Created
December 30, 2014 20:03
-
-
Save jerrinot/4a808eaa126e9ddb7827 to your computer and use it in GitHub Desktop.
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
package uk.co.rockstable.experiments.asm; | |
import org.objectweb.asm.ClassWriter; | |
import org.objectweb.asm.MethodVisitor; | |
import uk.co.rockstable.experiments.asm.utils.UnsafeUtils; | |
import static org.objectweb.asm.Opcodes.*; | |
public class FooBarFactory { | |
private static final FooBarFactory INSTANCE = new FooBarFactory(); | |
private static final String GENERATED_CLASS_NAME = "uk/co/rockstable/experiments/asm/FooBarFactoryImpl"; | |
private static final Class<?> clazz; | |
static { | |
clazz = newClazz(); | |
} | |
public static Object newInstance() { | |
try { | |
return clazz.newInstance(); | |
} catch (InstantiationException e) { | |
throw new RuntimeException(e); | |
} catch (IllegalAccessException e) { | |
throw new RuntimeException(e); | |
} | |
} | |
private static Class<?> newClazz() { | |
byte[] bytes = INSTANCE.generateByteCode(); | |
return INSTANCE.createClass(bytes); | |
} | |
public Class<?> createClass(byte[] bytecode) { | |
ClassLoader cl = getClass().getClassLoader(); | |
return UnsafeUtils.UNSAFE.defineClass(GENERATED_CLASS_NAME, bytecode, 0, bytecode.length, cl, null); | |
} | |
private byte[] generateByteCode() { | |
ClassWriter cw = new ClassWriter(0); | |
MethodVisitor mv; | |
cw.visit(V1_5, ACC_PUBLIC + ACC_SUPER, GENERATED_CLASS_NAME, | |
null, "java/lang/Object", | |
new String[]{"uk/co/rockstable/experiments/asm/FooFactory", "uk/co/rockstable/experiments/asm/BarFactory"}); | |
{ | |
mv = cw.visitMethod(ACC_PUBLIC, "<init>", "()V", null, null); | |
mv.visitCode(); | |
mv.visitVarInsn(ALOAD, 0); | |
mv.visitMethodInsn(INVOKESPECIAL, "java/lang/Object", "<init>", "()V", false); | |
mv.visitInsn(RETURN); | |
mv.visitMaxs(1, 1); | |
mv.visitEnd(); | |
} | |
{ | |
mv = cw.visitMethod(ACC_PUBLIC, "create", "()Luk/co/rockstable/experiments/asm/Bar;", null, null); | |
mv.visitCode(); | |
mv.visitTypeInsn(NEW, "uk/co/rockstable/experiments/asm/Bar"); | |
mv.visitInsn(DUP); | |
mv.visitMethodInsn(INVOKESPECIAL, "uk/co/rockstable/experiments/asm/Bar", "<init>", "()V", false); | |
mv.visitInsn(ARETURN); | |
mv.visitMaxs(2, 1); | |
mv.visitEnd(); | |
} | |
{ | |
mv = cw.visitMethod(ACC_PUBLIC, "create", "()Luk/co/rockstable/experiments/asm/Foo;", null, null); | |
mv.visitCode(); | |
mv.visitTypeInsn(NEW, "uk/co/rockstable/experiments/asm/Foo"); | |
mv.visitInsn(DUP); | |
mv.visitMethodInsn(INVOKESPECIAL, "uk/co/rockstable/experiments/asm/Foo", "<init>", "()V", false); | |
mv.visitInsn(ARETURN); | |
mv.visitMaxs(2, 1); | |
mv.visitEnd(); | |
} | |
cw.visitEnd(); | |
return cw.toByteArray(); | |
} | |
} |
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment