Android教程網
設為首頁|加入收藏
  1. 首頁
  2. Android 技術
  3. Android 手機
  4. Android 系統教程
  5. Android 游戲
 Android教程網 >> Android技術 >> 關於Android編程 >> Android使用文件進行IPC

Android使用文件進行IPC

編輯：關於Android編程

一、文件進行IPC介紹

共享文件也是一種不錯的進程間通信方式，兩個進程通過讀/寫同一個文件來交換數據。在Windows上，一個文件如果被加了排斥鎖將會導致其他線程無法對其進行訪問，包括讀寫，而由於Android系統基於Linux，使其並發讀/寫文件可以沒有限制地進行，甚至兩個線程同時對同一個文件進行讀寫操作是允許的，盡管這可能出現問題。通過文件交換數據很好使用，除了可以交換一些文本信息外，還可以序列化一個對象到文件系統中的同時從另一個進程中恢復這個對象。

二、使用方法

1.數據類實現Parcelable或Serializable接口

public class User implements Parcelable, Serializable {
public User() {
  }

  public User(int userId, String userName, boolean isMale) {
    ...
  }

  @Override
  public int describeContents() {
    return 0;
  }

  @Override
  public void writeToParcel(Parcel dest, int flags) {
    ...
  }

  public static final Parcelable.Creator<User> CREATOR = new Parcelable.Creator<User>() {
    @Override
    public User createFromParcel(Parcel source) {
      return ...;
    }

    @Override
    public User[] newArray(int size) {
      return ...;
    }
  };

  private User(Parcel in) {
    ...
  }

  @Override
  public String toString() {
    return ...;
  }
}

2.序列化一個對象到sd卡上的一個文件裡

private void persistToFile() {
    new Thread(new Runnable() {
      @Override
      public void run() {
        User user = new User(1, "hello world", false);
        File dir = new File(MyConstants.CHAPTER_2_PATH);
        if (!dir.exists()) {
          dir.mkdirs();
        }
        File cachedFile = new File(MyConstants.CACHE_FILE_PATH);
        ObjectOutputStream objectOutputStream = null;
        try {
          objectOutputStream = new ObjectOutputStream(new FileOutputStream(cachedFile));
          objectOutputStream.writeObject(user);
          Log.d(TAG, "persist user:" + user);
          mTextView.setText("persist user:" + user);
        } catch (IOException e) {
          e.printStackTrace();
        } finally {
          MyUtils.close(objectOutputStream);
        }
      }
    }).start();
  }

3.在另外的進程中反序列化

private void recoverFromFile(){
    new Thread(new Runnable() {
      @Override
      public void run() {
        User user = null;
        File cachedFile = new File(MyConstants.CACHE_FILE_PATH);
        if(cachedFile.exists()){
          ObjectInputStream objectInputStream = null;
          try{
            objectInputStream = new ObjectInputStream(new FileInputStream(cachedFile));
            user = (User)objectInputStream.readObject();
            Log.d(TAG,"recover user:"+user);
            mTextView.setText("recover user:"+user);
          }catch (IOException e) {
            e.printStackTrace();
          }catch (ClassNotFoundException e){
            e.printStackTrace();
          }finally {
            MyUtils.close(objectInputStream);
          }
        }
      }
    }).start();
  }

4.在AndroidManifest.xml中開啟多進程

   <activity
      ...
      android:process=":remote" />

三、小案例

1.修改activity_main.xml文件

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout
  xmlns:android="http://schemas.android.com/apk/res/android"
  xmlns:tools="http://schemas.android.com/tools"
  android:layout_width="match_parent"
  android:layout_height="match_parent"
  android:fitsSystemWindows="true"
  tools:context="com.zhangmiao.ipcdemo.MainActivity"
  android:orientation="vertical"
  >
  <TextView
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_gravity="center_horizontal"
    android:text="File">
  </TextView>
  <Button
    android:id="@+id/button1"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:text="open activity B"
    />

  <TextView
    android:id="@+id/textView1"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:text="A">
  </TextView>
</LinearLayout>

2.添加activity_second.xml文件

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout
  xmlns:android="http://schemas.android.com/apk/res/android"
  android:orientation="vertical"
  android:layout_width="match_parent"
  android:layout_height="match_parent">

  <TextView
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:text="at activity B"
    android:layout_gravity="center_horizontal"
    />
  <TextView
    android:id="@+id/textView1"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:text="Activity B"
    />
</LinearLayout>

3.添加MyUtils類與MyConstants類（輔助類）

package com.zhangmiao.ipcdemo;

import android.app.ActivityManager;
import android.content.Context;

import java.io.Closeable;
import java.io.IOException;
import java.util.List;
import java.util.concurrent.RecursiveTask;

/**
 * Created by zhangmiao on 2016/12/26.
 */
public class MyUtils {
  public static void close(Closeable closeable) {
    try {
      if (closeable != null) {
        closeable.close();
      }
    } catch (IOException e) {
      e.printStackTrace();
    }
  }
}



package com.zhangmiao.ipcdemo;

import android.os.Environment;

/**
 * Created by zhangmiao on 2016/12/26.
 */
public class MyConstants {
  public static final String CHAPTER_2_PATH = Environment.getExternalStorageDirectory().getPath() + "/zhangmiao/charpter_2/";
  public static final String CACHE_FILE_PATH = CHAPTER_2_PATH + "usercache";

  public static final int MSG_FROM_CLIENT = 0;
  public static final int MSG_FROM_SERVICE = 1;
}

4.添加User類

package com.zhangmiao.ipcdemo;

import android.os.Parcel;
import android.os.Parcelable;

import java.io.Serializable;

/**
 * Created by zhangmiao on 2016/12/26.
 */
public class User implements Parcelable, Serializable {

  public static int sUserId = 1;

  private int userId;
  private String userName;
  private Boolean isMale;

  public User() {
  }

  public User(int userId, String userName, boolean isMale) {
    this.userId = userId;
    this.userName = userName;
    this.isMale = isMale;
  }

  @Override
  public int describeContents() {
    return 0;
  }

  @Override
  public void writeToParcel(Parcel dest, int flags) {
    dest.writeInt(userId);
    dest.writeString(userName);
    dest.writeInt(isMale ? 1 : 0);
  }

  public static final Parcelable.Creator<User> CREATOR = new Parcelable.Creator<User>() {
    @Override
    public User createFromParcel(Parcel source) {
      return new User(source);
    }

    @Override
    public User[] newArray(int size) {
      return new User[size];
    }
  };

  private User(Parcel in) {
    userId = in.readInt();
    userName = in.readString();
    isMale = in.readInt() == 1;
  }

  @Override
  public String toString() {
    return String.format(
        "User:{userId:%s, userName:%s, isMale:%s},",userId, userName, isMale
    );
  }
}

5.添加SecondActivity類

package com.zhangmiao.ipcdemo;

import android.app.Activity;
import android.os.Bundle;
import android.util.Log;
import android.widget.TextView;

import java.io.File;
import java.io.FileInputStream;
import java.io.IOException;
import java.io.ObjectInputStream;

/**
 * Created by zhangmiao on 2016/12/26.
 */
public class SecondActivity extends Activity {

  private static final String TAG = "SecondActivity";

  private TextView mTextView;

  @Override
  protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_second);
    Log.d(TAG, "onCreate");
    mTextView = (TextView)findViewById(R.id.textView1);
  }

  @Override
  protected void onResume() {
    Log.d(TAG,"onResume");
    super.onResume();
    User user = (User)getIntent().getSerializableExtra("extra_user");
    Log.d(TAG,"user:"+user.toString());
    recoverFromFile();
  }

  private void recoverFromFile(){
    new Thread(new Runnable() {
      @Override
      public void run() {
        User user = null;
        File cachedFile = new File(MyConstants.CACHE_FILE_PATH);
        if(cachedFile.exists()){
          ObjectInputStream objectInputStream = null;
          try{
            objectInputStream = new ObjectInputStream(new FileInputStream(cachedFile));
            user = (User)objectInputStream.readObject();
            Log.d(TAG,"recover user:"+user);
            mTextView.setText("recover user:"+user);
          }catch (IOException e) {
            e.printStackTrace();
          }catch (ClassNotFoundException e){
            e.printStackTrace();
          }finally {
            MyUtils.close(objectInputStream);
          }
        }
      }
    }).start();
  }
}

6.修改MainActivity類

package com.zhangmiao.ipcdemo;

import android.content.ComponentName;
import android.content.Context;
import android.content.Intent;
import android.content.ServiceConnection;
import android.os.Bundle;
import android.os.Handler;
import android.os.IBinder;
import android.os.Message;
import android.os.Messenger;
import android.os.RemoteException;
import android.support.v7.app.AppCompatActivity;
import android.util.Log;
import android.view.View;
import android.widget.Button;
import android.widget.TextView;


import java.io.File;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.ObjectOutputStream;
import java.io.Serializable;

public class MainActivity extends AppCompatActivity {

  private static final String TAG = "MainActivity";
  private TextView mTextView;

  @Override
  protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
    User.sUserId = 2;
    findViewById(R.id.button1).setOnClickListener(new View.OnClickListener() {
      @Override
      public void onClick(View v) {
        Intent intent = new Intent();
        intent.setClass(MainActivity.this, SecondActivity.class);
        User user = new User(0, "jake", true);
        intent.putExtra("extra_user", (Serializable) user);
        startActivity(intent);
      }
    });
    mTextView = (TextView) findViewById(R.id.textView1);
  }

  @Override
  protected void onResume() {
    super.onResume();
    Log.d(TAG, "UserManager.sUserId=" + User.sUserId);
    super.onStart();
    persistToFile();
  }

  private void persistToFile() {
    new Thread(new Runnable() {
      @Override
      public void run() {
        User user = new User(1, "hello world", false);
        File dir = new File(MyConstants.CHAPTER_2_PATH);
        if (!dir.exists()) {
          dir.mkdirs();
        }
        File cachedFile = new File(MyConstants.CACHE_FILE_PATH);
        ObjectOutputStream objectOutputStream = null;
        try {
          objectOutputStream = new ObjectOutputStream(new FileOutputStream(cachedFile));
          objectOutputStream.writeObject(user);
          Log.d(TAG, "persist user:" + user);
          mTextView.setText("persist user:" + user);
        } catch (IOException e) {
          e.printStackTrace();
        } finally {
          MyUtils.close(objectOutputStream);
        }
      }
    }).start();
  }
}

7.修改AndroidManifest.xml文件

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

  <uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />

  <application
    android:allowBackup="true"
    android:icon="@mipmap/ic_launcher"
    android:label="@string/app_name"
    android:supportsRtl="true"
    android:theme="@style/AppTheme">
    <activity
      android:name=".MainActivity"
      android:label="@string/app_name"
      android:launchMode="standard"
      android:theme="@style/AppTheme.NoActionBar">
      <intent-filter>
        <action android:name="android.intent.action.MAIN" />
        <category android:name="android.intent.category.LAUNCHER" />
      </intent-filter>
    </activity>
    <activity
      android:name=".SecondActivity"
      android:configChanges="screenLayout"
      android:label="@string/app_name"
      android:process=":remote" />
  </application>
</manifest>

完整代碼下載地址：https://github.com/ZhangMiao147/IPCDemo

以上就是本文的全部內容，希望對大家的學習有所幫助，也希望大家多多支持本站。

  1. 上一頁:
  2. 下一頁:
關於Android編程
Android編程入門Android技術基礎Android資訊關於Android編程Android開發Android開發環境Android開發實例
相關文章
熱門文章
android開發筆記之高級主題—傳感器的簡單介紹 詳解Android中提示對話框（ProgressDialog和DatePickerDialog和TimePickerDialog&PopupWindow） Android自定義Style實現方法 Android源碼分析-資源加載機制 Android 接口的回調函數 Android利用ViewPager仿微信主界面-android學習之旅(78)
仿ViewPager相冊（使用HorizontalScrollView）

近期看了一堂某在線IT學習的視頻公開課，這裡就不說名字了，省的有打廣告的
sweet alert dialog 在android studio應用問題說明詳解

看到這個sweet-alert-dialog很親切，因為前端開發本人用的
Android全新的SwipeRefreshLayout控件教程

SwipeRefreshLayout感覺是Google在吸收了PullT
Android Studio初體驗之導入eclipse項目

本篇使用到的Android Studio版本為1.0， Eclipse

閱讀排行版
Copyright © Android教程網 All Rights Reserved