商品展示案例

来源：互联网发布：机器人编程需要学什么编辑：程序博客网时间：2024/05/17 02:16

一、实验目的

开发一个购物车，需要将购物车车中的商品以列表的形式展示，并且还需要对购物车中的商品进行增删改查操作。

二、训练目标

<1> 掌握SQLite存储方式

<2> 掌握如何使用SQLite完成CRUD操作

三、案例实现

1、商品展示案例对应的布局文件activity_main.xml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:orientation="vertical"    tools:context="com.example.bz0209.myapplication.MainActivity">    <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:layout_weight="1"            android:hint="商品名称"            android:inputType="text" />        <EditText            android:id="@+id/etNumber"            android:layout_width="wrap_content"            android:layout_height="wrap_content"            android:layout_weight="1"            android:hint="商品数量"            android:inputType="number" />        <ImageView            android:id="@+id/ivAdd"            android:layout_width="wrap_content"            android:layout_height="wrap_content"            android:onClick="addGoods"            android:src="@android:drawable/ic_input_add" />    </LinearLayout>    <ListView        android:id="@+id/lvGoods"        android:layout_width="match_parent"        android:layout_height="match_parent" /></LinearLayout>

2、由于本案例应用到ListView布局，因此需要编写一个ListViewItem的布局，item.xml

<?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:id="@+id/tvId"        android:layout_width="wrap_content"        android:layout_height="wrap_content"        android:layout_weight="1"        android:text="1"        android:textSize="20sp" />    <TextView        android:id="@+id/tvName"        android:layout_width="wrap_content"        android:layout_height="wrap_content"        android:layout_weight="2"        android:text="商品名称"        android:textSize="20sp" />    <TextView        android:id="@+id/tvAmount"        android:layout_width="wrap_content"        android:layout_height="wrap_content"        android:layout_weight="2"        android:text="商品数量"        android:textSize="20sp" />    <LinearLayout        android:layout_width="wrap_content"        android:layout_height="wrap_content"        android:orientation="vertical">        <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" />    </LinearLayout>    <ImageView        android:id="@+id/ivDelete"        android:layout_width="25dp"        android:layout_height="25dp"        android:src="@android:drawable/ic_menu_delete" /></LinearLayout>

3、创建数据库DBHelper继承SQLiteOpenHelper

package com.example.bz0209.myapplication.db;import android.content.Context;import android.database.sqlite.SQLiteDatabase;import android.database.sqlite.SQLiteOpenHelper;public class DBHelper extends SQLiteOpenHelper {    private static final String CREATE_GOODS="create table goods(_id integer primary 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 sqLiteDatabase, int i, int i1) {    }}

4、创建商品类Goods

package com.example.bz0209.shop.entity;public class Goods {    private long id;    private String name;    private int amount;    public Goods(long id,String name,int amount){        super();        this.id=id;        this.name=name;        this.amount=amount;    }    public long getId() {        return id;    }    public void setId(long id) {        this.id = id;    }    public String getName() {        return name;    }    public void setName(String name) {        this.name = name;    }    public int getAmount() {        return amount;    }    public void setAmount(int amount) {        this.amount = amount;    }    public Goods(String name,int amount){        super();        this.name=name;        this.amount=amount;    }    public Goods(){        super();    }    public String toString(){        return "[序号:"+id+",商品名称:"+name+",余额:"+amount+"]";    }}

5、创建数据库库逻辑类

package com.example.bz0209.myapplication.dao;import android.content.ContentValues;import android.content.Context;import android.database.Cursor;import android.database.sqlite.SQLiteDatabase;import com.example.bz0209.myapplication.db.DBHelper;import com.example.bz0209.myapplication.entity.Goods;import java.sql.SQLData;import java.util.ArrayList;import java.util.List；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());        long id=sqLiteDatabase.insert("goods",null,values);        goods.setId(id);        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()+""});
6、编写交互界面
package com.example.bz0209.myapplication;import android.support.v7.app.AppCompatActivity;import android.os.Bundle;import android.text.TextUtils;import android.view.View;import android.widget.EditText;import android.widget.ListView;import android.widget.Toast;import com.example.bz0209.myapplication.dao.GoodsDao;import com.example.bz0209.myapplication.entity.Goods;import com.example.bz0209.myapplication.entity.GoodsAdapter;import java.util.List;public class MainActivity extends AppCompatActivity {    private EditText etName;    private EditText etAmount;    private GoodsDao goodsDao;    private ListView lvGoods;    private GoodsAdapter goodsAdapter;    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,goodsDao);        lvGoods.setAdapter(goodsAdapter);    }    public void addGoods(View view){        String name=etName.getText().toString();        String amount=etAmount.getText().toString();        if(TextUtils.isEmpty(name)||TextUtils.isEmpty(amount))            return;        Goods goods=new Goods(name,Integer.parseInt(amount));        goodsDao.add(goods);        goodsList.add(goods);        goodsAdapter.notifyDataSetChanged();        etName.setText("");        etAmount.setText("");        Toast.makeText(this,"添加成功",Toast.LENGTH_LONG).show();    }}        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(id,name,amount);            goodsList.add(goods);        }        cursor.close();        sqLiteDatabase.close();        return goodsList;    }}
7、适配器
package com.example.bz0209.myapplication.entity;import android.content.Context;import android.content.DialogInterface;import android.preference.DialogPreference;import android.support.annotation.NonNull;import android.support.v7.app.AlertDialog;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.myapplication.R;import com.example.bz0209.myapplication.dao.GoodsDao;import java.util.List;public class GoodsAdapter extends ArrayAdapter<Goods> {    private int resounceId;    private GoodsDao goodsDao;    private List<Goods> goodsList;    public GoodsAdapter(Context context, int resource, List<Goods> objects,GoodsDao goodsDao) {        super(context, resource, objects);        resounceId = resource;        goodsList=objects;        this.goodsDao=goodsDao;    }    @NonNull    @Override    public View getView(int position, View convertView, ViewGroup parent) {        final Goods goods = getItem(position);        ViewHolder viewHolder;        View view =null;        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.tvAmount);            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()+"");        viewHolder.ivDelete.setOnClickListener(new View.OnClickListener(){            public void onClick(View v){                AlertDialog.Builder builder=new AlertDialog.Builder(getContext());                builder.setTitle("你确定要删除吗？");                builder.setPositiveButton("yes", new DialogInterface.OnClickListener() {                    @Override                    public void onClick(DialogInterface dialogInterface, int i) {                        goodsDao.delete(goods.getId());                        goodsList.remove(goods);                        notifyDataSetChanged();                    }                });                builder.setNegativeButton("cancel",null);                builder.show();            }        });        viewHolder.ivUp.setOnClickListener(new View.OnClickListener() {            @Override            public void onClick(View v) {                goods.setAmount(goods.getAmount()-1);                goodsDao.update(goods);                notifyDataSetChanged();            }        });        viewHolder.ivDown.setOnClickListener(new View.OnClickListener() {            @Override            public void onClick(View v) {                goods.setAmount(goods.getAmount()+1);                goodsDao.update(goods);                notifyDataSetChanged();            }        });        return view;    }    class ViewHolder{        TextView tvId;        TextView tvName;        TextView tvAmount;        ImageView ivUp;        ImageView ivDown;        ImageView ivDelete;    }}
四、最终结果

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