Kotlin android-freestyle

一、 配置

• Project/build.gradle 配置

buildscript {    ext {        support_version = '25.3.0'        gradle_version = '2.3.0'        kotlin_version = '1.1.2-3'        anko_version = '0.8.2'    }    repositories {        jcenter()        dependencies {            classpath 'com.android.tools.build:gradle:2.3.0'            classpath "org.jetbrains.kotlin:kotlin-gradle-plugin:$kotlin_version"            classpath "org.jetbrains.kotlin:kotlin-android-extensions:$kotlin_version"        }    }}

• Model/build.gradle 配置
  
  • kotlin-stdlib 为基础的依赖包
  • anko-common 为简化 Android 任务开发，大写的扩展函数
  • anko-sqlite 本地数据库

apply plugin: 'com.android.application'apply plugin: 'kotlin-android'apply plugin: 'kotlin-android-extensions'dependencies {    ...    compile "com.android.support:appcompat-v7:$support_version"    compile "org.jetbrains.kotlin:kotlin-stdlib:$kotlin_version"    compile "org.jetbrains.anko:anko-common:$anko_version"    compile "org.jetbrains.anko:anko-sqlite:$anko_version"}android{    sourceSets {        // 提示：需手动创建 kotlin 目录        main.java.srcDirs += 'src/main/kotlin'    }}

二、 实践

step1. 页面设计

• activity_layout.xml 创建，跟往常一样

<?xml version="1.0" encoding="utf-8"?><android.support.constraint.ConstraintLayout    xmlns:android="http://schemas.android.com/apk/res/android"    android:layout_width="match_parent"    android:layout_height="match_parent">    <android.support.v7.widget.RecyclerView        android:id="@+id/main_rv"        android:layout_width="match_parent"        android:layout_height="match_parent"/></android.support.constraint.ConstraintLayout>

• item_main.xml 同样是没啥特别的

<?xml version="1.0" encoding="utf-8"?><LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"    android:layout_width="match_parent"    android:layout_height="wrap_content"    android:orientation="vertical">    <TextView        android:id="@+id/main_item_tv"        android:layout_width="match_parent"        android:layout_height="wrap_content"/></LinearLayout>

• UserInfo.kt 用户信息-数据类
  
  • data 作为修饰符
  • Json 解析字段与参数名一致，也可 Serialised 实现序列化

data class UserInfo(val name: String, val age: Int)

• MainRvAdapter.kt 适配器创建与列表项展示，有如下改变：
  
  • 数组取值统一采用 .[index] 形式，抛去以往的 get 函数

import android.support.v7.widget.RecyclerViewimport android.view.LayoutInflaterimport android.view.Viewimport android.view.ViewGroupimport com.nuon.kj.MainRvAdapter.ViewHolderimport kotlinx.android.synthetic.main.item_main.view.*class MainRvAdapter(val items: List<UserInfo>, val itemClick: (UserInfo) -> Unit)    : RecyclerView.Adapter<ViewHolder>() {    override fun getItemCount(): Int {        return items.size    }    override fun onBindViewHolder(holder: ViewHolder?, position: Int) {        holder?.binData(items[position])    }    override fun onCreateViewHolder(parent: ViewGroup?, viewType: Int): ViewHolder {        val view = LayoutInflater.from(parent?.context).inflate(R.layout.item_main, null)        return ViewHolder(view, itemClick)    }    class ViewHolder(val view: View, val itemClick: (UserInfo) -> Unit)        : RecyclerView.ViewHolder(view) {        // val mNameTv: TextView = view.findViewById(R.id.main_item_tv) as TextView        fun binData(info: UserInfo) {            with(info) {                // mNameTv.text = name                // 这里通过 kotlin-android-extensions 提供的模板实现视图获取（id）                view.main_item_tv.text = name                view.main_item_tv.setTextColor(ContextCompat.getColor(view.context, R.color.colorAccent))            }            view.setOnClickListener {                itemClick.invoke(info)            }        }    }}

• MainActivity.kt 创建与视图声明，有如下改变：
  
  1. 数组定义使用 listOf 函数实现其赋值
  2. 对象定义使用 var/val 命名，类型转换 as
  3. setLayoutManager() 由 set 函数更新为 .layoutManager 表示
  4. 对象的实例化省去 new 字串的编辑

import android.content.Intentimport android.os.Bundleimport android.support.v7.app.AppCompatActivityimport android.support.v7.widget.LinearLayoutManagerimport android.support.v7.widget.RecyclerViewimport com.nuon.kj.db.UserInfoimport org.jetbrains.anko.startActivitylass MainActivity : AppCompatActivity() {    var mMainRv: RecyclerView? = null    override fun onCreate(savedInstanceState: Bundle?) {        super.onCreate(savedInstanceState)        setContentView(R.layout.activity_main)        initView()    }    fun initView() {        val user1 = UserInfo("Joke", 22)        val user2 = UserInfo("Ming", 26)        val user3 = user1.copy(name = "Tome")// 对象赋值        val userList = listOf(user1, user2, user3)        val mMainRv = findViewById(R.id.main_rv) as RecyclerView//        val mMainRv: RecyclerView = find(R.id.main_rv)// anko 简化实现        mMainRv.layoutManager = LinearLayoutManager(this)        mMainRv.adapter = MainRvAdapter(userList) {// 扩展函数引用//            Toast.makeText(this@MainActivity, it.name, Toast.LENGTH_SHORT).show()//            val intent = Intent(MainActivity@this, DetailActivity::class.java)//            intent.putExtra("userName", it.name)//            startActivity(intent)            startActivity<DetailActivity>("userName" to it.name)// anko 实现        }    }}

step2 数据库设计

• UserTable.kt 创建表结构，用于存储账号信息

object UserTable {    val TableName = "_user"    val ID = "_id"    val Pwd = "pwd"    val UserName = "userName"    val Age = "age"    val Sex = "sex"}

• UserInfo.kt 创建表对象

data class UserInfo(val map: MutableMap<String, Any?>) {    var _id: Long by map    var loginId: String by map    var pwd: String by map    var userName: String by map    var age: Int by map    var sex: String by map    constructor() : this(HashMap())    constructor(id: Long, loginId: String, pwd: String, userName: String, age: Int, sex: String) : this(HashMap()){        this._id = id        this.loginId = loginId        this.pwd = pwd        this.userName = userName        this.age = age        this.sex = sex    }}

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待更新…

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