The Android Open Source Project | 9066cfe | 2009-03-03 19:31:44 -0800 | [diff] [blame] | 1 | /* |
| 2 | * Copyright (C) 2006 The Android Open Source Project |
| 3 | * |
| 4 | * Licensed under the Apache License, Version 2.0 (the "License"); |
| 5 | * you may not use this file except in compliance with the License. |
| 6 | * You may obtain a copy of the License at |
| 7 | * |
| 8 | * http://www.apache.org/licenses/LICENSE-2.0 |
| 9 | * |
| 10 | * Unless required by applicable law or agreed to in writing, software |
| 11 | * distributed under the License is distributed on an "AS IS" BASIS, |
| 12 | * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| 13 | * See the License for the specific language governing permissions and |
| 14 | * limitations under the License. |
| 15 | */ |
| 16 | |
| 17 | package android.os; |
| 18 | |
| 19 | /** |
| 20 | * Reference to a Handler, which others can use to send messages to it. |
| 21 | * This allows for the implementation of message-based communication across |
| 22 | * processes, by creating a Messenger pointing to a Handler in one process, |
| 23 | * and handing that Messenger to another process. |
Dianne Hackborn | ab4a81b | 2014-10-09 17:59:38 -0700 | [diff] [blame] | 24 | * |
| 25 | * <p>Note: the implementation underneath is just a simple wrapper around |
| 26 | * a {@link Binder} that is used to perform the communication. This means |
| 27 | * semantically you should treat it as such: this class does not impact process |
| 28 | * lifecycle management (you must be using some higher-level component to tell |
| 29 | * the system that your process needs to continue running), the connection will |
| 30 | * break if your process goes away for any reason, etc.</p> |
The Android Open Source Project | 9066cfe | 2009-03-03 19:31:44 -0800 | [diff] [blame] | 31 | */ |
| 32 | public final class Messenger implements Parcelable { |
| 33 | private final IMessenger mTarget; |
| 34 | |
| 35 | /** |
| 36 | * Create a new Messenger pointing to the given Handler. Any Message |
| 37 | * objects sent through this Messenger will appear in the Handler as if |
| 38 | * {@link Handler#sendMessage(Message) Handler.sendMessage(Message)} had |
Dianne Hackborn | 8ea138c | 2010-01-26 18:01:04 -0800 | [diff] [blame] | 39 | * been called directly. |
The Android Open Source Project | 9066cfe | 2009-03-03 19:31:44 -0800 | [diff] [blame] | 40 | * |
| 41 | * @param target The Handler that will receive sent messages. |
| 42 | */ |
| 43 | public Messenger(Handler target) { |
| 44 | mTarget = target.getIMessenger(); |
| 45 | } |
| 46 | |
| 47 | /** |
| 48 | * Send a Message to this Messenger's Handler. |
| 49 | * |
| 50 | * @param message The Message to send. Usually retrieved through |
| 51 | * {@link Message#obtain() Message.obtain()}. |
| 52 | * |
| 53 | * @throws RemoteException Throws DeadObjectException if the target |
| 54 | * Handler no longer exists. |
| 55 | */ |
| 56 | public void send(Message message) throws RemoteException { |
| 57 | mTarget.send(message); |
| 58 | } |
| 59 | |
| 60 | /** |
| 61 | * Retrieve the IBinder that this Messenger is using to communicate with |
| 62 | * its associated Handler. |
| 63 | * |
| 64 | * @return Returns the IBinder backing this Messenger. |
| 65 | */ |
| 66 | public IBinder getBinder() { |
| 67 | return mTarget.asBinder(); |
| 68 | } |
| 69 | |
| 70 | /** |
| 71 | * Comparison operator on two Messenger objects, such that true |
| 72 | * is returned then they both point to the same Handler. |
| 73 | */ |
| 74 | public boolean equals(Object otherObj) { |
| 75 | if (otherObj == null) { |
| 76 | return false; |
| 77 | } |
| 78 | try { |
| 79 | return mTarget.asBinder().equals(((Messenger)otherObj) |
| 80 | .mTarget.asBinder()); |
| 81 | } catch (ClassCastException e) { |
| 82 | } |
| 83 | return false; |
| 84 | } |
| 85 | |
| 86 | public int hashCode() { |
| 87 | return mTarget.asBinder().hashCode(); |
| 88 | } |
| 89 | |
| 90 | public int describeContents() { |
| 91 | return 0; |
| 92 | } |
| 93 | |
| 94 | public void writeToParcel(Parcel out, int flags) { |
| 95 | out.writeStrongBinder(mTarget.asBinder()); |
| 96 | } |
| 97 | |
Jeff Sharkey | 9e8f83d | 2019-02-28 12:06:45 -0700 | [diff] [blame] | 98 | public static final @android.annotation.NonNull Parcelable.Creator<Messenger> CREATOR |
The Android Open Source Project | 9066cfe | 2009-03-03 19:31:44 -0800 | [diff] [blame] | 99 | = new Parcelable.Creator<Messenger>() { |
| 100 | public Messenger createFromParcel(Parcel in) { |
| 101 | IBinder target = in.readStrongBinder(); |
| 102 | return target != null ? new Messenger(target) : null; |
| 103 | } |
| 104 | |
| 105 | public Messenger[] newArray(int size) { |
| 106 | return new Messenger[size]; |
| 107 | } |
| 108 | }; |
| 109 | |
| 110 | /** |
| 111 | * Convenience function for writing either a Messenger or null pointer to |
| 112 | * a Parcel. You must use this with {@link #readMessengerOrNullFromParcel} |
| 113 | * for later reading it. |
| 114 | * |
| 115 | * @param messenger The Messenger to write, or null. |
| 116 | * @param out Where to write the Messenger. |
| 117 | */ |
| 118 | public static void writeMessengerOrNullToParcel(Messenger messenger, |
| 119 | Parcel out) { |
| 120 | out.writeStrongBinder(messenger != null ? messenger.mTarget.asBinder() |
| 121 | : null); |
| 122 | } |
| 123 | |
| 124 | /** |
| 125 | * Convenience function for reading either a Messenger or null pointer from |
| 126 | * a Parcel. You must have previously written the Messenger with |
| 127 | * {@link #writeMessengerOrNullToParcel}. |
| 128 | * |
| 129 | * @param in The Parcel containing the written Messenger. |
| 130 | * |
| 131 | * @return Returns the Messenger read from the Parcel, or null if null had |
| 132 | * been written. |
| 133 | */ |
| 134 | public static Messenger readMessengerOrNullFromParcel(Parcel in) { |
| 135 | IBinder b = in.readStrongBinder(); |
| 136 | return b != null ? new Messenger(b) : null; |
| 137 | } |
| 138 | |
| 139 | /** |
| 140 | * Create a Messenger from a raw IBinder, which had previously been |
| 141 | * retrieved with {@link #getBinder}. |
| 142 | * |
| 143 | * @param target The IBinder this Messenger should communicate with. |
| 144 | */ |
| 145 | public Messenger(IBinder target) { |
| 146 | mTarget = IMessenger.Stub.asInterface(target); |
| 147 | } |
| 148 | } |