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<String, Class<?>> primitiveTypeNameMap = new HashMap<String, Class<?>>(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<?>, Class<?>> primitiveWrapperTypeMap = new HashMap<Class<?>, 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<Class<?>> primitiveTypeNames = new HashSet<Class<?>>(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<Class<?>> 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 = "<init>";
/**
* ClassLoader - ClassPool
*/
private static final Map<ClassLoader, ClassPool> POOL_MAP = new ConcurrentHashMap<ClassLoader, ClassPool>();
private ClassPool mPool;
private CtClass mCtc;
private String mClassName, mSuperClass;
private Set<String> mInterfaces;
private List<String> mFields, mConstructors, mMethods;
/**
* <method desc,method instance>
*/
private Map<String, Method> mCopyMethods;
// <constructor desc,constructor instance>
private Map<String, Constructor<?>> 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<String>();
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<String>();
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<String>();
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<String, Method>(8);
mCopyMethods.put(desc, m);
return this;
} public ClassGenerator addConstructor(String code) {
if (mConstructors == null)
mConstructors = new LinkedList<String>();
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<String, Constructor<?>>(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<ClassLoader, Map<String, Object>> ProxyCacheMap = new WeakHashMap<ClassLoader, Map<String, Object>>(); 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<String, Object> cache;
synchronized (ProxyCacheMap) {
cache = ProxyCacheMap.get(cl);
if (cache == null) {
cache = new HashMap<String, Object>();
ProxyCacheMap.put(cl, cache);
}
} Proxy proxy = null;
synchronized (cache) {
do {
Object value = cache.get(key);
if (value instanceof Reference<?>) {
proxy = (Proxy) ((Reference<?>) value).get();
if (proxy != null)
return proxy;
} if (value == PendingGenerationMarker) {
try {
cache.wait();
} catch (InterruptedException e) {
}
} else {
cache.put(key, PendingGenerationMarker);
break;
}
}
while (true);
} long id = PROXY_CLASS_COUNTER.getAndIncrement();
String pkg = null;
ClassGenerator ccp = null, ccm = null;
try {
ccp = ClassGenerator.newInstance(cl); Set<String> worked = new HashSet<String>();
List<Method> methods = new ArrayList<Method>(); // 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>(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;
}
}

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