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背景：

近来在体验调试aosp15时候，使用了dumpsys activity containers时候，发现wms层级结构树有一个巨大的变化。
很多学员朋友对这个优化改进都给出巨大的点赞，有的学员朋友还想老版本自己实现一下这种树绘制：

对比安卓14老版本情况

明显可以看出以前的wms层级结构树看着不像一颗树，靠的序号和空格在区分，但是层级一多，而且相差不多时候，如果只相差一层空格就不明显了，经常可能需要对半天才对的清楚。

aosp15和老版本的源码分析对比：

aosp15代码

/*** Dumps the names of this container children in the input print writer indenting each* level with the input prefix.*/public void dumpChildrenNames(PrintWriter pw, String prefix, boolean isLastChild) {int curWinMode = getWindowingMode();String winMode = windowingModeToString(curWinMode);if (curWinMode != WINDOWING_MODE_UNDEFINED &&curWinMode != WINDOWING_MODE_FULLSCREEN) {winMode = winMode.toUpperCase();}int requestedWinMode = getRequestedOverrideWindowingMode();String overrideWinMode = windowingModeToString(requestedWinMode);if (requestedWinMode != WINDOWING_MODE_UNDEFINED &&requestedWinMode != WINDOWING_MODE_FULLSCREEN) {overrideWinMode = overrideWinMode.toUpperCase();}String actType = activityTypeToString(getActivityType());if (getActivityType() != ACTIVITY_TYPE_UNDEFINED&& getActivityType() != ACTIVITY_TYPE_STANDARD) {actType = actType.toUpperCase();}pw.print(prefix + (isLastChild ? "└─ " : "├─ "));//isLastChild属于新参数，绘制树枝的看看是不是最后一个childpw.println(getName()+ " type=" + actType+ " mode=" + winMode+ " override-mode=" + overrideWinMode+ " requested-bounds=" + getRequestedOverrideBounds().toShortString()+ " bounds=" + getBounds().toShortString());String childPrefix = prefix + (isLastChild ? "   " : "│  ");//注意这个是给子节点的标签，要么是空格要么是竖线for (int i = getChildCount() - 1; i >= 0; --i) {final E cc = getChildAt(i);cc.dumpChildrenNames(pw, childPrefix, i == 0 /* isLastChild */);}}

aosp14代码

      /*** Dumps the names of this container children in the input print writer indenting each* level with the input prefix.*/public void dumpChildrenNames(PrintWriter pw, String prefix) {final String childPrefix = prefix + " ";//这里有给每一层增加空格pw.println(getName()+ " type=" + activityTypeToString(getActivityType())+ " mode=" + windowingModeToString(getWindowingMode())+ " override-mode=" + windowingModeToString(getRequestedOverrideWindowingMode())+ " requested-bounds=" + getRequestedOverrideBounds().toShortString()+ " bounds=" + getBounds().toShortString());for (int i = getChildCount() - 1; i >= 0; --i) {final E cc = getChildAt(i);pw.print(childPrefix + "#" + i + " ");//这里主要表示child的索引cc.dumpChildrenNames(pw, childPrefix);}}

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