Android开发键盘事件移动米老鼠案例

MainAcitity.java文件
package com.example;
import android.os.Bundle;
import android.view.KeyEvent;
import android.view.View;
import android.widget.ImageView;
import android.widget.LinearLayout;
import android.widget.Toast;

import androidx.appcompat.app.AppCompatActivity;
public class MainActivity extends AppCompatActivity {
    protected static final int STEP = 10;
    private ImageView ivMickey;
    private LinearLayout root;
    private LinearLayout.LayoutParams layoutParams;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        //利用布局资源文件设置用户界面
        setContentView(R.layout.activity_main);
        //通过资源索引获得控件实例
        ivMickey = findViewById(R.id.ivMickey);
        root = findViewById(R.id.root);
        //设置根布局可以获得焦点
        root.setFocusable(true);
        //让根布局获得焦点
        root.requestFocus();
        //获取图像控件的布局参数
        layoutParams = (LinearLayout.LayoutParams) ivMickey.getLayoutParams();
        //给根布局注册监听器
        root.setOnKeyListener(new View.OnKeyListener() {
            @Override
            public boolean onKey(View v, int keyCode, KeyEvent event) {
                switch (keyCode) {
                    //根据按键修改图像控件的布局参数
                    case KeyEvent.KEYCODE_DPAD_UP://按上方向键
                        //上边界碰撞检测
                        if (ivMickey.getTop() >= 10) {
                            layoutParams.topMargin = layoutParams.topMargin - STEP;
                        } else {
                            Toast.makeText(MainActivity.this, "碰到上边界了", Toast.LENGTH_SHORT).show();
                        }
                        break;
                    case KeyEvent.KEYCODE_DPAD_DOWN://按下方向键
                        if (ivMickey.getBottom() <=root.getHeight()) {
                        layoutParams.topMargin = layoutParams.topMargin + STEP;
                        } else {
                            Toast.makeText(MainActivity.this,"碰到下边界了",Toast.LENGTH_SHORT).show();
                        }
                        break;
                    case KeyEvent.KEYCODE_DPAD_LEFT://按左方向键
                        if (ivMickey.getLeft() >= 9) {
                            layoutParams.leftMargin = layoutParams.leftMargin - STEP;
                        }else {
                            Toast.makeText(MainActivity.this,"碰到左边界了",Toast.LENGTH_SHORT).show();
                        }
                        break;
                    case KeyEvent.KEYCODE_DPAD_RIGHT://按右方向键
                        if(ivMickey.getRight() <= root.getWidth()) {
                            layoutParams.leftMargin = layoutParams.leftMargin + STEP;
                        } else {
                            Toast.makeText(MainActivity.this,"碰到右边距了",Toast.LENGTH_SHORT).show();
                        }
                        break;
                }
                //重新设置图像控件的布局参数
                ivMickey.setLayoutParams(layoutParams);
                return false;
            }
        });


    }
}

activity_main.xml文件

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:id="@+id/root"
    android:background="@drawable/background"
    android:orientation="vertical"
    tools:context=".MainActivity">
<ImageView
    android:id="@+id/ivMickey"
    android:layout_width="100dp"
    android:layout_height="100dp"
    android:gravity="center"
    android:src="@drawable/mickey"/>

</LinearLayout>