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法律研究如何在 Android 中使用 Kotlin 创建分页文本？
此示例演示了如何在 Android 中使用 Kotlin 创建分页文本。
步骤 1 − 在 Android Studio 中创建一个新项目，转到文件 ⇒ 新建项目，并填写所有必要信息以创建新项目。
步骤 2 − 将以下代码添加到 res/layout/activity_main.xml。
<?xml version="1.0" encoding="utf-8"?> <RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android" android:layout_width="match_parent" android:layout_height="match_parent" android:paddingLeft="16dp" android:paddingTop="16dp" android:paddingRight="16dp" android:paddingBottom="16dp"> <LinearLayout android:layout_width="match_parent" android:layout_height="match_parent"> <Button android:id="@+id/buttonBack" style="?android:attr/buttonBarButtonStyle" android:layout_width="0dp" android:layout_height="match_parent" android:layout_weight="1" android:background="@android:color/transparent" /> <Button android:id="@+id/buttonForward" style="?android:attr/buttonBarButtonStyle" android:layout_width="0dp" android:layout_height="match_parent" android:layout_weight="1" android:background="@android:color/transparent" /> </LinearLayout> <TextView android:id="@+id/tv" android:layout_width="match_parent" android:layout_height="match_parent" /> </RelativeLayout>
步骤 3 − 将以下代码添加到 src/MainActivity.kt
import android.graphics.Color
import android.graphics.Typeface
import android.os.Bundle
import android.text.Html
import android.text.Spannable
import android.text.SpannableString
import android.text.TextUtils
import android.text.style.ForegroundColorSpan
import android.text.style.RelativeSizeSpan
import android.text.style.StyleSpan
import android.view.ViewTreeObserver
import android.widget.Button
import android.widget.TextView
import androidx.appcompat.app.AppCompatActivity
class MainActivity : AppCompatActivity() {
lateinit var buttonBack: Button
lateinit var buttonForward: Button
private lateinit var textView: TextView
private var pagination: Pagination? = null
private lateinit var charSequence: CharSequence
private var currentIndex = 0
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
setContentView(R.layout.activity_main)
title = "KotlinApp"
buttonBack = findViewById(R.id.buttonBack)
buttonForward = findViewById(R.id.buttonForward)
textView = findViewById(R.id.tv)
val htmlString = Html.fromHtml(getString(R.string.html_string))
val spanString = SpannableString(getString(R.string.long_string))
spanString.setSpan(ForegroundColorSpan(Color.BLUE), 0, 24, Spannable.SPAN_EXCLUSIVE_EXCLUSIVE)
spanString.setSpan(RelativeSizeSpan(2f), 0, 24, Spannable.SPAN_EXCLUSIVE_EXCLUSIVE)
spanString.setSpan(StyleSpan(Typeface.MONOSPACE.style), 0, 24, Spannable.SPAN_EXCLUSIVE_EXCLUSIVE)
spanString.setSpan(ForegroundColorSpan(Color.BLUE), 536, spanString.length,
Spannable.SPAN_EXCLUSIVE_EXCLUSIVE)
spanString.setSpan(RelativeSizeSpan(2f), 536, spanString.length, Spannable.SPAN_EXCLUSIVE_EXCLUSIVE)
spanString.setSpan(StyleSpan(Typeface.MONOSPACE.style), 536, spanString.length,
Spannable.SPAN_EXCLUSIVE_EXCLUSIVE)
charSequence = TextUtils.concat(htmlString, spanString)
textView.viewTreeObserver.addOnGlobalLayoutListener(object : ViewTreeObserver.OnGlobalLayoutListener {
override fun onGlobalLayout() {
// Removing layout listener to avoid multiple calls
textView.viewTreeObserver.removeOnGlobalLayoutListener(this)
pagination = Pagination(
charSequence, textView.width,
textView.height,
textView.paint,
textView.lineSpacingMultiplier,
textView.lineSpacingExtra,
textView.includeFontPadding
)
update()
}
})
buttonBack.setOnClickListener {
currentIndex = if ((currentIndex > 0)) currentIndex - 1 else 0
update()
}
buttonForward.setOnClickListener {
currentIndex = if ((currentIndex <pagination!!.size() - 1)) currentIndex + 1 else pagination!!.size() - 1
update()
}
}
private fun update() {
val text = pagination!![currentIndex]
if (text != null) textView.text = text
}
}步骤 4 − 创建一个 Kotlin 类并添加以下代码 -
import android.graphics.Color
import android.graphics.Typeface
import android.os.Bundle
import android.text.Html
import android.text.Spannable
import android.text.SpannableString
import android.text.TextUtils
import android.text.style.ForegroundColorSpan
import android.text.style.RelativeSizeSpan
import android.text.style.StyleSpan
import android.view.ViewTreeObserver
import android.widget.Button
import android.widget.TextView
import androidx.appcompat.app.AppCompatActivity
class MainActivity : AppCompatActivity() {
lateinit var buttonBack: Button
lateinit var buttonForward: Button
private lateinit var textView: TextView
private var pagination: Pagination? = null
private lateinit var charSequence: CharSequence
private var currentIndex = 0
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
setContentView(R.layout.activity_main)
title = "KotlinApp"
buttonBack = findViewById(R.id.buttonBack)
buttonForward = findViewById(R.id.buttonForward)
textView = findViewById(R.id.tv)
val htmlString = Html.fromHtml(getString(R.string.html_string))
val spanString = SpannableString(getString(R.string.long_string))
spanString.setSpan(ForegroundColorSpan(Color.BLUE), 0, 24, Spannable.SPAN_EXCLUSIVE_EXCLUSIVE)
spanString.setSpan(RelativeSizeSpan(2f), 0, 24, Spannable.SPAN_EXCLUSIVE_EXCLUSIVE)
spanString.setSpan(StyleSpan(Typeface.MONOSPACE.style), 0, 24,
Spannable.SPAN_EXCLUSIVE_EXCLUSIVE)
spanString.setSpan(ForegroundColorSpan(Color.BLUE), 536, spanString.length,
Spannable.SPAN_EXCLUSIVE_EXCLUSIVE)
spanString.setSpan(RelativeSizeSpan(2f), 536, spanString.length, Spannable.SPAN_EXCLUSIVE_EXCLUSIVE)
spanString.setSpan(StyleSpan(Typeface.MONOSPACE.style), 536, spanString.length,
Spannable.SPAN_EXCLUSIVE_EXCLUSIVE)
charSequence = TextUtils.concat(htmlString, spanString)
textView.viewTreeObserver.addOnGlobalLayoutListener(object : ViewTreeObserver.OnGlobalLayoutListener {
override fun onGlobalLayout() {
// Removing layout listener to avoid multiple calls
textView.viewTreeObserver.removeOnGlobalLayoutListener(this)
pagination = Pagination(
charSequence, textView.width,
textView.height,
textView.paint,
textView.lineSpacingMultiplier,
textView.lineSpacingExtra,
textView.includeFontPadding
)
update()
}
})
buttonBack.setOnClickListener {
currentIndex = if ((currentIndex > 0)) currentIndex - 1 else 0
update()
}
buttonForward.setOnClickListener {
currentIndex = if ((currentIndex < pagination!!.size() - 1)) currentIndex + 1 else pagination!!.size() - 1
update()
}
}
private fun update() {
val text = pagination!![currentIndex]
if (text != null) textView.text = text
}
}步骤 5 − 将以下代码添加到 androidManifest.xml
<?xml version="1.0" encoding="utf-8"?> <manifest xmlns:android="http://schemas.android.com/apk/res/android" package="com.example.q11"> <application android:allowBackup="true" android:icon="@mipmap/ic_launcher" android:label="@string/app_name" android:roundIcon="@mipmap/ic_launcher_round" android:supportsRtl="true" android:theme="@style/AppTheme"> <activity android:name=".MainActivity"> <intent-filter> <action android:name="android.intent.action.MAIN" /> <category android:name="android.intent.category.LAUNCHER" /> </intent-filter> </activity> </application> </manifest>
让我们尝试运行您的应用程序。我假设您已将您的实际 Android 移动设备连接到您的计算机。要从 Android Studio 运行应用程序，请打开您项目中的一个活动文件，然后单击工具栏中的运行 
图标。选择您的移动设备作为选项，然后检查您的移动设备，它将显示您的默认屏幕。
更新于: 2020年8月18日
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