Java tutorial
/** * <copyright> * * Copyright (c) 2013 CEA LIST and others. * All rights reserved. This program and the accompanying materials * are made available under the terms of the Eclipse Public License v1.0 * which accompanies this distribution, and is available at * http://www.eclipse.org/legal/epl-v10.html * * Contributors: * E.D.Willink(CEA LIST) - Initial API and implementation * * </copyright> */ package org.eclipse.ocl.examples.codegen.java; import java.io.IOException; import java.io.InputStream; import java.lang.reflect.Method; import java.util.HashMap; import java.util.HashSet; import java.util.Map; import java.util.Set; import org.apache.log4j.Logger; import org.eclipse.jdt.annotation.NonNull; import org.eclipse.jdt.annotation.Nullable; import org.objectweb.asm.AnnotationVisitor; import org.objectweb.asm.Attribute; import org.objectweb.asm.ClassReader; import org.objectweb.asm.ClassVisitor; import org.objectweb.asm.FieldVisitor; import org.objectweb.asm.Label; import org.objectweb.asm.MethodVisitor; import org.objectweb.asm.Type; /** * JavaAnnotationReader supports determination of the declared @NonNull, @Nullable state of a method . */ public class JavaAnnotationReader { private static final Logger logger = Logger.getLogger(JavaAnnotationReader.class); private final @NonNull Map<String, Boolean> desc2state = new HashMap<String, Boolean>(); private final @NonNull Set<String> readClasses = new HashSet<String>(); private final @SuppressWarnings("null") @NonNull String nonNullDesc = Type.getDescriptor(NonNull.class); private final @SuppressWarnings("null") @NonNull String nullableDesc = Type.getDescriptor(Nullable.class); public JavaAnnotationReader() { } /** * Return true for an @NonNull annotation, false for an @Nullable annotation, null otherwise. */ public Boolean getIsNonNull(@NonNull Method method) { final String className = method.getDeclaringClass().getName(); final String requiredDesc = className + ";" + method.getName() + Type.getMethodDescriptor(method); Boolean state = desc2state.get(requiredDesc); if (state != null) { return state; } if (!readClasses.add(className)) { return null; } // System.out.println("getIsNonNull: " + requiredDesc); InputStream classStream = null; try { final int flags = ClassReader.SKIP_DEBUG | ClassReader.SKIP_FRAMES | ClassReader.SKIP_CODE; ClassLoader contextClassLoader = Thread.currentThread().getContextClassLoader(); String classFileName = className.replace('.', '/') + ".class"; classStream = contextClassLoader.getResourceAsStream(classFileName); final ClassReader cr = new ClassReader(classStream); ClassVisitor cv = new ClassVisitor() { @Override public MethodVisitor visitMethod(int access, String name, String desc, String signature, String[] exceptions) { final String methodDesc = className + ";" + name + desc; // System.out.println(" ClassVisitor.visitMethod: " + methodDesc); desc2state.put(methodDesc, null); return new MethodVisitor() { @Override public AnnotationVisitor visitAnnotation(String annotationDesc, boolean visible) { // System.out.println(" MethodVisitor:" + annotationDesc + " " + true); if (annotationDesc.equals(nonNullDesc)) { desc2state.put(methodDesc, true); } else if (annotationDesc.equals(nullableDesc)) { desc2state.put(methodDesc, false); } return null; } @Override public AnnotationVisitor visitAnnotationDefault() { return null; } @Override public AnnotationVisitor visitParameterAnnotation(int parameter, String desc, boolean visible) { return null; } @Override public void visitAttribute(Attribute attr) { } @Override public void visitCode() { } @Override public void visitFrame(int type, int nLocal, Object[] local, int nStack, Object[] stack) { } @Override public void visitInsn(int opcode) { } @Override public void visitIntInsn(int opcode, int operand) { } @Override public void visitVarInsn(int opcode, int var) { } @Override public void visitTypeInsn(int opcode, String type) { } @Override public void visitFieldInsn(int opcode, String owner, String name, String desc) { } @Override public void visitMethodInsn(int opcode, String owner, String name, String desc) { } @Override public void visitJumpInsn(int opcode, Label label) { } @Override public void visitLabel(Label label) { } @Override public void visitLdcInsn(Object cst) { } @Override public void visitIincInsn(int var, int increment) { } @Override public void visitTableSwitchInsn(int min, int max, Label dflt, Label[] labels) { } @Override public void visitLookupSwitchInsn(Label dflt, int[] keys, Label[] labels) { } @Override public void visitMultiANewArrayInsn(String desc, int dims) { } @Override public void visitTryCatchBlock(Label start, Label end, Label handler, String type) { } @Override public void visitLocalVariable(String name, String desc, String signature, Label start, Label end, int index) { } @Override public void visitLineNumber(int line, Label start) { } @Override public void visitMaxs(int maxStack, int maxLocals) { } @Override public void visitEnd() { } }; } @Override public void visit(int version, int access, String name, String signature, String superName, String[] interfaces) { } @Override public void visitSource(String source, String debug) { } @Override public void visitOuterClass(String owner, String name, String desc) { } @Override public AnnotationVisitor visitAnnotation(String desc, boolean visible) { return null; } @Override public void visitAttribute(Attribute attr) { } @Override public void visitInnerClass(String name, String outerName, String innerName, int access) { } @Override public FieldVisitor visitField(int access, String name, String desc, String signature, Object value) { return null; } @Override public void visitEnd() { } }; cr.accept(cv, flags); } catch (IOException e) { logger.error("Failed to read '" + className + "'", e); } finally { if (classStream != null) { try { classStream.close(); } catch (IOException e) { } } } return desc2state.get(requiredDesc); } }