com.android.tools.lint.checks.HandlerDetector Maven / Gradle / Ivy
/*
* Copyright (C) 2012 The Android Open Source Project
*
* Licensed 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 com.android.tools.lint.checks;
import static com.android.SdkConstants.CONSTRUCTOR_NAME;
import com.android.annotations.NonNull;
import com.android.tools.lint.detector.api.Category;
import com.android.tools.lint.detector.api.ClassContext;
import com.android.tools.lint.detector.api.Detector;
import com.android.tools.lint.detector.api.Detector.ClassScanner;
import com.android.tools.lint.detector.api.Implementation;
import com.android.tools.lint.detector.api.Issue;
import com.android.tools.lint.detector.api.LintUtils;
import com.android.tools.lint.detector.api.Location;
import com.android.tools.lint.detector.api.Scope;
import com.android.tools.lint.detector.api.Severity;
import com.android.tools.lint.detector.api.Speed;
import org.objectweb.asm.tree.ClassNode;
import org.objectweb.asm.tree.MethodNode;
/**
* Checks that Handler implementations are top level classes or static.
* See the corresponding check in the android.os.Handler source code.
*/
public class HandlerDetector extends Detector implements ClassScanner {
/** Potentially leaking handlers */
public static final Issue ISSUE = Issue.create(
"HandlerLeak", //$NON-NLS-1$
"Handler reference leaks",
"Since this Handler is declared as an inner class, it may prevent the outer " +
"class from being garbage collected. If the Handler is using a Looper or " +
"MessageQueue for a thread other than the main thread, then there is no issue. " +
"If the Handler is using the Looper or MessageQueue of the main thread, you " +
"need to fix your Handler declaration, as follows: Declare the Handler as a " +
"static class; In the outer class, instantiate a WeakReference to the outer " +
"class and pass this object to your Handler when you instantiate the Handler; " +
"Make all references to members of the outer class using the WeakReference object.",
Category.PERFORMANCE,
4,
Severity.WARNING,
new Implementation(
HandlerDetector.class,
Scope.CLASS_FILE_SCOPE));
/** Constructs a new {@link HandlerDetector} */
public HandlerDetector() {
}
@NonNull
@Override
public Speed getSpeed() {
return Speed.FAST;
}
// ---- Implements ClassScanner ----
@Override
public void checkClass(@NonNull ClassContext context, @NonNull ClassNode classNode) {
if (classNode.name.indexOf('$') == -1) {
return;
}
if (context.getDriver().isSubclassOf(classNode, "android/os/Handler") //$NON-NLS-1$
&& !LintUtils.isStaticInnerClass(classNode)) {
// Only flag handlers using the default looper
for (Object m : classNode.methods) {
MethodNode method = (MethodNode) m;
if (CONSTRUCTOR_NAME.equals(method.name) &&
method.desc.contains("Landroid/os/Looper;")) {
return;
}
}
Location location = context.getLocation(classNode);
context.report(ISSUE, location, String.format(
"This Handler class should be static or leaks might occur (%1$s)",
ClassContext.createSignature(classNode.name, null, null)));
}
}
}