findfinalizeinvocations.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

/*
 * FindBugs - Find bugs in Java programs
 * 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.detect;

import edu.umd.cs.findbugs.BugInstance;
import edu.umd.cs.findbugs.BugReporter;
import edu.umd.cs.findbugs.BytecodeScanningDetector;
import edu.umd.cs.findbugs.Lookup;
import edu.umd.cs.findbugs.visitclass.Constants2;
import org.apache.bcel.classfile.Code;
import org.apache.bcel.classfile.Method;

public class FindFinalizeInvocations extends BytecodeScanningDetector implements Constants2 {
	private static final boolean DEBUG = Boolean.getBoolean("ffi.debug");

	private BugReporter bugReporter;

	public FindFinalizeInvocations(BugReporter bugReporter) {
		this.bugReporter = bugReporter;
	}

	boolean sawSuperFinalize;

	public void visit(Method obj) {
		if (DEBUG) System.out.println("FFI: visiting " + getFullyQualifiedMethodName());
		if (getMethodName().equals("finalize")
		        && getMethodSig().equals("()V")
		        && (obj.getAccessFlags() & (ACC_PUBLIC)) != 0
		)
			bugReporter.reportBug(new BugInstance(this, "FI_PUBLIC_SHOULD_BE_PROTECTED", NORMAL_PRIORITY).addClassAndMethod(this));
	}

	public void visit(Code obj) {
		sawSuperFinalize = false;
		super.visit(obj);
		if (!getMethodName().equals("finalize")
		        || !getMethodSig().equals("()V"))
			return;
		String overridesFinalizeIn
		        = Lookup.findSuperImplementor(getDottedClassName(),
		                "finalize",
		                "()V",
		                bugReporter);
		boolean superHasNoFinalizer = overridesFinalizeIn.equals("java.lang.Object");
		// System.out.println("superclass: " + superclassName);
		if (obj.getCode().length == 1) {
			if (superHasNoFinalizer)
				bugReporter.reportBug(new BugInstance(this, "FI_EMPTY", NORMAL_PRIORITY).addClassAndMethod(this));
			else
				bugReporter.reportBug(new BugInstance(this, "FI_NULLIFY_SUPER", NORMAL_PRIORITY)
				        .addClassAndMethod(this)
				        .addClass(overridesFinalizeIn));
		} else if (obj.getCode().length == 5 && sawSuperFinalize)
			bugReporter.reportBug(new BugInstance(this, "FI_USELESS", NORMAL_PRIORITY).addClassAndMethod(this));
		else if (!sawSuperFinalize && !superHasNoFinalizer)
			bugReporter.reportBug(new BugInstance(this, "FI_MISSING_SUPER_CALL", NORMAL_PRIORITY).addClassAndMethod(this)
			        .addClass(overridesFinalizeIn));
	}

	public void sawOpcode(int seen) {
		if (seen == INVOKEVIRTUAL && getNameConstantOperand().equals("finalize"))
			bugReporter.reportBug(new BugInstance(this, "FI_EXPLICIT_INVOCATION", NORMAL_PRIORITY)
			        .addClassAndMethod(this)
			        .addCalledMethod(this).describe("METHOD_CALLED")
			        .addSourceLine(this, getPC()));
		if (seen == INVOKESPECIAL && getNameConstantOperand().equals("finalize"))
			sawSuperFinalize = true;
	}
}