使用SqlLite数据库创建数据库library，并创建Book和Category这两个表。往Category里插入2条默认书类别数据（如：经济类， 1）。 （2）界面设计： ① 创建一个MainActivity，对应的布局为activity_main。 ② 添加一个RecyclerView，用于显示所有的图书条目信息，每个条目显示书的名字、作者、类别和价格。 ③ 添加一个“添加书目”的按钮，用于跳转进入AddBookActivity。 ④ 在AddBookActivity中，可以添加一本书的信息到数据库中。提示：AddBookActivity需要的组件包括：EditText、TextView、Button

好的，这是一个关于SQLite数据库和Android界面设计的问题。下面是答案：

1. 使用SqlLite数据库创建数据库library，并创建Book和Category这两个表。往Category里插入2条默认书类别数据（如：经济类， 1）。

CREATE TABLE Category (
    id INTEGER PRIMARY KEY AUTOINCREMENT,
    name TEXT
);

CREATE TABLE Book (
    id INTEGER PRIMARY KEY AUTOINCREMENT,
    name TEXT,
    author TEXT,
    category_id INTEGER,
    price REAL,
    FOREIGN KEY (category_id) REFERENCES Category(id)
);

INSERT INTO Category (name) VALUES ('经济类');
INSERT INTO Category (name) VALUES ('其他类');

2. 界面设计：

① 创建一个MainActivity，对应的布局为activity_main。

MainActivity.java

public class MainActivity extends AppCompatActivity {

    private RecyclerView mRecyclerView;

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

        mRecyclerView = findViewById(R.id.recycler_view);
        mRecyclerView.setLayoutManager(new LinearLayoutManager(this));
        mRecyclerView.setAdapter(new BookAdapter(this));
    }
}

activity_main.xml

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:id="@+id/activity_main"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context=".MainActivity">

    <androidx.recyclerview.widget.RecyclerView
        android:id="@+id/recycler_view"
        android:layout_width="match_parent"
        android:layout_height="match_parent" />

    <Button
        android:id="@+id/add_book_button"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_alignParentBottom="true"
        android:layout_alignParentEnd="true"
        android:layout_marginBottom="16dp"
        android:layout_marginEnd="16dp"
        android:text="添加书目" />

</RelativeLayout>

② 添加一个RecyclerView，用于显示所有的图书条目信息，每个条目显示书的名字、作者、类别和价格。

BookAdapter.java

public class BookAdapter extends RecyclerView.Adapter<BookAdapter.ViewHolder> {

    private Context mContext;
    private List<Book> mBookList;

    public BookAdapter(Context context) {
        mContext = context;
        mBookList = new ArrayList<>();
        loadBooks();
    }

    private void loadBooks() {
        DBHelper dbHelper = new DBHelper(mContext);
        SQLiteDatabase db = dbHelper.getReadableDatabase();
        Cursor cursor = db.query("Book", null, null, null, null, null, null);
        while (cursor.moveToNext()) {
            Book book = new Book();
            book.setName(cursor.getString(cursor.getColumnIndex("name")));
            book.setAuthor(cursor.getString(cursor.getColumnIndex("author")));
            book.setPrice(cursor.getFloat(cursor.getColumnIndex("price")));
            int categoryId = cursor.getInt(cursor.getColumnIndex("category_id"));
            book.setCategory(getCategoryName(categoryId));
            mBookList.add(book);
        }
        cursor.close();
        dbHelper.close();
    }

    private String getCategoryName(int categoryId) {
        String categoryName = "";
        DBHelper dbHelper = new DBHelper(mContext);
        SQLiteDatabase db = dbHelper.getReadableDatabase();
        Cursor cursor = db.query("Category", null, "id = ?", new String[]{String.valueOf(categoryId)}, null, null, null);
        if (cursor.moveToFirst()) {
            categoryName = cursor.getString(cursor.getColumnIndex("name"));
        }
        cursor.close();
        dbHelper.close();
        return categoryName;
    }

    @NonNull
    @Override
    public ViewHolder onCreateViewHolder(@NonNull ViewGroup parent, int viewType) {
        View view = LayoutInflater.from(parent.getContext()).inflate(R.layout.item_book, parent, false);
        return new ViewHolder(view);
    }

    @Override
    public void onBindViewHolder(@NonNull ViewHolder holder, int position) {
        Book book = mBookList.get(position);
        holder.mNameTextView.setText(book.getName());
        holder.mAuthorTextView.setText(book.getAuthor());
        holder.mCategoryTextView.setText(book.getCategory());
        holder.mPriceTextView.setText(String.valueOf(book.getPrice()));
    }

    @Override
    public int getItemCount() {
        return mBookList.size();
    }

    static class ViewHolder extends RecyclerView.ViewHolder {
        TextView mNameTextView;
        TextView mAuthorTextView;
        TextView mCategoryTextView;
        TextView mPriceTextView;

        ViewHolder(View itemView) {
            super(itemView);
            mNameTextView = itemView.findViewById(R.id.name_text_view);
            mAuthorTextView = itemView.findViewById(R.id.author_text_view);
            mCategoryTextView = itemView.findViewById(R.id.category_text_view);
            mPriceTextView = itemView.findViewById(R.id.price_text_view);
        }
    }
}

item_book.xml

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

    <TextView
        android:id="@+id/name_text_view"
        android:layout_width="0dp"
        android:layout_height="wrap_content"
        android:layout_weight="1"
        android:text="Book Name" />

    <TextView
        android:id="@+id/author_text_view"
        android:layout_width="0dp"
        android:layout_height="wrap_content"
        android:layout_weight="1"
        android:text="Author" />

    <TextView
        android:id="@+id/category_text_view"
        android:layout_width="0dp"
        android:layout_height="wrap_content"
        android:layout_weight="1"
        android:text="Category" />

    <TextView
        android:id="@+id/price_text_view"
        android:layout_width="0dp"
        android:layout_height="wrap_content"
        android:layout_weight="1"
        android:text="Price" />

</LinearLayout>

③ 添加一个“添加书目”的按钮，用于跳转进入AddBookActivity。

MainActivity.java

public class MainActivity extends AppCompatActivity {

    private RecyclerView mRecyclerView;

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

        mRecyclerView = findViewById(R.id.recycler_view);
        mRecyclerView.setLayoutManager(new LinearLayoutManager(this));
        mRecyclerView.setAdapter(new BookAdapter(this));

        Button addBookButton = findViewById(R.id.add_book_button);
        addBookButton.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                Intent intent = new Intent(MainActivity.this, AddBookActivity.class);
                startActivity(intent);
            }
        });
    }
}

activity_main.xml

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:id="@+id/activity_main"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context=".MainActivity">

    <androidx.recyclerview.widget.RecyclerView
        android:id="@+id/recycler_view"
        android:layout_width="match_parent"
        android:layout_height="match_parent" />

    <Button
        android:id="@+id/add_book_button"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_alignParentBottom="true"
        android:layout_alignParentEnd="true"
        android:layout_marginBottom="16dp"
        android:layout_marginEnd="16dp"
        android:text="添加书目" />

</RelativeLayout>

④ 在AddBookActivity中，可以添加一本书的信息到数据库中。提示：AddBookActivity需要的组件包括：EditText、TextView、Button

AddBookActivity.java

public class AddBookActivity extends AppCompatActivity {

    private EditText mNameEditText;
    private EditText mAuthorEditText;
    private Spinner mCategorySpinner;
    private EditText mPriceEditText;

    private List<Category> mCategoryList;

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

        mNameEditText = findViewById(R.id.name_edit_text);
        mAuthorEditText = findViewById(R.id.author_edit_text);
        mCategorySpinner = findViewById(R.id.category_spinner);
        mPriceEditText = findViewById(R.id.price_edit_text);

        loadCategories();

        Button addButton = findViewById(R.id.add_button);
        addButton.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                String name = mNameEditText.getText().toString().trim();
                String author = mAuthorEditText.getText().toString().trim();
                Category category = mCategoryList.get(mCategorySpinner.getSelectedItemPosition());
                float price = Float.parseFloat(mPriceEditText.getText().toString().trim());

                if (TextUtils.isEmpty(name)) {
                    Toast.makeText(AddBookActivity.this, "请输入书名", Toast.LENGTH_SHORT).show();
                    return;
                }
                if (TextUtils.isEmpty(author)) {
                    Toast.makeText(AddBookActivity.this, "请输入作者", Toast.LENGTH_SHORT).show();
                    return;
                }
                if (price <= 0) {
                    Toast.makeText(AddBookActivity.this, "请输入价格", Toast.LENGTH_SHORT).show();
                    return;
                }

                DBHelper dbHelper = new DBHelper(AddBookActivity.this);
                SQLiteDatabase db = dbHelper.getWritableDatabase();
                ContentValues values = new ContentValues();
                values.put("name", name);
                values.put("author", author);
                values.put("category_id", category.getId());
                values.put("price", price);
                db.insert("Book", null, values);
                dbHelper.close();

                finish();
            }
        });
    }

    private void loadCategories() {
        mCategoryList = new ArrayList<>();
        DBHelper dbHelper = new DBHelper(this);
        SQLiteDatabase db = dbHelper.getReadableDatabase();
        Cursor cursor = db.query("Category", null, null, null, null, null, null);
        while (cursor.moveToNext()) {
            Category category = new Category();
            category.setId(cursor.getInt(cursor.getColumnIndex("id")));
            category.setName(cursor.getString(cursor.getColumnIndex("name")));
            mCategoryList.add(category);
        }
        cursor.close();
        dbHelper.close();

        ArrayAdapter<Category> adapter = new ArrayAdapter<>(this, android.R.layout.simple_spinner_item, mCategoryList);
        adapter.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item);
        mCategorySpinner.setAdapter(adapter);
    }
}

activity_add_book.xml

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:orientation="vertical"
    android:padding="16dp">

    <EditText
        android:id="@+id/name_edit_text"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:hint="书名" />

    <EditText
        android:id="@+id/author_edit_text"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:hint="作者" />

    <TextView
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="类别" />

    <Spinner
        android:id="@+id/category_spinner"
        android:layout_width="match_parent"
        android:layout_height="wrap_content" />

    <EditText
        android:id="@+id/price_edit_text"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:hint="价格"
        android:inputType="numberDecimal" />

    <Button
        android:id="@+id/add_button"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="添加" />

</LinearLayout>

Category.java

public class Category {
    
    private int mId;
    private String mName;

    public int getId() {
        return mId;
    }

    public void setId(int id) {
        mId = id;
    }

    public String getName() {
        return mName;
    }

    public void setName(String name) {
        mName = name;
    }

    @NonNull
    @Override
    public String toString() {
        return mName;
    }
}

以上是关于SQLite数据库和Android界面设计的答案，希望能够帮到你！