android用sqllite数据库实现古诗的增、改、查，写一个完整的简单示例，点明文件名

好的，这里是一个简单的示例，演示了如何在 Android 应用程序中使用 SQLite 数据库来实现古诗的增、改、查。

首先，创建一个名为 "PoetryDbHelper.java" 的类，该类将承担与 SQLite 数据库的连接和数据读写的任务。

import android.content.Context;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteOpenHelper;

public class PoetryDbHelper extends SQLiteOpenHelper {
    private static final int DATABASE_VERSION = 1;
    private static final String DATABASE_NAME = "PoetryDatabase.db";

    public PoetryDbHelper(Context context) {
        super(context, DATABASE_NAME, null, DATABASE_VERSION);
    }

    @Override
    public void onCreate(SQLiteDatabase db) {
        db.execSQL(PoetryContract.PoetryEntry.CREATE_TABLE);
    }

    @Override
    public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
        db.execSQL(PoetryContract.PoetryEntry.DELETE_TABLE);
        onCreate(db);
    }
}

接下来，创建一个名为 "PoetryContract.java" 的类，该类定义了数据库表的结构和字段。

import android.provider.BaseColumns;

public final class PoetryContract {
    private PoetryContract() {}

    public static class PoetryEntry implements BaseColumns {
        public static final String TABLE_NAME = "poetry";
        public static final String COLUMN_TITLE = "title";
        public static final String COLUMN_AUTHOR = "author";
        public static final String COLUMN_CONTENT = "content";

        public static final String CREATE_TABLE = "CREATE TABLE " +
                TABLE_NAME + " (" +
                _ID + " INTEGER PRIMARY KEY," +
                COLUMN_TITLE + " TEXT," +
                COLUMN_AUTHOR + " TEXT," +
                COLUMN_CONTENT + " TEXT)";

        public static final String DELETE_TABLE = "DROP TABLE IF EXISTS " + TABLE_NAME;
    }
}

然后，在要使用数据库的 Activity 中，创建一个 PoetryDbHelper 对象，并使用它来打开数据库。接下来，您可以使用 SQLiteDatabase 对象执行查询、插入、更新和删除操作。

import android.content.ContentValues;
import android.database.Cursor;
import android.database.sqlite.SQLiteDatabase;
import android.os.Bundle;
import android.widget.TextView;

import androidx.appcompat.app.AppCompatActivity;

public class MainActivity extends AppCompatActivity {
    private PoetryDbHelper dbHelper;

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

        dbHelper = new PoetryDbHelper(this);

        // 添加新的古诗
        addPoetry("静夜思", "李白", "床前明月光，疑是地上霜。举头望明月，低头思故乡。");

        // 更新一首古诗
        updatePoetry(1, "静夜思", "李白", "床前明月光，疑是地上霜。举头望明月，低头思故乡。\n窗前明月光，疑是地上霜。举头望明月，低头思故乡。");

        // 查询所有的古诗
        String allPoetry = getAllPoetry();
        TextView textView = findViewById(R.id.text_view);
        textView.setText(allPoetry);
    }

    private void addPoetry(String title, String author, String content) {
        SQLiteDatabase db = dbHelper.getWritableDatabase();

        ContentValues values = new ContentValues();
        values.put(PoetryContract.PoetryEntry.COLUMN_TITLE, title);
        values.put(PoetryContract.PoetryEntry.COLUMN_AUTHOR, author);
        values.put(PoetryContract.PoetryEntry.COLUMN_CONTENT, content);

        db.insert(PoetryContract.PoetryEntry.TABLE_NAME, null, values);
    }

    private void updatePoetry(int id, String title, String author, String content) {
        SQLiteDatabase db = dbHelper.getWritableDatabase();

        ContentValues values = new ContentValues();
        values.put(PoetryContract.PoetryEntry.COLUMN_TITLE, title);
        values.put(PoetryContract.PoetryEntry.COLUMN_AUTHOR, author);
        values.put(PoetryContract.PoetryEntry.COLUMN_CONTENT, content);

        String selection = PoetryContract.PoetryEntry._ID + " = ?";
        String[] selectionArgs = { String.valueOf(id) };

        db.update(PoetryContract.PoetryEntry.TABLE_NAME, values, selection, selectionArgs);
    }

    private String getAllPoetry() {
        SQLiteDatabase db = dbHelper.getReadableDatabase();

        String[] projection = {
                PoetryContract.PoetryEntry._ID,
                PoetryContract.PoetryEntry.COLUMN_TITLE,
                PoetryContract.PoetryEntry.COLUMN_AUTHOR,
                PoetryContract.PoetryEntry.COLUMN_CONTENT
        };

        Cursor cursor = db.query(
                PoetryContract.PoetryEntry.TABLE_NAME,
                projection,
                null,
                null,
                null,
                null,
                null
        );

        StringBuilder builder = new StringBuilder();
        while (cursor.moveToNext()) {
            int id = cursor.getInt(cursor.getColumnIndexOrThrow(PoetryContract.PoetryEntry._ID));
            String title = cursor.getString(cursor.getColumnIndexOrThrow(PoetryContract.PoetryEntry.COLUMN_TITLE));
            String author = cursor.getString(cursor.getColumnIndexOrThrow(PoetryContract.PoetryEntry.COLUMN_AUTHOR));
            String content = cursor.getString(cursor.getColumnIndexOrThrow(PoetryContract.PoetryEntry.COLUMN_CONTENT));

            builder.append(id).append(". ").append(title).append(" - ").append(author).append("\n").append(content).append("\n\n");
        }

        cursor.close();

        return builder.toString();
    }
}

以上就是一个简单的使用 SQLite 数据库的示例。请注意，由于这只是一个演示，您需要自己创建布局文件等其他必要文件。