安卓商品展示案例

一、 创建手机界面布局

创建一个activity_main.xml文件代码如下：

<?xml version="1.0" encoding="utf-8"?><LinearLayout 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"    android:paddingBottom="@dimen/activity_vertical_margin"    android:paddingLeft="@dimen/activity_horizontal_margin"    android:paddingRight="@dimen/activity_horizontal_margin"    android:paddingTop="@dimen/activity_vertical_margin"    tools:context="com.example.bz0209.shopshowdemo.activity_main"    android:orientation="vertical">    <LinearLayout        android:layout_width="match_parent"        android:layout_height="wrap_content">    <EditText    android:id="@+id/etName"    android:layout_width="wrap_content"    android:layout_height="wrap_content"    android:hint="商品名称"    android:inputType="text"    android:layout_weight="1"    />    <EditText        android:id="@+id/etAmount"        android:layout_width="wrap_content"        android:layout_height="wrap_content"        android:hint="商品金额"        android:inputType="number"        android:layout_weight="1"        />    <ImageView        android:id="@+id/ivAdd"        android:layout_width="wrap_content"        android:layout_height="wrap_content"        android:onClick="addGoods"        android:inputType="text"        android:src="@android:drawable/ic_input_add"        />        </LinearLayout>    <ListView        android:id="@+id/lvGoods"        android:layout_width="match_parent"        android:layout_height="match_parent">    </ListView></LinearLayout>

效果图如下：

二、创建一个存储展示的xml文件

创建一个名为item.xml的布局文件，代码如下：

<?xml version="1.0" encoding="utf-8"?><LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"    android:layout_width="match_parent"    android:layout_height="match_parent">    <TextView        android:text="1"        android:layout_width="wrap_content"        android:layout_height="wrap_content"        android:id="@+id/tvId"        android:textSize="20sp"        android:layout_weight="2"        />    <TextView        android:text="商品名称"        android:layout_width="wrap_content"        android:layout_height="wrap_content"        android:id="@+id/tvName"        android:textSize="20sp"        android:layout_weight="2"        />    <TextView        android:text="金额"        android:layout_width="wrap_content"        android:layout_height="wrap_content"        android:id="@+id/tvAmount"        android:textSize="20sp"        android:layout_weight="2"        />        <ImageView            android:id="@+id/ivUP"            android:layout_width="wrap_content"            android:layout_height="wrap_content"            android:src="@android:drawable/arrow_up_float"            />        <ImageView            android:id="@+id/ivDown"            android:layout_width="wrap_content"            android:layout_height="wrap_content"            android:src="@android:drawable/arrow_down_float"            />        <ImageView            android:id="@+id/ivDelete"            android:layout_width="wrap_content"            android:layout_height="wrap_content"            android:src="@android:drawable/arrow_down_float"            /></LinearLayout>

三、创建数据库

在com.example.bz0209.shopshowdemo 的包下创建一个名为db的包，并在该包下定义一个dbHelper类继承自SQLiteOpenHelper，创建数据库代码如下：

package com.example.bz0209.shopshowdemo.db;import android.content.Context;import android.database.sqlite.SQLiteDatabase;import android.database.sqlite.SQLiteOpenHelper;/** * Created by Administrator on 2017/4/28. */public class DBHelper extends SQLiteOpenHelper{    public static final String CREATE_GOODS="create table goods(_id integer primary key autoincrement,name varchar(20),amount integer)";    public DBHelper(Context context,int version){        super(context,"goods.db",null,version);        }    @Override    public void onCreate(SQLiteDatabase db) {        db.execSQL(CREATE_GOODS);        }    @Override    public void onUpgrade(SQLiteDatabase db,int oldVersion,int newVersion) {    }}

四、创建GoodsAdapter类

为了操作数据库方便，创建一个GoodsAdapter类。因此需要在com.example.bz0209.shopshowdemo 的包下创建一个名为entity的包，然后在com.example.bz0209.shopshowdemo.entityd的包下定义一个GoodsAdapter类，代码如下：

package com.example.bz0209.shopshowdemo;import android.content.Context;import android.support.annotation.NonNull;import android.view.LayoutInflater;import android.view.View;import android.view.ViewGroup;import android.widget.ArrayAdapter;import android.widget.ImageView;import android.widget.TextView;import com.example.bz0209.shopshowdemo.entity.Goods;import java.util.List;/** * Created by Administrator on 2017/4/27. */public class GoodsAdapter extends ArrayAdapter<Goods>{    private int resounceId;    public GoodsAdapter(Context context, int resource, List<Goods> objects) {        super(context, resource, objects);        resounceId=resource;    }    @NonNull    @Override    public View getView(int position, View convertView, ViewGroup parent) {        Goods goods=getItem(position);        View view=null;        ViewHolder viewHolder;        if (convertView==null){            view = LayoutInflater.from(getContext()).inflate(resounceId,null);            viewHolder =new ViewHolder();            viewHolder.tvId=(TextView) view.findViewById(R.id.tvId);            viewHolder.tvName=(TextView) view.findViewById(R.id.tvName);            viewHolder.tvAmount=(TextView) view.findViewById(R.id.etAmount);            viewHolder.ivUp=(ImageView) view.findViewById(R.id.ivUP);            viewHolder.ivDown=(ImageView) view.findViewById(R.id.ivDown);            viewHolder.ivDelete=(ImageView) view.findViewById(R.id.ivDelete);            view.setTag(viewHolder);        }else {            view=convertView;            viewHolder=(ViewHolder) view.getTag();        }        viewHolder.tvId.setText(goods.getId()+"");        viewHolder.tvName.setText(goods.getName());        viewHolder.tvAmount.setText(goods.getAmount()+"");        return view;        }    class ViewHolder{        TextView tvId;        TextView tvName;        TextView tvAmount;        ImageView ivUp;        ImageView ivDown;        ImageView ivDelete;        }}

五、创建数据操作逻辑类

在com.example.bz0209.shopshowdemo 的包下创建一个名为dao的包，并创建一个名为GoodsDao的类，用于操作数据。代码如下：

public class GoodsDao {    private DBHelper dbHelper;    public GoodsDao(Context context){        dbHelper=new DBHelper(context,1);    }    public void add(Goods goods){        SQLiteDatabase sqLiteDatabase=dbHelper.getWritableDatabase();        ContentValues values=new ContentValues();        values.put("name",goods.getName());        values.put("amount",goods.getAmount());        sqLiteDatabase.insert("goods",null,values);        sqLiteDatabase.close();    }    public int delete(long id){        SQLiteDatabase sqLiteDatabase=dbHelper.getWritableDatabase();        int count=sqLiteDatabase.delete("goods","id=?",new String[]{id+""});        sqLiteDatabase.close();        return count;    }    public int update(Goods goods){        SQLiteDatabase sqLiteDatabase=dbHelper.getWritableDatabase();        ContentValues values=new ContentValues();        values.put("name",goods.getName());        values.put("amount",goods.getAmount());        int count=sqLiteDatabase.update("goods",values,"id=?",new String[]{goods.getId()+""});        sqLiteDatabase.close();        return count;    }    public List<Goods> queryAll(){        List<Goods>goodsList=new ArrayList<>();        SQLiteDatabase sqLiteDatabase=dbHelper.getReadableDatabase();        Cursor cursor=sqLiteDatabase.query("goods",null,null,null,null,null,"amount desc");        while (cursor.moveToNext()){            long id=cursor.getLong(cursor.getColumnIndex("_id"));            String name=cursor.getString(cursor.getColumnIndex("name"));            int amount=cursor.getInt(cursor.getColumnIndex("amount"));            Goods goods=new Goods(name,amount);            goodsList.add(goods);        }        cursor.close();        sqLiteDatabase.close();        return goodsList;    }}

六、编写界面交互代码

数据库操作完成后，需要界面与数据库进行交互，用于实现将数据库中的数据以ListView的形式展现在界面上具体代码如下：

package com.example.bz0209.shopshowdemo;import android.support.v7.app.AppCompatActivity;import android.os.Bundle;import android.view.View;import android.widget.EditText;import android.widget.ListView;import com.example.bz0209.shopshowdemo.dao.GoodsDao;import com.example.bz0209.shopshowdemo.entity.Goods;import java.util.List;public class activity_main extends AppCompatActivity {    private EditText etName;    private EditText etAmount;    private ListView lvGoods;    private GoodsAdapter goodsAdapter;    private GoodsDao goodsDao;    private List<Goods>goodsList;    @Override    protected void onCreate(Bundle savedInstanceState) {        super.onCreate(savedInstanceState);        setContentView(R.layout.activity_main);        etName=(EditText)findViewById(R.id.etName);        etAmount=(EditText)findViewById(R.id.etAmount);        lvGoods=(ListView)findViewById(R.id.lvGoods);        goodsDao=new GoodsDao(this);        goodsList=goodsDao.queryAll();        goodsAdapter=new GoodsAdapter(this,R.layout.item,goodsList);        lvGoods.setAdapter(goodsAdapter);    }    public void  addGoods(View view){        String name=etName.getText().toString();        String amount=etAmount.getText().toString();        Goods goods=new Goods(name,amount.equals("")?0:Integer.parseInt(amount));        goodsDao.add(goods);    }}

七、完成后的结果展示

（1）创建起数据库的图为：


（2）最后的运行结果图：