RRIT（Run-Time Type Identification）运行时类型识别。在《Thinking in Java》一书第十四章中有提到，其作用是**在运行时识别一个对象的类型和类的信息。**主要有两种方式：一种是“传统的”RTTI，它假定我们在编译时已经知道了所有的类型；另一种是“反射”机制，它允许我们在运行时发现和使用类的信息。
Class类，Class类也是一个实实在在的类，存在于JDK的java.lang包中。Class类的实例表示java应用运行时的类(class ans enum)或接口(interface and annotation)（每个java类运行时都在JVM里表现为一个class对象，可通过类名.class、类型.getClass()、Class.forName("类名")等方法获取class对象）。数组同样也被映射为为class 对象的一个类，所有具有相同元素类型和维数的数组都共享该 Class 对象。基本类型boolean，byte，char，short，int，long，float，double和关键字void同样表现为 class 对象。
某种意义上来说，Java有两种对象：实例对象和Class对象。
每个类的运行时的类型信息就是用Class对象表示的。它包含了与类有关的信息。
我们的实例对象就通过Class对象来创建的。Java使用Class对象执行其RTTI（运行时类型识别，Run-Time Type Identification），多态是基于RTTI实现的。
public final class Class<T> implements java.io.Serializable,
GenericDeclaration,
Type,
AnnotatedElement {
private static final int ANNOTATION= 0x00002000;
private static final int ENUM = 0x00004000;
private static final int SYNTHETIC = 0x00001000;
private static native void registerNatives();
static {
registerNatives();
}
/*
* Private constructor. Only the Java Virtual Machine creates Class objects. //私有构造器，只有JVM才能调用创建Class对象
* This constructor is not used and prevents the default constructor being
* generated.
*/
private Class(ClassLoader loader) {
// Initialize final field for classLoader. The initialization value of non-null
// prevents future JIT optimizations from assuming this final field is null.
classLoader = loader;
}
@Test
public void classTest() throws Exception {
// 获取Class对象的三种方式
logger.info("根据类名: \t" + User.class);
logger.info("根据对象: \t" + new User().getClass());
logger.info("根据全限定类名:\t" + Class.forName("com.test.User"));
// 常用的方法
logger.info("获取全限定类名:\t" + userClass.getName());
logger.info("获取类名:\t" + userClass.getSimpleName());
logger.info("实例化:\t" + userClass.newInstance());
}
// ...
package com.test;
public class User {
private String name = "init";
private int age;
public User() {}
public User(String name, int age) {
super();
this.name = name;
this.age = age;
}
private String getName() {
return name;
}
private void setName(String name) {
this.name = name;
}
public int getAge() {
return age;
}
public void setAge(int age) {
this.age = age;
}
@Override
public String toString() {
return "User [name=" + name + ", age=" + age + "]";
}
}
输出结果：
根据类名: class com.test.User
根据对象: class com.test.User
根据全限定类名: class com.test.User
获取全限定类名: com.test.User
获取类名: com.test.User
实例化: User [name=init, age=0]
package com.cry;
import java.lang.reflect.Field;
interface I1 {
}
interface I2 {
}
class Cell{
public int mCellPublic;
}
class Animal extends Cell{
private int mAnimalPrivate;
protected int mAnimalProtected;
int mAnimalDefault;
public int mAnimalPublic;
private static int sAnimalPrivate;
protected static int sAnimalProtected;
static int sAnimalDefault;
public static int sAnimalPublic;
}
class Dog extends Animal implements I1, I2 {
private int mDogPrivate;
public int mDogPublic;
protected int mDogProtected;
private int mDogDefault;
private static int sDogPrivate;
protected static int sDogProtected;
static int sDogDefault;
public static int sDogPublic;
}
public class Test {
public static void main(String[] args) throws IllegalAccessException, InstantiationException {
Class<Dog> dog = Dog.class;
//类名打印
System.out.println(dog.getName()); //com.cry.Dog
System.out.println(dog.getSimpleName()); //Dog
System.out.println(dog.getCanonicalName());//com.cry.Dog
//接口
System.out.println(dog.isInterface()); //false
for (Class iI : dog.getInterfaces()) {
System.out.println(iI);
}
/*
interface com.cry.I1
interface com.cry.I2
*/
//父类
System.out.println(dog.getSuperclass());//class com.cry.Animal
//创建对象
Dog d = dog.newInstance();
//字段
for (Field f : dog.getFields()) {
System.out.println(f.getName());
}
/*
mDogPublic
sDogPublic
mAnimalPublic
sAnimalPublic
mCellPublic //父类的父类的公共字段也打印出来了
*/
System.out.println("---------");
for (Field f : dog.getDeclaredFields()) {
System.out.println(f.getName());
}
/** 只有自己类声明的字段
mDogPrivate
mDogPublic
mDogProtected
mDogDefault
sDogPrivate
sDogProtected
sDogDefault
sDogPublic
*/
}
}
//
public Class<?> loadClass(String name) throws ClassNotFoundException {
return loadClass(name, false);
}
// sun.misc.Launcher
public Class<?> loadClass(String var1, boolean var2) throws ClassNotFoundException {
int var3 = var1.lastIndexOf(46);
if(var3 != -1) {
SecurityManager var4 = System.getSecurityManager();
if(var4 != null) {
var4.checkPackageAccess(var1.substring(0, var3));
}
}
if(this.ucp.knownToNotExist(var1)) {
Class var5 = this.findLoadedClass(var1);
if(var5 != null) {
if(var2) {
this.resolveClass(var5);
}
return var5;
} else {
throw new ClassNotFoundException(var1);
}
} else {
return super.loadClass(var1, var2);
}
}
// java.lang.ClassLoader
protected Class<?> loadClass(String name, boolean resolve)
throws ClassNotFoundException
{
// 先获取锁
synchronized (getClassLoadingLock(name)) {
// First, check if the class has already been loaded
// 如果已经加载了的话，就不用再加载了
Class<?> c = findLoadedClass(name);
if (c == null) {
long t0 = System.nanoTime();
try {
// 双亲委托加载
if (parent != null) {
c = parent.loadClass(name, false);
} else {
c = findBootstrapClassOrNull(name);
}
} catch (ClassNotFoundException e) {
// ClassNotFoundException thrown if class not found
// from the non-null parent class loader
}
// 父类没有加载到时，再自己加载
if (c == null) {
// If still not found, then invoke findClass in order
// to find the class.
long t1 = System.nanoTime();
c = findClass(name);
// this is the defining class loader; record the stats
sun.misc.PerfCounter.getParentDelegationTime().addTime(t1 - t0);
sun.misc.PerfCounter.getFindClassTime().addElapsedTimeFrom(t1);
sun.misc.PerfCounter.getFindClasses().increment();
}
}
if (resolve) {
resolveClass(c);
}
return c;
}
}
protected Object getClassLoadingLock(String className) {
Object lock = this;
if (parallelLockMap != null) {
// 使用 ConcurrentHashMap来保存锁
Object newLock = new Object();
lock = parallelLockMap.putIfAbsent(className, newLock);
if (lock == null) {
lock = newLock;
}
}
return lock;
}
protected final Class<?> findLoadedClass(String name) {
if (!checkName(name))
return null;
return findLoadedClass0(name);
}
下面来看一下 newInstance() 的实现方式。
// 首先肯定是 Class.newInstance
@CallerSensitive
public T newInstance()
throws InstantiationException, IllegalAccessException
{
if (System.getSecurityManager() != null) {
checkMemberAccess(Member.PUBLIC, Reflection.getCallerClass(), false);
}
// NOTE: the following code may not be strictly correct under
// the current Java memory model.
// Constructor lookup
// newInstance() 其实相当于调用类的无参构造函数，所以，首先要找到其无参构造器
if (cachedConstructor == null) {
if (this == Class.class) {
// 不允许调用 Class 的 newInstance() 方法
throw new IllegalAccessException(
"Can not call newInstance() on the Class for java.lang.Class"
);
}
try {
// 获取无参构造器
Class<?>[] empty = {};
final Constructor<T> c = getConstructor0(empty, Member.DECLARED);
// Disable accessibility checks on the constructor
// since we have to do the security check here anyway
// (the stack depth is wrong for the Constructor's
// security check to work)
java.security.AccessController.doPrivileged(
new java.security.PrivilegedAction<Void>() {
public Void run() {
c.setAccessible(true);
return null;
}
});
cachedConstructor = c;
} catch (NoSuchMethodException e) {
throw (InstantiationException)
new InstantiationException(getName()).initCause(e);
}
}
Constructor<T> tmpConstructor = cachedConstructor;
// Security check (same as in java.lang.reflect.Constructor)
int modifiers = tmpConstructor.getModifiers();
if (!Reflection.quickCheckMemberAccess(this, modifiers)) {
Class<?> caller = Reflection.getCallerClass();
if (newInstanceCallerCache != caller) {
Reflection.ensureMemberAccess(caller, this, null, modifiers);
newInstanceCallerCache = caller;
}
}
// Run constructor
try {
// 调用无参构造器
return tmpConstructor.newInstance((Object[])null);
} catch (InvocationTargetException e) {
Unsafe.getUnsafe().throwException(e.getTargetException());
// Not reached
return null;
}
}
newInstance() 主要做了三件事：
权限检测，如果不通过直接抛出异常；
查找无参构造器，并将其缓存起来；
调用具体方法的无参构造方法，生成实例并返回；
下面是获取构造器的过程：
private Constructor<T> getConstructor0(Class<?>[] parameterTypes,
int which) throws NoSuchMethodException
{
// 获取所有构造器
Constructor<T>[] constructors = privateGetDeclaredConstructors((which == Member.PUBLIC));
for (Constructor<T> constructor : constructors) {
if (arrayContentsEq(parameterTypes,
constructor.getParameterTypes())) {
return getReflectionFactory().copyConstructor(constructor);
}
}
throw new NoSuchMethodException(getName() + ".<init>" + argumentTypesToString(parameterTypes));
}
getConstructor0() 为获取匹配的构造方器；分三步：
先获取所有的constructors, 然后通过进行参数类型比较；
找到匹配后，通过 ReflectionFactory copy一份constructor返回；
否则抛出 NoSuchMethodException;
// 获取当前类所有的构造方法，通过jvm或者缓存
// Returns an array of "root" constructors. These Constructor
// objects must NOT be propagated to the outside world, but must
// instead be copied via ReflectionFactory.copyConstructor.
private Constructor<T>[] privateGetDeclaredConstructors(boolean publicOnly) {
checkInitted();
Constructor<T>[] res;
// 调用 reflectionData(), 获取保存的信息，使用软引用保存，从而使内存不够可以回收
ReflectionData<T> rd = reflectionData();
if (rd != null) {
res = publicOnly ? rd.publicConstructors : rd.declaredConstructors;
// 存在缓存，则直接返回
if (res != null) return res;
}
// No cached value available; request value from VM
if (isInterface()) {
@SuppressWarnings("unchecked")
Constructor<T>[] temporaryRes = (Constructor<T>[]) new Constructor<?>[0];
res = temporaryRes;
} else {
// 使用native方法从jvm获取构造器
res = getDeclaredConstructors0(publicOnly);
}
if (rd != null) {
// 最后，将从jvm中读取的内容，存入缓存
if (publicOnly) {
rd.publicConstructors = res;
} else {
rd.declaredConstructors = res;
}
}
return res;
}
// Lazily create and cache ReflectionData
private ReflectionData<T> reflectionData() {
SoftReference<ReflectionData<T>> reflectionData = this.reflectionData;
int classRedefinedCount = this.classRedefinedCount;
ReflectionData<T> rd;
if (useCaches &&
reflectionData != null &&
(rd = reflectionData.get()) != null &&
rd.redefinedCount == classRedefinedCount) {
return rd;
}
// else no SoftReference or cleared SoftReference or stale ReflectionData
// -> create and replace new instance
return newReflectionData(reflectionData, classRedefinedCount);
}
// 新创建缓存，保存反射信息
private ReflectionData<T> newReflectionData(SoftReference<ReflectionData<T>> oldReflectionData,
int classRedefinedCount) {
if (!useCaches) return null;
// 使用cas保证更新的线程安全性，所以反射是保证线程安全的
while (true) {
ReflectionData<T> rd = new ReflectionData<>(classRedefinedCount);
// try to CAS it...
if (Atomic.casReflectionData(this, oldReflectionData, new SoftReference<>(rd))) {
return rd;
}
// 先使用CAS更新，如果更新成功，则立即返回，否则测查当前已被其他线程更新的情况，如果和自己想要更新的状态一致，则也算是成功了
oldReflectionData = this.reflectionData;
classRedefinedCount = this.classRedefinedCount;
if (oldReflectionData != null &&
(rd = oldReflectionData.get()) != null &&
rd.redefinedCount == classRedefinedCount) {
return rd;
}
}
}
// reflection data that might get invalidated when JVM TI RedefineClasses() is called
private static class ReflectionData<T> {
volatile Field[] declaredFields;
volatile Field[] publicFields;
volatile Method[] declaredMethods;
volatile Method[] publicMethods;
volatile Constructor<T>[] declaredConstructors;
volatile Constructor<T>[] publicConstructors;
// Intermediate results for getFields and getMethods
volatile Field[] declaredPublicFields;
volatile Method[] declaredPublicMethods;
volatile Class<?>[] interfaces;
// Value of classRedefinedCount when we created this ReflectionData instance
final int redefinedCount;
ReflectionData(int redefinedCount) {
this.redefinedCount = redefinedCount;
}
}
private static boolean arrayContentsEq(Object[] a1, Object[] a2) {
if (a1 == null) {
return a2 == null || a2.length == 0;
}
if (a2 == null) {
return a1.length == 0;
}
if (a1.length != a2.length) {
return false;
}
for (int i = 0; i < a1.length; i++) {
if (a1[i] != a2[i]) {
return false;
}
}
return true;
}
// sun.reflect.ReflectionFactory
/** Makes a copy of the passed constructor. The returned
constructor is a "child" of the passed one; see the comments
in Constructor.java for details. */
public <T> Constructor<T> copyConstructor(Constructor<T> arg) {
return langReflectAccess().copyConstructor(arg);
}
// java.lang.reflect.Constructor, copy 其实就是新new一个 Constructor 出来
Constructor<T> copy() {
// This routine enables sharing of ConstructorAccessor objects
// among Constructor objects which refer to the same underlying
// method in the VM. (All of this contortion is only necessary
// because of the "accessibility" bit in AccessibleObject,
// which implicitly requires that new java.lang.reflect
// objects be fabricated for each reflective call on Class
// objects.)
if (this.root != null)
throw new IllegalArgumentException("Can not copy a non-root Constructor");
Constructor<T> res = new Constructor<>(clazz,
parameterTypes,
exceptionTypes, modifiers, slot,
signature,
annotations,
parameterAnnotations);
// root 指向当前 constructor
res.root = this;
// Might as well eagerly propagate this if already present
res.constructorAccessor = constructorAccessor;
return res;
}
通过上面，获取到 Constructor 了。
接下来就只需调用其相应构造器的 newInstance()，即返回实例了。
// return tmpConstructor.newInstance((Object[])null);
// java.lang.reflect.Constructor
@CallerSensitive
public T newInstance(Object ... initargs)
throws InstantiationException, IllegalAccessException,
IllegalArgumentException, InvocationTargetException
{
if (!override) {
if (!Reflection.quickCheckMemberAccess(clazz, modifiers)) {
Class<?> caller = Reflection.getCallerClass();
checkAccess(caller, clazz, null, modifiers);
}
}
if ((clazz.getModifiers() & Modifier.ENUM) != 0)
throw new IllegalArgumentException("Cannot reflectively create enum objects");
ConstructorAccessor ca = constructorAccessor; // read volatile
if (ca == null) {
ca = acquireConstructorAccessor();
}
@SuppressWarnings("unchecked")
T inst = (T) ca.newInstance(initargs);
return inst;
}
// sun.reflect.DelegatingConstructorAccessorImpl
public Object newInstance(Object[] args)
throws InstantiationException,
IllegalArgumentException,
InvocationTargetException
{
return delegate.newInstance(args);
}
// sun.reflect.NativeConstructorAccessorImpl
public Object newInstance(Object[] args)
throws InstantiationException,
IllegalArgumentException,
InvocationTargetException
{
// We can't inflate a constructor belonging to a vm-anonymous class
// because that kind of class can't be referred to by name, hence can't
// be found from the generated bytecode.
if (++numInvocations > ReflectionFactory.inflationThreshold()
&& !ReflectUtil.isVMAnonymousClass(c.getDeclaringClass())) {
ConstructorAccessorImpl acc = (ConstructorAccessorImpl)
new MethodAccessorGenerator().
generateConstructor(c.getDeclaringClass(),
c.getParameterTypes(),
c.getExceptionTypes(),
c.getModifiers());
parent.setDelegate(acc);
}
// 调用native方法，进行调用 constructor
return newInstance0(c, args);
}
返回构造器的实例后，可以根据外部进行进行类型转换，从而使用接口或方法进行调用实例功能了。
3.2 反射获取方法
第一步，先获取 Method;
// java.lang.Class
@CallerSensitive
public Method getDeclaredMethod(String name, Class<?>... parameterTypes)
throws NoSuchMethodException, SecurityException {
checkMemberAccess(Member.DECLARED, Reflection.getCallerClass(), true);
Method method = searchMethods(privateGetDeclaredMethods(false), name, parameterTypes);
if (method == null) {
throw new NoSuchMethodException(getName() + "." + name + argumentTypesToString(parameterTypes));
}
return method;
}
忽略第一个检查权限，剩下就只有两个动作了。
获取所有方法列表；
根据方法名称和方法列表，选出符合要求的方法；
如果没有找到相应方法，抛出异常，否则返回对应方法；
所以，先看一下怎样获取类声明的所有方法？
// Returns an array of "root" methods. These Method objects must NOT
// be propagated to the outside world, but must instead be copied
// via ReflectionFactory.copyMethod.
private Method[] privateGetDeclaredMethods(boolean publicOnly) {
checkInitted();
Method[] res;
ReflectionData<T> rd = reflectionData();
if (rd != null) {
res = publicOnly ? rd.declaredPublicMethods : rd.declaredMethods;
if (res != null) return res;
}
// No cached value available; request value from VM
res = Reflection.filterMethods(this, getDeclaredMethods0(publicOnly));
if (rd != null) {
if (publicOnly) {
rd.declaredPublicMethods = res;
} else {
rd.declaredMethods = res;
}
}
return res;
}
// probably make the implementation more scalable.
private MethodAccessor acquireMethodAccessor() {
// First check to see if one has been created yet, and take it
// if so
MethodAccessor tmp = null;
if (root != null) tmp = root.getMethodAccessor();
if (tmp != null) {
// 存在缓存时，存入 methodAccessor，否则调用 ReflectionFactory 创建新的 MethodAccessor
methodAccessor = tmp;
} else {
// Otherwise fabricate one and propagate it up to the root
tmp = reflectionFactory.newMethodAccessor(this);
setMethodAccessor(tmp);
}
return tmp;
}
// sun.reflect.ReflectionFactory
public MethodAccessor newMethodAccessor(Method method) {
checkInitted();
if (noInflation && !ReflectUtil.isVMAnonymousClass(method.getDeclaringClass())) {
return new MethodAccessorGenerator().
generateMethod(method.getDeclaringClass(),
method.getName(),
method.getParameterTypes(),
method.getReturnType(),
method.getExceptionTypes(),
method.getModifiers());
} else {
NativeMethodAccessorImpl acc =
new NativeMethodAccessorImpl(method);
DelegatingMethodAccessorImpl res =
new DelegatingMethodAccessorImpl(acc);
acc.setParent(res);
return res;
}
}
两个Accessor详情：
// NativeMethodAccessorImpl / DelegatingMethodAccessorImpl
class NativeMethodAccessorImpl extends MethodAccessorImpl {
private final Method method;
private DelegatingMethodAccessorImpl parent;
private int numInvocations;
NativeMethodAccessorImpl(Method method) {
this.method = method;
}
public Object invoke(Object obj, Object[] args)
throws IllegalArgumentException, InvocationTargetException
{
// We can't inflate methods belonging to vm-anonymous classes because
// that kind of class can't be referred to by name, hence can't be
// found from the generated bytecode.
if (++numInvocations > ReflectionFactory.inflationThreshold()
&& !ReflectUtil.isVMAnonymousClass(method.getDeclaringClass())) {
MethodAccessorImpl acc = (MethodAccessorImpl)
new MethodAccessorGenerator().
generateMethod(method.getDeclaringClass(),
method.getName(),
method.getParameterTypes(),
method.getReturnType(),
method.getExceptionTypes(),
method.getModifiers());
parent.setDelegate(acc);
}
return invoke0(method, obj, args);
}
void setParent(DelegatingMethodAccessorImpl parent) {
this.parent = parent;
}
private static native Object invoke0(Method m, Object obj, Object[] args);
}
class DelegatingMethodAccessorImpl extends MethodAccessorImpl {
private MethodAccessorImpl delegate;
DelegatingMethodAccessorImpl(MethodAccessorImpl delegate) {
setDelegate(delegate);
}
public Object invoke(Object obj, Object[] args)
throws IllegalArgumentException, InvocationTargetException
{
return delegate.invoke(obj, args);
}
void setDelegate(MethodAccessorImpl delegate) {
this.delegate = delegate;
}
}
public Object invoke(Object obj, Object[] args)
throws IllegalArgumentException, InvocationTargetException
{
// We can't inflate methods belonging to vm-anonymous classes because
// that kind of class can't be referred to by name, hence can't be
// found from the generated bytecode.
if (++numInvocations > ReflectionFactory.inflationThreshold()
&& !ReflectUtil.isVMAnonymousClass(method.getDeclaringClass())) {
MethodAccessorImpl acc = (MethodAccessorImpl)
new MethodAccessorGenerator().
generateMethod(method.getDeclaringClass(),
method.getName(),
method.getParameterTypes(),
method.getReturnType(),
method.getExceptionTypes(),
method.getModifiers());
parent.setDelegate(acc);
}
// invoke0 是个 native 方法，由jvm进行调用业务方法。从而完成反射调用功能。
return invoke0(method, obj, args);
}
其中， generateMethod() 是生成具体类的方法：
/** This routine is not thread-safe */
public MethodAccessor generateMethod(Class<?> declaringClass,
String name,
Class<?>[] parameterTypes,
Class<?> returnType,
Class<?>[] checkedExceptions,
int modifiers)
{
return (MethodAccessor) generate(declaringClass,
name,
parameterTypes,
returnType,
checkedExceptions,
modifiers,
false,
false,
null);
}
generate() 戳详情。
/** This routine is not thread-safe */
private MagicAccessorImpl generate(final Class<?> declaringClass,
String name,
Class<?>[] parameterTypes,
Class<?> returnType,
Class<?>[] checkedExceptions,
int modifiers,
boolean isConstructor,
boolean forSerialization,
Class<?> serializationTargetClass)
{
ByteVector vec = ByteVectorFactory.create();
asm = new ClassFileAssembler(vec);
this.declaringClass = declaringClass;
this.parameterTypes = parameterTypes;
this.returnType = returnType;
this.modifiers = modifiers;
this.isConstructor = isConstructor;
this.forSerialization = forSerialization;
asm.emitMagicAndVersion();
// Constant pool entries:
// ( * = Boxing information: optional)
// (+ = Shared entries provided by AccessorGenerator)
// (^ = Only present if generating SerializationConstructorAccessor)
// [UTF-8] [This class's name]
// [CONSTANT_Class_info] for above
// [UTF-8] "sun/reflect/{MethodAccessorImpl,ConstructorAccessorImpl,SerializationConstructorAccessorImpl}"
// [CONSTANT_Class_info] for above
// [UTF-8] [Target class's name]
// [CONSTANT_Class_info] for above
// ^ [UTF-8] [Serialization: Class's name in which to invoke constructor]
// ^ [CONSTANT_Class_info] for above
// [UTF-8] target method or constructor name
// [UTF-8] target method or constructor signature
// [CONSTANT_NameAndType_info] for above
// [CONSTANT_Methodref_info or CONSTANT_InterfaceMethodref_info] for target method
// [UTF-8] "invoke" or "newInstance"
// [UTF-8] invoke or newInstance descriptor
// [UTF-8] descriptor for type of non-primitive parameter 1
// [CONSTANT_Class_info] for type of non-primitive parameter 1
// ...
// [UTF-8] descriptor for type of non-primitive parameter n
// [CONSTANT_Class_info] for type of non-primitive parameter n
// + [UTF-8] "java/lang/Exception"
// + [CONSTANT_Class_info] for above
// + [UTF-8] "java/lang/ClassCastException"
// + [CONSTANT_Class_info] for above
// + [UTF-8] "java/lang/NullPointerException"
// + [CONSTANT_Class_info] for above
// + [UTF-8] "java/lang/IllegalArgumentException"
// + [CONSTANT_Class_info] for above
// + [UTF-8] "java/lang/InvocationTargetException"
// + [CONSTANT_Class_info] for above
// + [UTF-8] "<init>"
// + [UTF-8] "()V"
// + [CONSTANT_NameAndType_info] for above
// + [CONSTANT_Methodref_info] for NullPointerException's constructor
// + [CONSTANT_Methodref_info] for IllegalArgumentException's constructor
// + [UTF-8] "(Ljava/lang/String;)V"
// + [CONSTANT_NameAndType_info] for "<init>(Ljava/lang/String;)V"
// + [CONSTANT_Methodref_info] for IllegalArgumentException's constructor taking a String
// + [UTF-8] "(Ljava/lang/Throwable;)V"
// + [CONSTANT_NameAndType_info] for "<init>(Ljava/lang/Throwable;)V"
// + [CONSTANT_Methodref_info] for InvocationTargetException's constructor
// + [CONSTANT_Methodref_info] for "super()"
// + [UTF-8] "java/lang/Object"
// + [CONSTANT_Class_info] for above
// + [UTF-8] "toString"
// + [UTF-8] "()Ljava/lang/String;"
// + [CONSTANT_NameAndType_info] for "toString()Ljava/lang/String;"
// + [CONSTANT_Methodref_info] for Object's toString method
// + [UTF-8] "Code"
// + [UTF-8] "Exceptions"
// * [UTF-8] "java/lang/Boolean"
// * [CONSTANT_Class_info] for above
// * [UTF-8] "(Z)V"
// * [CONSTANT_NameAndType_info] for above
// * [CONSTANT_Methodref_info] for above
// * [UTF-8] "booleanValue"
// * [UTF-8] "()Z"
// * [CONSTANT_NameAndType_info] for above
// * [CONSTANT_Methodref_info] for above
// * [UTF-8] "java/lang/Byte"
// * [CONSTANT_Class_info] for above
// * [UTF-8] "(B)V"
// * [CONSTANT_NameAndType_info] for above
// * [CONSTANT_Methodref_info] for above
// * [UTF-8] "byteValue"
// * [UTF-8] "()B"
// * [CONSTANT_NameAndType_info] for above
// * [CONSTANT_Methodref_info] for above
// * [UTF-8] "java/lang/Character"
// * [CONSTANT_Class_info] for above
// * [UTF-8] "(C)V"
// * [CONSTANT_NameAndType_info] for above
// * [CONSTANT_Methodref_info] for above
// * [UTF-8] "charValue"
// * [UTF-8] "()C"
// * [CONSTANT_NameAndType_info] for above
// * [CONSTANT_Methodref_info] for above
// * [UTF-8] "java/lang/Double"
// * [CONSTANT_Class_info] for above
// * [UTF-8] "(D)V"
// * [CONSTANT_NameAndType_info] for above
// * [CONSTANT_Methodref_info] for above
// * [UTF-8] "doubleValue"
// * [UTF-8] "()D"
// * [CONSTANT_NameAndType_info] for above
// * [CONSTANT_Methodref_info] for above
// * [UTF-8] "java/lang/Float"
// * [CONSTANT_Class_info] for above
// * [UTF-8] "(F)V"
// * [CONSTANT_NameAndType_info] for above
// * [CONSTANT_Methodref_info] for above
// * [UTF-8] "floatValue"
// * [UTF-8] "()F"
// * [CONSTANT_NameAndType_info] for above
// * [CONSTANT_Methodref_info] for above
// * [UTF-8] "java/lang/Integer"
// * [CONSTANT_Class_info] for above
// * [UTF-8] "(I)V"
// * [CONSTANT_NameAndType_info] for above
// * [CONSTANT_Methodref_info] for above
// * [UTF-8] "intValue"
// * [UTF-8] "()I"
// * [CONSTANT_NameAndType_info] for above
// * [CONSTANT_Methodref_info] for above
// * [UTF-8] "java/lang/Long"
// * [CONSTANT_Class_info] for above
// * [UTF-8] "(J)V"
// * [CONSTANT_NameAndType_info] for above
// * [CONSTANT_Methodref_info] for above
// * [UTF-8] "longValue"
// * [UTF-8] "()J"
// * [CONSTANT_NameAndType_info] for above
// * [CONSTANT_Methodref_info] for above
// * [UTF-8] "java/lang/Short"
// * [CONSTANT_Class_info] for above
// * [UTF-8] "(S)V"
// * [CONSTANT_NameAndType_info] for above
// * [CONSTANT_Methodref_info] for above
// * [UTF-8] "shortValue"
// * [UTF-8] "()S"
// * [CONSTANT_NameAndType_info] for above
// * [CONSTANT_Methodref_info] for above
short numCPEntries = NUM_BASE_CPOOL_ENTRIES + NUM_COMMON_CPOOL_ENTRIES;
boolean usesPrimitives = usesPrimitiveTypes();
if (usesPrimitives) {
numCPEntries += NUM_BOXING_CPOOL_ENTRIES;
}
if (forSerialization) {
numCPEntries += NUM_SERIALIZATION_CPOOL_ENTRIES;
}
// Add in variable-length number of entries to be able to describe
// non-primitive parameter types and checked exceptions.
numCPEntries += (short) (2 * numNonPrimitiveParameterTypes());
asm.emitShort(add(numCPEntries, S1));
final String generatedName = generateName(isConstructor, forSerialization);
asm.emitConstantPoolUTF8(generatedName);
asm.emitConstantPoolClass(asm.cpi());
thisClass = asm.cpi();
if (isConstructor) {
if (forSerialization) {
asm.emitConstantPoolUTF8
("sun/reflect/SerializationConstructorAccessorImpl");
} else {
asm.emitConstantPoolUTF8("sun/reflect/ConstructorAccessorImpl");
}
} else {
asm.emitConstantPoolUTF8("sun/reflect/MethodAccessorImpl");
}
asm.emitConstantPoolClass(asm.cpi());
superClass = asm.cpi();
asm.emitConstantPoolUTF8(getClassName(declaringClass, false));
asm.emitConstantPoolClass(asm.cpi());
targetClass = asm.cpi();
short serializationTargetClassIdx = (short) 0;
if (forSerialization) {
asm.emitConstantPoolUTF8(getClassName(serializationTargetClass, false));
asm.emitConstantPoolClass(asm.cpi());
serializationTargetClassIdx = asm.cpi();
}
asm.emitConstantPoolUTF8(name);
asm.emitConstantPoolUTF8(buildInternalSignature());
asm.emitConstantPoolNameAndType(sub(asm.cpi(), S1), asm.cpi());
if (isInterface()) {
asm.emitConstantPoolInterfaceMethodref(targetClass, asm.cpi());
} else {
if (forSerialization) {
asm.emitConstantPoolMethodref(serializationTargetClassIdx, asm.cpi());
} else {
asm.emitConstantPoolMethodref(targetClass, asm.cpi());
}
}
targetMethodRef = asm.cpi();
if (isConstructor) {
asm.emitConstantPoolUTF8("newInstance");
} else {
asm.emitConstantPoolUTF8("invoke");
}
invokeIdx = asm.cpi();
if (isConstructor) {
asm.emitConstantPoolUTF8("([Ljava/lang/Object;)Ljava/lang/Object;");
} else {
asm.emitConstantPoolUTF8
("(Ljava/lang/Object;[Ljava/lang/Object;)Ljava/lang/Object;");
}
invokeDescriptorIdx = asm.cpi();
// Output class information for non-primitive parameter types
nonPrimitiveParametersBaseIdx = add(asm.cpi(), S2);
for (int i = 0; i < parameterTypes.length; i++) {
Class<?> c = parameterTypes[i];
if (!isPrimitive(c)) {
asm.emitConstantPoolUTF8(getClassName(c, false));
asm.emitConstantPoolClass(asm.cpi());
}
}
// Entries common to FieldAccessor, MethodAccessor and ConstructorAccessor
emitCommonConstantPoolEntries();
// Boxing entries
if (usesPrimitives) {
emitBoxingContantPoolEntries();
}
if (asm.cpi() != numCPEntries) {
throw new InternalError("Adjust this code (cpi = " + asm.cpi() +
", numCPEntries = " + numCPEntries + ")");
}
// Access flags
asm.emitShort(ACC_PUBLIC);
// This class
asm.emitShort(thisClass);
// Superclass
asm.emitShort(superClass);
// Interfaces count and interfaces
asm.emitShort(S0);
// Fields count and fields
asm.emitShort(S0);
// Methods count and methods
asm.emitShort(NUM_METHODS);
emitConstructor();
emitInvoke();
// Additional attributes (none)
asm.emitShort(S0);
// Load class
vec.trim();
final byte[] bytes = vec.getData();
// Note: the class loader is the only thing that really matters
// here -- it's important to get the generated code into the
// same namespace as the target class. Since the generated code
// is privileged anyway, the protection domain probably doesn't
// matter.
return AccessController.doPrivileged(
new PrivilegedAction<MagicAccessorImpl>() {
public MagicAccessorImpl run() {
try {
return (MagicAccessorImpl)
ClassDefiner.defineClass
(generatedName,
bytes,
0,
bytes.length,
declaringClass.getClassLoader()).newInstance();
} catch (InstantiationException | IllegalAccessException e) {
throw new InternalError(e);
}
}
});
}
