135 lines
5.2 KiB
Java
135 lines
5.2 KiB
Java
/*
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* Copyright (C) 2016 The Android Open Source Project
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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package com.android.internal.util;
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import android.os.Message;
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import android.util.Log;
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import android.util.SparseArray;
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import java.lang.reflect.Field;
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import java.lang.reflect.Modifier;
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/**
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* Static utility class for dealing with {@link Message} objects.
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*/
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// Exported to Mainline modules; cannot use annotations
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// @android.ravenwood.annotation.RavenwoodKeepWholeClass
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public class MessageUtils {
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private static final String TAG = MessageUtils.class.getSimpleName();
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private static final boolean DBG = false;
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/** Thrown when two different constants have the same value. */
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public static class DuplicateConstantError extends Error {
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private DuplicateConstantError() {}
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public DuplicateConstantError(String name1, String name2, int value) {
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super(String.format("Duplicate constant value: both %s and %s = %d",
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name1, name2, value));
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}
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}
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/**
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* Finds the names of integer constants. Searches the specified {@code classes}, looking for
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* accessible static integer fields whose names begin with one of the specified
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* {@code prefixes}.
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*
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* @param classes the classes to examine.
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* @param prefixes only consider fields names starting with one of these prefixes.
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* @return a {@link SparseArray} mapping integer constants to their names.
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*/
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public static SparseArray<String> findMessageNames(Class[] classes, String[] prefixes) {
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SparseArray<String> messageNames = new SparseArray<>();
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for (Class c : classes) {
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String className = c.getName();
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if (DBG) Log.d(TAG, "Examining class " + className);
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Field[] fields;
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try {
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fields = c.getDeclaredFields();
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} catch (SecurityException e) {
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Log.e(TAG, "Can't list fields of class " + className);
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continue;
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}
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for (Field field : fields) {
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int modifiers = field.getModifiers();
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if (!Modifier.isStatic(modifiers) | !Modifier.isFinal(modifiers)) {
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continue;
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}
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String name = field.getName();
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for (String prefix : prefixes) {
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// Does this look like a constant?
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if (!name.startsWith(prefix)) {
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continue;
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}
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try {
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// TODO: can we have the caller try to access the field instead, so we don't
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// expose constants it does not have access to?
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field.setAccessible(true);
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// Fetch the constant's value.
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int value;
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try {
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value = field.getInt(null);
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} catch (IllegalArgumentException | ExceptionInInitializerError e) {
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// The field is not an integer (or short or byte), or c's static
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// initializer failed and we have no idea what its value is.
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// Either way, give up on this field.
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break;
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}
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// Check for duplicate values.
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String previousName = messageNames.get(value);
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if (previousName != null && !previousName.equals(name)) {
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throw new DuplicateConstantError(name, previousName, value);
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}
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messageNames.put(value, name);
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if (DBG) {
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Log.d(TAG, String.format("Found constant: %s.%s = %d",
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className, name, value));
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}
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} catch (SecurityException | IllegalAccessException e) {
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// Not allowed to make the field accessible, or no access. Ignore.
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continue;
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}
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}
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}
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}
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return messageNames;
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}
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/**
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* Default prefixes for constants.
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*/
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public static final String[] DEFAULT_PREFIXES = {"CMD_", "EVENT_"};
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/**
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* Finds the names of integer constants. Searches the specified {@code classes}, looking for
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* accessible static integer values whose names begin with {@link #DEFAULT_PREFIXES}.
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*
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* @param classNames the classes to examine.
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* @return a {@link SparseArray} mapping integer constants to their names.
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*/
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public static SparseArray<String> findMessageNames(Class[] classNames) {
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return findMessageNames(classNames, DEFAULT_PREFIXES);
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}
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}
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