signatureconverter.java

一个查找java程序里bug的程序的源代码,该程序本身也是java写的,对提高java编程水平很有用

/*
 * Bytecode Analysis Framework
 * Copyright (C) 2003,2004 University of Maryland
 * 
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2.1 of the License, or (at your option) any later version.
 * 
 * This library is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * Lesser General Public License for more details.
 * 
 * You should have received a copy of the GNU Lesser General Public
 * License along with this library; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 */

package edu.umd.cs.findbugs.ba;

import org.apache.bcel.classfile.JavaClass;
import org.apache.bcel.classfile.Method;
import org.apache.bcel.generic.ConstantPoolGen;
import org.apache.bcel.generic.InvokeInstruction;
import org.apache.bcel.generic.MethodGen;

/**
 * Convert part or all of a Java type signature into something
 * closer to what types look like in the source code.
 * Both field and method signatures may be processed by this class.
 * For a field signature, just call parseNext() once.
 * For a method signature, parseNext() must be called multiple times,
 * and the parens around the arguments must be skipped manually
 * (by calling the skip() method).
 *
 * @author David Hovemeyer
 */
public class SignatureConverter {
	private String signature;

	/**
	 * Constructor.
	 *
	 * @param signature the field or method signature to convert
	 */
	public SignatureConverter(String signature) {
		this.signature = signature;
	}

	/**
	 * Get the first character of the remaining part of the signature.
	 */
	public char getFirst() {
		return signature.charAt(0);
	}

	/**
	 * Skip the first character of the remaining part of the signature.
	 */
	public void skip() {
		signature = signature.substring(1);
	}

	/**
	 * Parse a single type out of the signature, starting at the beginning
	 * of the remaining part of the signature.  For example, if the first
	 * character of the remaining part is "I", then this method will return
	 * "int", and the "I" will be consumed.  Arrays, reference types,
	 * and basic types are all handled.
	 *
	 * @return the parsed type string
	 */
	public String parseNext() {
		StringBuffer result = new StringBuffer();

		if (signature.startsWith("[")) {
			int dimensions = 0;
			do {
				++dimensions;
				signature = signature.substring(1);
			} while (signature.charAt(0) == '[');
			result.append(parseNext());

			while (dimensions-- > 0) {
				result.append("[]");
			}
		} else if (signature.startsWith("L")) {
			int semi = signature.indexOf(';');
			if (semi < 0)
				throw new IllegalStateException("missing semicolon in signature " + signature);
			result.append(signature.substring(1, semi).replace('/', '.'));
			signature = signature.substring(semi + 1);
		} else {
			switch (signature.charAt(0)) {
			case 'B':
				result.append("byte");
				break;
			case 'C':
				result.append("char");
				break;
			case 'D':
				result.append("double");
				break;
			case 'F':
				result.append("float");
				break;
			case 'I':
				result.append("int");
				break;
			case 'J':
				result.append("long");
				break;
			case 'S':
				result.append("short");
				break;
			case 'Z':
				result.append("boolean");
				break;
			default:
				throw new IllegalStateException("bad signature " + signature);
			}
			skip();
		}

		return result.toString();
	}

	/**
	 * Convenience method for generating a method signature in
	 * human readable form.
	 *
	 * @param javaClass the class
	 * @param method    the method
	 */
	public static String convertMethodSignature(JavaClass javaClass, Method method) {
		return convertMethodSignature(javaClass.getClassName(), method.getName(), method.getSignature());
	}

	/**
	 * Convenience method for generating a method signature in
	 * human readable form.
	 *
	 * @param methodGen the method to produce a method signature for
	 */
	public static String convertMethodSignature(MethodGen methodGen) {
		return convertMethodSignature(methodGen.getClassName(), methodGen.getName(), methodGen.getSignature());
	}

	/**
	 * Convenience method for generating a method signature in
	 * human readable form.
	 *
	 * @param inv an InvokeInstruction
	 * @param cpg the ConstantPoolGen for the class the instruction belongs to
	 */
	public static String convertMethodSignature(InvokeInstruction inv, ConstantPoolGen cpg) {
		return convertMethodSignature(inv.getClassName(cpg), inv.getName(cpg), inv.getSignature(cpg));
	}

	/**
	 * Convenience method for generating a method signature in
	 * human readable form.
	 *
	 * @param className  name of the class containing the method
	 * @param methodName the name of the method
	 * @param methodSig  the signature of the method
	 */
	public static String convertMethodSignature(String className, String methodName, String methodSig) {
		return convertMethodSignature(className, methodName, methodSig, "");
	}

	/**
	 * Convenience method for generating a method signature in
	 * human readable form.
	 *
	 * @param className  name of the class containing the method
	 * @param methodName the name of the method
	 * @param methodSig  the signature of the method
	 * @param pkgName    the name of the package the method is in (used to shorten
	 *                   class names)
	 */
	public static String convertMethodSignature(String className, String methodName, String methodSig, String pkgName) {
		StringBuffer args = new StringBuffer();
		SignatureConverter converter = new SignatureConverter(methodSig);

		converter.skip();
		args.append('(');

		while (converter.getFirst() != ')') {
			if (args.length() > 1)
				args.append(", ");
			args.append(shorten(pkgName, converter.parseNext()));
		}
		converter.skip();
		args.append(')');

		// Ignore return type

		StringBuffer result = new StringBuffer();
		result.append(className);
		result.append('.');
		result.append(methodName);
		result.append(args.toString());

		return result.toString();
	}

	/**
	 * Convenience method for converting a single signature component to
	 * human-readable form.
	 *
	 * @param signature the signature
	 */
	public static String convert(String signature) {
		return new SignatureConverter(signature).parseNext();
	}

	public static String shorten(String pkgName, String typeName) {
		int index = typeName.lastIndexOf('.');
		if (index >= 0) {
			String otherPkg = typeName.substring(0, index);
			if (otherPkg.equals(pkgName) || otherPkg.equals("java.lang"))
				typeName = typeName.substring(index + 1);
		}
		return typeName;
	}
}

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