Android数据 存储和访问——商品展示

一.实验目的

1）掌握SQLite的存储方式

2）掌握如何使用SQLite完成CRUD操作 掌握ListView控件的使用

二.实验效果图



三.1)创建程序

首先建立一个新的项目MyApplication,设计一个交互式的页面，在包下分别新建包entity,db,dao然后在entity下建Goods和GoodsAdapter类,在db下建DBHelper类

在dao下建GoodsDao类，在layout下新建一个item.xml

2）代码展示

GoodsDao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;
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<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;

}
}

DBHelper:

package com.edu.bzu.cn.shopshowdemo.db;
import android.content.Context;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteOpenHelper;

public class DBHelper extends SQLiteOpenHelper {
4000
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;
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;

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);
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<
cfa7
span class="hljs-preprocessor">.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 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();

}
}

activity_main.xml:

<?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.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>

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: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>

四.运行结果图





说明：在这个商品展示页面中，可以对商品进行添加和删除的操作