商品展示

创建一个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="cn.edu.bzu.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"></ListView> </LinearLayout>

创建一个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:layout_weight="1" android:textSize="20sp"/> <TextView android:text="商品名称" android:layout_width="0dp" android:layout_height="wrap_content" android:id="@+id/tvName" android:maxLines="1" android:gravity="left" android:layout_weight="2" android:textSize="20sp"/> <TextView android:text="金额" android:layout_width="0dp" android:layout_height="wrap_content" android:id="@+id/tvAmount" android:gravity="left" android:maxLines="1" android:layout_weight="2" 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>

新建一个名为Dao的包，在包中新建一个GoodsDao类

package cn.edu.bzu.shopshowdemo.dao; import android.content.ContentValues; import android.content.Context; import android.database.sqlite.SQLiteDatabase; import android.database.sqlite.SQLiteOpenHelper; import java.util.ArrayList; import java.util.List; import cn.edu.bzu.shopshowdemo.db.DBHelper; import cn.edu.bzu.shopshowdemo.entity.Goods; /** * Created by Administrator on 2017/4/27. */ 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; } }

新建一个名为db的包，在包中新建一个名为DBHelper的类

package cn.edu.bzu.shopshowdemo.db; import android.content.Context; import android.database.sqlite.SQLiteDatabase; import android.database.sqlite.SQLiteOpenHelper; /** * Created by Administrator on 2017/4/27. */ 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) { } }

建一个名为entity的包，在包中建一个Goods类

package cn.edu.bzu.shopshowdemo.entity; /** * Created by Administrator on 2017/4/27. */ public class Goods { private Long id; private String name; private Integer amount; public Goods(Integer amount, String name, Long id) { this.amount = amount; this.name = name; this.id = id; } public Goods(Integer amount, String name) { this.amount = amount; this.name = name; } 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 + '}'; } }

建立一个GoodsAdapter类

package cn.edu.bzu.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 java.util.List; import cn.edu.bzu.shopshowdemo.entity.Goods; /** * Created by Administrator on 2017/4/27. */ 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 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 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); notifyDataChanged(); } }); viewHolder.ivDown.setOnClickListener(new View.OnClickListener(){ @Override public void onClick(View v){ goods.setAmount(goods.getAmount()-1); goodsDao.update(goods); notifyDataChanged(); } }); return view; } class ViewHolder{ TextView tvId; TextView tvName; TextView tvAmount; ImageView ivUp; ImageView ivDown; ImageView ivDelete; } }

建立一个MainActivity类

package cn.edu.bzu.shopshowdemo; import android.support.v7.app.AppCompatActivity; import android.os.Bundle; 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_SHORT).show(); } }

实验结果