在安卓开发中默认的数据库是

安卓开发中默认使用的数据库是SQLite，它是一个轻量级的关系型数据库，不需要安装即可使用，是一种自带的数据库管理系统，内建于安卓系统中，可以为应用程序提供简单、可靠的数据存储功能。它支持标准的SQL语句，也可以在应用程序中使用API来 *** 作数据库。它的开发者可以轻松的使用SQLite来创建、修改表，插入数据，查询和更新数据，以及从数据库中删除数据。

Android数据库 *** 作类实例

实体类：UserInfo.java

package my.db

import java.io.Serializable

import android.graphics.drawable.Drawable

public class UserInfo implements Serializable {

public static final String ID = "_id"

public static final String USERID = "userId"

public static final String TOKEN = "token"

public static final String TOKENSECRET = "tokenSecret"

public static final String USERNAME = "userName"

public static final String USERICON = "userIcon"

private String id

private String userId// 用户id

private String token

private String tokenSecret

private String userName

private Drawable userIcon

//getter and setter省略

}

SqliteHelper类：

package my.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

public class SqliteHelper extends SQLiteOpenHelper{

//用来保存UserID、Access Token、Access Secret的表名

public static final String TB_NAME= "users"

public SqliteHelper(Context context, String name, CursorFactory factory, int version) {

super(context, name, factory, version)

}

//创建表

@Override

public void onCreate(SQLiteDatabase db) {

db.execSQL( "CREATE TABLE IF NOT EXISTS "+

TB_NAME+ "("+

UserInfo. ID+ " integer primary key,"+

UserInfo. USERID+ " varchar,"+

UserInfo. TOKEN+ " varchar,"+

UserInfo. TOKENSECRET+ " varchar,"+

UserInfo. USERNAME+ " varchar,"+

UserInfo. USERICON+ " blob"+

")"

)

Log. e("Database" ,"onCreate" )

}

//更新表

@Override

public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {

db.execSQL( "DROP TABLE IF EXISTS " + TB_NAME )

onCreate(db)

Log. e("Database" ,"onUpgrade" )

}

//更新列

public void updateColumn(SQLiteDatabase db, String oldColumn, String newColumn, String typeColumn){

try{

db.execSQL( "ALTER TABLE " +

TB_NAME + " CHANGE " +

oldColumn + " "+ newColumn +

" " + typeColumn

)

} catch(Exception e){

e.printStackTrace()

}

}

}

CRUD类DataHelper:

package my.db

import java.io.ByteArrayInputStream

import java.io.ByteArrayOutputStream

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 android.graphics.Bitmap

import android.graphics.drawable.Drawable

import android.util.Log

public class DataHelper {

// 数据库名称

private static String DB_NAME = "weibo.db"

// 数据库版本

private static int DB_VERSION = 2

private SQLiteDatabase db

private SqliteHelper dbHelper

public DataHelper(Context context) {

dbHelper = new SqliteHelper(context, DB_NAME, null, DB_VERSION )

db = dbHelper.getWritableDatabase()

}

public void Close() {

db.close()

dbHelper.close()

}

// 获取users表中的UserID、Access Token、Access Secret的记录

public List<UserInfo>GetUserList(Boolean isSimple) {

List<UserInfo>userList = new ArrayList<UserInfo>()

Cursor cursor = db.query(SqliteHelper. TB_NAME, null, null , null, null,

null, UserInfo. ID + " DESC")

cursor.moveToFirst()

while (!cursor.isAfterLast() &&(cursor.getString(1) != null )) {

UserInfo user = new UserInfo()

user.setId(cursor.getString(0))

user.setUserId(cursor.getString(1))

user.setToken(cursor.getString(2))

user.setTokenSecret(cursor.getString(3))

if (!isSimple) {

user.setUserName(cursor.getString(4))

ByteArrayInputStream stream = new ByteArrayInputStream(cursor.getBlob(5))

Drawable icon = Drawable.createFromStream(stream, "image")

user.setUserIcon(icon)

}

userList.add(user)

cursor.moveToNext()

}

cursor.close()

return userList

}

// 判断users表中的是否包含某个UserID的记录

public Boolean HaveUserInfo(String UserId) {

Boolean b = false

Cursor cursor = db.query(SqliteHelper. TB_NAME, null, UserInfo.USERID

+ "=?", new String[]{UserId}, null, null, null )

b = cursor.moveToFirst()

Log. e("HaveUserInfo", b.toString())

cursor.close()

return b

}

// 更新users表的记录，根据UserId更新用户昵称和用户图标

public int UpdateUserInfo(String userName, Bitmap userIcon, String UserId) {

ContentValues values = new ContentValues()

values.put(UserInfo. USERNAME, userName)

// BLOB类型

final ByteArrayOutputStream os = new ByteArrayOutputStream()

// 将Bitmap压缩成PNG编码，质量为100%存储

userIcon.compress(Bitmap.CompressFormat. PNG, 100, os)

// 构造SQLite的Content对象，这里也可以使用raw

values.put(UserInfo. USERICON, os.toByteArray())

int id = db.update(SqliteHelper. TB_NAME, values, UserInfo.USERID + "=?" , new String[]{UserId})

Log. e("UpdateUserInfo2", id + "")

return id

}

// 更新users表的记录

public int UpdateUserInfo(UserInfo user) {

ContentValues values = new ContentValues()

values.put(UserInfo. USERID, user.getUserId())

values.put(UserInfo. TOKEN, user.getToken())

values.put(UserInfo. TOKENSECRET, user.getTokenSecret())

int id = db.update(SqliteHelper. TB_NAME, values, UserInfo.USERID + "="

+ user.getUserId(), null)

Log. e("UpdateUserInfo", id + "")

return id

}

// 添加users表的记录

public Long SaveUserInfo(UserInfo user) {

ContentValues values = new ContentValues()

values.put(UserInfo. USERID, user.getUserId())

values.put(UserInfo. TOKEN, user.getToken())

values.put(UserInfo. TOKENSECRET, user.getTokenSecret())

Long uid = db.insert(SqliteHelper. TB_NAME, UserInfo.ID, values)

Log. e("SaveUserInfo", uid + "")

return uid

}

// 添加users表的记录

public Long SaveUserInfo(UserInfo user, byte[] icon) {

ContentValues values = new ContentValues()

values.put(UserInfo. USERID, user.getUserId())

values.put(UserInfo. USERNAME, user.getUserName())

values.put(UserInfo. TOKEN, user.getToken())

values.put(UserInfo. TOKENSECRET, user.getTokenSecret())

if(icon!= null){

values.put(UserInfo. USERICON, icon)

}

Long uid = db.insert(SqliteHelper. TB_NAME, UserInfo.ID, values)

Log. e("SaveUserInfo", uid + "")

return uid

}

// 删除users表的记录

public int DelUserInfo(String UserId) {

int id = db.delete(SqliteHelper. TB_NAME,

UserInfo. USERID + "=?", new String[]{UserId})

Log. e("DelUserInfo", id + "")

return id

}

public static UserInfo getUserByName(String userName,List<UserInfo>userList){

UserInfo userInfo = null

int size = userList.size()

for( int i=0i<sizei++){

if(userName.equals(userList.get(i).getUserName())){

userInfo = userList.get(i)

break

}

}

return userInfo

}

}

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