SQLite数据库---ListView控件之商品展示案例
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转自:http://blog.csdn.net/winnie_hu/article/details/70254380?locationNum=10&fps=1
运用ListView控件在界面上操作数据库。开发一个购物车,需要将购物车中的商品以陈列的形式展示,并且还需要对购物车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”案例实现在界面上的操作数据库。具体步骤如下:
1.创建程序
首先创建程序,修改包名,设计用户交互界面。此程序对应的布局文件(activity_main.xml)如下所示:
- <span style="font-size:18px;"><?xml version="1.0" encoding="utf-8"?>
- <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
- xmlns:app="http://schemas.android.com/apk/res-auto"
- xmlns:tools="http://schemas.android.com/tools"
- android:layout_width="match_parent"
- android:layout_height="match_parent"
- android:layout_margin="8dp"
- android:orientation="vertical"
- tools:context=".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:id="@+id/addIV"
- android:layout_width="wrap_content"
- android:layout_height="wrap_content"
- android:onClick="add"
- 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></span>
android:src="@android:drawable/ic_input_add" 显示图片的原图大小效果图展示:
2.创建ListView
Item布局 在res/layout下创建一个item.xml文件,创建三个TextView和三个ImageView,代码如下:
- <span style="font-size:18px;"><?xml version="1.0" encoding="utf-8"?>
- <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
- xmlns:app="http://schemas.android.com/apk/res-auto"
- android:orientation="horizontal"
- android:layout_width="match_parent"
- android:layout_height="wrap_content"
- 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:singleLine="true"
- android:text="PQ"
- 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:singleLine="true"
- android:text="12345"
- android:textColor="#000000"
- android:textSize="20sp" />
-
- <LinearLayout
- android:layout_width="wrap_content"
- android:layout_height="wrap_content"
- android:orientation="vertical" >
-
- <ImageView
- 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" />
- </LinearLayout>
-
- <ImageView
- android:id="@+id/deleteIV"
- android:layout_width="25dp"
- android:layout_height="25dp"
- android:src="@android:drawable/ic_menu_delete" />
-
- </LinearLayout></span>
添加的三个TextView分别用于显示数据库中的某条数据的id,商品名称,金额。添加的三个ImageView用于增加金额,减少金额,删除数据。
效果图展示:
3.创建数据库
创建数据库属于数据操作,因此需要在cn.edu.bzu.productshow包下创建一个名为Dao的包。并在该包下定义一个MyHelper类继承自SQLiteOpenHelper,创建数据库的代码如下:
- package cn.edu.bzu.productshow.Dao;
-
- import android.content.Context;
- import android.database.sqlite.SQLiteDatabase;
- import android.database.sqlite.SQLiteOpenHelper;
- import android.util.Log;
-
- import cn.edu.bzu.productshow.MainActivity;
-
- public class MyHelper extends SQLiteOpenHelper{
-
- public MyHelper(Context context) {
- super(context, "product.db", null, 2);
- }
-
- @Override
- public void onCreate(SQLiteDatabase db) {
- Log.d("MyHelper","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) {
- Log.d("MyHelper","OnUpgrade");
- }
- }
4.创建Account类
在操作数据库时将数据存放至一个JavaBean对象操作起来比较方便。因此需要在cn.edu.bzu.productshow包下创建一个Bean包用于存放JavaBean类,然后在cn.edu.bzu.productshow.Bean包下定义一个类Account。具体代码如下:
- package cn.edu.bzu.productshow.Bean;
-
- 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 Integer getBalance() {
- return balance;
- }
-
- public void setBalance(Integer balance) {
- if(balance>=0)
- this.balance = balance;
- }
-
- public String getName() {
- return name;
- }
-
- public void setName(String name) {
- this.name = name;
- }
-
- public Account(long id, String name, Integer balance) {
- super();
- this.balance = balance;
- this.name = name;
- this.id = id;
- }
-
- 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.创建数据操作逻辑类
在cn.edu.bzu.productshow.Dao包下创建一个AccountDao类用于操作数据。具体代码如下:
- <span style="font-size:18px;">package cn.edu.bzu.productshow.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 cn.edu.bzu.productshow.Bean.Account;
-
- 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<Account>();
- 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;
- }
- }</span>
上述代码是操作数据库的逻辑类AccountDao。该类创建了对数据库的增删改查操作的方法。
6.编写页面交互代码
数据库操作完成之后需要界面与数据库交互,用于实现将数据库中的数据以ListView的形式展示在界面上,具体代码如下所示:
- <span style="font-size:14px;">package cn.edu.bzu.productshow;
- import android.app.Activity;
- import android.app.AlertDialog.Builder;
- import android.content.DialogInterface;
- import android.os.Bundle;
- import android.view.View;
- import android.view.View.OnClickListener;
- import android.view.ViewGroup;
- import android.widget.AdapterView;
- import android.widget.AdapterView.OnItemClickListener;
- 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 cn.edu.bzu.productshow.Bean.Account;
-
- import java.util.List;
- import java.util.Locale;
-
- import cn.edu.bzu.productshow.Dao.AccountDao;
-
- public class MainActivity extends Activity {
-
- private List<Account> list;
-
- private AccountDao dao;
-
- private EditText nameET;
-
- private EditText balanceET;
-
- 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(adapter);
- }
-
- 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();
- if("".equals(name)||"".equals(balance))
- {
- Toast.makeText(getApplicationContext(),"商品名称和金额不能为空",Toast.LENGTH_LONG).show();
- return;
- }
-
-
- 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("");
- }
-
- 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 upTV=(ImageView) item.findViewById(R.id.upIV);
- ImageView downTV=(ImageView) item.findViewById(R.id.downIV);
- ImageView deleteTV=(ImageView) item.findViewById(R.id.deleteIV);
-
- upTV.setOnClickListener(new View.OnClickListener() {
- @Override
- public void onClick(View v) {
- a.setBalance(a.getBalance()+1)n
- notifyDataSetChanged();
- dao.update(a);
- }
- });
-
- upTV.setOnClickListener(new View.OnClickListener() {
- @Override
- public void onClick(View v) {
- a.setBalance(a.getBalance()-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();
- }
- };
-
- Builder builder =new 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 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_SHORT).show();
- }
- }
- }
- </span>
7.运行程序展示商品信息
运行程序时首先添加商品名称以及金额,点击加号就会将Edittext中输入的内容添加至数据库并显示适配到ListView中。多添加几条数据,然后点击某条数据的向上的按钮,金额就会增加。向下按钮同理。点击某条数据的删除图案,会弹出一个对话框,确认后就能删除数据了。单击某条数据室,会弹出toast。
添加 多添加几条数据 向上使金额增加
显示属性 删除提示 删除成功