Android数据存储和访问-商品展示

1:运行效果图:
Android数据存储和访问-商品展示_第1张图片
Android数据存储和访问-商品展示_第2张图片
2:首先建立一个ShopShowDemo的应用程序,将包名改为cn.bzu.edu.com。设计用户交互界面。ShopShoeDemo程序对应的布局文件如下所示:
activity_main.xml:


<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.edu.bzu.cn.shopshowdemo.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: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:src="@android:drawable/ic_input_add"
            />

    LinearLayout>

    <ListView
        android:id="@+id/lvGoods"
        android:layout_width="match_parent"
        android:layout_height="match_parent" />


LinearLayout>

3:在res/layout目录下创建一个item.xml文件,该文件下有三个TextView,分别用于显示数据库中的某条数据的id,商品名称,金额。三个ImageView用于增加金额,减少金额,删除数据。
item.xml:


<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="1" />
    <TextView
        android:text="商品名称"
        android:layout_width="0dp"
        android:layout_height="wrap_content"
        android:maxLines="1"
        android:gravity="left"
        android:id="@+id/tvName"
        android:textSize="20sp"
        android:layout_weight="2" />
    <TextView
        android:text="金额"
        android:gravity="left"
        android:layout_width="0dp"
        android:layout_height="wrap_content"
        android:id="@+id/tvAmount"
        android:textSize="20sp"
        android:layout_weight="2" />
    <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>

4:在com.edu.bzu.cn.shopshowdemo下分别建三个包dao,db,entity,在dao包下建一个GoodsDao类,db包下建一个DBHelper类,entity包下建Goods类,GoodsAdapter类
GoodsDao:

package com.edu.bzu.cn.shopshowdemo.dao;
import android.content.ContentValues;
import android.content.Context;
import android.database.Cursor;
import android.database.sqlite.SQLiteDatabase;

import com.edu.bzu.cn.shopshowdemo.db.DBHelper;
import com.edu.bzu.cn.shopshowdemo.entity.Goods;

import java.util.ArrayList;
import java.util.List;

/**
 * Created by Administrator on 2017/4/28.
 */

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() + ""});

        sqLiteDatabase.close();
        return count;
    }

    public List queryAll() {
        List 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;


    }
}


DBHelper:

package com.edu.bzu.cn.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) {

    }
}


Goods:

package com.edu.bzu.cn.shopshowdemo.entity;

/**
 * Created by Administrator on 2017/4/28.
 */

public class Goods {
    private Long id;
    private String name;
    private Integer amount;

    public Goods(Long id, String name, Integer amount) {
        this.id = id;
        this.name = name;
        this.amount = amount;
    }

    public Goods(String name, Integer amount) {
        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 Integer getAmount() {
        return amount;
    }

    public void setAmount(Integer amount) {
        this.amount = amount;
    }

    @Override
    public String toString() {
        return "Goods{" +
                "id=" + id +
                ", name='" + name + '\'' +
                ", amount=" + amount +
                '}';
    }
}

GoodsAdapter:

package com.edu.bzu.cn.shopshowdemo.entity;
import android.content.Context;
import android.content.DialogInterface;
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.edu.bzu.cn.shopshowdemo.R;
import com.edu.bzu.cn.shopshowdemo.dao.GoodsDao;
import com.edu.bzu.cn.shopshowdemo.entity.Goods;

import java.util.List;

/**
 * Created by Administrator on 2017/4/28.
 */

public class GoodsAdapter extends ArrayAdapter {
    private int resounceId;
    private GoodsDao goodsDao;
    private List goodsList;
    public GoodsAdapter(Context context, int resource, List 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);
        View view=null;
        ViewHolder viewHolder;

        if (convertView==null){
            view=LayoutInflater.from(getContext()).inflate(R.layout.item,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() {
            @Override
            public void onClick(View view) {
                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 dialog, int which) {
                        goodsList.remove(goods);

                        goodsDao.delete(goods.getId());
                        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;


    }
}


MainActivity:

package com.edu.bzu.cn.shopshowdemo;

import android.content.SharedPreferences;
import android.database.sqlite.SQLiteDatabase;
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.edu.bzu.cn.shopshowdemo.dao.GoodsDao;
import com.edu.bzu.cn.shopshowdemo.entity.Goods;
import com.edu.bzu.cn.shopshowdemo.entity.GoodsAdapter;

import java.util.List;

public class MainActivity extends AppCompatActivity {
    private EditText etName;
    private EditText etAmount;
    private ListView lvGoods;
    private GoodsAdapter goodsAdapter;
    private GoodsDao goodsDao;
    private ListgoodsList;

    @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();

    }
}


5:首先添加三个商品:
Android数据存储和访问-商品展示_第3张图片
继续添加一个如图:
Android数据存储和访问-商品展示_第4张图片
点右边的小三角增删按钮,可实现对金额的增删:
Android数据存储和访问-商品展示_第5张图片
Android数据存储和访问-商品展示_第6张图片
删除操作:点右方的删除按钮,会出现“你确定要删除吗”的提示,点“YES”,就删除成功了
Android数据存储和访问-商品展示_第7张图片
Android数据存储和访问-商品展示_第8张图片

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