Android（三）数据存储之三SQLite嵌入式数据库 2

4.编写ContactsService类

       ContactsService类主要实现对业务逻辑和数据库的操作。

package com.changcheng.sqlite.service;

 

import java.util.ArrayList;

import java.util.List;

import android.content.Context;

import android.database.Cursor;

import com.changcheng.sqlite.MyOpenHelper;

import com.changcheng.sqlite.entity.Contact;

 

public class ContactsService {

 

         private MyOpenHelper openHelper;

 

         public ContactsService(Context context) {

                   this.openHelper = new MyOpenHelper(context);

         }

 

         /**

          * 保存

          *

          * @param contact

          */

         public void save(Contact contact) {

                   String sql = "INSERT INTO contacts (name, phone) VALUES (?, ?)";

                   Object[] bindArgs = { contact.getName(), contact.getPhone() };

                   this.openHelper.getWritableDatabase().execSQL(sql, bindArgs);

         }

 

         /**

          * 查找

          *

          * @param id

          * @return

          */

         public Contact find(Integer id) {

                   String sql = "SELECT _id,name, phone FROM contacts WHERE _id=?";

                   String[] selectionArgs = { id + "" };

                   Cursor cursor = this.openHelper.getReadableDatabase().rawQuery(sql,

                                     selectionArgs);

                   if (cursor.moveToFirst())

                            return new Contact(cursor.getInt(0), cursor.getString(1), cursor

                                               .getString(2));

                   return null;

         }

 

         /**

          * 更新

          *

          * @param contact

          */

         public void update(Contact contact) {

                   String sql = "UPDATE contacts SET name=?, phone=? WHERE _id=?";

                   Object[] bindArgs = { contact.getName(), contact.getPhone(),

                                     contact.get_id() };

                   this.openHelper.getWritableDatabase().execSQL(sql, bindArgs);

         }

 

         /**

          * 删除

          *

          * @param id

          */

         public void delete(Integer id) {

                   String sql = "DELETE FROM contacts WHERE _id=?";

                   Object[] bindArgs = { id };

                   this.openHelper.getReadableDatabase().execSQL(sql, bindArgs);

         }

 

         /**

          * 获取记录数量

          *

          * @return

          */

         public long getCount() {

                   String sql = "SELECT count(*) FROM contacts";

                   Cursor cursor = this.openHelper.getReadableDatabase().rawQuery(sql,

                                     null);

                   cursor.moveToFirst();

                   return cursor.getLong(0);

         }

 

         /**

          * 获取分页数据

          *

          * @param startIndex

          * @param maxCount

          * @return

          */

         public List<Contact> getScrollData(long startIndex, long maxCount) {

                   String sql = "SELECT _id,name,phone FROM contacts LIMIT ?,?";

                   String[] selectionArgs = { String.valueOf(startIndex),

                                     String.valueOf(maxCount) };

                   Cursor cursor = this.openHelper.getReadableDatabase().rawQuery(sql,

                                     selectionArgs);

                   List<Contact> contacts = new ArrayList<Contact>();

                   while (cursor.moveToNext()) {

                            Contact contact = new Contact(cursor.getInt(0),

                                               cursor.getString(1), cursor.getString(2));

                            contacts.add(contact);

                   }

                   return contacts;

         }

 

         /**

          * 获取分页数据，提供给SimpleCursorAdapter使用。

          *

          * @param startIndex

          * @param maxCount

          * @return

          */

         public Cursor getScrollDataCursor(long startIndex, long maxCount) {

                   String sql = "SELECT _id,name,phone FROM contacts LIMIT ?,?";

                   String[] selectionArgs = { String.valueOf(startIndex),

                                     String.valueOf(maxCount) };

                   Cursor cursor = this.openHelper.getReadableDatabase().rawQuery(sql,

                                     selectionArgs);

                   return cursor;

         }

}

 

       5.编写测试类

       编写一个针对ContactsService的测试类，测试ContactsService类中的各个方法是否正确。

package com.changcheng.sqlite.test;

 

import java.util.List;

import com.changcheng.sqlite.MyOpenHelper;

import com.changcheng.sqlite.entity.Contact;

import com.changcheng.sqlite.service.ContactsService;

import android.database.Cursor;

import android.test.AndroidTestCase;

import android.util.Log;

 

public class ContactsServiceTest extends AndroidTestCase {

 

         private static final String TAG = "ContactsServiceTest";

 

         // 测试创建表

         public void testCreateTable() throws Throwable {

                   MyOpenHelper openHelper = new MyOpenHelper(this.getContext());

                   openHelper.getWritableDatabase();

         }

 

         // 测试save

         public void testSave() throws Throwable {

                   ContactsService contactsService = new ContactsService(this.getContext());

                   Contact contact1 = new Contact(null, "tom", "13898679876");

                   Contact contact2 = new Contact(null, "lili", "13041094909");

                   Contact contact3 = new Contact(null, "jack", "13504258899");

                   Contact contact4 = new Contact(null, "heary", "1335789789");

                   contactsService.save(contact1);

                   contactsService.save(contact2);

                   contactsService.save(contact3);

                   contactsService.save(contact4);

         }

 

         // 测试find

         public void testFind() throws Throwable {

                   ContactsService contactsService = new ContactsService(this.getContext());

                   Contact contact = contactsService.find(1);

                   Log.i(TAG, contact.toString());

         }

 

         // 测试update

         public void testUpdate() throws Throwable {

                   ContactsService contactsService = new ContactsService(this.getContext());

                   Contact contact = contactsService.find(1);

                   contact.setPhone("1399889955");

                   contactsService.update(contact);

         }

 

         // 测试getCount

         public void testGetCount() throws Throwable {

                   ContactsService contactsService = new ContactsService(this.getContext());

                   Log.i(TAG, contactsService.getCount() + "");

         }

 

         // 测试getScrollData

         public void testGetScrollData() throws Throwable {

                   ContactsService contactsService = new ContactsService(this.getContext());

                   List<Contact> contacts = contactsService.getScrollData(0, 3);

                   Log.i(TAG, contacts.toString());

         }

        

         // 测试getScrollDataCursor

         public void testGetScrollDataCursor() throws Throwable {

                   ContactsService contactsService = new ContactsService(this.getContext());

                   Cursor cursor = contactsService.getScrollDataCursor(0, 3);

                   while (cursor.moveToNext()) {

                            Contact contact = new Contact(cursor.getInt(0),

                                               cursor.getString(1), cursor.getString(2));

                            Log.i(TAG, contact.toString());

                   }

         }

 

}

       启用测试功能，不要忘记在AndroidManifest.xml文件中加入测试环境。为application元素添加一个子元素：<uses-library android:name="android.test.runner"/>，为application元素添加一个兄弟元素：<instrumentation android:name="android.test.InstrumentationTestRunner"     android:targetPackage="com.changcheng.sqlite" android:label="Tests for My App" />。

 

       SQLite数据库以单个文件存储，就像微软的Access数据库。有一个查看SQLite数据库文件的工具——SQLite Developer，我们可以使用它来查看数据库。Android将创建的数据库存放在”/data/data/ com.changcheng.sqlite/databases/contacts”，我们将它导出然后使用SQLite Developer打开。

 

       6.分页显示数据

       我们在ContactsService类中，提供了一个获取分页数据的方法。我们将调用它获取的数据，使用ListView组件显示出来。

 

       编辑mail.xml：

<?xml version="1.0" encoding="utf-8"?>

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"

         android:orientation="vertical" android:layout_width="fill_parent"

         android:layout_height="fill_parent">

         <!-- ListView -->

         <ListView android:layout_width="fill_parent"

                   android:layout_height="fill_parent" android:id="@+id/listView" />

 

</LinearLayout>