实例教程六：创建数据库与完成数据添删改查--第一种写法

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

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

package="cn.itcast.db"

android:versionCode="1"

android:versionName="1.0" >

<uses-sdk android:minSdkVersion="8" />

<application

android:icon="@drawable/ic_launcher"

android:label="@string/app_name" >

<activity

android:name=".MainActivity"

android:label="@string/app_name" >

<intent-filter>

<action android:name="android.intent.action.MAIN" />

<category android:name="android.intent.category.LAUNCHER" />

</intent-filter>

</activity>

<uses-library android:name="android.test.runner"/>

</application>

<instrumentation android:name="android.test.InstrumentationTestRunner"

android:targetPackage="cn.itcast.db" android:label="Tests for My App"></instrumentation>

</manifest>

package cn.itcast.db;

import android.app.Activity;

import android.os.Bundle;

public class MainActivity extends Activity {

/** Called when the activity is first created. */

@Override

public void onCreate(Bundle savedInstanceState) {

super.onCreate(savedInstanceState);

setContentView(R.layout.main);

}

//在Android平台上，集成了一个嵌入式关系型数据库——SQLite

//SQLite3支持NULL、INTEGER、REAL(浮点数字)、TEXT(字符串文本)和BLOB(二进制对象)数据类型

//虽然它支持的类型只有5种，但实际上sqlite3也接受varchar(n)、char(n)、decimal(p, s)等数据

//只不过在运行或保存时会转成对应的五种数据类型

//SQLite最大的特点是你可以把各种类型的数据保存到任何字段中，而不用关心字段声明的数据类型是什么

}

package cn.itcast.domain;

public class Person {

private Integer id;

private String name;

private String phone;

public Person(String name, String phone){

this.name = name;

this.phone = phone;

}

public Person(Integer id, String name, String phone){

this.id = id;

this.name = name;

this.phone = phone;

}

public Integer getId() {

return id;

}

public void setId(Integer id) {

this.id = id;

}

public String getName() {

return name;

}

public void setName(String name) {

this.name = name;

}

public String getPhone() {

return phone;

}

public void setPhone(String phone) {

this.phone = phone;

}
}

package cn.itcast.service;

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

public class DBOpenHelper extends SQLiteOpenHelper{

private static final int VERSION = 2; //数据库版本

public DBOpenHelper(Context context){
super(context, "itcast.db", null, VERSION); //<包>/database/

}

@Override

public void onCreate(SQLiteDatabase db) { //是在数据库第一次被创建的时候调用的

db.execSQL("CREATE TABLE person(personId integer primary key autoincrement, " + "name varchar(20))");
}

@Override

public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) { //数据库版本号发生改变的时候调用的
db.execSQL("ALTER TABLE person ADD phone VARCHAR(12) NULL");

}

}

package cn.itcast.service;

import java.util.ArrayList;
import java.util.List;
import android.content.Context;
import android.database.Cursor;
import android.database.sqlite.SQLiteDatabase;
import cn.itcast.domain.Person;

public class PersonService {

private DBOpenHelper dbOpenHelper;
public PersonService(Context context){

this.dbOpenHelper = new DBOpenHelper(context);
}

/**
* 添加记录
* @param person
*/

public void save(Person person){

SQLiteDatabase db = dbOpenHelper.getWritableDatabase();
db.execSQL("insert into person(name, phone) values(?, ?)",new Object[]{person.getName(), person.getPhone()});

//如果只在一个类中使用db，则不需要关闭，提高性能
//但是若是多处使用，则需要关闭

//                db.close();
}

/**
* 删除记录
* @param id 记录ID
*/

public void delete(Integer id){

SQLiteDatabase db = dbOpenHelper.getWritableDatabase();
db.execSQL("delete from person where personId=?", new Object[]{id});

}

/**
* 更新记录
* @param person
*/

public void update(Person person){

SQLiteDatabase db = dbOpenHelper.getWritableDatabase();
db.execSQL("update person set name=?, phone=? where personId=?",
new Object[]{person.getName(), person.getPhone(), person.getId()});

}

/**
* 查询记录
* @param id 记录ID
* @return
*/

public Person find(Integer id){

SQLiteDatabase db = dbOpenHelper.getReadableDatabase();
Cursor cursor = db.rawQuery("select * from person where personId=?", new String[]{id.toString()});

if(cursor.moveToFirst()){

int personId = cursor.getInt(cursor.getColumnIndex("personId"));
String name = cursor.getString(cursor.getColumnIndex("name"));
String phone = cursor.getString(cursor.getColumnIndex("phone"));
return new Person(personId, name, phone);
}

cursor.close();
return null;
}

/**
* 分布获取记录
* @param offset 跳过前面 多少条记录
* @param maxResult 每页获取多少条记录
* @return
*/

public List<Person> getScrollData(int offset, int maxResult){

List<Person> persons = new ArrayList<Person>();

SQLiteDatabase db = dbOpenHelper.getReadableDatabase();
Cursor cursor = db.rawQuery("select * from person order by personId asc limit ?,?",
new String[]{String.valueOf(offset), String.valueOf(maxResult)});

while(cursor.moveToNext()){

int personId = cursor.getInt(cursor.getColumnIndex("personId"));
String name = cursor.getString(cursor.getColumnIndex("name"));
String phone = cursor.getString(cursor.getColumnIndex("phone"));
persons.add(new Person(personId, name, phone));
}

cursor.close();
return null;

}

/**
* 获取记录总数
* @return
*/

public long getCount(){

SQLiteDatabase db = dbOpenHelper.getReadableDatabase();
Cursor cursor = db.rawQuery("select count(*) from person", null);
cursor.moveToFirst();
long result = cursor.getLong(0);
cursor.close();
return result;
}
}

package cn.itcast.test;

import java.util.List;
import cn.itcast.domain.Person;
import cn.itcast.service.DBOpenHelper;
import cn.itcast.service.PersonService;
import android.test.AndroidTestCase;
import android.util.Log;

public class PersonServiceTest extends AndroidTestCase{

private static final String TAG = "PersonServiceTest";

public void testCreateDB() throws Exception{

DBOpenHelper dbOpenHelper = new DBOpenHelper(getContext());
dbOpenHelper.getWritableDatabase();
}

public void testSave() throws Exception{

PersonService service = new PersonService(this.getContext());
for(int i = 0; i < 20; i++){

Person person = new Person("zhangsan", "123456");
service.save(person);
}
}

public void testDelete() throws Exception{

PersonService service = new PersonService(this.getContext());
service.delete(21);
}

public void testUpdate() throws Exception{

PersonService service = new PersonService(this.getContext());
Person person = service.find(1);
person.setName("zhangxiaoxiao");
service.update(person);
}

public void testFind() throws Exception{

PersonService service = new PersonService(this.getContext());
Person person = service.find(1);
Log.i(TAG, person.toString());

}

public void testScrollData() throws Exception{

PersonService service = new PersonService(this.getContext());
List<Person> persons = service.getScrollData(0, 5);
for(Person person : persons){
Log.i(TAG, person.toString());
}
}

public void testCount() throws Exception{

PersonService service = new PersonService(this.getContext());
long result = service.getCount();
Log.i(TAG, result + "");
}

//除了execSQL()和rawQuery方法，还提供了对应于添加、删除、更新、查询的操作方法
//insert(), delete(), update(), query()

}