org.sfm.reflect.asm.AsmConstructorDefinitionFactory Maven / Gradle / Ivy
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Java library to map flat record - ResultSet, csv - to java object with minimum configuration and low footprint.
package org.sfm.reflect.asm;
import org.objectweb.asm.*;
import org.sfm.reflect.ConstructorDefinition;
import org.sfm.reflect.ConstructorParameter;
import org.sfm.reflect.TypeHelper;
import java.io.IOException;
import java.io.InputStream;
import java.lang.reflect.Type;
import java.util.ArrayList;
import java.util.Collections;
import java.util.List;
public class AsmConstructorDefinitionFactory {
public static List> extractConstructors(final Type target) throws IOException {
final List> constructors = new ArrayList>();
final Class targetClass = TypeHelper.toClass(target);
ClassLoader cl = targetClass.getClassLoader();
if (cl == null) {
cl = ClassLoader.getSystemClassLoader();
}
final InputStream is = cl.getResourceAsStream(targetClass.getName().replace('.', '/') + ".class");
try {
ClassReader classReader = new ClassReader(is);
classReader.accept(new ClassVisitor(Opcodes.ASM5) {
List genericTypeNames;
@Override
public void visit(int version, int access, String name, String signature, String superName, String[] interfaces) {
if (signature != null) {
genericTypeNames = AsmUtils.extractGenericTypeNames(signature);
} else {
genericTypeNames = Collections.emptyList();
}
super.visit(version, access, name, signature, superName, interfaces);
}
@Override
public MethodVisitor visitMethod(int access,
String name,
String desc,
String signature,
String[] exceptions) {
if ("".equals(name)) {
final List descTypes = AsmUtils.extractConstructorTypeNames(desc);
final List genericTypes;
final List names = new ArrayList();
if (signature != null) {
genericTypes = AsmUtils.extractConstructorTypeNames(signature);
} else {
genericTypes = descTypes;
}
return new MethodVisitor(Opcodes.ASM5) {
Label firstLabel;
Label lastLabel;
@Override
public void visitLabel(Label label) {
if (firstLabel == null) {
firstLabel = label;
}
lastLabel = label;
}
@Override
public void visitLocalVariable(String name, String desc, String signature, Label start, Label end, int index) {
if (start.equals(firstLabel) && end.equals(lastLabel) && ! "this".equals(name)) {
names.add(name);
}
}
@Override
public void visitEnd() {
try {
final List parameters = new ArrayList();
for(int i = 0; i < descTypes.size(); i ++) {
String name = "arg" + i;
if (i < names.size()) {
name =names.get(i);
}
parameters.add(createParameter(name, descTypes.get(i), genericTypes.get(i)));
}
constructors.add(new ConstructorDefinition(targetClass.getDeclaredConstructor(toTypeArray(parameters)), parameters.toArray(new ConstructorParameter[parameters.size()])));
} catch(Exception e) {
throw new Error("Unexpected error " + e, e);
}
}
private Class[] toTypeArray(List parameters) {
Class[] types = new Class[parameters.size()];
for(int i = 0; i < types.length; i++) {
types[i] = TypeHelper.toClass(parameters.get(i).getType());
}
return types;
}
private ConstructorParameter createParameter(String name,
String desc, String signature) {
try {
Type basicType = AsmUtils.toGenericType(desc, genericTypeNames, target);
Type genericType = basicType;
if (signature != null) {
genericType = AsmUtils.toGenericType(signature, genericTypeNames, target);
}
return new ConstructorParameter(name, basicType, genericType);
} catch (ClassNotFoundException e) {
throw new Error("Unexpected error " + e, e);
}
}
};
} else {
return null;
}
}
}, 0);
} finally {
try { is.close(); } catch(Exception e) {}
}
return constructors;
}
}