老罗的Android之旅 - AShmem学习笔记

原文: https://blog.csdn.net/luoshengyang/article/details/6666491

包名: com.ashmem.client

已知问题:

1. MemoryFile没有获取FileDescriptor的方法, 只能反射调取

2. 没有办法通过fd去创建MemoryFile, 只能通过String name的方式创建, 用FileInputStream取代

3. 第一次setVal读回来是对的, 第二次setVal读回来的不正确.

aidl文件,  Client/app/src/main/aidl/com/ashmem/client/IMemoryService.aidl:

// IMemoryService.aidl
package com.ashmem.client;

// Declare any non-default types here with import statements

interface IMemoryService {
    /**
     * Demonstrates some basic types that you can use as parameters
     * and return values in AIDL.
     */
    void basicTypes(int anInt, long aLong, boolean aBoolean, float aFloat,
            double aDouble, String aString);

    void setValue(int val);

    ParcelFileDescriptor getFileDescriptor();
}

生成的IMemoryService.java, Client/app/build/generated/aidl_source_output_dir/debug/compileDebugAidl/out/com/ashmem/client/IMemoryService.java:

/*
 * This file is auto-generated.  DO NOT MODIFY.
 */
package com.ashmem.client;
// Declare any non-default types here with import statements

public interface IMemoryService extends android.os.IInterface
{
  /** Default implementation for IMemoryService. */
  public static class Default implements com.ashmem.client.IMemoryService
  {
    /**
         * Demonstrates some basic types that you can use as parameters
         * and return values in AIDL.
         */
    @Override public void basicTypes(int anInt, long aLong, boolean aBoolean, float aFloat, double aDouble, java.lang.String aString) throws android.os.RemoteException
    {
    }
    @Override public void setValue(int val) throws android.os.RemoteException
    {
    }
    @Override public android.os.ParcelFileDescriptor getFileDescriptor() throws android.os.RemoteException
    {
      return null;
    }
    @Override
    public android.os.IBinder asBinder() {
      return null;
    }
  }
  /** Local-side IPC implementation stub class. */
  public static abstract class Stub extends android.os.Binder implements com.ashmem.client.IMemoryService
  {
    private static final java.lang.String DESCRIPTOR = "com.ashmem.client.IMemoryService";
    /** Construct the stub at attach it to the interface. */
    public Stub()
    {
      this.attachInterface(this, DESCRIPTOR);
    }
    /**
     * Cast an IBinder object into an com.ashmem.client.IMemoryService interface,
     * generating a proxy if needed.
     */
    public static com.ashmem.client.IMemoryService asInterface(android.os.IBinder obj)
    {
      ...
    }
    @Override public android.os.IBinder asBinder()
    {
      return this;
    }
    @Override public boolean onTransact(int code, android.os.Parcel data, android.os.Parcel reply, int flags) throws android.os.RemoteException
    {
      ...
    }
    private static class Proxy implements com.ashmem.client.IMemoryService
    {
      private android.os.IBinder mRemote;
      Proxy(android.os.IBinder remote)
      {
        mRemote = remote;
      }
      @Override public android.os.IBinder asBinder()
      {
        return mRemote;
      }
      public java.lang.String getInterfaceDescriptor()
      {
        return DESCRIPTOR;
      }
      /**
           * Demonstrates some basic types that you can use as parameters
           * and return values in AIDL.
           */
      @Override public void basicTypes(int anInt, long aLong, boolean aBoolean, float aFloat, double aDouble, java.lang.String aString) throws android.os.RemoteException
      {
        ...
      }
      @Override public void setValue(int val) throws android.os.RemoteException
      {
        ...
      }
      @Override public android.os.ParcelFileDescriptor getFileDescriptor() throws android.os.RemoteException
      {
        ...
      }
      public static com.ashmem.client.IMemoryService sDefaultImpl;
    }
    static final int TRANSACTION_basicTypes = (android.os.IBinder.FIRST_CALL_TRANSACTION + 0);
    static final int TRANSACTION_setValue = (android.os.IBinder.FIRST_CALL_TRANSACTION + 1);
    static final int TRANSACTION_getFileDescriptor = (android.os.IBinder.FIRST_CALL_TRANSACTION + 2);
    public static boolean setDefaultImpl(com.ashmem.client.IMemoryService impl) {
      ...
    }
    public static com.ashmem.client.IMemoryService getDefaultImpl() {
      return Stub.Proxy.sDefaultImpl;
    }
  }
  /**
       * Demonstrates some basic types that you can use as parameters
       * and return values in AIDL.
       */
  public void basicTypes(int anInt, long aLong, boolean aBoolean, float aFloat, double aDouble, java.lang.String aString) throws android.os.RemoteException;
  public void setValue(int val) throws android.os.RemoteException;
  public android.os.ParcelFileDescriptor getFileDescriptor() throws android.os.RemoteException;
}

实现的Service端, Client/app/src/main/java/com/ashmem/client/MemoryService.java:

package com.ashmem.client;

import android.os.MemoryFile;
import android.os.ParcelFileDescriptor;
import android.os.RemoteException;
import android.util.Log;

import java.io.FileDescriptor;
import java.io.IOException;
import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;

public class MemoryService extends IMemoryService.Stub {
    private final static String LOG_TAG = "MemoryService";
    private MemoryFile memoryFile = null;
    static int value = 0;

    public MemoryService() {
        value = -1;
        try {
            memoryFile = new MemoryFile("Ashmem", 4);
            setValue(0);
        } catch (IOException e) {
            Log.i(LOG_TAG, "Failed to create memory file.");
            e.printStackTrace();
        }
    }

    @Override
    public void setValue(int val) {
        if(memoryFile == null)
            return;
        byte[] buffer = new byte[4];
        buffer[0] = (byte) ((val >>> 24) & 0xFF);
        buffer[1] = (byte) ((val >>> 16) & 0xFF);
        buffer[2] = (byte) ((val >>> 8) & 0xFF);
        buffer[3] = (byte) (val & 0xFF);

        try {
            Log.i(LOG_TAG, "Set value " + val + " to memory file. ");
            memoryFile.writeBytes(buffer, 0, 0, 4);
        } catch (IOException e) {
            Log.i(LOG_TAG, "Failed to write bytes to memory file.");
            e.printStackTrace();
        }
    }

    @Override
    public ParcelFileDescriptor getFileDescriptor() {
        Log.i(LOG_TAG, "Get File Descriptor.");
        FileDescriptor fileDescriptor = null;
        ParcelFileDescriptor dup = null;
        Method method = null;
        try {
            method = MemoryFile.class.getDeclaredMethod("getFileDescriptor");
        } catch (NoSuchMethodException ex) {
            ex.printStackTrace();
        }

        try {
            fileDescriptor = (FileDescriptor)method.invoke(memoryFile);
        }catch (IllegalAccessException ea) {

        } catch (InvocationTargetException ei) {

        }
        try {
            dup = ParcelFileDescriptor.dup(fileDescriptor);
        } catch (IOException e) {
            e.printStackTrace();
        }
        return dup;
    }

    @Override
    public void basicTypes(int anInt, long aLong, boolean aBoolean, float aFloat, double aDouble, String aString) throws RemoteException {

    }
}

实现的Client端, Client/app/src/main/java/com/ashmem/client/MainActivity.java:

package com.ashmem.client;

import androidx.appcompat.app.AppCompatActivity;

import android.content.ComponentName;
import android.content.Intent;
import android.content.ServiceConnection;
import android.os.Bundle;
import android.os.IBinder;
import android.os.MemoryFile;
import android.os.ParcelFileDescriptor;
import android.os.RemoteException;
import android.os.SharedMemory;
import android.util.Log;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;

import java.io.FileDescriptor;
import java.io.FileInputStream;
import java.io.IOException;
import java.nio.ByteBuffer;

public class MainActivity extends AppCompatActivity {
    private final static String LOG_TAG = "MainActivity";
    private IMemoryService memoryService = null;
    private FileInputStream fileInputStream = null;
    private ByteBuffer mMapping;
    private int val;
    Button readButton = null;
    Button writeButton = null;
    EditText editText = null;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        Intent intent = new Intent("com.ashmem.client.server");
        intent.setPackage("com.ashmem.client");
        bindService(intent, new MyConnection(), BIND_AUTO_CREATE);

        readButton = findViewById(R.id.read);
        writeButton = findViewById(R.id.write);
        editText = findViewById(R.id.edit);
        editText.setText("123");

        readButton.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                if(null != memoryService) {
                    if(null == fileInputStream) {
                        getInputStream();
                        if(null == fileInputStream) {
                            return;
                        }
                    }
                    if(null != fileInputStream) {
                        try {
                            byte[] buffer = new byte[4];
                            fileInputStream.read(buffer, 0, 4);
                            fileInputStream.close();
                            fileInputStream = null;

                            int val = (buffer[0] << 24) | ((buffer[1] & 0xFF) << 16) | ((buffer[2] & 0xFF) << 8) | (buffer[3] & 0xFF);
                            Log.i(LOG_TAG, "Read: " + Integer.toString(val));
                            editText.setText(Integer.toString(val));
                        } catch (IOException ex) {
                            ex.printStackTrace();
                        }
                    } else {
                        Log.e(LOG_TAG, "fileInputStream is null");
                    }
                }
            }
        });

        writeButton.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                if(null != memoryService) {
                    try {
                        int vall = Integer.parseInt(editText.getText().toString());
                        Log.i(LOG_TAG, "Set va;: " + vall);
                        memoryService.setValue(vall);
                    } catch (RemoteException ex) {
                        ex.printStackTrace();
                    }
                }
            }
        });
    }

    private void getInputStream() {
        if(null == memoryService) {
            return;
        }

        try {
            ParcelFileDescriptor parcelFileDescriptor = memoryService.getFileDescriptor();
            if(null == parcelFileDescriptor) {
                return ;
            }
            FileDescriptor fileDescriptor = parcelFileDescriptor.getFileDescriptor();
            if(null == fileDescriptor) {
                return ;
            }
            fileInputStream = new FileInputStream(fileDescriptor);
        } catch (RemoteException er) {
            er.printStackTrace();
        }
    }

    class MyConnection implements ServiceConnection {
        @Override
        public void onServiceConnected(ComponentName name, IBinder service) {
            Log.e(LOG_TAG, "onServiceConnected");
            memoryService = IMemoryService.Stub.asInterface(service);
            getInputStream();
        }

        @Override
        public void onServiceDisconnected(ComponentName name) {
            memoryService = null;
        }
    }
}

AndroidManifest文件,  Client/app/src/main/AndroidManifest.xml:

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="com.ashmem.client">

    <application
        android:allowBackup="true"
        android:icon="@mipmap/ic_launcher"
        android:label="@string/app_name"
        android:roundIcon="@mipmap/ic_launcher_round"
        android:supportsRtl="true"
        android:theme="@style/AppTheme">
        <service
            android:name=".Server"
            android:enabled="true"
            android:exported="true">
            <intent-filter>
                <action android:name="com.ashmem.client.server" />
            </intent-filter>
        </service>

        <activity android:name=".MainActivity">
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />

                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
        </activity>
    </application>

</manifest>

Layout文件,  Client/app/src/main/res/layout/activity_main.xml:

<?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context=".MainActivity">

    <TextView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="value"
        android:id="@+id/view1"
        app:layout_constraintLeft_toLeftOf="parent"
        app:layout_constraintRight_toRightOf="parent"
        app:layout_constraintTop_toTopOf="parent" />

    <EditText
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:id="@+id/edit"
        app:layout_constraintLeft_toLeftOf="parent"
        app:layout_constraintRight_toRightOf="parent"
        app:layout_constraintTop_toBottomOf="@+id/view1" />

    <Button
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:id="@+id/read"
        android:text="Read"
        android:orientation="horizontal"
        app:layout_constraintLeft_toLeftOf="parent"
        app:layout_constraintTop_toBottomOf="@id/edit"
        app:layout_constraintRight_toLeftOf="@id/write"
        />
    <Button
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:id="@+id/write"
        android:orientation="horizontal"
        android:text="Write"
        app:layout_constraintTop_toBottomOf="@id/edit"
        app:layout_constraintLeft_toRightOf="@id/read"
        app:layout_constraintRight_toRightOf="parent"
        />

</androidx.constraintlayout.widget.ConstraintLayout>

build.gradle文件:

apply plugin: 'com.android.application'

android {
    compileSdkVersion 29
    buildToolsVersion "29.0.2"
    defaultConfig {
        applicationId "com.ashmem.client"
        minSdkVersion 15
        targetSdkVersion 29
        versionCode 1
        versionName "1.0"
        testInstrumentationRunner "androidx.test.runner.AndroidJUnitRunner"
    }
    buildTypes {
        release {
            minifyEnabled false
            proguardFiles getDefaultProguardFile('proguard-android-optimize.txt'), 'proguard-rules.pro'
        }
    }
}

dependencies {
    implementation fileTree(dir: 'libs', include: ['*.jar'])
    implementation 'androidx.appcompat:appcompat:1.0.2'
    implementation 'androidx.constraintlayout:constraintlayout:1.1.3'
    testImplementation 'junit:junit:4.12'
    androidTestImplementation 'androidx.test.ext:junit:1.1.0'
    androidTestImplementation 'androidx.test.espresso:espresso-core:3.1.1'
}

顶层build.gradle文件:

// Top-level build file where you can add configuration options common to all sub-projects/modules.

buildscript {
    repositories {
        google()
        jcenter()
        
    }
    dependencies {
        classpath 'com.android.tools.build:gradle:3.5.2'
        
        // NOTE: Do not place your application dependencies here; they belong
        // in the individual module build.gradle files
    }
}

allprojects {
    repositories {
        google()
        jcenter()
        
    }
}

task clean(type: Delete) {
    delete rootProject.buildDir
}