案例—商品展示

首先创建一个名为“商品展示”的应用程序，将包名修改为cn.itcast.product.代码如下

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
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"
<
11980
/strong>[b]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>

创建ListView Item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="wrap_content"
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: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>

创建数据库

package cn.itcast.product.dao;

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

public class MyHelper extends SQLiteOpenHelper {

public MyHelper(Context context) {
super(context, "itcast.db", null, 2);
}

public void onCreate(SQLiteDatabase db) {
System.out.println("onCreate");
db.execSQL("CREATE TABLE account(_id INTEGER PRIMARY KEY AUTOINCREMENT,"
+ "name VARCHAR(20)," +
"balance INTEGER)");
}

public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
System.out.println("onUpgrade");
}
}myhelper类继承自sqliteopenhelper

创建Account类

ackage cn.itcast.product.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 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 "[���: " + id + ", ��Ʒ��������: " + name + ", ���: " + balance + "]";
}
}

创建数据操作逻辑类

package cn.itcast.product.dao;

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

import android.content.ContentValues;
import android.content.Context;
import android.database.Cursor;
import android.database.sqlite.SQLiteDatabase;
import cn.itcast.product.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.getReadableDatabase();
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;
}
}

编写界面交互代码

package cn.itcast.product;

import java.util.List;

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.itcast.product.bean.Account;
import cn.itcast.product.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;

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();

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 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 OnClickListener() {
public void onClick(View v) {
a.setBalance(a.getBalance() + 1);
notifyDataSetChanged();
dao.update(a);
}
});

downIV.setOnClickListener(new OnClickListener() {
public void onClick(View v) {
a.setBalance(a.getBalance() - 1);
notifyDataSetChanged();
dao.update(a);
}
});

deleteIV.setOnClickListener(new OnClickListener() {
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("ȷ��Ҫɾ����?");

builder.setPositiveButton("ȷ��", listener);
builder.setNegativeButton("ȡ��", 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();
}
}
}

就是这样了。这样就能完整的跑出来了。