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| package moe.xinmu.j2019;
import org.objectweb.asm.ClassWriter;
import org.objectweb.asm.Opcodes;
import org.objectweb.asm.Type;
import org.objectweb.asm.commons.GeneratorAdapter;
import java.io.PrintStream;
import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;
import java.lang.reflect.Modifier;
import java.security.AccessController;
import java.security.PrivilegedActionException;
import java.security.PrivilegedExceptionAction;
import java.util.Arrays;
import java.util.Objects;
import java.util.Random;
import java.util.UUID;
public interface Main {
static void main(String[] args) throws Exception{
@SuppressWarnings("unchecked")
R<String> stringR=(R<String>)genClass(
new LClassLoader(),
System.out,
PrintStream.class.getMethod("print", Object.class),
R.class.getMethod("run",Object.class),
R.class, true);
stringR.run("Hello, World!");
}
class LClassLoader extends ClassLoader implements LambdaClassLoader {
LClassLoader(){
super(Main.class.getClassLoader());
}
@Override
public Class<?> l_defineClass(String name, byte[] b, int off, int len) {
return defineClass(name, b, off, len);
}
}
interface R<T>{
void run(T t) throws Exception;
}
int class_version = ((Double) (Double.parseDouble(System.getProperty("java.class.version")))).intValue();
Type object_class = Type.getType(Object.class);
org.objectweb.asm.commons.Method object_constructor = new org.objectweb.asm.commons.Method("<init>","()V");
static <T>T genClass(
LambdaClassLoader loader,
Object o,
Method source,
Method target,
Class<T> target_class,
boolean force_cast) throws PrivilegedActionException {
Objects.requireNonNull(loader);
Objects.requireNonNull(source);
Objects.requireNonNull(target);
Objects.requireNonNull(target_class);
if(target.getDeclaringClass()!=target_class)
throw new IllegalArgumentException();
final boolean isStatic= Modifier.isStatic(source.getModifiers());
final boolean isInterface=target_class.isInterface();
final boolean sourceIsInterface=source.getDeclaringClass().isInterface();
String clazzname=Type.getInternalName(source.getDeclaringClass());
ClassWriter cw=new ClassWriter(ClassWriter.COMPUTE_MAXS);
String cwname="x"+Type.getInternalName(target.getDeclaringClass())+"$"+ (new Random().nextDouble()+"").replace(".","/");
cw.visit(class_version, Opcodes.ACC_PUBLIC|Opcodes.ACC_SUPER,cwname,null,isInterface?"java/lang/Object":Type.getInternalName(target_class),isInterface?new String[]{Type.getInternalName(target.getDeclaringClass())}:new String[0]);
final GeneratorAdapter constructor=new GeneratorAdapter(cw.visitMethod(Opcodes.ACC_PUBLIC,"<init>","()V",null,null),Opcodes.ACC_PUBLIC,"<init>","()V");
constructor.loadThis();
constructor.invokeConstructor(object_class,object_constructor);
constructor.returnValue();
constructor.endMethod();
String setname=null;
if(!isStatic) {
cw.visitField(Opcodes.ACC_PRIVATE, "$this", Type.getDescriptor(source.getDeclaringClass()),clazzname, null);
setname="set$this"+ UUID.randomUUID();
final GeneratorAdapter set=new GeneratorAdapter(cw.visitMethod(Opcodes.ACC_PUBLIC,setname,"(L"+clazzname+";)V",null,null),Opcodes.ACC_PUBLIC,setname,"(L"+clazzname+";)V");
set.loadThis();
set.loadArg(0);
set.putField(Type.getType("L"+cwname+";"),"$this",Type.getType("L"+clazzname+";"));
set.returnValue();
set.endMethod();
}
org.objectweb.asm.commons.Method targetmethod=org.objectweb.asm.commons.Method.getMethod(target);
String[] exceptions= Arrays.stream(target.getExceptionTypes()).map(Type::getInternalName).toArray(String[]::new);
final GeneratorAdapter invoke=new GeneratorAdapter(cw.visitMethod(Opcodes.ACC_PUBLIC,targetmethod.getName(),targetmethod.getDescriptor(),null,exceptions),Opcodes.ACC_PUBLIC,targetmethod.getName(),targetmethod.getDescriptor());
if(!isStatic){
invoke.loadThis();
invoke.getField(Type.getType("L"+cwname+";"),"$this",Type.getType(source.getDeclaringClass()));
}
Type[] types=targetmethod.getArgumentTypes();
Type[] types1=org.objectweb.asm.commons.Method.getMethod(source).getArgumentTypes();
for (int i = 0; i < types.length; i++){
invoke.loadArg(i);
if(force_cast)
if(!types[i].equals(types1[i]))
invoke.checkCast(types1[i]);
}
if(!isStatic)
invoke.visitMethodInsn(sourceIsInterface?Opcodes.INVOKEINTERFACE:Opcodes.INVOKEVIRTUAL,Type.getType(source.getDeclaringClass()).getInternalName(),source.getName(),org.objectweb.asm.commons.Method.getMethod(source).getDescriptor(),sourceIsInterface);
else
invoke.visitMethodInsn(Opcodes.INVOKESTATIC,Type.getType(source.getDeclaringClass()).getInternalName(),source.getName(),org.objectweb.asm.commons.Method.getMethod(source).getDescriptor(),sourceIsInterface);
if(force_cast)
if(!targetmethod.getReturnType().equals(org.objectweb.asm.commons.Method.getMethod(source).getReturnType()))
invoke.checkCast(org.objectweb.asm.commons.Method.getMethod(source).getReturnType());
invoke.returnValue();
invoke.endMethod();
byte[] bytes=cw.toByteArray();
Class<?> t =AccessController.doPrivileged((PrivilegedExceptionAction<Class<?>>)()-> loader.l_defineClass(cwname.replace("/","."),bytes,0,bytes.length));
T tt=null;
try {
tt=target_class.cast(t.getConstructor().newInstance());
} catch (InstantiationException | IllegalAccessException | NoSuchMethodException | InvocationTargetException e) {
e.printStackTrace();
}
if(!isStatic) {
for(Method method:t.getMethods()){
if(method.getName().equals(setname)) {
try {
method.invoke(tt,o);
} catch (IllegalAccessException | InvocationTargetException e) {
e.printStackTrace();
}
}
}
}
return tt;
}
interface LambdaClassLoader{
Class<?> l_defineClass(String name, byte[] b, int off, int len);
}
}
|