android开发——001：从SQLite中读取数据到ListView中

一、建数据库

MyDatabaseHelper.java

public class MyDatabaseHelper extends SQLiteOpenHelper {
    /*integer 整型，real 浮点型，primary key 主键，autoincrement 自增长，text 文本类型，blob 二进制数，*/
    public static final String CREATE_BOOK="create table Book("
        +"id integer primary key autoincrement,"
            +"author text,"
            +"price real,"
            +"pages integer,"+
            "name text)";
    public static final String CREATE_CATEGORY="create table Category("
            +"id integer primary key autoincrement,"
            +"category_name text,"
            +"category_code integer)";
    private Context mContext;

    public MyDatabaseHelper(Context context, String name, SQLiteDatabase.CursorFactory factory, int version) {
        super(context, name, factory, version);
        mContext=context;
    }

    @Override
    public void onCreate(SQLiteDatabase sqLiteDatabase) {
        sqLiteDatabase.execSQL(CREATE_BOOK);
        sqLiteDatabase.execSQL(CREATE_CATEGORY);
        Toast.makeText(mContext,"create success!",Toast.LENGTH_SHORT).show();
    }

    @Override
    public void onUpgrade(SQLiteDatabase sqLiteDatabase, int i, int i1) {
        sqLiteDatabase.execSQL("drop table if exists Book");
        sqLiteDatabase.execSQL("drop table if exists Category");
        onCreate(sqLiteDatabase);
    }

}

main活动布局文件 activity_main.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout 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"
    android:orientation="vertical"
    tools:context=".MainActivity">

    <Button
        android:id="@+id/Create_button"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="创建数据库"
        />

    <Button
        android:id="@+id/Add_button"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="添加数据"
        />

    <Button
        android:id="@+id/Update_button"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="更新数据"/>

    <Button
    android:id="@+id/Delete_button"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:text="删除数据"/>

    <Button
        android:id="@+id/Query_button"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="查询数据"/>
</LinearLayout>

在main活动中操作数据库（增删改查）：

public class MainActivity extends AppCompatActivity {
    private Button bt1,bt2,bt3,bt4,bt5;
    private MyDatabaseHelper databaseHelper;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        databaseHelper=new MyDatabaseHelper(this,"BookStore.db",null,2);
        setContentView(R.layout.activity_main);
        bt1=(Button)findViewById(R.id.Create_button);
        bt1.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                databaseHelper.getWritableDatabase();//先检测程序中有无这个数据库，如果没有，则创建
            }
        });
        bt2=(Button)findViewById(R.id.Add_button);
        bt2.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                SQLiteDatabase db=databaseHelper.getWritableDatabase();
                ContentValues values=new ContentValues();//获取ContentValues对象
                values.put("name","The Da Code");
                values.put("author","Dan");
                values.put("pages",454);
                values.put("price",46.69);
                db.insert("Book",null,values);//插入第一条数据
                values.clear();

                values.put("name","The Lost Symbol");
                values.put("author","Lost");
                values.put("pages",996);
                values.put("price",82.65);
                db.insert("Book",null,values);//插入第二条数据
            }
        });
        bt3=(Button)findViewById(R.id.Update_button);
        bt3.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                SQLiteDatabase db=databaseHelper.getWritableDatabase();
                ContentValues values=new ContentValues();
                values.put("price",10.99);
                db.update("Book",values,"name=?",new String[]{"The Da Code"});
            }
        });
        bt4=(Button)findViewById(R.id.Delete_button);
        bt4.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                SQLiteDatabase db=databaseHelper.getWritableDatabase();
                db.delete("Book","pages > ?",new String[]{"500"});//删除页数超过500的书
            }
        });
        bt5=(Button)findViewById(R.id.Query_button);
        bt5.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
//                SQLiteDatabase db=databaseHelper.getWritableDatabase();//获取数据库对象
//                Cursor cursor=db.query("Book",null,null,null,null,null,null);//查询Book表中的所有数据
//                if(cursor.moveToFirst()){
//                    do{
//                        String name=cursor.getString(cursor.getColumnIndex("name"));
//                        String author=cursor.getString(cursor.getColumnIndex("author"));
//                        int pages=cursor.getInt(cursor.getColumnIndex("pages"));
//                        double price=cursor.getDouble(cursor.getColumnIndex("price"));
//                        Log.d("MainActivity","Book name is:"+name);
//                        Log.d("MainActivity","Book author is:"+author);
//                        Log.d("MainActivity","Book page is:"+pages);
//                        Log.d("MainActivity","Book price is:"+price);
//                    }while(cursor.moveToNext());
//                }
//                cursor.close();
                Intent intent=new Intent(MainActivity.this,ShowDataActivity.class);
                startActivity(intent);
            }
        });
    }
}

BookStore.java

public class BookStore {
    private int id;
    private String name;
    private String author;
    private int pages;
    private double price;

    public BookStore(int id,String name,String author,int pages,double price){
        this.id=id;
        this.name=name;
        this.author=author;
        this.pages=pages;
        this.price=price;
    }

    public int getId() {
        return id;
    }

    public String getName() {
        return name;
    }

    public String getAuthor() {
        return author;
    }

    public int getPages() {
        return pages;
    }

    public double getPrice() {
        return price;
    }

}

建适配布局文件 book_item.xml

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

    <TextView
        android:id="@+id/book_id"
        android:gravity="center"
        android:layout_weight="1"
        android:text="编号"
        android:layout_width="0dp"
        android:layout_height="50dp" />
    <TextView
        android:id="@+id/book_name"
        android:gravity="center"
        android:layout_weight="1"
        android:text="书名"
        android:layout_width="0dp"
        android:layout_height="50dp" />
    <TextView
        android:id="@+id/book_author"
        android:gravity="center"
        android:layout_weight="1"
        android:text="作者"
        android:layout_width="0dp"
        android:layout_height="50dp" />
    <TextView
        android:id="@+id/book_pages"
        android:gravity="center"
        android:layout_weight="1"
        android:text="页数"
        android:layout_width="0dp"
        android:layout_height="50dp" />
    <TextView
        android:id="@+id/book_price"
        android:gravity="center"
        android:layout_weight="1"
        android:text="价格"
        android:layout_width="0dp"
        android:layout_height="50dp" />

</LinearLayout>

ListView显示界面 datalayout.xml

<?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">

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

        <TextView
            android:id="@+id/book_id"
            android:gravity="center"
            android:layout_weight="1"
            android:text="编号"
            android:layout_width="0dp"
            android:layout_height="50dp" />
        <TextView
            android:id="@+id/book_name"
            android:gravity="center"
            android:layout_weight="1"
            android:text="书名"
            android:layout_width="0dp"
            android:layout_height="50dp" />
        <TextView
            android:id="@+id/book_author"
            android:gravity="center"
            android:layout_weight="1"
            android:text="作者"
            android:layout_width="0dp"
            android:layout_height="50dp" />
        <TextView
            android:id="@+id/book_pages"
            android:gravity="center"
            android:layout_weight="1"
            android:text="页数"
            android:layout_width="0dp"
            android:layout_height="50dp" />
        <TextView
            android:id="@+id/book_price"
            android:gravity="center"
            android:layout_weight="1"
            android:text="价格"
            android:layout_width="0dp"
            android:layout_height="50dp" />

    </LinearLayout>

    <TextView
             android:layout_width="match_parent"
             android:layout_height="1dp"
             android:background="@android:color/background_dark"/>
         <ListView
             android:id="@+id/book_lv"
             android:layout_width="match_parent"
             android:layout_height="match_parent">
         </ListView>

</LinearLayout>

ListView适配器：BookAdapter.java

public class BookAdapter extends ArrayAdapter<BookStore> {
    private int resourceId;
    public BookAdapter(Context context, int resource,List<BookStore>objects) {
        super(context, resource,objects);
        resourceId=resource;
    }

    @NonNull
    public View getView(int position, View convertView,ViewGroup parent) {
        BookStore bs=getItem(position);//获取当前项的book实例
        View view= LayoutInflater.from(getContext()).inflate(resourceId,parent,false);
        TextView book_id=(TextView)view.findViewById(R.id.book_id);
        TextView book_name=(TextView)view.findViewById(R.id.book_name);
        TextView book_author=(TextView)view.findViewById(R.id.book_author);
        TextView book_pages=(TextView)view.findViewById(R.id.book_pages);
        TextView book_price=(TextView)view.findViewById(R.id.book_price);
        book_id.setText(String.valueOf(bs.getId()));
        book_name.setText(bs.getName());
        book_author.setText(bs.getAuthor());
        book_pages.setText(String.valueOf(bs.getPages()));
        book_price.setText(String.valueOf(bs.getPrice()));
        return view;
    }
}

ListView显示页面：ShowDataActivity.java

public class ShowDataActivity extends AppCompatActivity {
    private List<BookStore> bookList=new ArrayList<>();
    private ListView lv;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.datalayout);
        initBooks();
        BookAdapter adapter = new BookAdapter(ShowDataActivity.this, R.layout.book_item, bookList);
        ListView listView = (ListView) findViewById(R.id.book_lv);
        listView.setAdapter(adapter);
    }

    private void initBooks() {
        //扫描数据库，将信息放入booklist
        MyDatabaseHelper mdb = new MyDatabaseHelper(this, "BookStore.db", null, 2);//打开数据库
        SQLiteDatabase sd = mdb.getReadableDatabase();//获取数据库
        Cursor cursor=sd.query("Book",null,null,null,null,null,null);//查询Book表中的所有数据
        while(cursor.moveToNext()){
            int id=cursor.getInt(cursor.getColumnIndex("id"));
            String name=cursor.getString(cursor.getColumnIndex("name"));
            String author=cursor.getString(cursor.getColumnIndex("author"));
            int pages=cursor.getInt(cursor.getColumnIndex("pages"));
            double price=cursor.getDouble(cursor.getColumnIndex("price"));
            BookStore bookStore=new BookStore(id,name,author,pages,price);
            bookList.add(bookStore);
        }
        cursor.close();
    }
}

运行截图：

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android开发——001：从SQLite中读取数据到ListView中

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