access to {@code intf};</li>
 *          <li> any of the given proxy interfaces is non-public and the
 *               caller class is not in the same {@linkplain Package runtime package}
 *               as the non-public interface and the invocation of
 *               {@link SecurityManager#checkPermission s.checkPermission} with
 *               {@code ReflectPermission("newProxyInPackage.{package name}")}
 *               permission denies access.</li>
 *          </ul>
 * @throws  NullPointerException if the {@code interfaces} array
 *          argument or any of its elements are {@code null}, or
 *          if the invocation handler, {@code h}, is
 *          {@code null}
 */
@CallerSensitive 
public static Object newProxyInstance(ClassLoader loader,
                                          Class<?>[] interfaces,
                                          InvocationHandler h) throws IllegalArgumentException {
        //检查h 不为空，否则抛异常
        Objects.requireNonNull(h);
 
        final Class<?>[] intfs = interfaces.clone();
        final SecurityManager sm = System.getSecurityManager();
        if (sm != null) {
            checkProxyAccess(Reflection.getCallerClass(), loader, intfs);
        }
 
        /*
         * 获得与指定类装载器和一组接口相关的代理类类型对象
         */
        Class<?> cl = getProxyClass0(loader, intfs);
 
        /*
         * 通过反射获取构造函数对象并生成代理类实例
         */
        try {
            if (sm != null) {
                checkNewProxyPermission(Reflection.getCallerClass(), cl);
            }
            //获取代理对象的构造方法（也就是$Proxy0(InvocationHandler h)） 
            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;
                    }
                });
            }
            //生成代理类的实例并把InvocationHandlerImpl的实例传给它的构造方法
            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);
        }
    }

/**
 * Generate a proxy class.  Must call the checkProxyAccess method
 * to perform permission checks before calling this.
 */
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);
}

 /**
 * a cache of proxy classes
 */
private static final WeakCache<ClassLoader, Class<?>[], Class<?>> proxyClassCache = new WeakCache<>(new KeyFactory(), new ProxyClassFactory());

/**
 * Look-up the value through the cache. This always evaluates the
 * {@code subKeyFactory} function and optionally evaluates
 * {@code valueFactory} function if there is no entry in the cache for given
 * pair of (key, subKey) or the entry has already been cleared.
 *
 * @param key       possibly null key
 * @param parameter parameter used together with key to create sub-key and
 *                  value (should not be null)
 * @return the cached value (never null)
 * @throws NullPointerException if {@code parameter} passed in or
 *                              {@code sub-key} calculated by
 *                              {@code subKeyFactory} or {@code value}
 *                              calculated by {@code valueFactory} is null.
 */
public V get(K key, P parameter) {
    Objects.requireNonNull(parameter);
    expungeStaleEntries();
    Object cacheKey = CacheKey.valueOf(key, refQueue);
    // lazily install the 2nd level valuesMap for the particular cacheKey
    ConcurrentMap<Object, Supplier<V>> valuesMap = map.get(cacheKey);
    if (valuesMap == null) {
       //putIfAbsent这个方法在key不存在的时候加入一个值,如果key存在就不放入
        ConcurrentMap<Object, Supplier<V>> oldValuesMap = map.putIfAbsent(cacheKey,valuesMap = new ConcurrentHashMap<>());
        if (oldValuesMap != null) {
            valuesMap = oldValuesMap;
        }
    }
 
    // create subKey and retrieve the possible Supplier<V> stored by that
    // subKey from valuesMap
    Object subKey = Objects.requireNonNull(subKeyFactory.apply(key, parameter));
    Supplier<V> supplier = valuesMap.get(subKey);
    Factory factory = null;
 
    while (true) {
        if (supplier != null) {
            // supplier might be a Factory or a CacheValue<V> instance
            V value = supplier.get();
            if (value != null) {
                return value;
            }
        }
        // else no supplier in cache
        // or a supplier that returned null (could be a cleared CacheValue
        // or a Factory that wasn't successful in installing the CacheValue)
 
        // lazily construct a Factory
        if (factory == null) {
            factory = new Factory(key, parameter, subKey, valuesMap);
        }
 
        if (supplier == null) {        
            supplier = valuesMap.putIfAbsent(subKey, factory);
            if (supplier == null) {
                // successfully installed Factory
                supplier = factory;
            }
            // else retry with winning supplier
        } else {
            if (valuesMap.replace(subKey, supplier, factory)) {
                // successfully replaced
                // cleared CacheEntry / unsuccessful Factory
                // with our Factory
                supplier = factory;
            } else {
                // retry with current supplier
                supplier = valuesMap.get(subKey);
            }
        }
    }
}

public synchronized V get() { // serialize access
            // re-check
            Supplier<V> supplier = valuesMap.get(subKey);
            if (supplier != this) {
                // something changed while we were waiting:
                // might be that we were replaced by a CacheValue
                // or were removed because of failure ->
                // return null to signal WeakCache.get() to retry
                // the loop
                return null;
            }
            // else still us (supplier == this)
 
            // create new value
            V value = null;
            try {
                value = Objects.requireNonNull(valueFactory.apply(key, parameter));
            } finally {
                if (value == null) { // remove us on failure
                    valuesMap.remove(subKey, this);
                }
            }
            // the only path to reach here is with non-null value
            assert value != null;
 
            // wrap value with CacheValue (WeakReference)
            CacheValue<V> cacheValue = new CacheValue<>(value);
 
            // try replacing us with CacheValue (this should always succeed)
            if (valuesMap.replace(subKey, this, cacheValue)) {
                // put also in reverseMap
                reverseMap.put(cacheValue, Boolean.TRUE);
            } else {
                throw new AssertionError("Should not reach here");
            }
 
            // successfully replaced us with new CacheValue -> return the value
            // wrapped by it
            return value;
        }
    }

 /**
 * A factory function that generates, defines and returns the proxy class given
 * the ClassLoader and array of interfaces.
 */
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());
        }
    }
}

//生成字节码
byte[] proxyClassFile = ProxyGenerator.generateProxyClass(proxyName, interfaces, accessFlags);

package jiankunking;
 
import sun.misc.ProxyGenerator;
 
import java.io.File;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.IOException;
import java.lang.reflect.InvocationHandler;
import java.lang.reflect.Proxy;
 
/**
 * 动态代理演示
 */
public class DynamicProxyDemonstration {
    public static void main(String[] args) {
        //代理的真实对象
        Subject realSubject = new RealSubject();
 
        /**
         * InvocationHandlerImpl 实现了 InvocationHandler 接口，并能实现方法调用从代理类到委托类的分派转发
         * 其内部通常包含指向委托类实例的引用，用于真正执行分派转发过来的方法调用.
         * 即：要代理哪个真实对象，就将该对象传进去，最后是通过该真实对象来调用其方法
         */
        InvocationHandler handler = new InvocationHandlerImpl(realSubject);
 
        ClassLoader loader = handler.getClass().getClassLoader();
        Class[] interfaces = realSubject.getClass().getInterfaces();
        /**
         * 该方法用于为指定类装载器、一组接口及调用处理器生成动态代理类实例
         */
        Subject subject = (Subject) Proxy.newProxyInstance(loader, interfaces, handler);
        System.out.println("动态代理对象的类型："+subject.getClass().getName());

        String hello = subject.SayHello("jiankunking");
        System.out.println(hello);
        // 将生成的字节码保存到本地，
        createProxyClassFile();
    }
    private static void createProxyClassFile(){
        String name = "ProxySubject";
        byte[] data = ProxyGenerator.generateProxyClass(name,new Class[]{Subject.class});
        FileOutputStream out =null;
        try {
            out = new FileOutputStream(name+".class");
            System.out.println((new File("hello")).getAbsolutePath());
            out.write(data);
        } catch (FileNotFoundException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        }finally {
            if(null!=out) try {
                out.close();
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
    }
}

import java.lang.reflect.InvocationHandler;
import java.lang.reflect.Method;
import java.lang.reflect.Proxy;
import java.lang.reflect.UndeclaredThrowableException;
import jiankunking.Subject;
 
public final class ProxySubject extends Proxy implements Subject {
  private static Method m1;
  private static Method m3;
  private static Method m4;
  private static Method m2;
  private static Method m0;
  
  public ProxySubject(InvocationHandler paramInvocationHandler) {
    super(paramInvocationHandler);
  }
  
  public final boolean equals(Object paramObject){
    try {
        return ((Boolean)this.h.invoke(this, m1, new Object[] { paramObject })).booleanValue();
    } catch (Error|RuntimeException localError){
        throw localError;
    } catch (Throwable localThrowable) {
      throw new UndeclaredThrowableException(localThrowable);
    }
  }
  
  public final String SayGoodBye() {
    try{
      return (String)this.h.invoke(this, m3, null);
    } catch (Error|RuntimeException localError) {
      throw localError;
    } catch (Throwable localThrowable) {
      throw new UndeclaredThrowableException(localThrowable);
    }
  }
  
  public final String SayHello(String paramString) {
    try {
      return (String)this.h.invoke(this, m4, new Object[] { paramString });
    } catch (Error|RuntimeException localError){
      throw localError;
    } catch (Throwable localThrowable){
      throw new UndeclaredThrowableException(localThrowable);
    }
  }
  
  public final String toString() {
    try {
      return (String)this.h.invoke(this, m2, null);
    } catch (Error|RuntimeException localError) {
      throw localError;
    } catch (Throwable localThrowable) {
      throw new UndeclaredThrowableException(localThrowable);
    }
  }
  
  public final int hashCode() {
    try {
      return ((Integer)this.h.invoke(this, m0, null)).intValue();
    } catch (Error|RuntimeException localError) {
      throw localError;
    } catch (Throwable localThrowable) {
      throw new UndeclaredThrowableException(localThrowable);
    }
  }
  
  static
  {
    try {
      m1 = Class.forName("java.lang.Object").getMethod("equals", new Class[] { Class.forName("java.lang.Object") });
      m3 = Class.forName("jiankunking.Subject").getMethod("SayGoodBye", new Class[0]);
      m4 = Class.forName("jiankunking.Subject").getMethod("SayHello", new Class[] { Class.forName("java.lang.String") });
      m2 = Class.forName("java.lang.Object").getMethod("toString", new Class[0]);
      m0 = Class.forName("java.lang.Object").getMethod("hashCode", new Class[0]);
      return;
    } catch (NoSuchMethodException localNoSuchMethodException) {
      throw new NoSuchMethodError(localNoSuchMethodException.getMessage());
    } catch (ClassNotFoundException localClassNotFoundException) {
      throw new NoClassDefFoundError(localClassNotFoundException.getMessage());
    }
  }
}

Subject subject = (Subject) Proxy.newProxyInstance(loader, interfaces, handler);

public final String SayHello(String paramString)