Android中商品展示案例

 

开发一个简单的购物车：

（1）需要将购物车中的商品以列表的形式展示

（2）并且还需要对购物车中的 商品进行增删改查操作。

（3）要实现这些功能就需要使用
ListView 和
SQLite 数据库。
 

 

1.创建一个名为ProdectDisplay的程序

2.（1）在activity_main.xml文件中设计布局：

<?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="bzu.edu.cn.prodectdisply.MainActivity">

 

    <LinearLayout        android:id="@+id/addLL"        android:layout_width="match_parent"        android:layout_height="wrap_content"        android:orientation="horizontal">

        <EditText            android:id="@+id/nameET"            android:layout_width="0dp"            android:layout_height="wrap_content"            android:layout_weight="1"
           android:hint="商品名称"            android:inputType="textPersonName"
/>

        <EditText            android:id="@+id/balanceET"            android:layout_width="0dp"            android:layout_height="wrap_content"            android:layout_weight="1"
           android:hint="金额"            android:inputType="number" />

        <ImageView            android:onClick="add"            android:id="@+id/addIV"            android:layout_width="wrap_content"            android:layout_height="wrap_content"
           android:src="@android:drawable/ic_input_add" />

 

    </LinearLayout>

 

    <ListView        android:id="@+id/accountLV"        android:layout_width="match_parent"        android:layout_height="match_parent"        android:layout_below="@id/addLL">

    </ListView>

</LinearLayout>

 

（2）在layout下创建一个item.xml，编写一个ListViewItem的布局：

  

<?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"    android:orientation="horizontal"    android:padding="10dp">

 

    <TextView        android:id="@+id/idTV"        android:layout_width="0dp"        android:layout_height="wrap_content"        android:layout_weight="1"        android:text="13"
       android:textColor="#000000"        android:textSize="20sp" />

 

    <TextView        android:id="@+id/nameTV"        android:layout_width="0dp"        android:layout_height="wrap_content"        android:layout_weight="2"        android:text="PQ"
       android:singleLine="true"        android:textColor="#000000"        android:textSize="20sp"
/>

 

    <TextView        android:id="@+id/balanceTV"        android:layout_width="0dp"        android:layout_height="wrap_content"        android:layout_weight="2"        android:text="12345"
       android:singleLine="true"        android:textColor="#000000"        android:textSize="20sp"
/>

 

    <LinearLayout        android:layout_width="wrap_content"        android:layout_height="wrap_content"        android:orientation="vertical">

 

        <ImageV
4000
iew            android:id="@+id/upIV"            android:layout_width="wrap_content"            android:layout_height="wrap_content"            android:layout_marginBottom="2dp"
           android:src="@android:drawable/arrow_up_float" />

        <ImageView            android:id="@+id/downIV"            android:layout_width="wrap_content"            android:layout_height="wrap_content"            android:src="@android:drawable/arrow_down_float"
/>

        <ImageView            android:id="@+id/deleteIV"            android:layout_width="25dp"            android:layout_height="25dp"            android:src="@android:drawable/ic_menu_delete"
/>

    </LinearLayout>

</LinearLayout>

3.(1)创建数据库，在包dao下创建一个MyHelper类，继承SQLiteOpenHelper：

package bzu.edu.cn.prodectdisply.dao;

import android.content.Context;import
android.database.sqlite.SQLiteDatabase;import
android.database.sqlite.SQLiteOpenHelper;

/** * Created by gxw on 2017/5/3. */public class
MyHelper extends
SQLiteOpenHelper {

    public  MyHelper(Context context)    {       

    super(context,"itcast.db",null,2);
 

  }   

 @Override   

 public void
onCreate(SQLiteDatabase db) {        

       System.out.println("onCreate");
       

       db.execSQL("CREATE TABLE account(_id INTEGER PRIMARY KEY AUTOINCREMENT,name VARCHAR(20),balance INTEGER)");   

 }    

@Override    

public void onUpgrade(SQLiteDatabase db,
int oldVersion,
int newVersion) {     

   System.out.println("onUpgrade");   

 }

}

 

(2)在包dao下创建类AccountDao类，用于操作数据库：

package bzu.edu.cn.prodectdisply.dao;

import android.content.ContentValues;import
android.content.Context;import
android.database.Cursor;import
android.database.sqlite.SQLiteDatabase;

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

import bzu.edu.cn.prodectdisply.bean.Account;

/** * Created by gxw on 2017/4/17. */public class
AccountDao {

    private
MyHelper helper;

    public
AccountDao(Context context){

        helper=new
MyHelper(context);

    }

    public void
insert(Account account){

       

        SQLiteDatabase db=helper.getWritableDatabase();

        ContentValues values=new
ContentValues();        

        values.put("name",account.getName());        

        values.put("balance",account.getBalance());       

        long
id=db.insert("account",null,values);
       

        account.setId(id);       

        db.close();   

}

    public int
delete(long
id){      

    SQLiteDatabase db=helper.getWritableDatabase();

      

    int
count=db.delete("account","_id=?",new
String[]{id+""});    

    db.close();       

    return
count;   

 }   

   public int
update(Account account){        

   SQLiteDatabase db=helper.getWritableDatabase();       

   ContentValues values=new
ContentValues();        

   values.put("name",account.getName());       

   values.put("balance",account.getBalance());     

   int
count=db.update("account",values,"_id=?",new
String[]{account.getId()+""});       

   db.close();        

   return count;   

 }  

 public
List<Account> queryAll(){        

    SQLiteDatabase db=helper.getWritableDatabase();        

    Cursor c=db.query("account",null,null,null,null,null,"balance
DESC");   

    List<Account> list=new
ArrayList<>();        

    while(c.moveToNext()){          

    long
id=c.getLong(c.getColumnIndex("_id"));           

    String name=c.getString(1);           

    int
balance=c.getInt(2);           

    list.add(new
Account(id,name,balance));      

  }        

    c.close();       

    db.close();       

    return
list;    

}

}
124e3

 

4.创建一个bean包，用于存放JavaBean类，此包下创建一个Account类：

package bzu.edu.cn.prodectdisply.bean;

/** * Created by gxw on 2017/5/3. */public class
Account {

    private
Long id;

    private
String name;

    private
Integer balance;

 

    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 getBalance(){

        return balance;

    }

    public void
setBalance(Integer balance){

        this.balance=balance;

    }

    public
Account(Long id,String name,Integer balance){

        super();

        this.id=id;

        this.name=name;

        this.balance=balance;

    }

    public
Account(String name,Integer balance){

        super();

        this.name=name;

        this.balance=balance;

    }

    public
Account(){

        super();

    }

    public
String toString(){

        return "[序号："+id+",商品名称："+name+",余额："+balance+"]";

    }

}

5.编写界面交互代码：

package bzu.edu.cn.prodectdisply;

import android.content.DialogInterface;import
android.net.Uri;import
android.support.v7.app.AlertDialog;import
android.support.v7.app.AppCompatActivity;import
android.os.Bundle;import
android.support.v7.app.NotificationCompat;import
android.view.View;import
android.view.ViewGroup;import
android.widget.AdapterView;import
android.widget.BaseAdapter;import
android.widget.EditText;import
android.widget.ImageView;import
android.widget.ListView;import
android.widget.TextView;import
android.widget.Toast;

import com.google.android.gms.appindexing.Action;import
com.google.android.gms.appindexing.AppIndex;import
com.google.android.gms.appindexing.Thing;import
com.google.android.gms.common.api.GoogleApiClient;

import java.util.List;

import bzu.edu.cn.prodectdisply.bean.Account;import
bzu.edu.cn.prodectdisply.dao.AccountDao;

public class MainActivity
extends AppCompatActivity {

    private
List<Account> list;

    private
AccountDao dao;

    private
EditText nameET;

    private
EditText balanceET;

    private
MyAdapter adapter;

    private
ListView accountLV;    private
GoogleApiClient client;

 

    @Override    protected void
onCreate(Bundle savedInstanceState) {

        super.onCreate(savedInstanceState);

        setContentView(R.layout.activity_main);

        initView();

        dao
= new
AccountDao(this);

        list
= dao.queryAll();

        adapter
= new
MyAdapter();

        accountLV.setAdapter(adapter);        client
= new
GoogleApiClient.Builder(this).addApi(AppIndex.API).build();

    }

    private void
initView() {

        accountLV
= (ListView) findViewById(R.id.accountLV);

        nameET
= (EditText) findViewById(R.id.nameET);

        balanceET
= (EditText) findViewById(R.id.balanceET);

        accountLV.setOnItemClickListener(new
MyOnItemClickListener());

    }

 

    public void
add(View v) {

        String name = nameET.getText().toString().trim();

        String balance = balanceET.getText().toString().trim();

        Account a = new
Account(name, balance.equals("") ? 0 : Integer.parseInt(balance));

        dao.insert(a);

        list.add(a);

        adapter.notifyDataSetChanged();

        accountLV.setSelection(accountLV.getCount()
- 1);

        nameET.setText("");

        balanceET.setText("");

    }    public
Action getIndexApiAction() {

        Thing object = new
Thing.Builder().setName("Main Page")
// TODO: Define a title for the content shown.                //
TODO: Make sure this auto-generated URL is correct.                .setUrl(Uri.parse("http://[ENTER-YOUR-URL-HERE]"))

                .build();

        return new
Action.Builder(Action.TYPE_VIEW)

                .setObject(object)

                .setActionStatus(Action.STATUS_TYPE_COMPLETED)

                .build();

    }

 

    @Override    public void
onStart() {

        super.onStart();

        client.connect();

        AppIndex.AppIndexApi.start(client,
getIndexApiAction());

    }

 

    @Override    public void
onStop() {

        super.onStop();

        AppIndex.AppIndexApi.end(client,
getIndexApiAction());

        client.disconnect();

    }

 

    private class
MyAdapter extends
BaseAdapter {

        public int
getCount() {

            return list.size();

        }

        public
Object getItem(int
position) {

            return list.get(position);

        }

        public long
getItemId(int
position) {

            return
position;

        }

        public
View getView(int
position, View convertView, ViewGroup parent) {

            View item = convertView !=
null ? convertView : View.inflate(getApplicationContext(), R.layout.item,
null);

            TextView idTV = (TextView) item.findViewById(R.id.idTV);

            TextView nameTV = (TextView) item.findViewById(R.id.nameTV);

            TextView balanceTV = (TextView) item.findViewById(R.id.balanceTV);

            final
Account a = list.get(position);

            idTV.setText(a.getId() +
"");

            nameTV.setText(a.getName() +
"");

            balanceTV.setText(a.getBalance() +
"");

            ImageView upIV = (ImageView) item.findViewById(R.id.upIV);

            ImageView downIV = (ImageView) item.findViewById(R.id.downIV);

            ImageView deleteIV = (ImageView) item.findViewById(R.id.deleteIV);

            upIV.setOnClickListener(new
View.OnClickListener() {

                @Override                public void
onClick(View v) {

                    a.setBalance(a.getBalance() + 1);

                    notifyDataSetChanged();

                    dao.update(a);

                }

            });

            downIV.setOnClickListener(new
View.OnClickListener() {

                @Override                public void
onClick(View v) {

                    a.setBalance(a.getBalance() - 1);

                    notifyDataSetChanged();

                    dao.update(a);

                }

            });

            deleteIV.setOnClickListener(new
View.OnClickListener() {

                @Override                public void
onClick(View v) {

                    android.content.DialogInterface.OnClickListener listener=new
android.content.DialogInterface.OnClickListener() {

                        public void
onClick(DialogInterface dialog,
int which) {

                            list.remove(a);

                            dao.delete(a.getId());

                            notifyDataSetChanged();

                        }

                    };

                    AlertDialog.Builder builder =
new AlertDialog.Builder(MainActivity.this);

                    builder.setTitle("确定要删除吗？");

                    builder.setPositiveButton("确定", listener);

                    builder.setNegativeButton("取消",
null);

                    builder.show();

                }

            });

            return
item;

        }

    }

    private class
MyOnItemClickListener implements
AdapterView.OnItemClickListener {

           public void
onItemClick(AdapterView<?> parent,View view,int
position,long
id){

               Account a=(Account) parent.getItemAtPosition(position);               Toast.makeText(getApplicationContext(),a.toString(),Toast.LENGTH_LONG).show();
          }    }}