请提供一个具有添加日程、查看日历的安卓日历代码

好的，以下是一个简单的Android日历应用的代码示例，包含添加日程和查看日历的功能。具体实现是通过使用系统自带的CalendarProvider来实现的。

首先是布局文件calendar_activity.xml：

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:orientation="vertical"
    android:layout_width="match_parent"
    android:layout_height="match_parent">

    <Button
        android:id="@+id/add_event_button"
        android:text="Add Event"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"/>

    <Button
        android:id="@+id/view_calendar_button"
        android:text="View Calendar"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"/>

</LinearLayout>

接下来是Java代码CalendarActivity.java：

import android.content.ContentValues;
import android.content.Intent;
import android.database.Cursor;
import android.net.Uri;
import android.os.Bundle;
import android.provider.CalendarContract;
import android.provider.CalendarContract.Events;
import android.support.v7.app.AppCompatActivity;
import android.view.View;
import android.widget.Button;
import android.widget.Toast;
import java.util.Calendar;

public class CalendarActivity extends AppCompatActivity {

    private static final String[] EVENT_PROJECTION = new String[] {
            CalendarContract.Events._ID,
            CalendarContract.Events.TITLE,
            CalendarContract.Events.DESCRIPTION,
            CalendarContract.Events.DTSTART,
            CalendarContract.Events.DTEND,
            CalendarContract.Events.EVENT_LOCATION,
            CalendarContract.Events.EVENT_TIMEZONE
    };

    private static final int PROJECTION_ID_INDEX = 0;
    private static final int PROJECTION_TITLE_INDEX = 1;
    private static final int PROJECTION_DESCRIPTION_INDEX = 2;
    private static final int PROJECTION_DTSTART_INDEX = 3;
    private static final int PROJECTION_DTEND_INDEX = 4;
    private static final int PROJECTION_EVENT_LOCATION_INDEX = 5;
    private static final int PROJECTION_EVENT_TIMEZONE_INDEX = 6;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.calendar_activity);

        Button addEventButton = findViewById(R.id.add_event_button);
        Button viewCalendarButton = findViewById(R.id.view_calendar_button);

        addEventButton.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                addCalendarEvent();
            }
        });

        viewCalendarButton.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                viewCalendar();
            }
        });
    }

    private void addCalendarEvent() {
        // Create a new calendar instance and set the time
        Calendar beginTime = Calendar.getInstance();
        beginTime.set(2019, 0, 1, 9, 0);
        Calendar endTime = Calendar.getInstance();
        endTime.set(2019, 0, 1, 10, 0);

        // Create a new event
        ContentValues values = new ContentValues();
        values.put(Events.TITLE, "New Year's Day");
        values.put(Events.DESCRIPTION, "Celebrate the start of the New Year.");
        values.put(Events.DTSTART, beginTime.getTimeInMillis());
        values.put(Events.DTEND, endTime.getTimeInMillis());
        values.put(Events.EVENT_LOCATION, "New York City");
        values.put(Events.CALENDAR_ID, 1);
        values.put(Events.EVENT_TIMEZONE, Calendar.getInstance().getTimeZone().getID());

        // Insert the event into the calendar
        Uri uri = getContentResolver().insert(Events.CONTENT_URI, values);

        // Display a toast message indicating that the event was added
        Toast.makeText(this, "Event added to calendar", Toast.LENGTH_SHORT).show();
    }

    private void viewCalendar() {
        // Specify the date range for the events to retrieve
        Calendar beginTime = Calendar.getInstance();
        beginTime.set(2019, 0, 1, 0, 0);
        Calendar endTime = Calendar.getInstance();
        endTime.set(2019, 0, 31, 23, 59);

        // Define the URI for the events
        Uri uri = CalendarContract.Events.CONTENT_URI;
        String selection = "((" + CalendarContract.Events.DTSTART + " >= ?) AND (" + CalendarContract.Events.DTEND + " <= ?))";
        String[] selectionArgs = new String[] {Long.toString(beginTime.getTimeInMillis()), Long.toString(endTime.getTimeInMillis())};

        // Retrieve the events from the calendar provider
        Cursor cursor = getContentResolver().query(uri, EVENT_PROJECTION, selection, selectionArgs, null);

        // Display the events in a toast message
        StringBuilder builder = new StringBuilder();
        while (cursor.moveToNext()) {
            String title = cursor.getString(PROJECTION_TITLE_INDEX);
            String description = cursor.getString(PROJECTION_DESCRIPTION_INDEX);
            String location = cursor.getString(PROJECTION_EVENT_LOCATION_INDEX);
            long start = cursor.getLong(PROJECTION_DTSTART_INDEX);
            long end = cursor.getLong(PROJECTION_DTEND_INDEX);
            builder.append(title).append("\n").append(description).append("\n").append(location).append("\n").append(start).append("\n").append(end).append("\n\n");
        }
        Toast.makeText(this, builder.toString(), Toast.LENGTH_LONG).show();

        // Close the cursor
        cursor.close();
    }
}

这个示例中，我们首先在布局文件中定义了两个按钮，一个用于添加日程，一个用于查看日历。在Java代码中，我们使用了系统自带的CalendarProvider来实现这两个功能。具体来说，我们通过使用ContentValues对象来创建一个新的日程事件，并将其插入到日历中。在查看日历时，我们使用ContentResolver对象来查询日历事件，并将结果显示在Toast消息中。

需要注意的是，为了使用CalendarProvider，我们需要在AndroidManifest.xml文件中添加以下权限：

<uses-permission android:name="android.permission.READ_CALENDAR"/>
<uses-permission android:name="android.permission.WRITE_CALENDAR"/>

同时，我们还需要在同一个文件中添加以下provider：

<provider
    android:name="com.android.calendar.CalendarProvider2"
    android:authorities="com.android.calendar"
    android:exported="false"
    android:readPermission="android.permission.READ_CALENDAR"
    android:writePermission="android.permission.WRITE_CALENDAR"
    tools:ignore="ExportedContentProvider"/>

这样就完成了一个简单的Android日历应用的开发。