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本篇內(nèi)容介紹了“如何寫java代理”的有關(guān)知識(shí)，在實(shí)際案例的操作過(guò)程中，不少人都會(huì)遇到這樣的困境，接下來(lái)就讓小編帶領(lǐng)大家學(xué)習(xí)一下如何處理這些情況吧！希望大家仔細(xì)閱讀，能夠?qū)W有所成！
一般經(jīng)常做java開(kāi)發(fā)的知道java的代理模式一共有三種，第一種也就是靜態(tài)代理，這種用法比較簡(jiǎn)單，沒(méi)有什么魔法棒，比較好理解，另外兩種分別是JDK代理和cglib代理，他們分別是對(duì)接口代理和對(duì)class類本身進(jìn)行代理，jdk代理要求類必須實(shí)現(xiàn)有一個(gè)或者多個(gè)接口，對(duì)接口進(jìn)行字節(jié)碼增強(qiáng)在內(nèi)存中實(shí)現(xiàn)新的class類去反射調(diào)用用戶target的實(shí)現(xiàn)類，這里需要說(shuō)明的是不管是cglic代理也好還是jdk代理他們?cè)趦?nèi)存中都要占據(jù)方法區(qū)資源(jdk8 叫原空間)，從而達(dá)到代理目的，而cglib代理是對(duì)class類本身進(jìn)行字節(jié)碼增強(qiáng)配合fastclass來(lái)實(shí)現(xiàn)代理，關(guān)于更多的cglib和jdk代理相關(guān)的內(nèi)容大家可以google搜索一下，網(wǎng)上有很多這里不做再多的說(shuō)明。下面我們摒棄jdk，和cglib的復(fù)雜源碼來(lái)自己實(shí)現(xiàn)一個(gè)代理模式，來(lái)更深刻的了解一下代理究竟是怎么形成的。
代理模式是指給某一個(gè)對(duì)象提供一個(gè)代理對(duì)象，并由代理對(duì)象控制對(duì)原對(duì)象的引用。通俗的來(lái)講代理模式就是我們生活中常見(jiàn)的中介。這種模式有什么用呢？它可以在原對(duì)象的基礎(chǔ)上增強(qiáng)原對(duì)象的功能，比如在原對(duì)象調(diào)用一個(gè)方法的前后進(jìn)行日志、事務(wù)操作等。Spring AOP就使用了代理模式。如何實(shí)現(xiàn)代理模式呢？首先來(lái)看靜態(tài)代理。靜態(tài)代理是指在程序運(yùn)行前就已經(jīng)存在的編譯好的代理類是為靜態(tài)代理。實(shí)現(xiàn)靜態(tài)代理有四個(gè)步驟：
①定義業(yè)務(wù)接口；
②被代理類實(shí)現(xiàn)業(yè)務(wù)接口；
③定義代理類并實(shí)現(xiàn)業(yè)務(wù)接口；
④最后便可通過(guò)客戶端進(jìn)行調(diào)用。（這里可以理解成程序的main方法里的內(nèi)容）
我們按照這個(gè)步驟去實(shí)現(xiàn)靜態(tài)代理。需求：在向數(shù)據(jù)庫(kù)添加一個(gè)用戶時(shí)前后打印日志。
JDK DEMO示例
IUserService.java
public interface IUserService {
void add(String name);
}UserServiceImpl.java
public class UserServiceImpl implements IUserService{
@Override
public void add(String name) {
System.out.println("數(shù)據(jù)庫(kù)中插入： "+name+" 的用戶");
}
}MyInvocationHandler.java
public class MyInvocationHandler implements InvocationHandler {
//被代理對(duì)象，Object類型
private Object target;
public MyInvocationHandler(Object target) {
this.target = target;
}
@Override
public Object invoke(Object proxy, Method method, Object[] args) throws Throwable {
System.out.println("準(zhǔn)備向數(shù)據(jù)庫(kù)中插入數(shù)據(jù)");
Object returnvalue = method.invoke(target, args);
System.out.println("插入數(shù)據(jù)庫(kù)成功");
return returnvalue;
}
}測(cè)試類
public static void main(String[] args) {
IUserService target = new UserServiceImpl();
MyInvocationHandler handler = new MyInvocationHandler(target);
IUserService proxyObject = (IUserService) Proxy.newProxyInstance(DynamicProxyTest.class.getClassLoader(),
target.getClass().getInterfaces(), handler);
proxyObject.add("張玉龍");
}使用上非常簡(jiǎn)單、網(wǎng)上demo也很多，不做充分講解，對(duì)jdk代理用法的小伙伴如果還不熟悉這塊代碼，就先了解一下jdk代理的使用方式，然后在回來(lái)繼續(xù)看下面的源碼分析
JDK代理源碼深度分析
這部分如果想要更快更好的理解，建議一邊對(duì)著源碼(本文JDK 1.8)，一邊看著博客。畢竟自己親身實(shí)踐效果才好嘛。
Proxy.newProxyInstance( ClassLoaderloader, Class[] interfaces, InvocationHandler h)
產(chǎn)生了代理對(duì)象，所以我們進(jìn)到
newProxyInstance
的實(shí)現(xiàn)：
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);
}
}這段代碼核心就是通過(guò) getProxyClass0(loader, intfs)得到代理類的Class對(duì)象，然后通過(guò)Class對(duì)象得到構(gòu)造方法，進(jìn)而創(chuàng)建代理對(duì)象。下一步看 getProxyClass0這個(gè)方法。
//此方法也是Proxy類下的方法
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
//意思是：如果代理類被指定的類加載器loader定義了，并實(shí)現(xiàn)了給定的接口interfaces，
//那么就返回緩存的代理類對(duì)象，否則使用ProxyClassFactory創(chuàng)建代理類。
return proxyClassCache.get(loader, interfaces);
}這里看到proxyClassCache，有Cache便知道是緩存的意思，正好呼應(yīng)了前面Look up or generate the designated proxy class。查詢（在緩存中已經(jīng)有）或生成指定的代理類的class對(duì)象這段注釋。
proxyClassCache是個(gè)WeakCache類的對(duì)象，調(diào)用proxyClassCache.get(loader, interfaces); 可以得到緩存的代理類或創(chuàng)建代理類（沒(méi)有緩存的情況）。說(shuō)明WeakCache中有
get這個(gè)方法。先看下WeakCache類的定義（這里先只給出變量的定義和構(gòu)造函數(shù)）：
//K代表key的類型，P代表參數(shù)的類型，V代表value的類型。
// WeakCache<ClassLoader, Class<?>[], Class<?>> proxyClassCache 說(shuō)明proxyClassCache存的值是Class<?>對(duì)象，正是我們需要的代理類對(duì)象。
final class WeakCache<K, P, V> {
private final ReferenceQueue<K> refQueue
= new ReferenceQueue<>();
// the key type is Object for supporting null key
private final ConcurrentMap<Object, ConcurrentMap<Object, Supplier<V>>> map
= new ConcurrentHashMap<>();
private final ConcurrentMap<Supplier<V>, Boolean> reverseMap
= new ConcurrentHashMap<>();
private final BiFunction<K, P, ?> subKeyFactory;
private final BiFunction<K, P, V> valueFactory;
public WeakCache(BiFunction<K, P, ?> subKeyFactory,
BiFunction<K, P, V> valueFactory) {
this.subKeyFactory = Objects.requireNonNull(subKeyFactory);
this.valueFactory = Objects.requireNonNull(valueFactory);
} 其中map變量是實(shí)現(xiàn)緩存的核心變量，他是一個(gè)雙重的Map結(jié)構(gòu):
(key, sub-key) -> value。其中key是傳進(jìn)來(lái)的Classloader進(jìn)行包裝后的對(duì)象，sub-key是由WeakCache構(gòu)造函數(shù)傳人的
KeyFactory()生成的。value就是產(chǎn)生代理類的對(duì)象，是由WeakCache構(gòu)造函數(shù)傳人的
ProxyClassFactory()生成的
好，大體上說(shuō)完WeakCache這個(gè)類的作用，我們回到剛才 proxyClassCache.get(loader, interfaces);這句代碼。get是WeakCache里的方法。源碼如下
//K和P就是WeakCache定義中的泛型，key是類加載器，parameter是接口類數(shù)組
public V get(K key, P parameter) {
//檢查parameter不為空
Objects.requireNonNull(parameter);
//清除無(wú)效的緩存
expungeStaleEntries();
// cacheKey就是(key, sub-key) -> value里的一級(jí)key，
Object cacheKey = CacheKey.valueOf(key, refQueue);
// lazily install the 2nd level valuesMap for the particular cacheKey
//根據(jù)一級(jí)key得到 ConcurrentMap<Object, Supplier<V>>對(duì)象。如果之前不存在，則新建一個(gè)ConcurrentMap<Object, Supplier<V>>和cacheKey（一級(jí)key）一起放到map中。
ConcurrentMap<Object, Supplier<V>> valuesMap = map.get(cacheKey);
if (valuesMap == null) {
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
//這部分就是調(diào)用生成sub-key的代碼，上面我們已經(jīng)看過(guò)怎么生成的了
Object subKey = Objects.requireNonNull(subKeyFactory.apply(key, parameter));
//通過(guò)sub-key得到supplier
Supplier<V> supplier = valuesMap.get(subKey);
//supplier實(shí)際上就是這個(gè)factory
Factory factory = null;
while (true) {
//如果緩存里有supplier ，那就直接通過(guò)get方法，得到代理類對(duì)象，返回，就結(jié)束了，一會(huì)兒分析get方法。
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
//下面的所有代碼目的就是：如果緩存中沒(méi)有supplier，則創(chuàng)建一個(gè)Factory對(duì)象，把factory對(duì)象在多線程的環(huán)境下安全的賦給supplier。
//因?yàn)槭窃趙hile（true）中，賦值成功后又回到上面去調(diào)get方法，返回才結(jié)束。
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);
}
}
}
}所以接下來(lái)我們看Factory類中的get方法。
public synchronized V get() { // serialize access
// re-check
Supplier<V> supplier = valuesMap.get(subKey);
//重新檢查得到的supplier是不是當(dāng)前對(duì)象
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 {
//代理類就是在這個(gè)位置調(diào)用valueFactory生成的
//valueFactory就是我們傳入的 new ProxyClassFactory()
//一會(huì)我們分析ProxyClassFactory()的apply方法
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)
//把value包裝成弱引用
CacheValue<V> cacheValue = new CacheValue<>(value);
// put into reverseMap
// reverseMap是用來(lái)實(shí)現(xiàn)緩存的有效性
reverseMap.put(cacheValue, Boolean.TRUE);
// try replacing us with CacheValue (this should always succeed)
if (!valuesMap.replace(subKey, this, cacheValue)) {
throw new AssertionError("Should not reach here");
}
// successfully replaced us with new CacheValue -> return the value
// wrapped by it
return value;
}
}撥云見(jiàn)日，來(lái)到ProxyClassFactory的apply方法，代理類就是在這里生成的。
//這里的BiFunction<T, U, R>是個(gè)函數(shù)式接口，可以理解為用T，U兩種類型做參數(shù)，得到R類型的返回值
private static final class ProxyClassFactory
implements BiFunction<ClassLoader, Class<?>[], Class<?>>
{
// prefix for all proxy class names
//所有代理類名字的前綴
private static final String proxyClassNamePrefix = "$Proxy";
// next number to use for generation of unique proxy class names
//用于生成代理類名字的計(jì)數(shù)器
private static final AtomicLong nextUniqueNumber = new AtomicLong();
@Override
public Class<?> apply(ClassLoader loader, Class<?>[] interfaces) {
Map<Class<?>, Boolean> interfaceSet = new IdentityHashMap<>(interfaces.length);
//驗(yàn)證代理接口，可不看
for (Class<?> intf : interfaces) {
/*
* Verify that the class loader resolves the name of this
* interface to the same Class object.
*/
Class<?> interfaceClass = null;
try {
interfaceClass = Class.forName(intf.getName(), false, loader);
} catch (ClassNotFoundException e) {
}
if (interfaceClass != intf) {
throw new IllegalArgumentException(
intf + " is not visible from class loader");
}
/*
* Verify that the Class object actually represents an
* interface.
*/
if (!interfaceClass.isInterface()) {
throw new IllegalArgumentException(
interfaceClass.getName() + " is not an interface");
}
/*
* Verify that this interface is not a duplicate.
*/
if (interfaceSet.put(interfaceClass, Boolean.TRUE) != null) {
throw new IllegalArgumentException(
"repeated interface: " + interfaceClass.getName());
}
}
//生成的代理類的包名
String proxyPkg = null; // package to define proxy class in
//代理類訪問(wèn)控制符: public ,final
int accessFlags = Modifier.PUBLIC | Modifier.FINAL;
/*
* Record the package of a non-public proxy interface so that the
* proxy class will be defined in the same package. Verify that
* all non-public proxy interfaces are in the same package.
*/
//驗(yàn)證所有非公共的接口在同一個(gè)包內(nèi)；公共的就無(wú)需處理
//生成包名和類名的邏輯，包名默認(rèn)是com.sun.proxy，類名默認(rèn)是$Proxy 加上一個(gè)自增的整數(shù)值
//如果被代理類是 non-public proxy interface ，則用和被代理類接口一樣的包名
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();
//代理類的完全限定名，如com.sun.proxy.$Proxy0.calss
String proxyName = proxyPkg + proxyClassNamePrefix + num;
/*
* Generate the specified proxy class.
*/
//核心部分，生成代理類的字節(jié)碼
byte[] proxyClassFile = ProxyGenerator.generateProxyClass(
proxyName, interfaces, accessFlags);
try {
//把代理類加載到JVM中，至此動(dòng)態(tài)代理過(guò)程基本結(jié)束了
return defineClass0(loader, proxyName,
proxyClassFile, 0, proxyClassFile.length);
} catch (ClassFormatError e) {
/*
* A ClassFormatError here means that (barring bugs in the
* proxy class generation code) there was some other
* invalid aspect of the arguments supplied to the proxy
* class creation (such as virtual machine limitations
* exceeded).
*/
throw new IllegalArgumentException(e.toString());
}
}
}到這里其實(shí)已經(jīng)分析完了，但是本著深究的態(tài)度，決定看看JDK生成的動(dòng)態(tài)代理字節(jié)碼是什么，于是我們將字節(jié)碼保存到磁盤上的class文件中。代碼如下：
public static void main(String[] args) {
IUserService target = new UserServiceImpl();
MyInvocationHandler handler = new MyInvocationHandler(target);
//第一個(gè)參數(shù)是指定代理類的類加載器（我們傳入當(dāng)前測(cè)試類的類加載器）
//第二個(gè)參數(shù)是代理類需要實(shí)現(xiàn)的接口（我們傳入被代理類實(shí)現(xiàn)的接口，這樣生成的代理類和被代理類就實(shí)現(xiàn)了相同的接口）
//第三個(gè)參數(shù)是invocation handler，用來(lái)處理方法的調(diào)用。這里傳入我們自己實(shí)現(xiàn)的handler
IUserService proxyObject = (IUserService) Proxy.newProxyInstance(DynamicProxyTest.class.getClassLoader(),
target.getClass().getInterfaces(), handler);
proxyObject.add("張玉龍");
String path = "D:/$Proxy0.class";
byte[] classFile = ProxyGenerator.generateProxyClass("$Proxy0", HelloworldImpl.class.getInterfaces());
FileOutputStream out = null;
try {
out = new FileOutputStream(path);
out.write(classFile);
out.flush();
} catch (Exception e) {
e.printStackTrace();
} finally {
try {
out.close();
} catch (IOException e) {
e.printStackTrace();
}
}
}運(yùn)行這段代碼，會(huì)在D盤生成一個(gè)名為$Proxy0.class的文件。通過(guò)反編譯工具,得到JDK為我們生成的代理類是這樣的：
// Decompiled by Jad v1.5.8e2. Copyright 2001 Pavel Kouznetsov.
// Jad home page: http://kpdus.tripod.com/jad.html
// Decompiler options: packimports(3) fieldsfirst ansi space
import com.zhb.jdk.proxy.IUserService;
import java.lang.reflect.*;
public final class $Proxy0 extends Proxy
implements IUserService
{
private static Method m1;
private static Method m2;
private static Method m3;
private static Method m0;
//代理類的構(gòu)造函數(shù)，其參數(shù)正是是InvocationHandler實(shí)例，
//Proxy.newInstance方法就是通過(guò)通過(guò)這個(gè)構(gòu)造函數(shù)來(lái)創(chuàng)建代理實(shí)例的
public $Proxy0(InvocationHandler invocationhandler)
{
super(invocationhandler);
}
// Object類中的三個(gè)方法，equals，toString， hashCode
public final boolean equals(Object obj)
{
try
{
return ((Boolean)super.h.invoke(this, m1, new Object[] {
obj
})).booleanValue();
}
catch (Error ) { }
catch (Throwable throwable)
{
throw new UndeclaredThrowableException(throwable);
}
}
public final String toString()
{
try
{
return (String)super.h.invoke(this, m2, null);
}
catch (Error ) { }
catch (Throwable throwable)
{
throw new UndeclaredThrowableException(throwable);
}
}
//接口代理方法
public final void add(String s)
{
try
{
// invocation handler的 invoke方法在這里被調(diào)用
super.h.invoke(this, m3, new Object[] {
s
});
return;
}
catch (Error ) { }
catch (Throwable throwable)
{
throw new UndeclaredThrowableException(throwable);
}
}
public final int hashCode()
{
try
{
// 在這里調(diào)用了invoke方法。
return ((Integer)super.h.invoke(this, m0, null)).intValue();
}
catch (Error ) { }
catch (Throwable throwable)
{
throw new UndeclaredThrowableException(throwable);
}
}
// 靜態(tài)代碼塊對(duì)變量進(jìn)行一些初始化工作
static
{
try
{
m1 = Class.forName("java.lang.Object").getMethod("equals", new Class[] {
Class.forName("java.lang.Object")
});
m2 = Class.forName("java.lang.Object").getMethod("toString", new Class[0]);
m3 = Class.forName("com.zhb.jdk.proxy.IUserService").getMethod("add", new Class[] {
Class.forName("java.lang.String")
});
m0 = Class.forName("java.lang.Object").getMethod("hashCode", new Class[0]);
}
catch (NoSuchMethodException nosuchmethodexception)
{
throw new NoSuchMethodError(nosuchmethodexception.getMessage());
}
catch (ClassNotFoundException classnotfoundexception)
{
throw new NoClassDefFoundError(classnotfoundexception.getMessage());
}
}
}生成了Object類的三個(gè)方法：toString，hashCode，equals。還有我們需要被代理的方法。
JDK代理類的cache clear機(jī)制
大家都知道、在項(xiàng)目中被代理的class越來(lái)越多，所以jdk會(huì)搞一個(gè)cache的方式來(lái)防止相同的代理接口重復(fù)生成class，影響性能不說(shuō)，實(shí)現(xiàn)也不是很優(yōu)雅，那么現(xiàn)在就會(huì)有一個(gè)問(wèn)題了，當(dāng)classloader已經(jīng)在內(nèi)存中沒(méi)有依賴的時(shí)候，被代理的proxy class其實(shí)也沒(méi)有什么意義了，這樣就需要清空無(wú)用的cache，java Proxy采用了非常巧妙的“弱引用機(jī)制”，我們來(lái)看下面的代碼
我們還是繼續(xù)看get方法的源碼
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) {
ConcurrentMap<Object, Supplier<V>> oldValuesMap
= map.putIfAbsent(cacheKey,
valuesMap = new ConcurrentHashMap<>());
if (oldValuesMap != null) {
valuesMap = oldValuesMap;
}
}
.......
}其中源碼中有一個(gè)方法expungeStaleEntries、我們進(jìn)去這個(gè)方法一窺究竟
private void expungeStaleEntries() {
CacheKey<K> cacheKey;
while ((cacheKey = (CacheKey<K>)refQueue.poll()) != null) {
cacheKey.expungeFrom(map, reverseMap);
}
}在看看expungeFrom方法源碼干了些什么
void expungeFrom(ConcurrentMap<?, ? extends ConcurrentMap<?, ?>> map,
ConcurrentMap<?, Boolean> reverseMap) {
// removing just by key is always safe here because after a CacheKey
// is cleared and enqueue-ed it is only equal to itself
// (see equals method)...
ConcurrentMap<?, ?> valuesMap = map.remove(this);
// remove also from reverseMap if needed
if (valuesMap != null) {
for (Object cacheValue : valuesMap.values()) {
reverseMap.remove(cacheValue);
}
}
}代碼很清晰了，清空被代理的對(duì)象。現(xiàn)在的關(guān)鍵就是refQueue對(duì)象是怎么來(lái)的。我們繼續(xù)找一下跟refQueue相關(guān)的源碼、在get中還有一段代碼是這樣的
Object cacheKey = CacheKey.valueOf(key, refQueue);
private static final class CacheKey<K> extends WeakReference<K> {
// a replacement for null keys
private static final Object NULL_KEY = new Object();
static <K> Object valueOf(K key, ReferenceQueue<K> refQueue) {
return key == null
// null key means we can't weakly reference it,
// so we use a NULL_KEY singleton as cache key
? NULL_KEY
// non-null key requires wrapping with a WeakReference
: new CacheKey<>(key, refQueue);
}
private final int hash;
private CacheKey(K key, ReferenceQueue<K> refQueue) {
super(key, refQueue);
this.hash = System.identityHashCode(key); // compare by identity
}
.....
}這樣看就非常清晰了、原來(lái)是CacheKey繼承了WeakReference弱引用機(jī)制，當(dāng)弱引用依賴的key沒(méi)有引用的時(shí)候，當(dāng)前失效的對(duì)象就會(huì)進(jìn)入ReferenceQueue中來(lái)實(shí)現(xiàn)清空cache的功能、這種實(shí)現(xiàn)思路和ThreadLocal的實(shí)現(xiàn)原理是一樣的、大家有興趣可以去閱讀以下相關(guān)源碼。
三:手把手寫基于接口的java代理
上面我們分析了jdk動(dòng)態(tài)代理源碼、那我們是不是可以自己用自己的方式去寫一個(gè)屬于自己的jdk代理呢，答案是可以的
首先我們寫一個(gè)基類，當(dāng)然我并沒(méi)有在基類里面寫什么東西，只是模擬java中的proxy類而已，當(dāng)然我們也可以豐富的去拓展一下這個(gè)類的方法，來(lái)實(shí)現(xiàn)更多的功能，讀者可以通過(guò)讀完這篇文章之后自己去考慮一下如何來(lái)拓展。
1 package meituan.zylproxy.handlder;2 public class ZylProxy {3 public ZylProxy(){4 }5 }代理的核心接口，我們?nèi)プ龃淼臅r(shí)候一定是通過(guò)反射去調(diào)用的，不管jdk也好還是cglib也好，永遠(yuǎn)也無(wú)法脫離反射，我們照貓畫虎，自己寫一個(gè)代理接口核心類，這并不是什么難題，看起來(lái)和jdk的核心類接口也沒(méi)有什么區(qū)別。
1 package meituan.zylproxy.handlder;2 3 import java.lang.reflect.Method;4 5 public interface ZYLInvocationHandler {6 7 public Object invoke(Object proxy, Method method, Object[] args)8 throws Exception;9 }說(shuō)明一下 第一個(gè)參數(shù)proxy是代表代理類，而不是用戶自己寫的原生類實(shí)現(xiàn)。參數(shù)Method是接口的方法,args是運(yùn)行時(shí)參數(shù)列表，在運(yùn)行時(shí)傳遞過(guò)來(lái)的實(shí)際上就是實(shí)現(xiàn)類的參數(shù)，好了，下面讓我們?nèi)ド钊牒诵摹?/p>
我們自定義兩個(gè)接口和接口的實(shí)現(xiàn)Idto，Idto2，和Dtoimpl如下：
1 package meituan.zylproxy.test.i;2 3 public interface Idto {4 5 public void add();6 7 public String get();8 9 }package meituan.zylproxy.test.i;public interface Idto2 {public void adda(); public String geta();
}package meituan.zylproxy.test.i.impl;import meituan.zylproxy.test.i.Idto;import meituan.zylproxy.test.i.Idto2;public class DtoImpl implements Idto,Idto2{
@Overridepublic void add() {
System.out.println("add");
}
@Overridepublic String get() {
System.out.println("get");return "return get";
}
@Overridepublic void adda() {
System.out.println("adda");
}
@Overridepublic String geta() {
System.out.println("geta");return "return geta";
}
}這是幾個(gè)再簡(jiǎn)單不過(guò)的接口和實(shí)現(xiàn)類了，也沒(méi)有什么可說(shuō)的。接下來(lái)我們想對(duì)接口進(jìn)行代理，無(wú)非是我們動(dòng)態(tài)將接口進(jìn)行實(shí)現(xiàn)，從而達(dá)到對(duì)使用者進(jìn)行自定義handle接口暴露而已，下面看一下我們需要生成一個(gè)什么樣的代理類。
import java.lang.reflect.Method;import meituan.zylproxy.handlder.ZylProxy;import meituan.zylproxy.handlder.ZYLInvocationHandler;import meituan.zylproxy.test.i.Idto;import meituan.zylproxy.test.i.Idto2;public class IdtoPorxy extends ZylProxy implements Idto, Idto2 {public ZYLInvocationHandler zYLInvocationHandler;public static Method add1;public static Method get2;public static Method adda3;public static Method geta4;static {try {
add1 = Class.forName ( "meituan.zylproxy.test.i.Idto" ).getMethod ( "add", new Class[0] );
get2 = Class.forName ( "meituan.zylproxy.test.i.Idto" ).getMethod ( "get", new Class[0] );
adda3 = Class.forName ( "meituan.zylproxy.test.i.Idto2" ).getMethod ( "adda", new Class[0] );
geta4 = Class.forName ( "meituan.zylproxy.test.i.Idto2" ).getMethod ( "geta", new Class[0] );
} catch (Exception e) {
}
}public IdtoPorxy(ZYLInvocationHandler zYLInvocationHandler) {this.zYLInvocationHandler = zYLInvocationHandler;
}public void add() {
Object[] o = {};try {this.zYLInvocationHandler.invoke ( this, add1, o );return;
} catch (Throwable e) {
e.printStackTrace ();
}
}public java.lang.String get() {
Object[] o = {};try {return (java.lang.String) this.zYLInvocationHandler.invoke ( this, get2, o );
} catch (Exception e) {
e.printStackTrace ();
}return null;
}public void adda() {
Object[] o = {};try {this.zYLInvocationHandler.invoke ( this, adda3, o );return;
} catch (Throwable e) {
e.printStackTrace ();
}
}public java.lang.String geta() {
Object[] o = {};try {return (java.lang.String) this.zYLInvocationHandler.invoke ( this, geta4, o );
} catch (Exception e) {
e.printStackTrace ();
}return null;
}
}這個(gè)類不是由用戶寫的，而是我們動(dòng)態(tài)生成的，對(duì)于jdk來(lái)說(shuō)是生成了字節(jié)碼，對(duì)cglib來(lái)說(shuō)是通過(guò)字節(jié)碼增強(qiáng)，其實(shí)實(shí)現(xiàn)的方式有多種，后面為了更方便大家理解我用字符串的形式來(lái)動(dòng)態(tài)生成這么一個(gè)"家伙"，先看看這個(gè)類干了些什么吧，也很簡(jiǎn)單。
public class IdtoPorxy extends ZylProxy implements Idto, Idto2
首先是繼承了剛才我們所說(shuō)的ZylProxy，留著今后拓展，可以參照java的Proxy，然后并且動(dòng)態(tài)的實(shí)現(xiàn)了這兩個(gè)接口。很簡(jiǎn)單
public ZYLInvocationHandler zYLInvocationHandler;
public IdtoPorxy(ZYLInvocationHandler zYLInvocationHandler) {
this.zYLInvocationHandler = zYLInvocationHandler;
}這個(gè)是通過(guò)構(gòu)造函數(shù)傳進(jìn)來(lái)一個(gè)handler對(duì)象，對(duì)實(shí)現(xiàn)類的操作都靠它了。
public static Method add1;public static Method get2;public static Method adda3;public static Method geta4;static {try {
add1 = Class.forName ( "meituan.zylproxy.test.i.Idto" ).getMethod ( "add", new Class[0] );
get2 = Class.forName ( "meituan.zylproxy.test.i.Idto" ).getMethod ( "get", new Class[0] );
adda3 = Class.forName ( "meituan.zylproxy.test.i.Idto2" ).getMethod ( "adda", new Class[0] );
geta4 = Class.forName ( "meituan.zylproxy.test.i.Idto2" ).getMethod ( "geta", new Class[0] );
} catch (Exception e) {
}
}枚舉出來(lái)所有的接口的方法，通過(guò)class.forname來(lái)獲取到Method元數(shù)據(jù)。備用
public void add() {
Object[] o = {};try {this.zYLInvocationHandler.invoke ( this, add1, o );return;
} catch (Throwable e) {
e.printStackTrace ();
}
}public java.lang.String get() {
Object[] o = {};try {return (java.lang.String) this.zYLInvocationHandler.invoke ( this, get2, o );
} catch (Exception e) {
e.printStackTrace ();
}return null;
}public void adda() {
Object[] o = {};try {this.zYLInvocationHandler.invoke ( this, adda3, o );return;
} catch (Throwable e) {
e.printStackTrace ();
}
}public java.lang.String geta() {
Object[] o = {};try {return (java.lang.String) this.zYLInvocationHandler.invoke ( this, geta4, o );
} catch (Exception e) {
e.printStackTrace ();
}return null;
}上面是要枚舉出來(lái)所有的方法的實(shí)現(xiàn)，很簡(jiǎn)單都一個(gè)模樣，把實(shí)現(xiàn)交給handler去做就可以了。至于怎么實(shí)現(xiàn)靠handler，我們動(dòng)態(tài)生成的這個(gè)類只負(fù)責(zé)委托，不做任何事情?？吹竭@里大家一定急不可待的想知道這個(gè)類怎么生成的了，我把我寫的源碼給大家貼出來(lái)看一下。
package meituan.zylproxy.util;import java.lang.reflect.Method;import java.lang.reflect.Modifier;import meituan.zylproxy.test.i.Idto;import meituan.zylproxy.test.i.Idto2;public class ClassUtil {public static String mackProxyClass(Class<?> c) throws Exception{if(!c.isInterface()){throw new Exception("代理的類必須是接口");
}
StringBuffer importsp = new StringBuffer();
importsp.append("import java.lang.reflect.Method;\n");
importsp.append("import meituan.zylproxy.handlder.ZylProxy;\n");
importsp.append("import meituan.zylproxy.handlder.ZYLInvocationHandler;\n");
importsp.append("import " +c.getName() + ";\n");
StringBuilder publicStaticMethods = new StringBuilder(); //public static Method add;StringBuilder publicMethods = new StringBuilder();
publicMethods.append("public ZYLInvocationHandler zYLInvocationHandler;\n");
StringBuilder constructorsp = new StringBuilder();
String interFaceName = c.getName().substring(c.getName().lastIndexOf(".")+1);
constructorsp.append("public ").append("" + interFaceName + "Porxy").
append("(ZYLInvocationHandler zYLInvocationHandler) { "
+ "this.zYLInvocationHandler = zYLInvocationHandler;"
+ "}");
publicStaticMethods.append(" static { try { ");
StringBuilder classsp = new StringBuilder();
classsp.append("public class").append(" " + interFaceName + "Porxy").append(" extends ZylProxy implements ").append(interFaceName).append("{");
StringBuilder allMethods = new StringBuilder();
Method[] Methods = c.getMethods(); int curr=0;for (Method m_:Methods) {
curr++;
publicMethods.append("public static Method ").append(m_.getName() + String.valueOf(curr)).append(";\n");
publicStaticMethods.append("").append(m_.getName() + String.valueOf(curr)).append("=");
publicStaticMethods.append("Class.forName(\"" + c.getName() + "\")" + ".getMethod(\""+ m_.getName() +"\", ");
StringBuilder sp =new StringBuilder();
StringBuilder spArgs = new StringBuilder();
spArgs.append("Object[] o ={");//public sp.append(Modifier.toString(m_.getModifiers()).replace("abstract", "")).append(" ");//void | java.lang.Stringsp.append(m_.getReturnType().getName()).append(" ");//add()|get()sp.append(m_.getName().concat("("));
StringBuilder methodCLass = new StringBuilder(); if(m_.getParameterTypes().length>0){
Class<?>[] claszz = m_.getParameterTypes();int methodOffset = 0;
methodCLass.append("new Class[] { ");for (Class<?> c_ : claszz) {
String paramStr = "obj" + String.valueOf(++methodOffset);
spArgs.append(paramStr.concat(","));
sp.append(c_.getName().toString().concat(" ").concat(paramStr)).append(",");
methodCLass.append("Class.forName(\"" + c_.getName()).append("\"),");
}
sp = new StringBuilder(sp.substring(0, sp.length()-1));
spArgs = new StringBuilder(spArgs.substring(0, spArgs.length()-1));
methodCLass = new StringBuilder(methodCLass.substring(0, methodCLass.length()-1));
} if(methodCLass.length()>0){
methodCLass.append("}");
} else{
methodCLass.append("new Class[0]");
}
sp.append("){\n");
spArgs.append("}");
sp.append(spArgs+";\n"); if(sp.toString().contains("void")){
sp.append("try {\n this.zYLInvocationHandler.invoke(this,").append(m_.getName() + String.valueOf(curr)).append(",").append("o);\n return;\n");
sp.append("} catch (Throwable e) {e.printStackTrace();}}");
} else{
sp.append("try {return "
+ "("
+ m_.getReturnType().getName()+ ")"
+ "this.zYLInvocationHandler.invoke(this,").append(m_.getName() + String.valueOf(curr)).append(",").append("o);\n");
sp.append("} catch (Exception e) {e.printStackTrace();} return null;");
}
publicStaticMethods.append(methodCLass).append(");\n");
allMethods.append(sp);
}
publicStaticMethods.append("} catch(Exception e){}}");
classsp.append(publicMethods)
.append(publicStaticMethods)
.append(constructorsp).append(allMethods).append("}");
classsp.append("}");
importsp.append(classsp);return importsp.toString();
} public static String mackMultiProxyClass(Class<?>[] cs) throws Exception{
StringBuffer importsp = new StringBuffer();
importsp.append("import java.lang.reflect.Method;\n");
importsp.append("import meituan.zylproxy.handlder.ZylProxy;\n");
importsp.append("import meituan.zylproxy.handlder.ZYLInvocationHandler;\n");
StringBuilder publicStaticMethods = new StringBuilder();
publicStaticMethods.append(" static { try { "); //public static Method add;StringBuilder publicMethods = new StringBuilder();
publicMethods.append("public ZYLInvocationHandler zYLInvocationHandler;\n"); int curr=0;
StringBuilder constructorsp = new StringBuilder();
String interFaceName = cs[0].getName().substring(cs[0].getName().lastIndexOf(".")+1);
constructorsp.append("public ").append("" + interFaceName + "Porxy").
append("(ZYLInvocationHandler zYLInvocationHandler) { "
+ "this.zYLInvocationHandler = zYLInvocationHandler;"
+ "}");
StringBuilder allMethods = new StringBuilder();
StringBuilder classsp = new StringBuilder();
classsp.append("public class").append(" " + interFaceName + "Porxy").append(" extends ZylProxy implements "); for (Class<?> c:cs) {if(!c.isInterface()){throw new Exception("代理的類必須是接口");
}
classsp.append(c.getName().substring(c.getName().lastIndexOf(".")+1)).append(",");
importsp.append("import " +c.getName() + ";\n");
Method[] Methods = c.getMethods();
for (Method m_:Methods) {
curr++;
publicMethods.append("public static Method ").append(m_.getName() + String.valueOf(curr)).append(";\n");
publicStaticMethods.append("").append(m_.getName() + String.valueOf(curr)).append("=");
publicStaticMethods.append("Class.forName(\"" + c.getName() + "\")" + ".getMethod(\""+ m_.getName() +"\", ");
StringBuilder sp =new StringBuilder();
StringBuilder spArgs = new StringBuilder();
spArgs.append("Object[] o ={");//public sp.append(Modifier.toString(m_.getModifiers()).replace("abstract", "")).append(" ");//void | java.lang.Stringsp.append(m_.getReturnType().getName()).append(" ");//add()|get()sp.append(m_.getName().concat("("));
StringBuilder methodCLass = new StringBuilder(); if(m_.getParameterTypes().length>0){
Class<?>[] claszz = m_.getParameterTypes();int methodOffset = 0;
methodCLass.append("new Class[] { ");for (Class<?> c_ : claszz) {
String paramStr = "obj" + String.valueOf(++methodOffset);
spArgs.append(paramStr.concat(","));
sp.append(c_.getName().toString().concat(" ").concat(paramStr)).append(",");
methodCLass.append("Class.forName(\"" + c_.getName()).append("\"),");
}
sp = new StringBuilder(sp.substring(0, sp.length()-1));
spArgs = new StringBuilder(spArgs.substring(0, spArgs.length()-1));
methodCLass = new StringBuilder(methodCLass.substring(0, methodCLass.length()-1));
} if(methodCLass.length()>0){
methodCLass.append("}");
} else{
methodCLass.append("new Class[0]");
}
sp.append("){\n");
spArgs.append("}");
sp.append(spArgs+";\n"); if(sp.toString().contains("void")){
sp.append("try {\n this.zYLInvocationHandler.invoke(this,").append(m_.getName() + String.valueOf(curr)).append(",").append("o);\n return;\n");
sp.append("} catch (Throwable e) {e.printStackTrace();}}");
} else{
sp.append("try {return "
+ "("
+ m_.getReturnType().getName()+ ")"
+ "this.zYLInvocationHandler.invoke(this,").append(m_.getName() + String.valueOf(curr)).append(",").append("o);\n");
sp.append("} catch (Exception e) {e.printStackTrace();} return null;}");
}
publicStaticMethods.append(methodCLass).append(");\n");
allMethods.append(sp);
}
}
classsp = new StringBuilder(classsp.substring(0, classsp.length()-1)).append("{");
publicStaticMethods.append("} catch(Exception e){}}");
classsp.append(publicMethods)
.append(publicStaticMethods)
.append(constructorsp).append(allMethods).append("");
classsp.append("}");
importsp.append(classsp);return importsp.toString();
}
public static void main(String[] args) throws Exception {
System.out.println(mackMultiProxyClass(new Class<?>[]{Idto.class}));
}
}看起來(lái)很復(fù)雜，仔細(xì)看一下就看了那么幾個(gè)事情，把一個(gè)接口class或者多個(gè)接口class變成純字符串的過(guò)程，一共兩個(gè)方法，一個(gè)是單接口的實(shí)現(xiàn)，很早之前寫的，第二個(gè)方法是多接口的實(shí)現(xiàn)支持多接口，只需要傳一個(gè)class對(duì)象就會(huì)生成代理類的字符串，這里僅僅是字符串，需要編譯成class使用。那么如何編譯成class呢。通過(guò)java中的工具類 JavaCompiler很簡(jiǎn)單的就可以生成了。我們來(lái)看兩個(gè)工具類實(shí)現(xiàn)
package meituan.zylproxy;import java.io.ByteArrayOutputStream;import java.io.File;import java.io.FilterOutputStream;import java.io.IOException;import java.io.OutputStream;import java.io.Reader;import java.io.StringReader;import java.net.URI;import java.nio.CharBuffer;import java.nio.file.WatchEvent.Kind;import java.util.HashMap;import java.util.Map;import javax.tools.FileObject;import javax.tools.ForwardingJavaFileManager;import javax.tools.JavaFileManager;import javax.tools.JavaFileObject;import javax.tools.SimpleJavaFileObject;
@SuppressWarnings("unchecked")final class MemoryJavaFileManager extends ForwardingJavaFileManager {private final static String EXT = ".java";private Map<String, byte[]> classBytes;public MemoryJavaFileManager(JavaFileManager fileManager) {super(fileManager);
classBytes = new HashMap<String, byte[]>();
}public Map<String, byte[]> getClassBytes() {return classBytes;
}public void close() throws IOException {
classBytes = new HashMap<String, byte[]>();
}public void flush() throws IOException {
} private static class StringInputBuffer extends SimpleJavaFileObject {final String code;
StringInputBuffer(String name, String code) {super(toURI(name), Kind.SOURCE);this.code = code;
}public CharBuffer getCharContent(boolean ignoreEncodingErrors) {return CharBuffer.wrap(code);
}public Reader openReader() {return new StringReader(code);
}
} private class ClassOutputBuffer extends SimpleJavaFileObject {private String name;
ClassOutputBuffer(String name) {super(toURI(name), Kind.CLASS);this.name = name;
}public OutputStream openOutputStream() {return new FilterOutputStream(new ByteArrayOutputStream()) {public void close() throws IOException {
out.close();
ByteArrayOutputStream bos = (ByteArrayOutputStream) out;
classBytes.put(name, bos.toByteArray());
}
};
}
}public JavaFileObject getJavaFileForOutput(JavaFileManager.Location location,
String className,
JavaFileObject.Kind kind,
FileObject sibling) throws IOException {if (kind == JavaFileObject.Kind.CLASS) {return new ClassOutputBuffer(className);
} else {return super.getJavaFileForOutput(location, className, kind, sibling);
}
}static JavaFileObject makeStringSource(String name, String code) {return new StringInputBuffer(name, code);
}static URI toURI(String name) {
File file = new File(name);if (file.exists()) {return file.toURI();
} else {try {final StringBuilder newUri = new StringBuilder();
newUri.append("mfm:///");
newUri.append(name.replace('.', '/'));if (name.endsWith(EXT)) newUri.replace(newUri.length() - EXT.length(), newUri.length(), EXT);return URI.create(newUri.toString());
} catch (Exception exp) {return URI.create("mfm:///com/sun/script/java/java_source");
}
}
}
}package meituan.zylproxy;import java.io.IOException;import java.net.URL;import java.net.URLClassLoader;import java.util.Arrays;import java.util.HashMap;import java.util.Map;import java.util.regex.Matcher;import java.util.regex.Pattern;import javax.tools.JavaCompiler;import javax.tools.JavaFileObject;import javax.tools.StandardJavaFileManager;import javax.tools.ToolProvider;public class DynamicLoader {public static Map<String, byte[]> compile(String javaSrc) {
Pattern pattern = Pattern.compile("public\\s+class\\s+(\\w+)");
Matcher matcher = pattern.matcher(javaSrc);if (matcher.find())return compile(matcher.group(1) + ".java", javaSrc);return null;
} public static Map<String, byte[]> compile(String javaName, String javaSrc) {
JavaCompiler compiler = ToolProvider.getSystemJavaCompiler();
StandardJavaFileManager stdManager = compiler.getStandardFileManager(null, null, null);try (MemoryJavaFileManager manager = new MemoryJavaFileManager(stdManager)) {
JavaFileObject javaFileObject = manager.makeStringSource(javaName, javaSrc);
JavaCompiler.CompilationTask task = compiler.getTask(null, manager, null, null, null, Arrays.asList(javaFileObject));if (task.call())return manager.getClassBytes();
} catch (IOException e) {
e.printStackTrace();
}return null;
}public static class MemoryClassLoader extends URLClassLoader {
Map<String, byte[]> classBytes = new HashMap<String, byte[]>();public MemoryClassLoader(Map<String, byte[]> classBytes) {super(new URL[0], MemoryClassLoader.class.getClassLoader());this.classBytes.putAll(classBytes);
}
@Overrideprotected Class<?> findClass(String name) throws ClassNotFoundException {byte[] buf = classBytes.get(name);if (buf == null) {return super.findClass(name);
}
classBytes.remove(name);return defineClass(name, buf, 0, buf.length);
}
}
}通過(guò)DynamicLoader的compile方法可以把純字符串的str轉(zhuǎn)成byte[]數(shù)組，有了byte[]數(shù)組就可以很方便的獲取到class對(duì)象了，自定義一個(gè)MemoryClassLoader通過(guò)defineClass方法來(lái)獲取到class對(duì)象。這樣基本所有的事情都做完了。下面我們寫一個(gè)工廠類來(lái)獲取代理類。
package meituan.zylproxy.util;import java.util.Map;import meituan.zylproxy.DynamicLoader;import meituan.zylproxy.handlder.ZYLInvocationHandler;public class PorxyFactory { //單interface的時(shí)候用public static Object newProxyInstance(Class<?> c,ZYLInvocationHandler h) throws Exception{
String classStr = ClassUtil.mackProxyClass(c);
Map<String, byte[]> m = DynamicLoader.compile(classStr);
DynamicLoader.MemoryClassLoader classLoader = new DynamicLoader.MemoryClassLoader(m);
Class<?> proxy =classLoader.loadClass(m.keySet().toArray(new String[0])[0]);return proxy.getConstructor(ZYLInvocationHandler.class).newInstance(h);
}//多interface的時(shí)候用public static Object newProxyInstancewWithMultiClass(Class<?>[] c,ZYLInvocationHandler h) throws Exception{
String classStr = ClassUtil.mackMultiProxyClass(c);
System.out.println (classStr);
Map<String, byte[]> m = DynamicLoader.compile(classStr);
DynamicLoader.MemoryClassLoader classLoader = new DynamicLoader.MemoryClassLoader(m);
Class<?> proxy =classLoader.loadClass(m.keySet().toArray(new String[0])[0]);return proxy.getConstructor(ZYLInvocationHandler.class).newInstance(h);
}
}最后一步我們測(cè)試一下結(jié)果吧，寫一個(gè)測(cè)試類
package meituan.zylproxy.test;import meituan.zylproxy.handlder.Hander;import meituan.zylproxy.test.i.Idto;import meituan.zylproxy.test.i.impl.DtoImpl;import meituan.zylproxy.util.PorxyFactory;public class ZylPorxyTest { public static void main(String[] args) throws Exception {
Idto d = (Idto) PorxyFactory.newProxyInstancewWithMultiClass(DtoImpl.class.getInterfaces(), new Hander(new DtoImpl()));
d.add();
}
}很簡(jiǎn)單，第一個(gè)參數(shù)是所有的接口，第二個(gè)是handler實(shí)現(xiàn)。最后我們看看結(jié)果。
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