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Add a MessageUtils class to convert int constants to strings.

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This class uses reflection to find accessible static integer
members in a specified list of classes and returns a SparseArray
mapping the integers to their names. This will allow us to
replace various 400-line switch statements with a simple
array access.

Change-Id: I3607e6389a423cde0bd83270c00b3c863ae1bb29
This commit is contained in:
Lorenzo Colitti
2016-02-18 00:32:44 +09:00
parent 0d0f0c7faf
commit d2457a3ee3
3 changed files with 144 additions and 47 deletions
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127
core/java/com/android/internal/util/MessageUtils.java Normal file
View File

@@ -0,0 +1,127 @@
/*
* Copyright (C) 2016 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.internal.util;
import android.os.Message;
import android.util.Log;
import android.util.SparseArray;
import java.lang.reflect.Field;
/**
* Static utility class for dealing with {@link Message} objects.
*/
public class MessageUtils {
private static final String TAG = MessageUtils.class.getSimpleName();
private static final boolean DBG = false;
/** Thrown when two different constants have the same value. */
public static class DuplicateConstantError extends Error {
private DuplicateConstantError() {}
public DuplicateConstantError(String name1, String name2, int value) {
super(String.format("Duplicate constant value: both %s and %s = %d",
name1, name2, value));
}
}
/**
* Finds the names of integer constants. Searches the specified {@code classes}, looking for
* accessible static integer fields whose names begin with one of the specified {@prefixes}.
*
* @param classes the classes to examine.
* @prefixes only consider fields names starting with one of these prefixes.
* @return a {@link SparseArray} mapping integer constants to their names.
*/
public static SparseArray<String> findMessageNames(Class[] classes, String[] prefixes) {
SparseArray<String> messageNames = new SparseArray<>();
for (Class c : classes) {
String className = c.getName();
if (DBG) Log.d(TAG, "Examining class " + className);
Field[] fields;
try {
fields = c.getDeclaredFields();
} catch (SecurityException e) {
Log.e(TAG, "Can't list fields of class " + className);
continue;
}
for (Field field : fields) {
String name = field.getName();
for (String prefix : prefixes) {
// Does this look like a constant?
if (!name.startsWith(prefix)) {
continue;
}
try {
// TODO: can we have the caller try to access the field instead, so we don't
// expose constants it does not have access to?
field.setAccessible(true);
// Fetch the constant's value.
int value;
try {
value = field.getInt(null);
} catch (IllegalArgumentException | ExceptionInInitializerError e) {
// The field is not an integer (or short or byte), or c's static
// initializer failed and we have no idea what its value is.
// Either way, give up on this field.
break;
}
// Check for duplicate values.
String previousName = messageNames.get(value);
if (previousName != null && !previousName.equals(name)) {
throw new DuplicateConstantError(name, previousName, value);
}
messageNames.put(value, name);
if (DBG) {
Log.d(TAG, String.format("Found constant: %s.%s = %d",
className, name, value));
}
} catch (SecurityException | IllegalAccessException e) {
// Not allowed to make the field accessible, or no access. Ignore.
continue;
}
}
}
}
return messageNames;
}
/**
* Default prefixes for constants.
*/
public static final String[] DEFAULT_PREFIXES = {"CMD_", "EVENT_"};
/**
* Finds the names of integer constants. Searches the specified {@code classes}, looking for
* accessible static integer values whose names begin with {@link #DEFAULT_PREFIXES}.
*
* @param classNames the classes to examine.
* @prefixes only consider fields names starting with one of these prefixes.
* @return a {@link SparseArray} mapping integer constants to their names.
*/
public static SparseArray<String> findMessageNames(Class[] classNames) {
return findMessageNames(classNames, DEFAULT_PREFIXES);
}
}

35
services/net/java/android/net/dhcp/DhcpClient.java
View File

@@ -19,6 +19,7 @@ package android.net.dhcp;
import com.android.internal.util.HexDump;
import com.android.internal.util.Protocol;
import com.android.internal.util.State;
import com.android.internal.util.MessageUtils;
import com.android.internal.util.StateMachine;
import android.app.AlarmManager;
@@ -34,7 +35,6 @@ import android.net.NetworkUtils;
import android.os.IBinder;
import android.os.INetworkManagementService;
import android.os.Message;
import android.os.PowerManager;
import android.os.RemoteException;
import android.os.ServiceManager;
import android.os.SystemClock;
@@ -42,16 +42,15 @@ import android.system.ErrnoException;
import android.system.Os;
import android.system.PacketSocketAddress;
import android.util.Log;
import android.util.SparseArray;
import android.util.TimeUtils;
import java.io.FileDescriptor;
import java.io.IOException;
import java.lang.Thread;
import java.net.Inet4Address;
import java.net.InetSocketAddress;
import java.net.NetworkInterface;
import java.net.SocketException;
import java.nio.BufferUnderflowException;
import java.nio.ByteBuffer;
import java.util.Arrays;
import java.util.Random;
@@ -133,6 +132,11 @@ public class DhcpClient extends StateMachine {
private static final int CMD_TIMEOUT = PRIVATE_BASE + 3;
private static final int CMD_ONESHOT_TIMEOUT = PRIVATE_BASE + 4;
// For message logging.
private static final Class[] sMessageClasses = { DhcpClient.class };
private static final SparseArray<String> sMessageNames =
MessageUtils.findMessageNames(sMessageClasses);
// DHCP parameters that we request.
private static final byte[] REQUESTED_PARAMS = new byte[] {
DHCP_SUBNET_MASK,
@@ -497,30 +501,7 @@ public class DhcpClient extends StateMachine {
}
private String messageName(int what) {
switch (what) {
case CMD_START_DHCP:
return "CMD_START_DHCP";
case CMD_STOP_DHCP:
return "CMD_STOP_DHCP";
case CMD_RENEW_DHCP:
return "CMD_RENEW_DHCP";
case CMD_PRE_DHCP_ACTION:
return "CMD_PRE_DHCP_ACTION";
case CMD_PRE_DHCP_ACTION_COMPLETE:
return "CMD_PRE_DHCP_ACTION_COMPLETE";
case CMD_POST_DHCP_ACTION:
return "CMD_POST_DHCP_ACTION";
case CMD_KICK:
return "CMD_KICK";
case CMD_RECEIVED_PACKET:
return "CMD_RECEIVED_PACKET";
case CMD_TIMEOUT:
return "CMD_TIMEOUT";
case CMD_ONESHOT_TIMEOUT:
return "CMD_ONESHOT_TIMEOUT";
default:
return Integer.toString(what);
}
return sMessageNames.get(what, Integer.toString(what));
}
private String messageToString(Message message) {

29
services/net/java/android/net/ip/IpManager.java
View File

@@ -16,6 +16,8 @@
package android.net.ip;
import com.android.internal.util.MessageUtils;
import android.content.Context;
import android.net.DhcpResults;
import android.net.InterfaceConfiguration;
@@ -30,6 +32,7 @@ import android.os.Message;
import android.os.RemoteException;
import android.os.ServiceManager;
import android.util.Log;
import android.util.SparseArray;
import com.android.internal.annotations.GuardedBy;
import com.android.internal.annotations.VisibleForTesting;
@@ -61,6 +64,11 @@ public class IpManager extends StateMachine {
private static final boolean DBG = true;
private static final boolean VDBG = false;
// For message logging.
private static final Class[] sMessageClasses = { IpManager.class, DhcpClient.class };
private static final SparseArray<String> sWhatToString =
MessageUtils.findMessageNames(sMessageClasses);
/**
* Callbacks for handling IpManager events.
*/
@@ -306,26 +314,7 @@ public class IpManager extends StateMachine {
@Override
protected String getWhatToString(int what) {
// TODO: Investigate switching to reflection.
switch (what) {
case CMD_STOP:
return "CMD_STOP";
case CMD_START:
return "CMD_START";
case CMD_CONFIRM:
return "CMD_CONFIRM";
case EVENT_PRE_DHCP_ACTION_COMPLETE:
return "EVENT_PRE_DHCP_ACTION_COMPLETE";
case EVENT_NETLINK_LINKPROPERTIES_CHANGED:
return "EVENT_NETLINK_LINKPROPERTIES_CHANGED";
case DhcpClient.CMD_PRE_DHCP_ACTION:
return "DhcpClient.CMD_PRE_DHCP_ACTION";
case DhcpClient.CMD_POST_DHCP_ACTION:
return "DhcpClient.CMD_POST_DHCP_ACTION";
case DhcpClient.CMD_ON_QUIT:
return "DhcpClient.CMD_ON_QUIT";
}
return "UNKNOWN:" + Integer.toString(what);
return sWhatToString.get(what, "UNKNOWN: " + Integer.toString(what));
}
@Override