添加自定义字体引起的Memory Leak
16lz
2021-01-24
问题描述
在项目中引入了新的字库，项目中也自定了一个TextView 和 EditView 使用这个新的字库。代码如下：
public class CustomCashDigitFontTextView extends android.support.v7.widget.AppCompatTextView { public CustomCashDigitFontTextView(Context context) { super(context); init(context); } public CustomCashDigitFontTextView(Context context, AttributeSet attrs) { super(context, attrs); init(context); } public CustomCashDigitFontTextView(Context context, AttributeSet attrs, int defStyleAttr) { super(context, attrs, defStyleAttr); init(context); } public void init(Context context) { Typeface newFont = Typeface.createTypeface(context.getAssets(), "DIN-Medium-Number.ttf"); setTypeface(newFont); }}我用下面的命令查看memory状况的时候发现：
adb shell dumpsys meminfo
内存的状况如下：
Asset Allocations zip:/data/app/com.sankuai.poscashier-2/base.apk:/assets/DIN-Medium-Number.ttf: 23K zip:/data/app/com.sankuai.poscashier-2/base.apk:/assets/DIN-Medium-Number.ttf: 23K zip:/data/app/com.sankuai.poscashier-2/base.apk:/assets/DIN-Medium-Number.ttf: 23K zip:/data/app/com.sankuai.poscashier-2/base.apk:/assets/DIN-Medium-Number.ttf: 23K zip:/data/app/com.sankuai.poscashier-2/base.apk:/assets/DIN-Medium-Number.ttf: 23K zip:/data/app/com.sankuai.poscashier-2/base.apk:/assets/DIN-Medium-Number.ttf: 23K zip:/data/app/com.sankuai.poscashier-2/base.apk:/assets/DIN-Medium-Number.ttf: 23K zip:/data/app/com.sankuai.poscashier-2/base.apk:/assets/DIN-Medium-Number.ttf: 23K zip:/data/app/com.sankuai.poscashier-2/base.apk:/assets/DIN-Medium-Number.ttf: 23K zip:/data/app/com.sankuai.poscashier-2/base.apk:/assets/DIN-Medium-Number.ttf: 23K zip:/data/app/com.sankuai.poscashier-2/base.apk:/assets/DIN-Medium-Number.ttf: 23K zip:/data/app/com.sankuai.poscashier-2/base.apk:/assets/DIN-Medium-Number.ttf: 23K zip:/data/app/com.sankuai.poscashier-2/base.apk:/assets/DIN-Medium-Number.ttf: 23K zip:/data/app/com.sankuai.poscashier-2/base.apk:/assets/DIN-Medium-Number.ttf: 23K zip:/data/app/com.sankuai.poscashier-2/base.apk:/assets/DIN-Medium-Number.ttf: 23K zip:/data/app/com.sankuai.poscashier-2/base.apk:/assets/DIN-Medium-Number.ttf: 23K zip:/data/app/com.sankuai.poscashier-2/base.apk:/assets/DIN-Medium-Number.ttf: 23K zip:/data/app/com.sankuai.poscashier-2/base.apk:/assets/DIN-Medium-Number.ttf: 23K zip:/data/app/com.sankuai.poscashier-2/base.apk:/assets/DIN-Medium-Number.ttf: 23K zip:/data/app/com.sankuai.poscashier-2/base.apk:/assets/DIN-Medium-Number.ttf: 23K zip:/data/app/com.sankuai.poscashier-2/base.apk:/assets/DIN-Medium-Number.ttf: 23K zip:/data/app/com.sankuai.poscashier-2/base.apk:/assets/DIN-Medium-Number.ttf: 23K zip:/data/app/com.sankuai.poscashier-2/base.apk:/assets/DIN-Medium-Number.ttf: 23K zip:/data/app/com.sankuai.poscashier-2/base.apk:/assets/DIN-Medium-Number.ttf: 23K zip:/data/app/com.sankuai.poscashier-2/base.apk:/assets/DIN-Medium-Number.ttf: 23K zip:/data/app/com.sankuai.poscashier-2/base.apk:/assets/DIN-Medium-Number.ttf: 23K zip:/data/app/com.sankuai.poscashier-2/base.apk:/assets/DIN-Medium-Number.ttf: 23K zip:/data/app/com.sankuai.poscashier-2/base.apk:/assets/DIN-Medium-Number.ttf: 23K zip:/data/app/com.sankuai.poscashier-2/base.apk:/assets/DIN-Medium-Number.ttf: 23Kasserts部分同样的字体库，内存被分配了多次。
原因分析
主要是下面的代码引起的：
Typeface newFont = Typeface.createFromAsset(context.getAssets(), "DIN-Medium-Number.ttf");每一次调用Typeface.createFromAsset，都会分配一次内存，导致同样的内容内存反复分配。
我有观察了最新的Android 源码，在最新的Android7.0的代码中，这个问题已经解决了。但是在Android 5.0+的版本上，问题依然存在。
解决方案
方案很简单，引入一个缓存，当时同样的字体，不再分配新的内存。
public class TypefaceHelper { private static final LruCache sDynamicTypefaceCache = new LruCache<>(8); public static Typeface createTypeface(AssetManager assetManager, String path) { synchronized (sDynamicTypefaceCache) { Typeface typeFace = sDynamicTypefaceCache.get(path); if (typeFace!=null) { return typeFace; } else { typeFace = Typeface.createFromAsset(assetManager, path); sDynamicTypefaceCache.put(path, typeFace); return typeFace; } } }} 注意，要加上synchronized (sDynamicTypefaceCache) 线程同步锁，否则，在某些线程同步的情况下，也可能导致偶先的多次分配。
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