Android应用开发性能优化

性能优化系列

常见android性能优化总结

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前言

本人一家之言，仅供参考

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提示：以下是本篇文章正文内容，下面案例可供参考

一、启动黑白屏优化

启动方式优化

1. 冷启动

1. 加载并启动APP
2. 启动后立即为该APP显示一个空白启动窗口
3. 创建APP进程（创建应用程序对象）
4. 启动主线程，创建主Activity
5. 加载布局，绘制

2. 热启动

1. 热启动中，系统所有工作是将Activity带到前台
2. 如果应用的所有Activity都驻留在内存中，则应用可以无须重复对象初始化，布局扩充和呈现

3. 温启动

温启动涵盖在冷启动期间发生的操作的一些子集，同时它的开销比热启动多

获取启动时间方式

1. log工具

ActivityTaskManager: Displayed com.example.testdemo/.MainActivity: +3s341ms

2. 命令

adb shell am start -W com.example.testdemo/.SplashActivity

D:\code\android studio code\testdemo>adb shell am start -W com.example.testdemo/.SplashActivity
Starting: Intent { act=android.intent.action.MAIN cat=[android.intent.category.LAUNCHER] cmp=com.example.testdemo/.SplashActivity }
Status: ok
LaunchState: COLD
Activity: com.example.testdemo/.SplashActivity
TotalTime: 384
WaitTime: 394
Complete

D:\code\android studio code\testdemo>adb shell am start -W com.example.testdemo/.SplashActivity
Starting: Intent { act=android.intent.action.MAIN cat=[android.intent.category.LAUNCHER] cmp=com.example.testdemo/.SplashActivity }
Warning: Activity not started, its current task has been brought to the front
Status: ok
LaunchState: HOT
Activity: com.example.testdemo/.SplashActivity
TotalTime: 120 所有activity的启动时间
WaitTime: 123  所有时间，ams启动activity的总时间
Complete

3. 手动获取

SplashActivity.java

    //跳转到MainActivity
    Intent intent = new Intent();
    intent.setClass(this, MainActivity.class);
    startActivity(intent);

	LauncherTime.java

	package com.example.testdemo;

	import android.util.Log;
	
	public class LauncherTime {
	    
	    public static long startTime;
	    
	    public static void logStart() {
	        startTime = System.currentTimeMillis();
	    }
	    
	    public static void logEnd() {
	        Log.d("time", "launcher time: " + (System.currentTimeMillis() - startTime));
	    }
	}

MainActivity.java

	package com.example.testdemo;

	import androidx.appcompat.app.AppCompatActivity;
	
	import android.os.Bundle;
	import android.util.Log;
	import android.view.View;
	import android.view.ViewTreeObserver;
	
	public class MainActivity extends AppCompatActivity {
	
	    private static final String TAG = "MainActivity";
	    @Override
	    protected void onCreate(Bundle savedInstanceState) {
	        setTheme(R.style.Theme_AppCompat);
	        super.onCreate(savedInstanceState);
	        setContentView(R.layout.activity_main);
	        findViews();
	    }
	
	    private void findViews() {
	        //调用跟布局开始绘制的时间
	        final View view = findViewById(R.id.root);
	        view.getViewTreeObserver().addOnPreDrawListener(new ViewTreeObserver.OnPreDrawListener() {
	            @Override
	            public boolean onPreDraw() {
	                LauncherTime.logEnd("Tag3");
	                view.getViewTreeObserver().removeOnPreDrawListener(this);
	                return false;
	            }
	        });
	    }
	
	    @Override
	    protected void onResume() {
	        super.onResume();
	        //调用onResume之后ui才会显示在手机上
	        LauncherTime.logEnd("Tag1");
	    }
	
	    @Override
	    public void onWindowFocusChanged(boolean hasFocus) {
	        super.onWindowFocusChanged(hasFocus);
	        //首帧开始绘制的时候回调
	        LauncherTime.logEnd("Tag2");
	    }
	}

MyApplication.java

	package com.example.testdemo;

	import android.app.Application;
	import android.content.Context;
	
	import java.util.concurrent.ExecutorService;
	
	public class MyApplication extends Application {
	
	    @Override
	    protected void attachBaseContext(Context base) {
	        LauncherTime.logStart();//开始
	        super.attachBaseContext(base);
	    }
	
	    protected Context context;
	    public static Application application;
	    ExecutorService executorService;
	
	    @Override
	    public void onCreate() {
	        super.onCreate();
	    }
	}

结果：
2021-04-03 16:13:32.085 15692-15692/com.example.testdemo D/Tag1: launcher time: 414
2021-04-03 16:13:32.114 15692-15692/com.example.testdemo D/Tag3: launcher time: 443
2021-04-03 16:13:32.300 15692-15692/com.example.testdemo D/Tag2: launcher time: 629

4. TraceView工具

@Override
    public void onCreate() {
        super.onCreate();
        Log.d(TAG, "onCreate");
        //方法耗时统计
        Debug.startMethodTracing("Launcher");
        coreSize = Runtime.getRuntime().availableProcessors();//cpu 核数
        executorService = Executors.newFixedThreadPool(Math.max(2, Math.min(coreSize - 1, 4)));
        a();
        application = this;
        context = this.getApplicationContext();
        Debug.stopMethodTracing();
    }

traceview 文件截图（待补充）

Total(us)	%	Self(us)	%	Children(us)	%
总共耗时			自身耗时main方法		孩子耗时
a			98%

启动优化 减少时间

1. 有些资源懒加载，异步加载
2. 初始化的资源和UI线程有关，不能放到子线程中

如果应用必须要在主线程3s

1. 资源拆分 （时间、空间）

启动白屏优化

代码如下（示例）：

    <!--plan1: 直接取消预览窗体或设置为透明，缺点：同样让用户感觉卡顿-->
    <!--<item name="android:windowDisablePreview">true</item>
    <item name="android:windowIsTranslucent">true</item>-->

    <!--plan2: 直接设置主题背景-->
    <!--<item name="android:windowBackground">@mipmap/ic_launcher</item>-->

    <!--plan2: 设置单个启动页主题背景-->
    <style name="Theme.AppCompat.Launcher1">
        <item name="android:windowBackground">@mipmap/ic_launcher</item>
    </style>

        <activity
            android:name=".MainActivity"
            android:theme="@style/Theme.AppCompat.Launcher1">
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />

                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
        </activity>
        
    <!--plan2: 设置单个启动页主题背景-->
    <style name="Theme.AppCompat.Launcher1">
        <item name="android:windowBackground">@mipmap/ic_launcher</item>
    </style>

MainActivity.java

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

网易云音乐闪屏页

代码如下（示例）：

SplashActivity.java

    @Override
    protected void onCreate(@Nullable Bundle savedInstanceState) {
        requestWindowFeature(Window.FEATURE_NO_TITLE);
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_splash);
    }
    
activity.splash.xml

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

    <ImageView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_alignParentBottom="true"
        android:layout_centerHorizontal="true"
        android:layout_marginBottom="30dp"
        android:background="@mipmap/ic_launcher">
    </ImageView>
    
</RelativeLayout>

theme.xml

<!--plan3: 终极版本-->
<style name="Theme.AppCompat.Launcher2">
    <item name="windowNoTitle">true</item>
    <item name="android:windowFullscreen">true</item>
    <item name="android:windowBackground">@drawable/splash_preview</item>
</style>

splash_preview.xml

<?xml version="1.0" encoding="utf-8"?>
<layer-list xmlns:android="http://schemas.android.com/apk/res/android">
    <!--启动页红色背景-->
    <item android:drawable="@color/red_bg"></item>
    <item android:top="30dp">
        <bitmap
            android:gravity="top"
            android:src="@drawable/ic_launcher_round"></bitmap>
    </item>
</layer-list>

AndroidManifest.xml

<activity
    android:name=".SplashActivity"
    android:theme="@style/Theme.AppCompat.Launcher2