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Android应用从一个界面打开新的Activity, 在桌面应用和web和页面上,都可以从窗体或页面打开另一个新的窗体,Android打开新的是Activity，本文示例通过按钮onClick事件打开新的Activity窗口，在Android Studio中新建项目默认生成“MainActivity”，然后再新建一个“FullscreenActivity”，用于打开新的Activity窗口切换。本文属于Android开发的基础篇，需要对Android Studio有基本入门（如：新建项目、文件等）， 并且对Java熟练才能顺利上手阅读。
先在Android Studio中新建项目，项目名称命名为“ActivityOpen”，可以根据自己随意命名，创建项目后，自动生成了“MainActivity”和“activity_main.xml”，先将“activity_main.xml”中默认的“TextView”删除，加入“Button”按钮，上下居中对齐，将其id命名为“btnOpen”，按钮用来点击打开新的“Activity”。代码如下：
<?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.ConstraintLayout 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:id="@+id/main"
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:context=".MainActivity">
<Button
android:id="@+id/btnOpen"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="open"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintHorizontal_bias="0.5"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent"
app:layout_constraintVertical_bias="0.5" />
</androidx.constraintlayout.widget.ConstraintLayout>
如下图：
接着在“Project”项目目录中右键“New”新建“Activity”文件，在“Activity”中选择“Fullscreen Views Activity”，为默认全屏模式，用于MainActivity中的按钮点击打开用。代码如下：
<?xml version="1.0" encoding="utf-8"?>
<FrameLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:background="?attr/fullscreenBackgroundColor"
android:theme="@style/ThemeOverlay.ActivityOpen.FullscreenContainer"
tools:context=".FullscreenActivity">
<!-- The primary full-screen view. This can be replaced with whatever view
is needed to present your content, e.g. VideoView, SurfaceView,
TextureView, etc. -->
<TextView
android:id="@+id/fullscreen_content"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:gravity="center"
android:keepScreenOn="true"
android:text="@string/dummy_content"
android:textColor="?attr/fullscreenTextColor"
android:textSize="50sp"
android:textStyle="bold" />
<!-- This FrameLayout insets its children based on system windows using
android:fitsSystemWindows. -->
<FrameLayout
android:layout_width="match_parent"
android:layout_height="match_parent"
android:fitsSystemWindows="true">
<LinearLayout
android:id="@+id/fullscreen_content_controls"
style="@style/Widget.Theme.ActivityOpen.ButtonBar.Fullscreen"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_gravity="bottom|center_horizontal"
android:orientation="horizontal"
tools:ignore="UselessParent">
<Button
android:id="@+id/dummy_button"
style="?android:attr/buttonBarButtonStyle"
android:layout_width="0dp"
android:layout_height="wrap_content"
android:layout_weight="1"
android:text="@string/dummy_button" />
</LinearLayout>
</FrameLayout>
</FrameLayout>
在“activity_fullscreen.xml”中“TextView”文字值绑定的"@string/dummy_content"，activity的背景颜色绑定的"?attr/fullscreenBackgroundColor"，在strings.xml文件中设置，如下：
<resources>
<string name="app_name">ActivityOpen</string>
<string name="title_activity_fullscreen">FullscreenActivity</string>
<string name="dummy_button">Dummy Button</string>
<string name="dummy_content"> | 遺昕传媒 | weisim3.com</string>
</resources>
FullscreenActivity的全屏模式，知识点如何进入全屏隐藏状态栏，这里可以参考下“run() ”方法，详细代码如下：
private View mContentView;
private final Runnable mHidePart2Runnable = new Runnable() {
@SuppressLint("InlinedApi")
@Override
public void run() {
// Delayed removal of status and navigation bar
if (Build.VERSION.SDK_INT >= 30) {
mContentView.getWindowInsetsController().hide(
WindowInsets.Type.statusBars() | WindowInsets.Type.navigationBars());
} else {
// Note that some of these constants are new as of API 16 (Jelly Bean)
// and API 19 (KitKat). It is safe to use them, as they are inlined
// at compile-time and do nothing on earlier devices.
mContentView.setSystemUiVisibility(View.SYSTEM_UI_FLAG_LOW_PROFILE
| View.SYSTEM_UI_FLAG_FULLSCREEN
| View.SYSTEM_UI_FLAG_LAYOUT_STABLE
| View.SYSTEM_UI_FLAG_IMMERSIVE_STICKY
| View.SYSTEM_UI_FLAG_LAYOUT_HIDE_NAVIGATION
| View.SYSTEM_UI_FLAG_HIDE_NAVIGATION);
}
}
};
private View mControlsView;
private final Runnable mShowPart2Runnable = new Runnable() {
@Override
public void run() {
// Delayed display of UI elements
ActionBar actionBar = getSupportActionBar();
if (actionBar != null) {
actionBar.show();
}
mControlsView.setVisibility(View.VISIBLE);
}
};
Activity准备工作做好之后， 回到“MainActivity”中将btnOpen按钮实例化，加入按钮事件触发打开新的Activity，这里按钮点击打开的是“FullscreenActivity”，代码如下：
package com.example.activityopen;
import android.content.Intent;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import androidx.activity.EdgeToEdge;
import androidx.appcompat.app.AppCompatActivity;
import androidx.core.graphics.Insets;
import androidx.core.view.ViewCompat;
import androidx.core.view.WindowInsetsCompat;
public class MainActivity extends AppCompatActivity {
private Button button;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
EdgeToEdge.enable(this);
setContentView(R.layout.activity_main);
button=(Button)findViewById(R.id.btnOpen);
/* Android打开新的Activity窗口(12.24.2024)
* Copyright (C) 遗昕传媒 | weisim3.com */
button.setOnClickListener( new View.OnClickListener() {
@Override
public void onClick(View v) {
Intent intent= new Intent(MainActivity.this,FullscreenActivity.class);
startActivity(intent);
finish();//退出结束主程
}
});
ViewCompat.setOnApplyWindowInsetsListener(findViewById(R.id.main), (v, insets) -> {
Insets systemBars = insets.getInsets(WindowInsetsCompat.Type.systemBars());
v.setPadding(systemBars.left, systemBars.top, systemBars.right, systemBars.bottom);
return insets;
});
}
}
最终效果如下：
