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.w
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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>

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