将dubbo中使用的动态代理作为工具类

ReflectUtils

package per.qiao.util.javassistUtil;

import java.lang.reflect.Constructor;
import java.lang.reflect.Method;

/**
 * Create by IntelliJ Idea 2018.2
 *
 * @author: qyp
 * Date: 2019-07-14 19:50
 */
public class ReflectUtils {

    /**
     * void(V).
     */
    public static final char JVM_VOID = 'V';

    /**
     * boolean(Z).
     */
    public static final char JVM_BOOLEAN = 'Z';

    /**
     * byte(B).
     */
    public static final char JVM_BYTE = 'B';

    /**
     * char(C).
     */
    public static final char JVM_CHAR = 'C';

    /**
     * double(D).
     */
    public static final char JVM_DOUBLE = 'D';

    /**
     * float(F).
     */
    public static final char JVM_FLOAT = 'F';

    /**
     * int(I).
     */
    public static final char JVM_INT = 'I';

    /**
     * long(J).
     */
    public static final char JVM_LONG = 'J';

    /**
     * short(S).
     */
    public static final char JVM_SHORT = 'S';

    public static String getDesc(final Method m) {
        StringBuilder ret = new StringBuilder(m.getName()).append('(');
        Class[] parameterTypes = m.getParameterTypes();
        for (int i = 0; i < parameterTypes.length; i++)
            ret.append(getDesc(parameterTypes[i]));
        ret.append(')').append(getDesc(m.getReturnType()));
        return ret.toString();
    }

    public static String getName(final Method m) {
        StringBuilder ret = new StringBuilder();
        ret.append(getName(m.getReturnType())).append(' ');
        ret.append(m.getName()).append('(');
        Class[] parameterTypes = m.getParameterTypes();
        for (int i = 0; i < parameterTypes.length; i++) {
            if (i > 0) {
                ret.append(',');
            }
            ret.append(getName(parameterTypes[i]));
        }
        ret.append(')');
        return ret.toString();
    }

    /**
     * get name.
     * java.lang.Object[][].class => "java.lang.Object[][]"
     *
     * @param c class.
     * @return name.
     */
    public static String getName(Class c) {
        if (c.isArray()) {
            StringBuilder sb = new StringBuilder();
            do {
                sb.append("[]");
                c = c.getComponentType();
            }
            while (c.isArray());

            return c.getName() + sb.toString();
        }
        return c.getName();
    }


    /**
     * get class desc.
     * boolean[].class => "[Z"
     * Object.class => "Ljava/lang/Object;"
     *
     * @param c class.
     * @return desc.
     */
    public static String getDesc(Class c) {
        StringBuilder ret = new StringBuilder();

        while (c.isArray()) {
            ret.append('[');
            c = c.getComponentType();
        }

        if (c.isPrimitive()) {
            String t = c.getName();
            if ("void".equals(t)) { ret.append(JVM_VOID);}
            else if ("boolean".equals(t)) { ret.append(JVM_BOOLEAN); }
            else if ("byte".equals(t)) {ret.append(JVM_BYTE);}
            else if ("char".equals(t)) { ret.append(JVM_CHAR);}
            else if ("double".equals(t)) { ret.append(JVM_DOUBLE); }
            else if ("float".equals(t)) { ret.append(JVM_FLOAT); }
            else if ("int".equals(t)) { ret.append(JVM_INT); }
            else if ("long".equals(t)) { ret.append(JVM_LONG); }
            else if ("short".equals(t)) { ret.append(JVM_SHORT); }
        } else {
            ret.append('L');
            ret.append(c.getName().replace('.', '/'));
            ret.append(';');
        }
        return ret.toString();
    }

    /**
     * get constructor desc.
     * "()V", "(Ljava/lang/String;I)V"
     *
     * @param c constructor.
     * @return desc
     */
    public static String getDesc(final Constructor c) {
        StringBuilder ret = new StringBuilder("(");
        Class[] parameterTypes = c.getParameterTypes();
        for (int i = 0; i < parameterTypes.length; i++)
            ret.append(getDesc(parameterTypes[i]));
        ret.append(')').append('V');
        return ret.toString();
    }

    /**
     * get method desc.
     * "(I)I", "()V", "(Ljava/lang/String;Z)V"
     *
     * @param m method.
     * @return desc.
     */
    public static String getDescWithoutMethodName(Method m) {
        StringBuilder ret = new StringBuilder();
        ret.append('(');
        Class[] parameterTypes = m.getParameterTypes();
        for (int i = 0; i < parameterTypes.length; i++)
            ret.append(getDesc(parameterTypes[i]));
        ret.append(')').append(getDesc(m.getReturnType()));
        return ret.toString();
    }

}

ClassHelper

package per.qiao.util.javassistUtil;

import java.util.*;

/**
 * Create by IntelliJ Idea 2018.2
 *
 * @author: qyp
 * Date: 2019-07-13 23:27
 */
public class ClassHelper {


    /**
     * Map with primitive type name as key and corresponding primitive type as
     * value, for example: "int" -> "int.class".
     */
    private static final Map> primitiveTypeNameMap = new HashMap>(16);
    /**
     * Map with primitive wrapper type as key and corresponding primitive type
     * as value, for example: Integer.class -> int.class.
     */
    private static final Map, Class> primitiveWrapperTypeMap = new HashMap, Class>(8);

    static {
        primitiveWrapperTypeMap.put(Boolean.class, boolean.class);
        primitiveWrapperTypeMap.put(Byte.class, byte.class);
        primitiveWrapperTypeMap.put(Character.class, char.class);
        primitiveWrapperTypeMap.put(Double.class, double.class);
        primitiveWrapperTypeMap.put(Float.class, float.class);
        primitiveWrapperTypeMap.put(Integer.class, int.class);
        primitiveWrapperTypeMap.put(Long.class, long.class);
        primitiveWrapperTypeMap.put(Short.class, short.class);

        Set> primitiveTypeNames = new HashSet>(16);
        primitiveTypeNames.addAll(primitiveWrapperTypeMap.values());
        primitiveTypeNames.addAll(Arrays
                .asList(new Class[]{boolean[].class, byte[].class, char[].class, double[].class,
                        float[].class, int[].class, long[].class, short[].class}));
        for (Iterator> it = primitiveTypeNames.iterator(); it.hasNext(); ) {
            Class primitiveClass = (Class) it.next();
            primitiveTypeNameMap.put(primitiveClass.getName(), primitiveClass);
        }
    }
    /**
     * get class loader
     *
     * @param cls
     * @return class loader
     */
    public static ClassLoader getClassLoader(Class cls) {
        ClassLoader cl = null;
        try {
            cl = Thread.currentThread().getContextClassLoader();
        } catch (Throwable ex) {
            // Cannot access thread context ClassLoader - falling back to system class loader...
        }
        if (cl == null) {
            // No thread context class loader -> use class loader of this class.
            cl = cls.getClassLoader();
        }
        return cl;
    }
}

ClassGenerator

package per.qiao.util.javassistUtil;


import javassist.*;

import java.lang.reflect.Constructor;
import java.lang.reflect.Method;
import java.security.ProtectionDomain;
import java.util.*;
import java.util.concurrent.ConcurrentHashMap;
import java.util.concurrent.atomic.AtomicLong;

/**
 * Create by IntelliJ Idea 2018.2
 *
 * @author: qyp
 * Date: 2019-07-13 23:13
 */
public final class ClassGenerator {
    private static final AtomicLong CLASS_NAME_COUNTER = new AtomicLong(0);
    private static final String SIMPLE_NAME_TAG = "";
    /**
     * ClassLoader - ClassPool
     */
    private static final Map POOL_MAP = new ConcurrentHashMap();
    private ClassPool mPool;
    private CtClass mCtc;
    private String mClassName, mSuperClass;
    private Set mInterfaces;
    private List mFields, mConstructors, mMethods;
    /**
     * 
     */
    private Map mCopyMethods;
    // 
    private Map> mCopyConstructors;
    private boolean mDefaultConstructor = false;

    private ClassGenerator() {
    }

    private ClassGenerator(ClassPool pool) {
        mPool = pool;
    }

    public static ClassGenerator newInstance() {
        return new ClassGenerator(getClassPool(Thread.currentThread().getContextClassLoader()));
    }

    public static ClassGenerator newInstance(ClassLoader loader) {
        return new ClassGenerator(getClassPool(loader));
    }


    public static ClassPool getClassPool(ClassLoader loader) {
        if (loader == null)
            return ClassPool.getDefault();

        ClassPool pool = POOL_MAP.get(loader);
        if (pool == null) {
            pool = new ClassPool(true);
            pool.appendClassPath(new LoaderClassPath(loader));
            POOL_MAP.put(loader, pool);
        }
        return pool;
    }

    private static String modifier(int mod) {
        if (Modifier.isPublic(mod)) return "public";
        if (Modifier.isProtected(mod)) return "protected";
        if (Modifier.isPrivate(mod)) return "private";
        return "";
    }

    public String getClassName() {
        return mClassName;
    }

    public ClassGenerator setClassName(String name) {
        mClassName = name;
        return this;
    }

    public ClassGenerator addInterface(String cn) {
        if (mInterfaces == null)
            mInterfaces = new HashSet();
        mInterfaces.add(cn);
        return this;
    }

    public ClassGenerator addInterface(Class cl) {
        return addInterface(cl.getName());
    }

    public ClassGenerator setSuperClass(String cn) {
        mSuperClass = cn;
        return this;
    }

    public ClassGenerator setSuperClass(Class cl) {
        mSuperClass = cl.getName();
        return this;
    }

    public ClassGenerator addField(String code) {
        if (mFields == null)
            mFields = new ArrayList();
        mFields.add(code);
        return this;
    }

    public ClassGenerator addField(String name, int mod, Class type) {
        return addField(name, mod, type, null);
    }

    public ClassGenerator addField(String name, int mod, Class type, String def) {
        StringBuilder sb = new StringBuilder();
        sb.append(modifier(mod)).append(' ').append(ReflectUtils.getName(type)).append(' ');
        sb.append(name);
        if (def != null && def.length() > 0) {
            sb.append('=');
            sb.append(def);
        }
        sb.append(';');
        return addField(sb.toString());
    }

    public ClassGenerator addMethod(String code) {
        if (mMethods == null)
            mMethods = new ArrayList();
        mMethods.add(code);
        return this;
    }

    public ClassGenerator addMethod(String name, int mod, Class rt, Class[] pts, String body) {
        return addMethod(name, mod, rt, pts, null, body);
    }

    public ClassGenerator addMethod(String name, int mod, Class rt, Class[] pts, Class[] ets, String body) {
        StringBuilder sb = new StringBuilder();
        sb.append(modifier(mod)).append(' ').append(ReflectUtils.getName(rt)).append(' ').append(name);
        sb.append('(');
        for (int i = 0; i < pts.length; i++) {
            if (i > 0)
                sb.append(',');
            sb.append(ReflectUtils.getName(pts[i]));
            sb.append(" arg").append(i);
        }
        sb.append(')');
        if (ets != null && ets.length > 0) {
            sb.append(" throws ");
            for (int i = 0; i < ets.length; i++) {
                if (i > 0)
                    sb.append(',');
                sb.append(ReflectUtils.getName(ets[i]));
            }
        }
        sb.append('{').append(body).append('}');
        return addMethod(sb.toString());
    }

    public ClassGenerator addMethod(Method m) {
        addMethod(m.getName(), m);
        return this;
    }

    public ClassGenerator addMethod(String name, Method m) {
        String desc = name + ReflectUtils.getDescWithoutMethodName(m);
        addMethod(':' + desc);
        if (mCopyMethods == null)
            mCopyMethods = new ConcurrentHashMap(8);
        mCopyMethods.put(desc, m);
        return this;
    }

    public ClassGenerator addConstructor(String code) {
        if (mConstructors == null)
            mConstructors = new LinkedList();
        mConstructors.add(code);
        return this;
    }

    public ClassGenerator addConstructor(int mod, Class[] pts, String body) {
        return addConstructor(mod, pts, null, body);
    }

    public ClassGenerator addConstructor(int mod, Class[] pts, Class[] ets, String body) {
        StringBuilder sb = new StringBuilder();
        sb.append(modifier(mod)).append(' ').append(SIMPLE_NAME_TAG);
        sb.append('(');
        for (int i = 0; i < pts.length; i++) {
            if (i > 0)
                sb.append(',');
            sb.append(ReflectUtils.getName(pts[i]));
            sb.append(" arg").append(i);
        }
        sb.append(')');
        if (ets != null && ets.length > 0) {
            sb.append(" throws ");
            for (int i = 0; i < ets.length; i++) {
                if (i > 0)
                    sb.append(',');
                sb.append(ReflectUtils.getName(ets[i]));
            }
        }
        sb.append('{').append(body).append('}');
        return addConstructor(sb.toString());
    }

    public ClassGenerator addConstructor(Constructor c) {
        String desc = ReflectUtils.getDesc(c);
        addConstructor(":" + desc);
        if (mCopyConstructors == null)
            mCopyConstructors = new ConcurrentHashMap>(4);
        mCopyConstructors.put(desc, c);
        return this;
    }

    public ClassGenerator addDefaultConstructor() {
        mDefaultConstructor = true;
        return this;
    }

    public ClassPool getClassPool() {
        return mPool;
    }

    public Class toClass() {
        return toClass(ClassHelper.getClassLoader(ClassGenerator.class), getClass().getProtectionDomain());
    }

    public Class toClass(ClassLoader loader, ProtectionDomain pd) {
        if (mCtc != null)
            mCtc.detach();
        long id = CLASS_NAME_COUNTER.getAndIncrement();
        try {
            CtClass ctcs = mSuperClass == null ? null : mPool.get(mSuperClass);
            if (mClassName == null)
                mClassName = (mSuperClass == null || javassist.Modifier.isPublic(ctcs.getModifiers())
                        ? ClassGenerator.class.getName() : mSuperClass + "$sc") + id;
            mCtc = mPool.makeClass(mClassName);
            if (mSuperClass != null)
                mCtc.setSuperclass(ctcs);
            // add dynamic class tag.  去掉dubbo回声测试的DC接口
            //mCtc.addInterface(mPool.get(DC.class.getName()));
            if (mInterfaces != null)
                for (String cl : mInterfaces) mCtc.addInterface(mPool.get(cl));
            if (mFields != null)
                for (String code : mFields) mCtc.addField(CtField.make(code, mCtc));
            if (mMethods != null) {
                for (String code : mMethods) {
                    if (code.charAt(0) == ':')
                        mCtc.addMethod(CtNewMethod.copy(getCtMethod(mCopyMethods.get(code.substring(1))), code.substring(1, code.indexOf('(')), mCtc, null));
                    else
                        // 这里将
                        mCtc.addMethod(CtNewMethod.make(code, mCtc));
                }
            }
            if (mDefaultConstructor)
                mCtc.addConstructor(CtNewConstructor.defaultConstructor(mCtc));
            if (mConstructors != null) {
                for (String code : mConstructors) {
                    if (code.charAt(0) == ':') {
                        mCtc.addConstructor(CtNewConstructor.copy(getCtConstructor(mCopyConstructors.get(code.substring(1))), mCtc, null));
                    } else {
                        String[] sn = mCtc.getSimpleName().split("\\$+"); // inner class name include $.
                        mCtc.addConstructor(CtNewConstructor.make(code.replaceFirst(SIMPLE_NAME_TAG, sn[sn.length - 1]), mCtc));
                    }
                }
            }
            return mCtc.toClass(loader, pd);
        } catch (RuntimeException e) {
            throw e;
        } catch (NotFoundException e) {
            throw new RuntimeException(e.getMessage(), e);
        } catch (CannotCompileException e) {
            throw new RuntimeException(e.getMessage(), e);
        }
    }

    public void release() {
        if (mCtc != null) mCtc.detach();
        if (mInterfaces != null) mInterfaces.clear();
        if (mFields != null) mFields.clear();
        if (mMethods != null) mMethods.clear();
        if (mConstructors != null) mConstructors.clear();
        if (mCopyMethods != null) mCopyMethods.clear();
        if (mCopyConstructors != null) mCopyConstructors.clear();
    }

    private CtClass getCtClass(Class c) throws NotFoundException {
        return mPool.get(c.getName());
    }

    private CtMethod getCtMethod(Method m) throws NotFoundException {
        return getCtClass(m.getDeclaringClass()).getMethod(m.getName(), ReflectUtils.getDescWithoutMethodName(m));
    }

    private CtConstructor getCtConstructor(Constructor c) throws NotFoundException {
        return getCtClass(c.getDeclaringClass()).getConstructor(ReflectUtils.getDesc(c));
    }
}

Proxy

package per.qiao.util.javassistUtil;




import sun.security.action.GetBooleanAction;

import java.lang.ref.Reference;
import java.lang.ref.WeakReference;
import java.lang.reflect.InvocationHandler;
import java.lang.reflect.Method;
import java.lang.reflect.Modifier;
import java.security.AccessController;
import java.util.*;
import java.util.concurrent.atomic.AtomicLong;

/**
 * Create by IntelliJ Idea 2018.2
 *
 * @author: qyp
 * Date: 2019-07-13 22:59
 */
public abstract class Proxy {
    public static final InvocationHandler RETURN_NULL_INVOKER = new InvocationHandler() {
        @Override
        public Object invoke(Object proxy, Method method, Object[] args) {
            return null;
        }
    };
    public static final InvocationHandler THROW_UNSUPPORTED_INVOKER = new InvocationHandler() {
        @Override
        public Object invoke(Object proxy, Method method, Object[] args) {
            throw new UnsupportedOperationException("Method [" + ReflectUtils.getName(method) + "] unimplemented.");
        }
    };
    private static final AtomicLong PROXY_CLASS_COUNTER = new AtomicLong(0);
    private static final String PACKAGE_NAME = Proxy.class.getPackage().getName();
    private static final Map> ProxyCacheMap = new WeakHashMap>();

    private static final Object PendingGenerationMarker = new Object();

    private static final boolean saveGeneratedFiles = (Boolean)AccessController.doPrivileged(new GetBooleanAction("per.qiao.ProxyGenerator.saveGeneratedFiles"));

    protected Proxy() {
    }

    /**
     * Get proxy.
     *
     * @param ics interface class array.
     * @return Proxy instance.
     */
    public static Proxy getProxy(Class... ics) {
        return getProxy(ClassHelper.getClassLoader(Proxy.class), ics);
    }

    /**
     * Get proxy.
     *
     * @param cl  class loader.
     * @param ics interface class array.
     * @return Proxy instance.
     */
    public static Proxy getProxy(ClassLoader cl, Class... ics) {
        if (ics.length > 65535)
            throw new IllegalArgumentException("interface limit exceeded");

        StringBuilder sb = new StringBuilder();
        // 校验接口的个数
        for (int i = 0; i < ics.length; i++) {
            String itf = ics[i].getName();
            if (!ics[i].isInterface())
                throw new RuntimeException(itf + " is not a interface.");

            Class tmp = null;
            try {
                tmp = Class.forName(itf, false, cl);
            } catch (ClassNotFoundException e) {
            }

            if (tmp != ics[i])
                throw new IllegalArgumentException(ics[i] + " is not visible from class loader");

            sb.append(itf).append(';');
        }

        // use interface class name list as key.
        String key = sb.toString();

        // get cache by class loader.
        Map cache;
        synchronized (ProxyCacheMap) {
            cache = ProxyCacheMap.get(cl);
            if (cache == null) {
                cache = new HashMap();
                ProxyCacheMap.put(cl, cache);
            }
        }

        Proxy proxy = null;
        synchronized (cache) {
            do {
                Object value = cache.get(key);
                if (value instanceof Reference) {
                    proxy = (Proxy) ((Reference) value).get();
                    if (proxy != null)
                        return proxy;
                }

                if (value == PendingGenerationMarker) {
                    try {
                        cache.wait();
                    } catch (InterruptedException e) {
                    }
                } else {
                    cache.put(key, PendingGenerationMarker);
                    break;
                }
            }
            while (true);
        }

        long id = PROXY_CLASS_COUNTER.getAndIncrement();
        String pkg = null;
        ClassGenerator ccp = null, ccm = null;
        try {
            ccp = ClassGenerator.newInstance(cl);

            Set worked = new HashSet();
            List methods = new ArrayList();

            // 如果没有被public修饰，那么就是default级别，那么该动态类的位置只能和接口在同一个包内
            for (int i = 0; i < ics.length; i++) {
                if (!Modifier.isPublic(ics[i].getModifiers())) {
                    String npkg = ics[i].getPackage().getName();
                    if (pkg == null) {
                        pkg = npkg;
                    } else {
                        if (!pkg.equals(npkg))
                            throw new IllegalArgumentException("non-public interfaces from different packages");
                    }
                }
                ccp.addInterface(ics[i]);

                for (Method method : ics[i].getMethods()) {
                    String desc = ReflectUtils.getDesc(method);
                    if (worked.contains(desc))
                        continue;
                    worked.add(desc);

                    int ix = methods.size();
                    Class rt = method.getReturnType();
                    Class[] pts = method.getParameterTypes();

                    StringBuilder code = new StringBuilder("Object[] args = new Object[").append(pts.length).append("];");
                    for (int j = 0; j < pts.length; j++)
                        code.append(" args[").append(j).append("] = ($w)$").append(j + 1).append(";");
                    code.append(" Object ret = handler.invoke(this, methods[" + ix + "], args);");
                    if (!Void.TYPE.equals(rt))
                        code.append(" return ").append(asArgument(rt, "ret")).append(";");

                    methods.add(method);
                    ccp.addMethod(method.getName(), method.getModifiers(), rt, pts, method.getExceptionTypes(), code.toString());
                }
            }

            if (pkg == null)
                pkg = PACKAGE_NAME;

            // create ProxyInstance class.
            String pcn = pkg + ".proxy" + id;
            ccp.setClassName(pcn);
            ccp.addField("public static java.lang.reflect.Method[] methods;");
            ccp.addField("private " + InvocationHandler.class.getName() + " handler;");
            ccp.addConstructor(Modifier.PUBLIC, new Class[]{InvocationHandler.class}, new Class[0], "handler=$1;");
            ccp.addDefaultConstructor();
            Class clazz = ccp.toClass();
            clazz.getField("methods").set(null, methods.toArray(new Method[0]));

            // create Proxy class.
            String fcn = Proxy.class.getName() + id;
            ccm = ClassGenerator.newInstance(cl);
            ccm.setClassName(fcn);
            ccm.addDefaultConstructor();
            ccm.setSuperClass(Proxy.class);
            ccm.addMethod("public Object newInstance(" + InvocationHandler.class.getName() + " h){ return new " + pcn + "($1); }");
            Class pc = ccm.toClass();

//            if (System.getProperty("per.qiao.ProxyGenerator.saveGeneratedFiles") != null) {
            if (saveGeneratedFiles) {
                ccp.getClassPool().get("per.qiao.util.javassistUtil.proxy0").writeFile("E:\\Java4IDEA\\dubboSource\\src\\main\\java\\");
            }

            proxy = (Proxy) pc.newInstance();
        } catch (RuntimeException e) {
            throw e;
        } catch (Exception e) {
            throw new RuntimeException(e.getMessage(), e);
        } finally {
            // release ClassGenerator
            if (ccp != null)
                ccp.release();
            if (ccm != null)
                ccm.release();
            synchronized (cache) {
                if (proxy == null)
                    cache.remove(key);
                else
                    cache.put(key, new WeakReference(proxy));
                cache.notifyAll();
            }
        }
        return proxy;
    }

    private static String asArgument(Class cl, String name) {
        if (cl.isPrimitive()) {
            if (Boolean.TYPE == cl)
                return name + "==null?false:((Boolean)" + name + ").booleanValue()";
            if (Byte.TYPE == cl)
                return name + "==null?(byte)0:((Byte)" + name + ").byteValue()";
            if (Character.TYPE == cl)
                return name + "==null?(char)0:((Character)" + name + ").charValue()";
            if (Double.TYPE == cl)
                return name + "==null?(double)0:((Double)" + name + ").doubleValue()";
            if (Float.TYPE == cl)
                return name + "==null?(float)0:((Float)" + name + ").floatValue()";
            if (Integer.TYPE == cl)
                return name + "==null?(int)0:((Integer)" + name + ").intValue()";
            if (Long.TYPE == cl)
                return name + "==null?(long)0:((Long)" + name + ").longValue()";
            if (Short.TYPE == cl)
                return name + "==null?(short)0:((Short)" + name + ").shortValue()";
            throw new RuntimeException(name + " is unknown primitive type.");
        }
        return "(" + ReflectUtils.getName(cl) + ")" + name;
    }

    /**
     * get instance with default handler.
     *
     * @return instance.
     */
    public Object newInstance() {
        return newInstance(THROW_UNSUPPORTED_INVOKER);
    }

    /**
     * get instance with special handler.
     *
     * @return instance.
     */
    abstract public Object newInstance(InvocationHandler handler);
}

测试

public class ProxyTest {

    public static void main(String[] args) {

        Person person = new Person();
        Class[] interfaces = Person.class.getInterfaces();
        System.getProperties().put("per.qiao.ProxyGenerator.saveGeneratedFiles", "true");
        BasePerson proxyperson = (BasePerson) Proxy.getProxy(interfaces).newInstance(new MyInvocationHandler(person));
//        BasePerson proxyperson = (BasePerson) Proxy.getProxy(interfaces).newInstance(Proxy.RETURN_NULL_INVOKER);

        proxyperson.doSth();
//        System.out.println(sth);
    }

}

class MyInvocationHandler implements InvocationHandler {

    Object targetObj;

    public MyInvocationHandler(Object obj) {
        targetObj = obj;
    }

    @Override
    public Object invoke(Object proxy, Method method, Object[] args) throws Throwable {
        System.out.println("代理前置");
        Object invoke = method.invoke(targetObj, args);
        System.out.println("代理后置");
        return invoke;
    }
}

转载于:https://www.cnblogs.com/qiaozhuangshi/p/11185460.html