Apache CXF example source code file (ASMHelper.java)

This example Apache CXF source code file (ASMHelper.java) is included in the DevDaily.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" ^TM.

Java - Apache CXF tags/keywords

class, class, genericarraytype, map, parameterizedtype, reflection, string, string, stringbuilder, threading, threads, type, type, typehelperclassloader, typehelperclassloader, typevariable, util, weakreference

The Apache CXF ASMHelper.java source code

/**
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements. See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership. The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License. You may obtain a copy of the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing,
 * software distributed under the License is distributed on an
 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
 * KIND, either express or implied. See the License for the
 * specific language governing permissions and limitations
 * under the License.
 */

package org.apache.cxf.common.util;

import java.lang.ref.WeakReference;
import java.lang.reflect.Constructor;
import java.lang.reflect.GenericArrayType;
import java.lang.reflect.Method;
import java.lang.reflect.ParameterizedType;
import java.lang.reflect.Type;
import java.lang.reflect.TypeVariable;
import java.lang.reflect.WildcardType;
import java.util.HashMap;
import java.util.Map;
import java.util.concurrent.ConcurrentHashMap;

import org.objectweb.asm.ClassWriter;

public class ASMHelper {
    protected static final Map<Class PRIMITIVE_MAP = new HashMap, String>();
    protected static final Map<Class NONPRIMITIVE_MAP = new HashMap, String>();
    
    protected static final Map<Class> LOADER_MAP 
        = new WeakIdentityHashMap<Class>();
    
    protected static boolean oldASM;
    
    static {
        PRIMITIVE_MAP.put(Byte.TYPE, "B");
        PRIMITIVE_MAP.put(Boolean.TYPE, "Z");
        PRIMITIVE_MAP.put(Long.TYPE, "J");
        PRIMITIVE_MAP.put(Integer.TYPE, "I");
        PRIMITIVE_MAP.put(Short.TYPE, "S");
        PRIMITIVE_MAP.put(Character.TYPE, "C");
        PRIMITIVE_MAP.put(Float.TYPE, "F");
        PRIMITIVE_MAP.put(Double.TYPE, "D");

        NONPRIMITIVE_MAP.put(Byte.TYPE, Byte.class.getName().replaceAll("\\.", "/"));
        NONPRIMITIVE_MAP.put(Boolean.TYPE, Boolean.class.getName().replaceAll("\\.", "/"));
        NONPRIMITIVE_MAP.put(Long.TYPE, Long.class.getName().replaceAll("\\.", "/"));
        NONPRIMITIVE_MAP.put(Integer.TYPE, Integer.class.getName().replaceAll("\\.", "/"));
        NONPRIMITIVE_MAP.put(Short.TYPE, Short.class.getName().replaceAll("\\.", "/"));
        NONPRIMITIVE_MAP.put(Character.TYPE, Character.class.getName().replaceAll("\\.", "/"));
        NONPRIMITIVE_MAP.put(Float.TYPE, Float.class.getName().replaceAll("\\.", "/"));
        NONPRIMITIVE_MAP.put(Double.TYPE, Double.class.getName().replaceAll("\\.", "/"));
    }
    
    protected static String getMethodSignature(Method m) {
        StringBuilder buf = new StringBuilder("(");
        for (Class<?> cl : m.getParameterTypes()) {
            buf.append(getClassCode(cl));
        }
        buf.append(")");
        buf.append(getClassCode(m.getReturnType()));
        
        return buf.toString();
    }
    
    protected static String periodToSlashes(String s) {
        char ch[] = s.toCharArray();
        for (int x = 0; x < ch.length; x++) {
            if (ch[x] == '.') {
                ch[x] = '/';
            }
        }
        return new String(ch);
    }
    
    
    public static String getClassCode(Class<?> cl) {
        if (cl == Void.TYPE) {
            return "V";
        }
        if (cl.isPrimitive()) {
            return PRIMITIVE_MAP.get(cl);
        }
        if (cl.isArray()) {
            return "[" + getClassCode(cl.getComponentType());
        }
        return "L" + periodToSlashes(cl.getName()) + ";";
    }
    public static String getClassCode(Type type) {
        if (type instanceof Class) {
            return getClassCode((Class)type);
        } else if (type instanceof GenericArrayType) {
            GenericArrayType at = (GenericArrayType)type;
            return "[" + getClassCode(at.getGenericComponentType());
        } else if (type instanceof TypeVariable) {
            TypeVariable tv = (TypeVariable)type;
            Type[] bounds = tv.getBounds();
            if (bounds != null && bounds.length == 1) {
                return getClassCode(bounds[0]);
            } else {
                throw new IllegalArgumentException("Unable to determine type for: " + tv);
            }
        } else if (type instanceof ParameterizedType) {
            ParameterizedType pt = (ParameterizedType)type;
            StringBuilder a = new StringBuilder(getClassCode(pt.getRawType()));
            a.setLength(a.length() - 1);
            a.append('<');
            for (Type t : pt.getActualTypeArguments()) {
                a.append(getClassCode(t));  
            }
            a.append(">;");
            return a.toString();
        } else if (type instanceof WildcardType) {
            WildcardType wt = (WildcardType)type;
            StringBuilder a = new StringBuilder();
            Type[] lowBounds = wt.getLowerBounds();
            Type[] upBounds = wt.getUpperBounds();
            for (Type t : upBounds) {
                a.append("+");
                a.append(getClassCode(t));
            }
            for (Type t : lowBounds) {
                a.append("-");
                a.append(getClassCode(t));
            }
            return a.toString();
        }
        return null;
    }
    
    
    public ClassWriter createClassWriter() {
        ClassWriter newCw = null;
        if (!oldASM) {
            Class<ClassWriter> cls;
            try {
                cls = ClassWriter.class;
            } catch (NoClassDefFoundError error) {
                throw new RuntimeException("No ASM ClassWriterFound", error);
            }
            try {
                // ASM 1.5.x/2.x
                Constructor<ClassWriter> cons = cls.getConstructor(new Class[] {Boolean.TYPE});
                
                try {
                    // got constructor, now check if it's 1.x which is very
                    // different from 2.x and 3.x
                    cls.getMethod("newConstInt", new Class<?>[] {Integer.TYPE});               
                    // newConstInt was removed in 2.x, if we get this far, we're
                    // using 1.5.x,
                    // set to null so we don't attempt to use it.
                    newCw = null;    
                    oldASM = true;
                } catch (Throwable t) {
                    newCw = cons.newInstance(new Object[] {Boolean.TRUE});
                }
                
            } catch (Throwable e) {
                // ASM 3.x
                try {
                    Constructor<ClassWriter> cons = cls.getConstructor(new Class[] {Integer.TYPE});
                    int i = cls.getField("COMPUTE_MAXS").getInt(null);
                    i |= cls.getField("COMPUTE_FRAMES").getInt(null);
                    newCw = cons.newInstance(new Object[] {Integer.valueOf(i)});
                } catch (Throwable e1) {
                    // ignore
                }
                
            }
        }
        return newCw;
    }
    
    
    public Class<?> loadClass(String className, Class clz , byte[] bytes) { 
        TypeHelperClassLoader loader = getTypeHelperClassLoader(clz);
        return loader.defineClass(className, bytes);
    }
    public Class<?> findClass(String className, Class clz) { 
        TypeHelperClassLoader loader = getTypeHelperClassLoader(clz);
        return loader.lookupDefinedClass(className);
    }
    
    private static synchronized TypeHelperClassLoader getTypeHelperClassLoader(Class<?> l) {
        WeakReference<TypeHelperClassLoader> ref = LOADER_MAP.get(l);
        TypeHelperClassLoader ret;
        if (ref == null || ref.get() == null) {
            ret = new TypeHelperClassLoader(l.getClassLoader());
            LOADER_MAP.put(l, new WeakReference<TypeHelperClassLoader>(ret));
        } else {
            ret = ref.get();
        }
        return ret;
    }
    
    public static class TypeHelperClassLoader extends ClassLoader {
        Map<String, Class defined = new ConcurrentHashMap>();
        
        TypeHelperClassLoader(ClassLoader parent) {
            super(parent);
        }
        public Class<?> lookupDefinedClass(String name) {
            return defined.get(name.replace('/', '.'));
        }
        
        public synchronized Class<?> defineClass(String name, byte bytes[]) {
            Class<?> ret = defined.get(name.replace('/', '.'));
            if (ret != null) {
                return ret;
            }
            if (name.endsWith("package-info")) {
                Package p = super.getPackage(name.substring(0, name.length() - 13));
                if (p == null) {
                    definePackage(name.substring(0, name.length() - 13).replace('/', '.'),
                                    null,
                                    null,
                                    null, 
                                    null,
                                    null,
                                    null,
                                    null);
                }
            }
            
            ret = super.defineClass(name.replace('/', '.'), bytes, 0, bytes.length);
            defined.put(name.replace('/', '.'), ret);
            return ret;
        }
    }
    
}