[移动开发]Android入门系列（四）：消息提示框与对话框

一、消息提示框和对话框

1.使用Toast显示消息提示框

消息提示框之前都有接触，最主要的应用就是

Toast.makeText().show

接下来详细学习

Toast类的对象有以下常用方法

setDuration(int duration)设置消息的持续时间Toast.LENGTH_LONG/SHORT

setGravity(int gravity,int xOffset,int yOffset)设置位置，参数分别是对齐方式和偏移量

setMargin(float horizontalMargin,float verticalMargin)设置消息提示框页边距

setText(CharSequence s)设置显示文本内容

setView(View view)显示的视图位置

java代码如下

package com.thundersoft.session2;

import android.annotation.SuppressLint;
import android.app.Activity;
import android.os.Bundle;
import android.view.Gravity;
import android.widget.ImageView;
import android.widget.LinearLayout;
import android.widget.TextView;
import android.widget.Toast;

import androidx.annotation.Nullable;

public class ToastActivity extends Activity {
    @SuppressLint("ResourceAsColor")
    @Override
    protected void onCreate(@Nullable Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);

        LinearLayout linearLayout = new LinearLayout(ToastActivity.this);
        Toast.makeText(this, "Toast的第一种创建方式", Toast.LENGTH_SHORT).show();
        setContentView(linearLayout);

        LinearLayout linearLayout1 = new LinearLayout(ToastActivity.this);
        ImageView imageView = new ImageView(ToastActivity.this);
        imageView.setImageResource(R.drawable.gif1);
        imageView.setPadding(0,0,5,0);
        imageView.setLayoutParams(new LinearLayout.LayoutParams(300,300));
        TextView textView = new TextView(ToastActivity.this);
        textView.setText("Toaset的第二种创建方式");

        Toast toast = new Toast(this);
        toast.setDuration(Toast.LENGTH_LONG);
        toast.setGravity(Gravity.CENTER,0,0);

        linearLayout1.addView(imageView);
        linearLayout1.addView(textView);
        linearLayout1.setBackgroundColor(R.color.purple_200);
        toast.setView(linearLayout1);
        toast.show();
    }
}

代码中的两个布局，第一个布局是总布局，也就是第一个页面，第二个布局是应用在Toaset中的布局

2.使用Notification在状态栏上显示通知

Android8以后，API26

安卓的通知管理类是Notification和NotiffcationManager类

Notification主要是代表全局效果的类，而Manager主要管理发送Notification，是系统服务

下面是一般通知实现的方法

package com.thundersoft.session2;

import android.app.Activity;
import android.app.Notification;
import android.app.NotificationChannel;
import android.app.NotificationManager;
import android.content.Context;
import android.graphics.BitmapFactory;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.LinearLayout;

import androidx.annotation.Nullable;

public class NotificationActivity extends Activity {
    @Override
    protected void onCreate(@Nullable Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);

        LinearLayout linearLayout = new LinearLayout(this);
        setContentView(linearLayout);

        Button button = new Button(this);
        linearLayout.addView(button);

        final NotificationManager manager = (NotificationManager) getSystemService(Context.NOTIFICATION_SERVICE);
//        自定义通道id
        String id = "channel_1";
//        自定义通道描述属性
        String description = "channel_description";
        int NOTIFY_ID_1=0x1;
        int NOTIFY_ID_2=0x2;
//        通道声音提示
        int importance = NotificationManager.IMPORTANCE_HIGH;

        button.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
//                建立通知通道类
                NotificationChannel channel = new NotificationChannel(id, "123", importance);
//                设置描述属性
                channel.setDescription(description);
//                开启闪光灯
                channel.enableLights(true);
//                开启震动
                channel.enableVibration(true);
                channel.setVibrationPattern(new long[]{100,200,300,400,500,400,300,200,400});
//                管理器创建通道
                manager.createNotificationChannel(channel);
//                创建notification对象
                Notification builder = new Notification.Builder(NotificationActivity.this, id)
//                        标题
                        .setContentTitle("通知标题")
//                        小图标
                        .setSmallIcon(R.drawable.gif1)
//                        大图标
                        .setLargeIcon(BitmapFactory.decodeResource(getResources(),R.drawable.gif1))
//                        内容
                        .setContentText("通知栏内容")
//                        设置自动删除通知
                        .setAutoCancel(true)
//                        构建
                        .build();
//                保留多行通知,需要唯一编号
                manager.notify(NOTIFY_ID_1,builder);
            }
        });
    }
}

通知首先需要定义几个值，一是通知通道的id，二是它的描述属性，三是它的编号

定义好值后，先获取系统服务，new一个通知管理对象

接着new通知通道对象，设置它的各种属性，将通道给通知管理对象管理

通道设置好了就开始new通知对象了，调用类的Builder方法构建，设置属性

最后把通知也交给管理对象管理即可

一般的通知点击会自动跳转到一个页面，这里写了个intent来实现点击通知跳转的功能

Intent intent = new Intent(Notification2Activity.this, NotificationActivity.class);
PendingIntent pendingIntent = PendingIntent.getActivity(Notification2Activity.this, 0, intent, 0);
Notification builder2 = new Notification.Builder(Notification2Activity.this, id)
        .setContentTitle("通知标题")
        .setSmallIcon(R.drawable.gif1)
        .setLargeIcon(BitmapFactory.decodeResource(getResources(),R.drawable.gif1))
        .setContentText("通知栏内容")
        .setAutoCancel(true)
        .setContentIntent(pendingIntent)
        .build()
        ;
manager.notify(NOTIFY_ID_2,builder2);

需要new一个intent接着用它pendingintent来传递意图，后面会详细讲解intent

通知的取消可以有以下代码控制

manager.cancel(NOTIFY_ID_1);
manager.cancelAll();

3.使用AlertDialog创建对话框

下面介绍了常用的四种对话框

对话框的运用步骤为：通过new AlertDialog.Builder，再设置它的属性和按钮等内容，最后别忘了create和show

新建四个按钮对应四种对话框，写第一个最基础的对话框，代码如下

package com.thundersoft.session2;

import android.app.Activity;
import android.app.AlertDialog;
import android.content.DialogInterface;
import android.os.Bundle;
import android.util.Log;
import android.view.View;
import android.widget.Button;
import android.widget.LinearLayout;

import androidx.annotation.Nullable;

public class AlertDialogActivity extends Activity {
    @Override
    protected void onCreate(@Nullable Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        LinearLayout linearLayout = new LinearLayout(this);
        setContentView(linearLayout);
        Button button1 = new Button(this);
        Button button2 = new Button(this);
        Button button3 = new Button(this);
        Button button4 = new Button(this);
        button1.setText("按钮对话框");
        button2.setText("列表对话框");
        button3.setText("列表+按钮对话框");
        button4.setText("多选+按钮对话框");
        linearLayout.addView(button1);
        linearLayout.addView(button2);
        linearLayout.addView(button3);
        linearLayout.addView(button4);

        button1.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                AlertDialog alertDialog = new AlertDialog.Builder(AlertDialogActivity.this).create();
                alertDialog.setIcon(R.drawable.gif1);
                alertDialog.setTitle("提示一：");
                alertDialog.setMessage("取消、中立和确定");
//        消极的
                alertDialog.setButton(DialogInterface.BUTTON_NEGATIVE, "取消", new DialogInterface.OnClickListener() {
                    @Override
                    public void onClick(DialogInterface dialog, int which) {
                        Log.i("对话框","点击了取消");
                    }
                });
//        积极的
                alertDialog.setButton(DialogInterface.BUTTON_POSITIVE, "确定", new DialogInterface.OnClickListener() {
                    @Override
                    public void onClick(DialogInterface dialog, int which) {
                        Log.i("对话框","点击了确定");
                    }
                });
//        中立
                alertDialog.setButton(DialogInterface.BUTTON_NEUTRAL, "中立", new DialogInterface.OnClickListener() {
                    @Override
                    public void onClick(DialogInterface dialog, int which) {
                        Log.i("对话框","点击了中立");
                    }
                });
                alertDialog.show();
            }
        });

二三四种如下

button2.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                String[] strings = {"第一条", "第二条", "第三条", "第四条"};
                AlertDialog.Builder alertDialog = new AlertDialog.Builder(AlertDialogActivity.this);
                alertDialog.setTitle("提示二：");
                alertDialog.setItems(strings, new DialogInterface.OnClickListener() {
                    @Override
                    public void onClick(DialogInterface dialog, int which) {
                        Log.i("对话框", "onClick: "+strings[which]);
                    }
                });
                alertDialog.create().show();
            }
        });
        button3.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                String[] strings = {"第一条", "第二条", "第三条", "第四条"};
                AlertDialog.Builder alertDialog = new AlertDialog.Builder(AlertDialogActivity.this);
                alertDialog.setTitle("提示三：");
                alertDialog.setSingleChoiceItems(strings, 0,new DialogInterface.OnClickListener() {
                    @Override
                    public void onClick(DialogInterface dialog, int which) {
                        Log.i("对话框", "onClick: "+strings[which]);
                    }
                });
                alertDialog.setPositiveButton("确定",null);
                alertDialog.create().show();
            }
        });
        button4.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                boolean[] items = {false,false,true,true};
                String[] strings = {"第一条", "第二条", "第三条", "第四条"};
                AlertDialog.Builder alertDialog = new AlertDialog.Builder(AlertDialogActivity.this);
                alertDialog.setTitle("提示三：");
                alertDialog.setMultiChoiceItems(strings, items, new DialogInterface.OnMultiChoiceClickListener() {
                    @Override
                    public void onClick(DialogInterface dialog, int which, boolean isChecked) {
                        items[which] = isChecked;
                    }
                });
                alertDialog.setPositiveButton("确定", new DialogInterface.OnClickListener() {
                    @Override
                    public void onClick(DialogInterface dialog, int which) {
                        String result = "";
                        for (int i = 0; i < items.length; i++) {
                            if (items[i]){
                                result+=strings[i]+"、";
                            }
                        }
                        if (!"".equals(result)){
                            result = result.substring(0,result.length()-1);
                            Log.i("对话框", result);
                        }
                    }
                });
                alertDialog.create().show();
            }
        });
    }
}

第四种中，增加了按钮直接再按钮里new DialogInterface.OnClickListener()来新建点击事件

下面的代码演示了退出确认的对话框提示

package com.thundersoft.session2;

import android.app.Activity;
import android.app.AlertDialog;
import android.content.DialogInterface;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.LinearLayout;

import androidx.annotation.Nullable;

public class Test1Activity extends Activity {
    @Override
    protected void onCreate(@Nullable Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        LinearLayout linearLayout = new LinearLayout(this);
        setContentView(linearLayout);

        Button button = new Button(this);
        button.setText("点击退出");
        linearLayout.addView(button);

        button.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                AlertDialog.Builder builder = new AlertDialog.Builder(Test1Activity.this);
                builder.setIcon(R.drawable.gif1);
                builder.setTitle("是否退出？");
                builder.setMessage("是否真的要退出码？");
                builder.setNegativeButton("取消", new DialogInterface.OnClickListener() {
                    @Override
                    public void onClick(DialogInterface dialog, int which) {

                    }
                });
                builder.setPositiveButton("确定", new DialogInterface.OnClickListener() {
                    @Override
                    public void onClick(DialogInterface dialog, int which) {
                        finish();
                    }
                });
                builder.create().show();
            }
        });

    }
}

二、实践

1.要求

实现一个登录页面，提供记住密码和用户名功能，登陆后显示列表视图必须包含登录用户名，且点击列表会显示点击那一项

（以上是Android 几 当中的实践要求）

在上一次的实践项目之上，登录后主界面列表选择第一个选项后，显示一组图片，图片加载完成前需要显示进度条，加载完成后，长按某一个图片弹出提示框是否删除，如果确定就不再显示该图片。

2.代码实现

image.xml显示图片的页面

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:orientation="vertical"
    android:layout_width="match_parent"
    android:layout_height="match_parent">
    <GridView
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:stretchMode="columnWidth"
        android:numColumns="3"
        android:id="@+id/gridview"/>
</LinearLayout>

items.xml每一个gridview里面的内容

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:orientation="vertical"
    android:layout_width="match_parent"
    android:layout_height="match_parent">
    <ImageView
        android:layout_width="150dp"
        android:layout_height="150dp"
        android:id="@+id/imageview"
        android:scaleType="fitXY"
        android:paddingLeft="10px"
        />
    <TextView
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:padding="5px"
        android:layout_gravity="center"
        android:id="@+id/titleview"/>
</LinearLayout>

title.xml自定义标题栏

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:orientation="vertical"
android:layout_width="match_parent"
android:layout_height="match_parent">
    <TextView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="图像预览"
        android:textStyle="bold"
        android:textColor="#FFFF0000"
        />
    <ProgressBar
        android:id="@+id/bartest"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        style="?android:attr/progressBarStyleHorizontal"
        android:max="80"/>
</LinearLayout>

在上一次的实践中，需要更改MainActivity.java以下代码

@Override
protected void onListItemClick(ListView l, View v, int position, long id) {
    super.onListItemClick(l, v, position, id);
    int index = position+1;
    if (index == 1){
        Intent intent = new Intent(MainActivity.this, ImageActivity.class);
        startActivity(intent);
    }
    Toast.makeText(this,"您选择了第"+ index +"项",Toast.LENGTH_SHORT).show();
}

最主要的部分ImageActivity

package com.thundersoft.login;

import android.app.Activity;
import android.app.AlertDialog;
import android.content.DialogInterface;
import android.os.AsyncTask;
import android.os.Bundle;
import android.view.View;
import android.view.Window;
import android.widget.AdapterView;
import android.widget.GridView;
import android.widget.ProgressBar;
import android.widget.SimpleAdapter;

import androidx.annotation.Nullable;

import java.util.ArrayList;
import java.util.HashMap;
import java.util.Map;

public class ImageActivity extends Activity {

    int[] image = new int[]{R.drawable.jpg1,R.drawable.jpg2,R.drawable.jpg3,R.drawable.jpg4,R.drawable.jpg5};
    String[] title = {"头像1", "头像2", "头像3", "头像4", "头像5"};
    ArrayList<Map<String, Object>> list = new ArrayList<>();
    private ProgressBar progressBar;
    private GridView gridView;
    private SimpleAdapter simpleAdapter;

    @Override
    protected void onCreate(@Nullable Bundle savedInstanceState) {

        super.onCreate(savedInstanceState);
        requestWindowFeature(Window.FEATURE_CUSTOM_TITLE);

        setContentView(R.layout.image);

        getWindow().setFeatureInt(Window.FEATURE_CUSTOM_TITLE,R.layout.title);
        progressBar = findViewById(R.id.bartest);
        gridView = findViewById(R.id.gridview);

        new MyTack().execute();

        gridView.setOnItemLongClickListener(new AdapterView.OnItemLongClickListener() {
            @Override
            public boolean onItemLongClick(AdapterView<?> parent, View view, int position, long id) {
//                Toast.makeText(ImageActivity.this, "第"+position, Toast.LENGTH_SHORT).show();

                AlertDialog.Builder builder = new AlertDialog.Builder(ImageActivity.this);
                builder.setTitle("是否删除？");
                builder.setMessage("是否真的要删除吗？");
                builder.setNegativeButton("取消", new DialogInterface.OnClickListener() {
                    @Override
                    public void onClick(DialogInterface dialog, int which) {

                    }
                });
                builder.setPositiveButton("确定", new DialogInterface.OnClickListener() {
                    @Override
                    public void onClick(DialogInterface dialog, int which) {
                        list.remove(position);
                        simpleAdapter.notifyDataSetChanged();
                    }
                });
                builder.create().show();

                return true;
            }
        });
    }
    class MyTack extends AsyncTask<Void,Integer,SimpleAdapter>{
        @Override
        protected SimpleAdapter doInBackground(Void... params) {
            for (int i = 0; i < image.length; i++) {
                HashMap<String, Object> map = new HashMap<>();
                map.put("imageview",image[i]);
                map.put("titleview",title[i]);

                try {
                    list.add(map);
                    Thread.sleep(600);
                } catch (InterruptedException e) {
                    e.printStackTrace();
                }

                publishProgress(i);
            }
            simpleAdapter = new SimpleAdapter(ImageActivity.this,
                    list,
                    R.layout.items,
                    new String[]{"titleview", "imageview"},
                    new int[]{R.id.titleview, R.id.imageview});
            return simpleAdapter;
        }
        //        publishProgress
        @Override
        protected void onProgressUpdate(Integer... values) {
            progressBar.setProgress(values[0]*20);
            super.onProgressUpdate(values);
        }
        @Override
        protected void onPostExecute(SimpleAdapter result) {
            progressBar.setVisibility(View.GONE);
//            setProgressBarVisibility(false);

            gridView.setAdapter(result);
//            linearLayout.addView(result);
            super.onPostExecute(result);
        }
    }
}

详细说下代码的运行过程

通过上一个页面的intent传递，到这个页面，开始oncreate方法

加载自定义标题栏，设置页面，找到控件等基本操作

接下来进行线程操作，写Tack继承AsyncTask，注意result参数应该是SimpleAdapter，实现三个方法

? doInBackground方法返回为SimpleAdapter，在这个里面，new一个SimpleAdapter对象，将图片和文字装载进这个适配器中，返回这个适配器

? onProgressUpdate方法显示更新操作，展示给用户查看进度

? onPostExecute方法参数，result应该是SimpleAdapter对象，通过gridView.setAdapter(result);来将适配器加载给gridview

线程操作完成后，显示gridview，给每一个元素设置长按点击操作，展示对话框询问删除，删除通过对list的操作在重载适配器完成操作

3.实现效果