android基本方式对数据库的操作

person表:

create table person(

_id integer primary key autoincrement,

name varchar(20),

age integer

);

<span style="font-size:14px;">package com.sqf.sql.db;

import android.content.Context;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteDatabase.CursorFactory;
import android.database.sqlite.SQLiteOpenHelper;
import android.util.Log;

/**
* 数据库帮助类，用于创建和管理数据库
* */
public class PersonSQLiteOpenHelper extends SQLiteOpenHelper{

private static final String TAG = "PersonSQLiteOpenHelper";

/**
* 构造方法的四个参数
* 1.上下文
* 2.数据库的名称
* 3.游标工程
* 4.数据库的版本，从1开始
* */
public PersonSQLiteOpenHelper(Context context, String name,
CursorFactory factory, int version) {
super(context, "sql.db", null, 2);
}

public PersonSQLiteOpenHelper(Context context) {
super(context, "sql.db", null, 2);
}

/**
* 数据库第一次创建的时，回调此方法
* 初始化一些表
* */
@Override
public void onCreate(SQLiteDatabase db) {

//操作数据库
String sql = "create table person(_id integer primary key autoincrement,name varchar(20),age integer);";
db.execSQL(sql);  //创建person表
}

/**
* 数据库版本号更新时回调此方法
* 更新数据库的内容(删除表，修改表，添加表)
* */
@Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {

if(oldVersion == 1 && newVersion == 2){ //在person表中添加余额列balance
Log.i(TAG, "数据库更新了");

//在person表添加一列
db.execSQL("alter table person add balance integer;");
}

}

}
</span>

<span style="font-size:14px;">package com.sqf.sql.dao;

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

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

import com.sqf.sql.db.PersonSQLiteOpenHelper;
import com.sqf.sql.entities.Person;

public class PersonDao {

PersonSQLiteOpenHelper mOpenHelper;//数据库的帮助类

public PersonDao(Context context){
mOpenHelper = new PersonSQLiteOpenHelper(context);
}

/**
* 添加到person表一条数据
* */
public void insert(Person person){

SQLiteDatabase db = mOpenHelper.getWritableDatabase();
if(db.isOpen()){  //如果数据库打开

//db.execSQL("insert into person(name,age) values('lisi','1');");

//执行添加到数据库的操作
db.execSQL("insert into person(name,age) values(?,?)", new Object[]{person.getName(),person.getAge()});

db.close(); //数据库关闭
}
}

public void delete(int id){
SQLiteDatabase db = mOpenHelper.getWritableDatabase();//获得可写入数据库对象
if(db.isOpen()){
db.execSQL("delete from person where _id = ?", new Integer[]{id});

db.close();
}

}

public void update(int id,String name){
SQLiteDatabase db = mOpenHelper.getWritableDatabase();

if(db.isOpen()){
db.execSQL("update person set name = ? where id = ?", new Object[]{name,id});
db.close();
}

}

public List<Person>	 queryAll(){
SQLiteDatabase db = mOpenHelper.getReadableDatabase();
if(db.isOpen()){

Cursor cursor = db.rawQuery("select _id,name,age from person", null);// 没有?  第二个参数为nul
if(cursor != null && cursor.getCount() > 0){

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

int id;
String name;
int age;
while(cursor.moveToNext()){
id = cursor.getInt(0); //取第0列的数据id
name = cursor.getString(1);
age = cursor.getInt(2);
personList.add(new Person(id,name,age));
}
db.close();
return personList;
}

db.close();
}

return null;
}

public Person queryItem(int id){
SQLiteDatabase db = mOpenHelper.getReadableDatabase();
if(db.isOpen()){
Cursor cursor = db.rawQuery("select _id,name,age from person where _id = ?", new String[]{id+""});

if(cursor != null && cursor.moveToFirst()){
int _id = cursor.getInt(0);
String name = cursor.getString(1);
int age = cursor.getInt(2);

db.close();
return new Person(_id,name,age);
}

db.close();
}

return null;
}

}
</span>

<span style="font-size:14px;">package com.sqf.sql.entities;

public class Person {

private int id;
private String name;
private int age;
public int getId() {
return id;
}
public void setId(int id) {
this.id = id;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public int getAge() {
return age;
}
public void setAge(int age) {
this.age = age;
}
@Override
public String toString() {
return "Person [id=" + id + ", name=" + name + ", age=" + age + "]";
}
public Person(int id, String name, int age) {
super();
this.id = id;
this.name = name;
this.age = age;
}
public Person() {
super();
}

}
</span>

Junit测试:

package com.sqf.sql.test;

import java.util.List;

import com.sqf.sql.dao.PersonDao;
import com.sqf.sql.db.PersonSQLiteOpenHelper;
import com.sqf.sql.entities.Person;

import android.database.SQLException;
import android.database.sqlite.SQLiteDatabase;
import android.test.AndroidTestCase;
import android.util.Log;

public class TestCase extends AndroidTestCase {

private static final String TAG = "TestCase";

public void test(){

//数据库什么时候创建
PersonSQLiteOpenHelper openHelper = new PersonSQLiteOpenHelper(getContext());
// 第一次连接数据库时创建数据库文件，并调用onCreate
openHelper.getReadableDatabase();
}

public void testInsert(){
PersonDao dao = new PersonDao(getContext());

for(int i=0;i<20;i++){
dao.insert(new Person(i,"大话"+i,20));
}
}

public void testDelete(){
PersonDao dao = new PersonDao(getContext());
dao.delete(1);
}

public void testUpdate(){
PersonDao dao = new PersonDao(getContext());
dao.update(2, "哈哈");
}

public void testQueryAll(){
PersonDao dao = new PersonDao(getContext());
List<Person> queryAll = dao.queryAll();

for(Person person:queryAll){
Log.i(TAG, person.toString());
}
}

public void testQuery(){
PersonDao dao = new PersonDao(getContext());
Person person = dao.queryItem(2);
Log.i(TAG, person.toString());
}

public void testTransaction(){
PersonSQLiteOpenHelper openHelper = new PersonSQLiteOpenHelper(getContext());
SQLiteDatabase db = openHelper.getWritableDatabase();

if(db.isOpen()){

try {

//开启事务
db.beginTransaction();

//从张三账户扣除1000
db.execSQL("update person set balance =balance-1000 where name = 'zhangsan'");

//ATM机挂了
//				 int a = 1/0;

//向李四账户加1000
db.execSQL("update person set balance =balance+1000 where name = 'lisi'");

//标记事务成功
db.setTransactionSuccessful();//标记，进行提交

} catch (SQLException e) {
e.printStackTrace();
} finally{
//停止事务
db.endTransaction();
}

db.close();
}

}

public void testTransactionInsert(){
PersonSQLiteOpenHelper openHelper = new PersonSQLiteOpenHelper(getContext());
SQLiteDatabase db = openHelper.getWritableDatabase();
//插入没有开启事务 消耗的毫秒37890
//插入10000条 开启事务    消耗的毫秒6112

if(db.isOpen()){
//1.记录当前时间
long start = System.currentTimeMillis();

//2.开始添加数据
try {
db.beginTransaction();
for(int i=0;i<10000;i++){
db.execSQL("insert into person(name,age,balance) values('wang"+i+"',"+(10+i)+","+(10000+i)+")");
}
db.setTransactionSuccessful();
} catch (SQLException e) {
db.endTransaction();
e.printStackTrace();
}

//3.记录结束时间,计算消耗
long end = System.currentTimeMillis();

long diff = end - start;

Log.i(TAG, "消耗的毫秒" + diff);

db.close();
}
}

}