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 Device：
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
-
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) -
编辑
src\main\res\layout\activity_main.xml文件，删除原有的TextView元素，分别新增 3 个SeekBar和 3 个TextView元素：提示：此处引入
TextView元素的目的是为了显示SeekBar元素的progress值。<?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"> <SeekBar android:id="@+id/seekBarR" android:layout_width="0dp" android:layout_height="wrap_content" android:layout_marginStart="16dp" android:layout_marginLeft="16dp" android:layout_marginTop="24dp" android:layout_marginEnd="16dp" android:layout_marginRight="16dp" android:max="100" app:layout_constraintEnd_toEndOf="parent" app:layout_constraintStart_toStartOf="parent" app:layout_constraintTop_toTopOf="parent" /> <SeekBar android:id="@+id/seekBarG" android:layout_width="0dp" android:layout_height="wrap_content" android:layout_marginStart="16dp" android:layout_marginLeft="16dp" android:layout_marginTop="24dp" android:layout_marginEnd="16dp" android:layout_marginRight="16dp" android:max="100" app:layout_constraintEnd_toEndOf="parent" app:layout_constraintStart_toStartOf="parent" app:layout_constraintTop_toBottomOf="@+id/seekBarR" /> <SeekBar android:id="@+id/seekBarB" android:layout_width="0dp" android:layout_height="wrap_content" android:layout_marginStart="16dp" android:layout_marginLeft="16dp" android:layout_marginTop="24dp" android:layout_marginEnd="16dp" android:layout_marginRight="16dp" android:max="100" app:layout_constraintEnd_toEndOf="parent" app:layout_constraintStart_toStartOf="parent" app:layout_constraintTop_toBottomOf="@+id/seekBarG" /> <TextView android:id="@+id/textViewR" android:layout_width="0dp" android:layout_height="wrap_content" android:layout_marginStart="16dp" android:layout_marginLeft="16dp" android:layout_marginTop="24dp" app:layout_constraintEnd_toStartOf="@+id/textViewG" app:layout_constraintHorizontal_bias="0.5" app:layout_constraintHorizontal_weight="1" app:layout_constraintStart_toStartOf="parent" app:layout_constraintTop_toBottomOf="@+id/seekBarB" /> <TextView android:id="@+id/textViewG" android:layout_width="0dp" android:layout_height="wrap_content" android:layout_marginStart="16dp" android:layout_marginLeft="16dp" app:layout_constraintBaseline_toBaselineOf="@+id/textViewR" app:layout_constraintEnd_toStartOf="@+id/textViewB" app:layout_constraintHorizontal_bias="0.5" app:layout_constraintHorizontal_weight="1" app:layout_constraintStart_toEndOf="@+id/textViewR" /> <TextView android:id="@+id/textViewB" android:layout_width="0dp" android:layout_height="wrap_content" android:layout_marginStart="16dp" android:layout_marginLeft="16dp" android:layout_marginEnd="16dp" android:layout_marginRight="16dp" app:layout_constraintBaseline_toBaselineOf="@+id/textViewG" app:layout_constraintEnd_toEndOf="parent" app:layout_constraintHorizontal_bias="0.5" app:layout_constraintHorizontal_weight="1" app:layout_constraintStart_toEndOf="@+id/textViewG" /> </androidx.constraintlayout.widget.ConstraintLayout> -
修改
MainActivity：package com.mk; import androidx.annotation.RequiresApi; import androidx.appcompat.app.AppCompatActivity; import android.os.Build; import android.os.Bundle; import android.util.Log; import android.view.View; import android.widget.SeekBar; import android.widget.TextView; import android.widget.Toast; public class MainActivity extends AppCompatActivity { private SeekBar seekBarR; private SeekBar seekBarG; private SeekBar seekBarB; private TextView textViewR; private TextView textViewG; private TextView textViewB; @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_main); initView(); } private void initView() { seekBarR = (SeekBar) findViewById(R.id.seekBarR); seekBarG = (SeekBar) findViewById(R.id.seekBarG); seekBarB = (SeekBar) findViewById(R.id.seekBarB); textViewR = (TextView) findViewById(R.id.textViewR); textViewG = (TextView) findViewById(R.id.textViewG); textViewB = (TextView) findViewById(R.id.textViewB); // 设置初始值 seekBarR.setProgress(10); seekBarG.setProgress(20); seekBarB.setProgress(30); textViewR.setText("R: " + seekBarR.getProgress()); textViewG.setText("G: " + seekBarG.getProgress()); textViewB.setText("B: " + seekBarB.getProgress()); seekBarR.setOnSeekBarChangeListener(new SeekBar.OnSeekBarChangeListener() { @Override public void onProgressChanged(SeekBar seekBar, int progress, boolean fromUser) { textViewR.setText("R: " + progress); } @Override public void onStartTrackingTouch(SeekBar seekBar) { } @Override public void onStopTrackingTouch(SeekBar seekBar) { } }); seekBarG.setOnSeekBarChangeListener(new SeekBar.OnSeekBarChangeListener() { @Override public void onProgressChanged(SeekBar seekBar, int progress, boolean fromUser) { textViewG.setText("G: " + progress); } @Override public void onStartTrackingTouch(SeekBar seekBar) { } @Override public void onStopTrackingTouch(SeekBar seekBar) { } }); seekBarB.setOnSeekBarChangeListener(new SeekBar.OnSeekBarChangeListener() { @Override public void onProgressChanged(SeekBar seekBar, int progress, boolean fromUser) { textViewB.setText("B: " + progress); } @Override public void onStartTrackingTouch(SeekBar seekBar) { } @Override public void onStopTrackingTouch(SeekBar seekBar) { } }); } } -
运行效果：
自定义样式
-
新建
src\main\res\drawable-v24\seek_bar_style_r.xml文件：<?xml version="1.0" encoding="utf-8"?> <layer-list xmlns:android="http://schemas.android.com/apk/res/android"> <item android:id="@android:id/background" android:gravity="center_vertical|fill_horizontal"> <shape android:shape="rectangle"> <corners android:radius="5dp"/> <size android:height="2dp"/> <solid android:color="#CCCCCC"/> </shape> </item> <item android:id="@android:id/progress" android:gravity="center_vertical|fill_horizontal"> <clip> <shape android:shape="rectangle"> <corners android:radius="5dp"/> <size android:height="2dp"/> <solid android:color="#FFFF0000"/> </shape> </clip> </item> </layer-list> -
在
seek_bar_style_r.xml文件所在目录下，新建两个类似的文件seek_bar_style_g.xml、seek_bar_style_b.xml文件，它们与seek_bar_style_r.xml文件的区别仅在于progress颜色不同，分别为#FF00FF00和#FF0000FF。 -
修改
src\main\res\layout\activity_main.xml文件，分别为 3 个SeekBar元素设置progressDrawable属性：<?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"> <SeekBar android:id="@+id/seekBarR" ... 其他，略 android:progressDrawable="@drawable/seek_bar_style_r" /> <SeekBar android:id="@+id/seekBarG" ... 其他，略 android:progressDrawable="@drawable/seek_bar_style_g" /> <SeekBar android:id="@+id/seekBarB" ... 其他，略 android:progressDrawable="@drawable/seek_bar_style_b" /> ... 其他，略 </androidx.constraintlayout.widget.ConstraintLayout> -
运行效果：
