判断 WLAN 是否启用,如果没有,询问用户是否前往开启;否则,告诉用户 WLAN 已经启用。
准备
IDE:
Android Studio 4.1.1
Build #AI-201.8743.12.41.6953283, built on November 5, 2020
Runtime version: 1.8.0_242-release-1644-b01 amd64
VM: OpenJDK 64-Bit Server VM by JetBrains s.r.o
Windows 10 10.0
Android Virtual Devices:
Name: Pixel_2_API_28
CPU/ABI: Google Play Intel Atom (x86)
Path: C:\Users\86188\.android\avd\Pixel_2_API_28.avd
Target: google_apis_playstore [Google Play] (API level 28)
Skin: pixel_2
SD Card: 512M
fastboot.chosenSnapshotFile:
runtime.network.speed: full
hw.accelerometer: yes
hw.device.name: pixel_2
hw.lcd.width: 1080
hw.initialOrientation: Portrait
image.androidVersion.api: 28
tag.id: google_apis_playstore
hw.mainKeys: no
hw.camera.front: emulated
avd.ini.displayname: Pixel 2 API 28
hw.gpu.mode: auto
hw.ramSize: 1536
PlayStore.enabled: true
fastboot.forceColdBoot: no
hw.cpu.ncore: 4
hw.keyboard: yes
hw.sensors.proximity: yes
hw.dPad: no
hw.lcd.height: 1920
vm.heapSize: 256
skin.dynamic: yes
hw.device.manufacturer: Google
hw.gps: yes
hw.audioInput: yes
image.sysdir.1: system-images\android-28\google_apis_playstore\x86\
showDeviceFrame: yes
hw.camera.back: virtualscene
AvdId: Pixel_2_API_28
hw.lcd.density: 420
hw.arc: false
hw.device.hash2: MD5:55acbc835978f326788ed66a5cd4c9a7
fastboot.forceChosenSnapshotBoot: no
fastboot.forceFastBoot: yes
hw.trackBall: no
hw.battery: yes
hw.sdCard: yes
tag.display: Google Play
runtime.network.latency: none
disk.dataPartition.size: 6442450944
hw.sensors.orientation: yes
avd.ini.encoding: UTF-8
hw.gpu.enabled: yes
注意:以下示例仅在安卓虚拟设备上运行测试,并没有在真实的设备上运行测试。
项目
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新建项目,选择 Empty Activity,在配置项目时,我选择的
Minimum SDK
是API 16: Android 4.1 (Jelly Bean)
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编辑
src\main\AndroidManifest.xml
清单文件,添加ACCESS_WIFI_STATE
权限(第 7 行):<?xml version="1.0" encoding="utf-8"?> <manifest xmlns:android="http://schemas.android.com/apk/res/android" package="com.mk"> <!-- https://developer.android.google.cn/reference/android/Manifest.permission?hl=zh-cn#ACCESS_WIFI_STATE--> <!-- Allows applications to access information about Wi-Fi networks.--> <uses-permission android:name="android.permission.ACCESS_WIFI_STATE" /> ... 其他,略 </manifest>
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编辑
src\main\res\layout\activity_main.xml
文件,删除原有的TextView
元素,新增Button
元素:<?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:layout_width="match_parent" android:layout_height="match_parent" tools:context=".MainActivity"> <Button android:id="@+id/button" android:layout_width="0dp" android:layout_height="wrap_content" android:layout_marginStart="16dp" android:layout_marginLeft="16dp" android:layout_marginTop="16dp" android:layout_marginEnd="16dp" android:layout_marginRight="16dp" android:text="Button" app:layout_constraintEnd_toEndOf="parent" app:layout_constraintStart_toStartOf="parent" app:layout_constraintTop_toTopOf="parent" /> </androidx.constraintlayout.widget.ConstraintLayout>
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编辑
MainActivity
文件:第 40 行:检测 WLAN 是否启用
第 52 ~ 58 行:询问用户是否前往开启 WLAN
package com.mk; import androidx.appcompat.app.AppCompatActivity; import android.app.Activity; import android.app.AlertDialog; import android.content.Context; import android.content.DialogInterface; import android.content.Intent; import android.net.wifi.WifiManager; import android.os.Bundle; import android.provider.Settings; import android.view.View; import android.widget.Button; import android.widget.LinearLayout; import android.widget.Toast; public class MainActivity extends AppCompatActivity { private Context context = this; private Button button = null; @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_main); initView(); } private void initView() { button = (Button) findViewById(R.id.button); button.setOnClickListener(new View.OnClickListener() { @Override public void onClick(View v) { // 检测 WLAN 是否启用,如果没有,提示用户前往启用 WifiManager wifiManager = (WifiManager) getApplicationContext().getSystemService(Context.WIFI_SERVICE); if (wifiManager == null || !wifiManager.isWifiEnabled()) { // 检测 WLAN 是否启用 AlertDialog.Builder builder = new AlertDialog.Builder(context); AlertDialog alertDialog = builder .setTitle("提示") .setMessage("前往打开 WLAN?") .setNegativeButton("取消", new DialogInterface.OnClickListener() { @Override public void onClick(DialogInterface dialog, int which) { } }) .setPositiveButton("确定", new DialogInterface.OnClickListener() { @Override public void onClick(DialogInterface dialog, int which) { Intent intent = new Intent(Settings.ACTION_WIFI_SETTINGS); // https://developer.android.google.cn/guide/components/intents-filters?hl=zh-cn#ExampleSend // https://developer.android.google.cn/reference/android/content/Intent?hl=zh-cn#resolveActivity(android.content.pm.PackageManager) // 判断是否有合适的应用能够处理该 Intent,并且可以安全调用 startActivity()。 if (intent.resolveActivity(getPackageManager()) != null) { startActivity(intent); } } }) .create(); alertDialog.show(); // 修改确定按钮的左边距 Button buttonPositive = alertDialog.getButton(AlertDialog.BUTTON_POSITIVE); LinearLayout.LayoutParams layoutParams = (LinearLayout.LayoutParams) buttonPositive.getLayoutParams(); layoutParams.setMargins(layoutParams.leftMargin + 20, layoutParams.topMargin, layoutParams.rightMargin, layoutParams.bottomMargin); buttonPositive.setLayoutParams(layoutParams); } else { Toast.makeText(context, "WLAN 已经启用", Toast.LENGTH_SHORT).show(); } } }); } }
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运行效果: