android kotlin用room实现数据库实现登录验证和注册界面
room数据库的配置
1room数据库使用前的准备工作
1在App下的build.gradle.kt中加入room数据库的依赖
//在plugin中加入kapt插件，否则会报错
apply plugin :'kotlin-kapt'
//在depedence中加入room数据库的依赖
implementation ("androidx.room:room-runtime:2.3.0")
annotationProcessor ("androidx.room:room-compiler:2.3.0")
implementation ("androidx.room:room-ktx:2.3.0")
kapt ("androidx.room:room-compiler:2.3.0")
//协程的依赖
implementation ("org.jetbrains.kotlinx:kotlinx-coroutines-android:1.1.1")
//引入lifecycle的依赖
implementation("androidx.lifecycle:lifecycle-runtime-ktx:2.3.1")
2准备数据库中存放数据的实体类，表名并且不指定的话，默认为实体类的姓名
import androidx.room.Entity
import androidx.room.PrimaryKey
@Entity
class User(var username: String, var password: String) {
@PrimaryKey(autoGenerate = true)
var id: Long = 0
override fun toString(): String {
return "id为：${id}用户名为：$username:密码为$password"
}
}
3准备和数据库进行交互的dao接口
import androidx.room.*
import com.mykotlintest.database.entity.User
@Dao
interface UserDao {
@Insert
fun insertUser(user: User):Long
@Update
fun updateUser(user:User):Int
@Query("select * from User")
fun queryAllUser():List<User>
@Delete()
fun deleteUser(user: User):Int
@Query("delete from User where username=:name")
fun deleteByName(name:String):Int
@Query("select id,username,password from User where username=:name")
fun queryUserByName(name:String):User
//验证密码对不对所以需要进行一个按照密码和用户名的查询
@Query("select id,username,password from User where username=:name and password=:password")
fun queryUserByName(name:String,password:String):User
}
4数据库的创建，并且在后期进行表的修改和添加时，按照如下方法进行数据库的更新操作
import android.content.Context
import androidx.room.Database
import androidx.room.Room
import androidx.room.RoomDatabase
import androidx.room.migration.Migration
import androidx.sqlite.db.SupportSQLiteDatabase
import com.mykotlintest.database.dao.FriendDao
import com.mykotlintest.database.dao.MessageDao
import com.mykotlintest.database.dao.UserDao
import com.mykotlintest.database.entity.Address
import com..mykotlintest.database.entity.Friend
import com.mykotlintest.database.entity.User
import com.mykotlintest.entity.Messages
@Database(version = 4, entities = [User::class,Friend::class,Messages::class], exportSchema = false)
abstract class AppDatabase : RoomDatabase() {
abstract fun userDao(): UserDao
//abstract fun addressDao(): AddressDao
abstract fun friendDao():FriendDao
abstract fun messageDao():MessageDao
companion object {
private var instance: AppDatabase? = null
//新增表时只需要将Migrate重写，然后重写方法，migrate,
/* private var Migrate_1_2=object : Migration(1,2){
override fun migrate(database: SupportSQLiteDatabase) {
database.execSQL("create table Address (id integer primary key autoincrement not null, name text not null, image text not null)" )
}
}*/
//新增一个friend表，用来在address界面点击friendList时，展现出friend的具体信息是什么
private var Migrate_2_3=object : Migration(2,3){
override fun migrate(database: SupportSQLiteDatabase) {
database.execSQL("create table Friend(id integer primary key autoincrement not null, name text not null,gender integer not null,nickname text not null," +
"wechatNum text not null,address text not null,avatar integer not null)" )
}
}
//新增了一个消息表。里面存放了和所有人的消息，根据用户的姓名和类别区分，如果是0.说明是发送的消息，如果是1，则是接收的消息
private var Migrate_3_4=object : Migration(3,4){
override fun migrate(database: SupportSQLiteDatabase) {
database.execSQL("create table Messages(id integer primary key autoincrement not null, name text not null,message text not null,type integer not null)" )
}
}
//kotlin的正规双重校验锁写法
fun getDatabaseSingleton2(context: Context): AppDatabase =
instance ?: synchronized(AppDatabase::class.java) {
instance ?: Room.databaseBuilder(
context.applicationContext,
AppDatabase::class.java,
"app__lang_database"
).addMigrations( Migrate_2_3, Migrate_3_4).allowMainThreadQueries().build().also {
instance = it
}
}
//返回一个数据库实例，单利模式，如果没创建过，就新创建一个名字为app_lang_database的数据库
@Synchronized
fun getDatabase(context: Context): AppDatabase {
instance?.let {
return it
}
return Room.databaseBuilder(
context.applicationContext,
AppDatabase::class.java,
"app__lang_database"
).allowMainThreadQueries()
.build().apply {
instance = this
}
}
//写一个双重校验的单利模式
fun getDatabaseSingleton(context: Context): AppDatabase {
if (instance == null) {
synchronized(AppDatabase::class.java) {
if (instance == null) {
instance = Room.databaseBuilder(
context.applicationContext,
AppDatabase::class.java,
"app__lang_database"
).allowMainThreadQueries().build()
.apply {
instance = this }
}
}
}
return instance!!
}
}
}
2room数据库的使用
1安装查看数据库是否创建成功的插件Database Navigator
Database Navigator添加插件成功后,DBManager会出现在Android Studio的左上角
2在逻辑代码中引入数据库的使用
1登录界面的layout
import android.content.Intent
import androidx.appcompat.app.AppCompatActivity
import android.os.Bundle
import android.text.method.HideReturnsTransformationMethod
import android.text.method.PasswordTransformationMethod
import android.view.MotionEvent
import android.view.View
import android.widget.Button
import android.widget.EditText
import android.widget.ImageView
import android.widget.TextView
import androidx.annotation.CallSuper
import com.mykotlintest.database.dao.UserDao
import com.mykotlintest.database.database.AppDatabase
import com.mykotlintest.recycle.NewsMainActivity
import com.mykotlintest.util.KeyboardSetting
import com.mykotlintest.util.KeyboardUtils
class MainActivity : AppCompatActivity() {
var count = 0;
var showPassword = false
//private lateinit var password:EditText
lateinit var name:EditText
lateinit var btnGoToRegister:Button
//创建出dao接口
private lateinit var userDao:UserDao
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
setContentView(R.layout.activity_main)
name =findViewById<EditText>(R.id.textOfName)
name.setText(intent?.getStringExtra("username"))
//实例化dao接口
userDao=AppDatabase.getDatabaseSingleton2(this).userDao()
//这里需要想恢复出用户名
btnGoToRegister=findViewById(R.id.goToRegister)
btnGoToRegister.setOnClickListener {
startActivityForResult(Intent(this,RegisterActivity::class.java),1)
}
}
//为当前确定登录按钮绑定监听事件
fun sureBtn1(view: View) {
var name =findViewById<TextView>(R.id.textOfName)
var password = findViewById<EditText>(R.id.textOfPassWord)
var message = findViewById<TextView>(R.id.mess)
var forgetPW=findViewById<TextView>(R.id.forgetPW)
/*
* 需要变化的资源，希望从一个锁定的状态变成一个解锁的状态，然后又可以点击后面的眼睛按钮，使密码进行显示
* */
var lockOpen = getDrawable(R.drawable.ic_baseline_lock_open_24)
var text = name.text.toString()
var text1 =password.text.toString()
//从数据库中查找是否存在当前用户，判断用户名和密码是否正确
if (userDao.queryUserByName(text,text1)!=null) {
var intent = Intent(this@MainActivity, ThanksActivity::class.java)
intent.putExtra("name", text)
//传递参数到另一个界面上
startActivity(intent)
} else {
count++
if (count < 10) {
message.setText("密码或用户名有误,你还有${10 - count}次机会")
password.setText("")
forgetPW.setText("忘记密码？点击找回")
} else {
message.setText("已锁定，请在10分钟后重试")
}
}
}
}
一旦执行此activity,就会创建出数据库，此时数据库就会创建成功，表也会按照实体类的字段属性自动创建出一张表，然后根据安装后的插件DB Browser，就可以查看出自己创建的表内的信息。