Android 全局监听软键盘弹起隐藏 动态修改布局并适配无限循环的问题

思路:

要在 Android 应用中全局检测软键盘的弹起,您可以使用 ViewTreeObserver.OnGlobalLayoutListener 监听器来监听布局树的变化。当软键盘弹起或隐藏时,布局树会发生变化,因此您可以在监听器中捕获这些变化。

以下是一个示例,展示如何在全局范围内检测软键盘的弹起:

import android.graphics.Rect;
import android.os.Bundle;
import android.view.View;
import android.view.ViewTreeObserver;
import androidx.appcompat.app.AppCompatActivity;

public class MainActivity extends AppCompatActivity {

    private View rootView;

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

        rootView = findViewById(R.id.rootView); // Replace with your root layout's ID

        // Register a global layout listener
        rootView.getViewTreeObserver().addOnGlobalLayoutListener(new ViewTreeObserver.OnGlobalLayoutListener() {
            @Override
            public void onGlobalLayout() {
                // Get the height of the visible display area
                Rect rect = new Rect();
                rootView.getWindowVisibleDisplayFrame(rect);
                int screenHeight = rootView.getHeight();
                int keyboardHeight = screenHeight - rect.bottom;

                // If the keyboard height is greater than a threshold (e.g., 100 pixels), the keyboard is likely visible
                if (keyboardHeight > 100) {
                    // Keyboard is visible, do something
                } else {
                    // Keyboard is hidden, do something else
                }
            }
        });
    }
}

在上面的代码中,rootView 是您布局的根视图,您需要将其替换为您实际布局的根视图。addOnGlobalLayoutListener 方法用于注册一个监听器,当布局树发生变化时会调用 onGlobalLayout 方法。

onGlobalLayout 方法中,您可以通过比较屏幕高度和可见区域的底部位置来计算软键盘的高度。根据计算结果,您可以判断软键盘是否可见,并执行相应的操作。

以下是一个在项目中的实际示例,解决无限循环的示例:

private void changerBottomView() {
        binding.includedNoteMenu.fragmentLl.getViewTreeObserver().addOnGlobalLayoutListener(onGlobalLayoutListener);
}
    

private ViewTreeObserver.OnGlobalLayoutListener onGlobalLayoutListener = new ViewTreeObserver.OnGlobalLayoutListener() {
        @Override
        public void onGlobalLayout() {
            Rect rect = new Rect();
            //取得 rootView 可视区域
            binding.includedNoteMenu.fragmentLl.getWindowVisibleDisplayFrame(rect);
            //取得 rootView 不可视区域高度 (被其他View遮挡的区域高度)
            int rootInvisibleHeight = binding.includedNoteMenu.fragmentLl.getRootView().getHeight() - rect.bottom;
            LogUtil.i("shawn","rootInvisibleHeight = " + rootInvisibleHeight);
            ViewGroup.MarginLayoutParams layoutParams = (ViewGroup.MarginLayoutParams)binding.includedNoteMenu.fragmentLl.getLayoutParams();
            if (layoutParams.bottomMargin != rootInvisibleHeight + UiUtil.dp2px(10)) {
                layoutParams.bottomMargin = rootInvisibleHeight + UiUtil.dp2px(10);
                binding.includedNoteMenu.fragmentLl.setLayoutParams(layoutParams);
            }

        }
    };

日志: 只会多调用一次,在第二次回调时,条件已不满足,不会再调用setLayoutParams

I/shawn: [ main: AddNoteFragment.java:173 onGlobalLayout ] - rootInvisibleHeight = 840
I/shawn: [ main: AddNoteFragment.java:173 onGlobalLayout ] - rootInvisibleHeight = 840
I/shawn: [ main: AddNoteFragment.java:173 onGlobalLayout ] - rootInvisibleHeight = -4
I/shawn: [ main: AddNoteFragment.java:173 onGlobalLayout ] - rootInvisibleHeight = -4

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