Android IME 中獲取狀態欄高度：無 Activity 上下文的通用反射方案

核心代碼

public int getStatusBarHeight() {
    int result = 0;
    int resourceId = getResources().getIdentifier("status_bar_height", "dimen", "android");
    if (resourceId > 0) {
        result = getResources().getDimensionPixelSize(resourceId);
    }
    return result;
}

適用場景

• InputMethodService (IME) 無 Activity 引用
• Dialog/PopupWindow 等非全屏上下文
• 系統進程、壁紙服務等

原理說明

Android 系統在 frameworks/base/core/res/res/values/dimens.xml 定義了 <dimen name="status_bar_height">25dp</dimen>，通過資源 ID 反射獲取，無需 Window 對象。

備用方案（反射類）

public int getStatusBarHeightFallback() {
    try {
        Class c = Class.forName("com.android.internal.R$dimen");
        Object obj = c.newInstance();
        Field field = c.getField("status_bar_height");
        int x = Integer.parseInt(field.get(obj).toString());
        return getResources().getDimensionPixelSize(x);
    } catch (Exception e) {
        return 0; // 默認值
    }
}

緩存優化

private Integer cachedStatusBarHeight;

public int getStatusBarHeight() {
    if (cachedStatusBarHeight != null) return cachedStatusBarHeight;
    int h = getResources().getIdentifier("status_bar_height", "dimen", "android");
    cachedStatusBarHeight = (h > 0) ? getResources().getDimensionPixelSize(h) : 0;
    return cachedStatusBarHeight;
}