认识IBinder和Binder

IBinder源码：

package android.os;

import android.annotation.NonNull;
import android.annotation.Nullable;

import java.io.FileDescriptor;

public interface IBinder {
    /**
     * The first transaction code available for user commands.
     */
    int FIRST_CALL_TRANSACTION  = 0x00000001;
    /**
     * The last transaction code available for user commands.
     */
    int LAST_CALL_TRANSACTION   = 0x00ffffff;
    
    /**
     * IBinder protocol transaction code: pingBinder().
     */
    int PING_TRANSACTION        = ('_'<<24)|('P'<<16)|('N'<<8)|'G';
    
    /**
     * IBinder protocol transaction code: dump internal state.
     */
    int DUMP_TRANSACTION        = ('_'<<24)|('D'<<16)|('M'<<8)|'P';
    
    /**
     * IBinder protocol transaction code: execute a shell command.
     * @hide
     */
    int SHELL_COMMAND_TRANSACTION = ('_'<<24)|('C'<<16)|('M'<<8)|'D';

    /**
     * IBinder protocol transaction code: interrogate the recipient side
     * of the transaction for its canonical interface descriptor.
     */
    int INTERFACE_TRANSACTION   = ('_'<<24)|('N'<<16)|('T'<<8)|'F';

    int TWEET_TRANSACTION   = ('_'<<24)|('T'<<16)|('W'<<8)|'T';


    int LIKE_TRANSACTION   = ('_'<<24)|('L'<<16)|('I'<<8)|'K';

    /** @hide */
    int SYSPROPS_TRANSACTION = ('_'<<24)|('S'<<16)|('P'<<8)|'R';


    int FLAG_ONEWAY             = 0x00000001;

    public static final int MAX_IPC_SIZE = 64 * 1024;

    public @Nullable String getInterfaceDescriptor() throws RemoteException;

    public boolean pingBinder();

    public boolean isBinderAlive();

    public @Nullable IInterface queryLocalInterface(@NonNull String descriptor);

    public void dump(@NonNull FileDescriptor fd, @Nullable String[] args) throws 
    RemoteException;

    public void dumpAsync(@NonNull FileDescriptor fd, @Nullable String[] args)
            throws RemoteException;

    public void shellCommand(@Nullable FileDescriptor in, @Nullable FileDescriptor out,
            @Nullable FileDescriptor err,
            @NonNull String[] args, @Nullable ShellCallback shellCallback,
            @NonNull ResultReceiver resultReceiver) throws RemoteException;

    public boolean transact(int code, @NonNull Parcel data, @Nullable Parcel reply, int flags)
        throws RemoteException;


    public interface DeathRecipient {
        public void binderDied();
    }


    public void linkToDeath(@NonNull DeathRecipient recipient, int flags)
            throws RemoteException;


    public boolean unlinkToDeath(@NonNull DeathRecipient recipient, int flags);
}

Binder源码：

---

public class Binder implements IBinder {
    /*
     * Set this flag to true to detect anonymous, local or member classes
     * that extend this Binder class and that are not static. These kind
     * of classes can potentially create leaks.
     */
    private static final boolean FIND_POTENTIAL_LEAKS = false;
    /** @hide */
    public static final boolean CHECK_PARCEL_SIZE = false;
    static final String TAG = "Binder";

    /** @hide */
    public static boolean LOG_RUNTIME_EXCEPTION = false; // DO NOT SUBMIT WITH TRUE

    /**
     * Control whether dump() calls are allowed.
     */
    private static volatile String sDumpDisabled = null;