android商品展示

来源：互联网发布：ztree check源码编辑：程序博客网时间：2024/05/16 11:14

在实际开发中，可能基础的界面都会做，但是让它实行并且运行一些功能的操作，想必还是有点懵，比如说，一些数据库的存储，操作数据库中的增删改查。例如，开发一个购物车，需要将购物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。要实现这些功能就需要使用ListView和SQLite数据库。接下来通过一个“”商品展示“”案例结合ListView下

如图可以看出前期工作我们需要activity— main.xml，ListView，Account，AccountDao，MyHelper等布局以及类操作

一.创建程序

首先创建一个名为“商品展示”的应用程序，设计用户交互界面，如图所示

“商品展示”程序的代码如下所示：

<?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:paddingBottom="@dimen/activity_vertical_margin"
android:paddingLeft="@dimen/activity_horizontal_margin"
android:paddingRight="@dimen/activity_horizontal_margin"
android:paddingTop="@dimen/activity_vertical_margin"
android:orientation="vertical"
tools:context="bzu.edhu.cn.product.MainActivity">
<LinearLayout
android:id="@+id/addLL"
android:orientation="horizontal"
android:layout_width="match_parent"
android:layout_height="wrap_content">
<EditText
android:layout_width="0dp"
android:layout_height="wrap_content"
android:layout_weight="1"
android:id="@+id/et1"
android:hint="商品名称"
android:inputType="textPersonName"
/>
<EditText
android:layout_width="0dp"
android:layout_height="wrap_content"
android:layout_weight="1"
android:id="@+id/et2"
android:hint="金额"
android:inputType="number"
/>
<ImageView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:onClick="add"
android:id="@+id/addIV"
android:src="@android:drawable/ic_input_add"
/>
</LinearLayout>

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

>

</ListView
>
</LinearLayout>

2.创建一个ListView Item布局

此布局文件主要对Item进行布局调整，代码如下：

<?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:layout_width="wrap_content"    android:layout_height="wrap_content"    android:text="1"    android:textColor="#000000"    android:layout_weight="1"    android:textSize="20sp"    android:id="@+id/t1"/>    <TextView        android:layout_width="wrap_content"        android:layout_height="wrap_content"        android:text="耳机"        android:textColor="#000000"        android:layout_weight="2"        android:textSize="20sp"        android:id="@+id/t2"/>    <TextView        android:layout_width="wrap_content"        android:layout_height="wrap_content"        android:text="20"        android:textColor="#000000"        android:layout_weight="2"        android:textSize="20sp"        android:id="@+id/t3"/>    <LinearLayout        android:layout_width="wrap_content"        android:layout_height="wrap_content"        android:orientation="vertical">        <ImageView            android:layout_width="wrap_content"            android:layout_height="wrap_content"            android:id="@+id/addup"            android:src="@android:drawable/arrow_up_float"            android:layout_marginBottom="2dp"/>        <ImageView            android:layout_width="wrap_content"            android:layout_height="wrap_content"            android:id="@+id/adddown"            android:src="@android:drawable/arrow_down_float"            android:layout_marginBottom="2dp"/>    </LinearLayout>    <ImageView        android:layout_width="wrap_content"        android:layout_height="wrap_content"        android:id="@+id/delete"        android:src="@android:drawable/ic_menu_delete"/></LinearLayout>

3.创建数据库

public class MyHelpr extends SQLiteOpenHelper {    public MyHelpr(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 i, int i1) {        System.out.println("onUpgrade");    }}

4.创建Accounty类

public class Account {    private Long id ;    private String name ;    private Integer balamce;    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 getBalamce() {        return balamce;    }    public void setBalamce(Integer balamce) {        this.balamce = balamce;    }    public Account(Long id, String name, Integer balamce) {        super();        this.id = id;        this.name = name;        this.balamce = balamce;    }    public Account(String name, Integer balamce) {        super();        this.name = name;        this.balamce = balamce;    }    @Override    public String toString() {        return "{" +                "序号=" + id +                ", 商品名称='" + name + '\'' +                ", 余额=" + balamce +                '}';    }}
5.创建数据库操作类

package com.example.bz0209.shangpin.cn.itcast.product.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.Collection;import java.util.List;/** * Created by Administrator on 2017/4/17. */public class AccountDao {//数据库操作类    private  MyHelpr helper;    public AccountDao(Context context) {        helper=new MyHelpr(context);    }    public void  insert(Account account){        SQLiteDatabase DB=helper.getWritableDatabase();        ContentValues values=new ContentValues();        values.put("name",account.getName());        values.put("balance",account.getBalamce());        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.getBalamce());        int count=db.update("account",values,"_id=?",new String[]{account.getId()+""});        db.close();        return count;    }    public List<Account>queryAll(){        SQLiteDatabase db=helper.getWritableDatabase();        Cursor cursor=db.query("account",null,null,null,null,null,"balance DESC");        List<Account> list=new ArrayList<Account>();        while (cursor.moveToNext()){            //可以根据列名获取索引            long id=cursor.getLong(cursor.getColumnIndex("id"));            String name=cursor.getString(1);            int balance=cursor.getInt(2);            list.add(new Account(id,name,balance));        }        cursor.close();        db.close();        return list;    }}
6.编写界面交互代码
package com.example.bz0209.shangpin;import android.app.Activity;import android.content.DialogInterface;import android.support.v7.app.AlertDialog;import android.support.v7.app.AppCompatActivity;import android.os.Bundle;import android.view.View;import android.view.ViewGroup;import android.widget.Adapter;import android.widget.AdapterView;import android.widget.BaseAdapter;import android.widget.EditText;import android.widget.ImageView;import android.widget.ListAdapter;import android.widget.ListView;import android.widget.TextView;import android.widget.Toast;import com.example.bz0209.shangpin.cn.itcast.product.dao.Account;import com.example.bz0209.shangpin.cn.itcast.product.dao.AccountDao;import java.util.List;public class MainActivity extends AppCompatActivity {    private List<Account> list;    private AccountDao dao;    private EditText nameET;    private EditText balabceET;    private MyAdapter adapter;    private ListView accountLV;    @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((ListAdapter) adapter);    }    private void initView(){        accountLV=(ListView) findViewById(R.id.accountLV);        nameET=(EditText) findViewById(R.id.ETName);        balabceET=(EditText) findViewById(R.id.ETBalance);        accountLV.setOnItemClickListener(new MyOnItemClickListener());    }    public void add(View v){        String name=nameET.getText().toString().trim();        String balance=balabceET.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("");        balabceET.setText("");    }    private class MyAdapter extends BaseAdapter {        @Override        public int getCount() {            return list.size();        }        @Override        public Object getItem(int position) {            return list.get(position);        }        @Override        public long getItemId(int position) {            return position;        }        //获取一个条目视图        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.textView1);            TextView nameTV=(TextView) findViewById(R.id.textView2);            TextView balanceTV=(TextView) findViewById(R.id.textView3);            final Account a=list.get(position);            idTV.setText(a.getId()+"");            nameTV.setText(a.getName());            balanceTV.setText(a.getBalamce()+"");            ImageView upIV=(ImageView)item.findViewById(R.id.imageView1);            ImageView downTV=(ImageView)item.findViewById(R.id.imageView2);            ImageView deleteTV=(ImageView)item.findViewById(R.id.imageView);            upIV.setOnClickListener(new View.OnClickListener() {                @Override                public void onClick(View v) {                    a.setBalamce(a.getBalamce()+1);                    notifyDataSetChanged();                    dao.update(a);                }            });            downTV.setOnClickListener(new View.OnClickListener() {                @Override                public void onClick(View v) {                    a.setBalamce(a.getBalamce()-1);                    notifyDataSetChanged();                    dao.update(a);                }            });            deleteTV.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;        }    }    //ListView 的item 点击事件    private class MyOnItemClickListener implements AdapterView.OnItemClickListener{        public void onItemClick(AdapterView<?> parent,View view,int position,long id){            //获取点击位置上的数据            Account a=(Account) parent.getItemAtPosition(position);            Toast.makeText(getApplicationContext(),a.toString(),Toast.LENGTH_SHORT).show();        }    }}
运行结果如下：

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