Android: the kotlin language uses grendao3, a cross platform app development framework

apply plugin: ‘org.greenrobot.greendao’

greendao {

// Database schema edition , It can also be understood as the database version number

schemaVersion 1

// Set up DaoMaster、DaoSession、Dao Package name , That is, the full path of the package where these classes are to be placed .

daoPackage ‘tsou.com.simple.greendaoforkotlin.greendao’

// Set up DaoMaster、DaoSession、Dao Catalog

targetGenDir ‘src/main/java’

}

dependencies

compile ‘org.greenrobot:greendao:3.2.0’

}

• In the project build.gradle in

buildscript {

ext.kotlin_version = ‘1.1.50’

repositories {

mavenCentral()

google()

jcenter()

}

dependencies {

classpath ‘com.android.tools.build:gradle:3.0.0-beta7’

classpath “org.jetbrains.kotlin:kotlin-gradle-plugin:$kotlin_version”

classpath ‘org.greenrobot:greendao-gradle-plugin:3.2.0’

// NOTE: Do not place your application dependencies here; they belong

// in the individual module build.gradle files

}

}

Step two 、 establish Student Entity class

---

package tsou.com.simple.greendaoforkotlin.bean;

import android.support.annotation.Keep;

import org.greenrobot.greendao.annotation.Entity;

import org.greenrobot.greendao.annotation.Id;

import org.greenrobot.greendao.annotation.Generated;

@Entity(generateConstructors = false)

public class Student {

@Id

private Long id;

private String name;

private int age;

public Student() {

}

@Keep

public Student(String name, int age) {

this.name = name;

this.age = age;

}

public Student(Long id, String name, int age) {

this.id = id;

this.name = name;

this.age = age;

}

@Keep

public Long getId() {

return id;

}

@Keep

public void setId(Long id) {

this.id = id;

}

@Keep

public String getName() {

return name;

}

@Keep

public void setName(String name) {

this.name = name;

}

@Keep

public int getAge() {

return age;

}

@Keep

public void setAge(int age) {

this.age = age;

}

@Keep

@Override

public boolean equals(Object o) {

if (this == o) return true;

if (!(o instanceof Student)) return false;

Student student = (Student) o;

return name.equals(student.name);

}

@Keep

@Override

public int hashCode() {

return (int) (id ^ (id >>> 32));

}

@Keep

@Override

public String toString() {

return “Student{” +

“id=” + id +

“, name=’” + name + ‘’’ +

“, age=” + age +

‘}’;

}

}

Step three 、 Fix the project , Automatic generation greendao Class under package （ Just click on the little hammer ）, You will generate it automatically greendao The class in the package .

---

Step four 、 Start using , Create management class

---

package tsou.com.simple.greendaoforkotlin.manager

import android.content.Context

import android.database.sqlite.SQLiteDatabase

import tsou.com.simple.greendaoforkotlin.greendao.DaoMaster

import tsou.com.simple.greendaoforkotlin.greendao.DaoSession

class DbManager private constructor(mContext: Context) {

private val DB_NAME = “test.db”

private var mDevOpenHelper: DaoMaster.DevOpenHelper? = null

private var mDaoMaster: DaoMaster? = null

private var mDaoSession: DaoSession? = null

init {

// Initialize database information

mDevOpenHelper = DaoMaster.DevOpenHelper(mContext, DB_NAME)

getDaoMaster(mContext)

getDaoSession(mContext)

}

companion object {

@Volatile

var instance: DbManager? = null

fun getInstance(mContext: Context): DbManager? {

if (instance == null) {

synchronized(DbManager::class) {

if (instance == null) {

instance = DbManager(mContext)

}

}

}

return instance

}

}

/**

• Get a readable database

• @param context

• @return

*/

fun getReadableDatabase(context: Context): SQLiteDatabase? {

if (null == mDevOpenHelper) {

getInstance(context)

}

return mDevOpenHelper?.getReadableDatabase()

}

/**

• Get writable database

• @param context

• @return

*/

fun getWritableDatabase(context: Context): SQLiteDatabase? {

if (null == mDevOpenHelper) {

getInstance(context)

}

return mDevOpenHelper?.getWritableDatabase()

}

/**

• obtain DaoMaster

• @param context

• @return

*/

fun getDaoMaster(context: Context): DaoMaster? {

if (null == mDaoMaster) {

synchronized(DbManager::class.java) {

if (null == mDaoMaster) {

mDaoMaster = DaoMaster(getWritableDatabase(context))

}

}

}

return mDaoMaster

}

/**

• obtain DaoSession

• @param context

• @return

*/

fun getDaoSession(context: Context): DaoSession? {

if (null == mDaoSession) {

synchronized(DbManager::class.java) {

mDaoSession = getDaoMaster(context)?.newSession()

}

}

return mDaoSession

}

}

Step five 、 Additions and deletions ,

---

package tsou.com.simple.greendaoforkotlin.dao

import android.content.Context

import tsou.com.simple.greendaoforkotlin.bean.Student

import tsou.com.simple.greendaoforkotlin.greendao.StudentDao

import tsou.com.simple.greendaoforkotlin.manager.DbManager

class StudentDaoOpe private constructor() {

private object mHolder {

val instance = StudentDaoOpe()

}

companion object {

fun getInstance(): StudentDaoOpe {

return mHolder.instance

}

}

/**

• Add data to database

• @param context

• @param stu

*/

fun insertData(context: Context?, stu: Student) {

DbManager.getInstance(context!!)?.getDaoSession(context)?.getStudentDao()?.insert(stu)

}

/**

• Add data entities to the database through transactions

• @param context

• @param list

*/

fun insertData(context: Context?, list: List?) {

if (null == list || list.size <= 0) {

return

}

DbManager.getInstance(context!!)?.getDaoSession(context)?.getStudentDao()?.insertInTx(list)

}

/**

• Add data to database , If there is , Overwrite the original data

• The internal code judges that if it exists update(entity); If it doesn't exist insert(entity);

• @param context

• @param student

*/

fun saveData(context: Context?, student: Student) {

DbManager.getInstance(context!!)?.getDaoSession(context)?.getStudentDao()?.save(student)

}

/**

• Delete data to database

• @param context

• @param student Delete specific content

*/

fun deleteData(context: Context?, student: Student) {

DbManager.getInstance(context!!)?.getDaoSession(context)?.getStudentDao()?.delete(student)

}

/**

• according to id Delete data to database

• @param context

• @param id Delete specific content

*/

fun deleteByKeyData(context: Context?, id: Long) {

DbManager.getInstance(context!!)?.getDaoSession(context)?.getStudentDao()?.deleteByKey(id)

}

/**

• Delete all data

• @param context

*/

fun deleteAllData(context: Context?) {

DbManager.getInstance(context!!)?.getDaoSession(context)?.getStudentDao()?.deleteAll()

}

/**

• Update the database

Last

May you one day , Love yourself , Treat yourself .

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