org.apache.bytecode.ParamReader Maven / Gradle / Ivy
/*
* 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.bytecode;
import java.io.IOException;
import java.lang.reflect.Constructor;
import java.lang.reflect.Member;
import java.lang.reflect.Method;
import java.lang.reflect.Modifier;
import java.util.HashMap;
import java.util.Map;
/**
* This is the class file reader for obtaining the parameter names
* for declared methods in a class. The class must have debugging
* attributes for us to obtain this information.
*
* This does not work for inherited methods. To obtain parameter
* names for inherited methods, you must use a paramReader for the
* class that originally declared the method.
*
* don't get tricky, it's the bare minimum. Instances of this class
* are not threadsafe -- don't share them.
*/
public class ParamReader
extends ClassReader {
private String methodName;
private Map methods = new HashMap();
private Class[] paramTypes;
/**
* Processes a class file, given it's class. We'll use the defining
* classloader to locate the bytecode.
*
* @param c
* @throws java.io.IOException
*/
public ParamReader(Class c) throws IOException {
this(getBytes(c));
}
/**
* Processes the given class bytes directly.
*
* @param b
* @throws IOException
*/
public ParamReader(byte[] b) throws IOException {
super(b, findAttributeReaders(ParamReader.class));
// check the magic number
if (readInt() != 0xCAFEBABE) {
// not a class file!
throw new IOException("Error looking for paramter names in bytecode: input does not appear to be a valid class file");
}
readShort(); // minor version
readShort(); // major version
readCpool(); // slurp in the constant pool
readShort(); // access flags
readShort(); // this class name
readShort(); // super class name
int count = readShort(); // ifaces count
for (int i = 0; i < count; i++) {
readShort(); // interface index
}
count = readShort(); // fields count
for (int i = 0; i < count; i++) {
readShort(); // access flags
readShort(); // name index
readShort(); // descriptor index
skipAttributes(); // field attributes
}
count = readShort(); // methods count
for (int i = 0; i < count; i++) {
readShort(); // access flags
int m = readShort(); // name index
String name = resolveUtf8(m);
int d = readShort(); // descriptor index
this.methodName = name + resolveUtf8(d);
readAttributes(); // method attributes
}
}
public void readCode() throws IOException {
readShort(); // max stack
int maxLocals = readShort(); // max locals
MethodInfo info = new MethodInfo(maxLocals);
if (methods != null && methodName != null) {
methods.put(methodName, info);
}
skipFully(readInt()); // code
skipFully(8 * readShort()); // exception table
// read the code attributes (recursive). This is where
// we will find the LocalVariableTable attribute.
readAttributes();
}
/**
* Reads a MethodParameters attribute.
*
* @throws IOException
*/
public void readMethodParameters() throws IOException {
int c = read(); // parameters count
MethodInfo info = new MethodInfo(c);
for(int i = 0; i