Android開發(fā)學(xué)習(xí)教程（11）- Android AlertDialog對(duì)話框用法和屬性
—— 不管前方的路有多苦，只要走的方向正確，不管多么崎嶇不平，都比站在原地接近幸福?！獙m崎駿
上一篇我們講了進(jìn)度條控件ProgressBar的基本用法，這里來學(xué)習(xí)對(duì)話框AlertDialog的基本用法。
AlertDialog是什么
AlertDialog是一個(gè)Android自帶的提示對(duì)話框。
AlertDialog有什么用
AlertDialog一般用來顯示比較簡(jiǎn)單的提示對(duì)話框，比如只有標(biāo)題、內(nèi)容、幾個(gè)按鈕的對(duì)話框。
AlertDialog怎么用
繼續(xù)基于上一篇的項(xiàng)目，我們?cè)黾訋讉€(gè)對(duì)話框AlertDialog：
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<?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=".TestActivity">????<ScrollView????????android:layout_width="match_parent"????????android:layout_height="wrap_content"????????app:layout_constraintBottom_toBottomOf="parent"????????app:layout_constraintTop_toTopOf="parent"????????app:layout_constraintVertical_bias="0.0">??????????????...??????????????...??????????????...????????????<LinearLayout????????????????android:id="@+id/layout1"????????????????android:layout_width="match_parent"????????????????android:layout_height="wrap_content"????????????????app:layout_constraintStart_toStartOf="@+id/progress_horizontal3"????????????????app:layout_constraintTop_toBottomOf="@+id/progress_horizontal3">????????????????<Button????????????????????android:id="@+id/btn1"????????????????????android:layout_width="wrap_content"????????????????????android:layout_height="wrap_content"????????????????????android:text="對(duì)話框1"?/>????????????????<Button????????????????????android:id="@+id/btn2"????????????????????android:layout_width="wrap_content"????????????????????android:layout_height="wrap_content"????????????????????android:text="對(duì)話框2"?/>????????????????<Button????????????????????android:id="@+id/btn3"????????????????????android:layout_width="wrap_content"????????????????????android:layout_height="wrap_content"????????????????????android:text="對(duì)話框3"?/>????????????????<Button????????????????????android:id="@+id/btn4"????????????????????android:layout_width="wrap_content"????????????????????android:layout_height="wrap_content"????????????????????android:text="對(duì)話框4"?/>????????????</LinearLayout>????????</androidx.constraintlayout.widget.ConstraintLayout>????</ScrollView></androidx.constraintlayout.widget.ConstraintLayout>上面加了四個(gè)按鈕，點(diǎn)擊每個(gè)分別會(huì)彈出對(duì)話框，我們看點(diǎn)擊第一個(gè)按鈕彈出來的對(duì)話框，這種對(duì)話框的特點(diǎn)是顯示的信息非常簡(jiǎn)單，標(biāo)題+內(nèi)容+1-3個(gè)按鈕，標(biāo)題設(shè)置了就顯示，沒設(shè)置就不顯示，按鈕也是一樣，如下：
對(duì)應(yīng)的對(duì)話框代碼：
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new?AlertDialog.Builder(TestActivity.this)????.setTitle("系統(tǒng)提示")????.setMessage("確定刪除？")????.setNegativeButton("取消",?new?DialogInterface.OnClickListener() {????????@Override????????public?void?onClick(DialogInterface dialog,?int?which) {????????????Toast.makeText(TestActivity.this,?"點(diǎn)擊了取消", Toast.LENGTH_SHORT).show();????????}????})????.setPositiveButton("確定",?new?DialogInterface.OnClickListener() {????????@Override????????public?void?onClick(DialogInterface dialog,?int?which) {????????????Toast.makeText(TestActivity.this,?"點(diǎn)擊了確定", Toast.LENGTH_SHORT).show();????????}????}).show();第二種對(duì)話框，特點(diǎn)是標(biāo)題+非常簡(jiǎn)單的列表樣式對(duì)話框，標(biāo)題設(shè)置了就顯示，沒設(shè)置就不顯示，只限如下圖這種純簡(jiǎn)單文字的列表：
對(duì)應(yīng)的對(duì)話框代碼：
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new?AlertDialog.Builder(TestActivity.this)????.setTitle("要發(fā)送給")????.setItems(str,?new?DialogInterface.OnClickListener() {????????@Override????????public?void?onClick(DialogInterface dialog,?int?which) {????????????Toast.makeText(TestActivity.this,?"點(diǎn)擊了 "?+ str[which], Toast.LENGTH_SHORT).show();????????}????})????.show();第三種對(duì)話框，標(biāo)題+xml布局文件+1-3個(gè)按鈕，標(biāo)題設(shè)置了就顯示，沒設(shè)置就不顯示，按鈕也是一樣，如圖：
對(duì)應(yīng)的對(duì)話框代碼：
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new?AlertDialog.Builder(TestActivity.this)????.setTitle("Apple ID 登錄")????.setView(R.layout.dialog_my1)????.setNegativeButton("取消",?new?DialogInterface.OnClickListener() {????????@Override????????public?void?onClick(DialogInterface dialog,?int?which) {????????????Toast.makeText(TestActivity.this,?"點(diǎn)擊了取消", Toast.LENGTH_SHORT).show();????????}????})????.setPositiveButton("確定",?new?DialogInterface.OnClickListener() {????????@Override????????public?void?onClick(DialogInterface dialog,?int?which) {????????????Toast.makeText(TestActivity.this,?"點(diǎn)擊了確定", Toast.LENGTH_SHORT).show();????????}????}).show();布局文件：
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<?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">????<EditText????????android:id="@+id/edittext1"????????android:layout_width="match_parent"????????android:layout_height="wrap_content"????????android:background="@drawable/bg_rectangle_c8c8c8_2"????????android:hint="請(qǐng)輸入賬號(hào)"????????android:padding="10dp"????????app:layout_constraintEnd_toEndOf="parent"????????app:layout_constraintStart_toStartOf="parent"????????app:layout_constraintTop_toTopOf="parent"?/>????<EditText????????android:id="@+id/edittext2"????????android:layout_width="match_parent"????????android:layout_height="wrap_content"????????android:background="@drawable/bg_rectangle_c8c8c8_2"????????android:hint="請(qǐng)輸入密碼"????????android:inputType="textPassword"????????android:padding="10dp"????????app:layout_constraintEnd_toEndOf="parent"????????app:layout_constraintStart_toStartOf="parent"????????app:layout_constraintTop_toBottomOf="@+id/edittext1"?/></androidx.constraintlayout.widget.ConstraintLayout>第四種對(duì)話框，也是我們最常用的自定義樣式對(duì)話框，這種對(duì)話框從頭到尾都是通過布局文件、style設(shè)置來自定義樣式的，如圖：
對(duì)應(yīng)的對(duì)話框代碼：
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class?MyDialog?extends?Dialog {????public?MyDialog(Context context) {????????super(context, R.style.MyDialog);????????setContentView(R.layout.dialog_my2);????????getWindow().getAttributes().gravity = Gravity.CENTER;????????WindowManager.LayoutParams lp = getWindow().getAttributes();????????DisplayMetrics metrics = TestActivity.this.getResources().getDisplayMetrics();????????lp.width = (int) (metrics.widthPixels *?0.8f);????????getWindow().setAttributes(lp);????????findViewById(R.id.tv_left).setOnClickListener(new?View.OnClickListener() {????????????@Override????????????public?void?onClick(View v) {????????????????dismiss();????????????}????????});????????findViewById(R.id.tv_right).setOnClickListener(new?View.OnClickListener() {????????????@Override????????????public?void?onClick(View v) {????????????????dismiss();????????????}????????});????}}布局文件：
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<?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="wrap_content"????android:background="@drawable/bg_rectangle_white_12"????tools:context=".MainActivity">????<TextView????????android:id="@+id/tv_title"????????android:layout_width="wrap_content"????????android:layout_height="wrap_content"????????android:layout_marginTop="20dp"????????android:text="微信想訪問您的照片"????????android:textColor="#222222"????????android:textSize="16sp"????????app:layout_constraintEnd_toEndOf="parent"????????app:layout_constraintStart_toStartOf="parent"????????app:layout_constraintTop_toTopOf="parent"?/>????<TextView????????android:id="@+id/tv_1"????????android:layout_width="wrap_content"????????android:layout_height="wrap_content"????????android:layout_marginTop="6dp"????????android:text="請(qǐng)點(diǎn)擊好以允許訪問。"????????android:textColor="#666666"????????app:layout_constraintEnd_toEndOf="parent"????????app:layout_constraintStart_toStartOf="parent"????????app:layout_constraintTop_toBottomOf="@+id/tv_title"?/>????<TextView????????android:id="@+id/tv_2"????????android:layout_width="match_parent"????????android:layout_height="wrap_content"????????android:layout_marginLeft="30dp"????????android:layout_marginTop="14dp"????????android:layout_marginRight="30dp"????????android:text="若不允許，您將無法在微信中給好友發(fā)送照片、保存照片，也無法在朋友圈中發(fā)表照片。"????????android:textColor="#666666"????????app:layout_constraintEnd_toEndOf="parent"????????app:layout_constraintStart_toStartOf="parent"????????app:layout_constraintTop_toBottomOf="@+id/tv_1"?/>????<View????????android:id="@+id/view1"????????android:layout_width="match_parent"????????android:layout_height="1px"????????android:layout_marginTop="30dp"????????android:background="#cccccc"????????app:layout_constraintEnd_toEndOf="parent"????????app:layout_constraintStart_toStartOf="parent"????????app:layout_constraintTop_toBottomOf="@+id/tv_2"?/>????<LinearLayout????????android:layout_width="match_parent"????????android:layout_height="wrap_content"????????app:layout_constraintEnd_toEndOf="parent"????????app:layout_constraintStart_toStartOf="parent"????????app:layout_constraintTop_toBottomOf="@+id/view1">????????<TextView????????????android:id="@+id/tv_left"????????????android:layout_width="0dp"????????????android:layout_height="wrap_content"????????????android:layout_weight="1"????????????android:gravity="center"????????????android:paddingTop="10dp"????????????android:paddingBottom="10dp"????????????android:text="不允許"????????????android:textColor="#226fff"????????????app:layout_constraintEnd_toEndOf="parent"????????????app:layout_constraintStart_toStartOf="parent"?/>????????<View????????????android:layout_width="1px"????????????android:layout_height="match_parent"????????????android:background="#cccccc"?/>????????<TextView????????????android:id="@+id/tv_right"????????????android:layout_width="0dp"????????????android:layout_height="wrap_content"????????????android:layout_weight="1"????????????android:gravity="center"????????????android:paddingTop="10dp"????????????android:paddingBottom="10dp"????????????android:text="好"????????????android:textColor="#226fff"????????????app:layout_constraintEnd_toEndOf="parent"????????????app:layout_constraintStart_toStartOf="parent"?/>????</LinearLayout></androidx.constraintlayout.widget.ConstraintLayout>標(biāo)簽：
