Kotlin+Retrofit+Recyclerview的使用以及示例代码

本文链接：https://blog.csdn.net/qq_40785165/article/details/109693263

大家好，我是小黑，一个还没秃头的程序员~~~

你必须特别努力，才能显得毫不费力。

今天的文章是为了前段时间学习kotlin所进行的接口对接，使用的网络数据传输框架为Retrofit，使用的接口为玩Android的开放接口,项目地址：https://gitee.com/fjjxxy/kotlin_retrofit.git

知识体系下的文章
https://www.wanandroid.com/article/list/0/json?cid=60
方法：GET
参数：cid 分类的id，上述二级目录的id
      页码：拼接在链接上，从0开始。
      
获取公众号列表
https://wanandroid.com/wxarticle/chapters/json  
方法：GET

需要申请的权限

<uses-permission android:name="android.permission.INTERNET" />

需要添加的依赖

def retrofit_version = '2.6.1'
//----------------- retrofit begin -----------------
implementation "com.squareup.retrofit2:retrofit:$retrofit_version"
implementation "com.squareup.retrofit2:converter-gson:$retrofit_version"
implementation "com.squareup.retrofit2:converter-scalars:$retrofit_version"
// ---- okhttp ----
implementation 'com.squareup.okhttp3:logging-interceptor:3.11.0'
// ---- okhttp ----
//----------------- retrofit end   -----------------
implementation 'androidx.recyclerview:recyclerview:1.0.0'

先来看一下效果图

效果图中由两个列表组成，上个列表对接第一个接口，下个列表对接第二个接口，好了，接下来是代码展示

（一）定义一个实体类Result，用来接收接口返回的数据

class Result<T> {
    var errorCode: String? = null
    var errorMsg: String? = null
    var data: T? = null
}

（二）定义一个接口Api，使用注解的方式为retrofit提供Restful风格的Api，各种注解的使用方式这里就不一一列举了，请大家自行百度

interface Api {
    /**
     * 微信公众号列表
     */
    @GET("wxarticle/chapters/json")
    fun getwxarticle(): Call<Result<List<User>>>

    /**
     * 文章列表
     */
    @GET("article/list/{page}/json")
    fun getArticle(@Path("page") page: String, @Query("cid") cid: String): Call<Result<Article>>
}

（三）封装接口请求工具类HttpHelper,获取 retrofit对象以及Api服务，设置拦截器以及处理日志，代码如下

/**
 * 接口请求工具类
 */
class HttpHelper {
    companion object {
        private val BASE_URL = "https://www.wanandroid.com/" //服务器地址
        private var sHttpClient: OkHttpClient? = null
        private var sApi: Api? = null

        /**
         * 添加拦截器，对返回的数据或者日志进行处理，对请求添加统一头部
         */
        fun getHttpClient(): OkHttpClient? {
            if (sHttpClient == null) {
                synchronized(HttpHelper::class.java) {
                    if (sHttpClient == null) {
                        val builder = OkHttpClient.Builder()
                        //添加拦截器
                        var interceptor = HttpLoggingInterceptor(
                            HttpLoggingInterceptor.Logger { message ->
                                //对日志进行处理
                                Log.e("Tag", message)
                            }
                        )
                        interceptor.setLevel(HttpLoggingInterceptor.Level.BODY)
                        builder.addInterceptor(interceptor)
                        builder.addInterceptor { chain ->
                            val request = chain.request()
                            val compressedRequest =
                                request.newBuilder()
                                    //添加头部
                                    .addHeader(
                                        "User-Agent",
                                        "Android"
                                    )
                                    .build()
                            chain.proceed(compressedRequest)
                        }
                        sHttpClient = builder
                            .callTimeout(40, TimeUnit.SECONDS)
                            .connectTimeout(40, TimeUnit.SECONDS)
                            .readTimeout(40, TimeUnit.SECONDS)
                            .writeTimeout(40, TimeUnit.SECONDS)
                            .build()
                    }
                }
            }
            return sHttpClient
        }

        /**
         * 获取接口服务
         */
        fun getApi(): Api? {
            if (sApi == null) {
                synchronized(HttpHelper::class.java) {
                    if (sApi == null) {
                        val retrofit = createRetrofit(BASE_URL)
                        sApi = retrofit.create(Api::class.java)
                    }
                }
            }
            return sApi
        }

        /**
         * 获取Retrofit对象，定义返回类型的转换器
         */
        private fun createRetrofit(baseUrl: String): Retrofit {
            val gsonBuilder = GsonBuilder()
            return Retrofit.Builder()
                .client(getHttpClient())
                .baseUrl(baseUrl)
                .addConverterFactory(ScalarsConverterFactory.create())
                .addConverterFactory(GsonConverterFactory.create(gsonBuilder.create()))
                .build()
        }
    }
}

（四）封装接口回调类SingleCallback，处理数据返回成功和失败状态的数据

/**
 * 接口请求基本回调
 */
abstract class SingleCallback<T : Result<*>?> :
    Callback<T> {
    //接口请求成功
    override fun onResponse(
        call: Call<T>,
        response: Response<T>
    ) {
        val result = response.body()
        if (result == null) {
            onFailure("-99", "请求异常", null)
        } else {
            if (apiFailure(result)) {
                onFailure(result.errorCode, result.errorMsg ?: "", result)
            } else {
                onSuccess(result)
            }
        }
    }

    override fun onFailure(call: Call<T>, t: Throwable) {
        Log.e("SingleCallback", "onFailure: " + t.message, t)
    }

    fun successCode(): String {
        return "0"
    }

    fun apiFailure(result: T?): Boolean {
        return result == null || successCode() != result.errorCode
    }

    /**
     * 失败回调。默认已经将失败信息提示出来
     */
    fun onFailure(code: String?, message: String, response: T?) {
        Toast.makeText(App.getContext(), message, Toast.LENGTH_SHORT).show()
    }

    abstract fun onSuccess(response: T)

}

（五）设计列表界面以及子项布局

activity_main.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical"
    tools:context=".MainActivity">

    <androidx.recyclerview.widget.RecyclerView
        android:id="@+id/rv_article_data"
        android:layout_width="match_parent"
        android:layout_height="0dp"
        android:layout_weight="1" />

    <androidx.recyclerview.widget.RecyclerView
        android:id="@+id/rv_user_data"
        android:layout_width="match_parent"
        android:layout_height="0dp"
        android:layout_weight="1" />
</LinearLayout>

item_article.xml

<?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:background="#fff">

    <TextView
        android:id="@+id/tv_article"
        android:layout_width="match_parent"
        android:layout_height="40dp"
        android:text=""
        android:textSize="14dp" />

</LinearLayout>

item_user.xml

<?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:background="#fff">

    <TextView
        android:id="@+id/tv_user"
        android:layout_width="match_parent"
        android:layout_height="40dp"
        android:text=""
        android:textSize="14dp" />
</LinearLayout>

（六）实体类

Article实体类

class Article {
   var datas: List<ArticleData>? = null
}

ArticleData实体类

class ArticleData{
    val title: String? = null
}

User实体类

class User{
    val name: String? = null
}

（七）逻辑以及数据适配器代码编写

MainActivity.kt

class MainActivity : AppCompatActivity() {
    private val mUserList: MutableList<User> = ArrayList()
    private var mArticleList: MutableList<ArticleData> = ArrayList();

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_main)
        //或者这里可以不用findViewById,直接用布局中的id作为变量名也可以
        var rvArticleData: RecyclerView = findViewById(R.id.rv_article_data)
        var rvUserData: RecyclerView = findViewById(R.id.rv_user_data)
        rvArticleData.layoutManager = LinearLayoutManager(this)
        rvUserData.layoutManager = LinearLayoutManager(this)
        rvArticleData.adapter = ArticleAdapter(this, mArticleList)
        var userAdapter = UserAdapter(mUserList)
        userAdapter.setOnUserClickListener(object : UserAdapter.OnUserClickListener {
            override fun click(text: String?) {
                Toast.makeText(applicationContext, text, Toast.LENGTH_SHORT).show()
            }
        })
        rvUserData.adapter = userAdapter
       //请求微信公众号接口
        var api = HttpHelper.getApi()
        api!!.getwxarticle()!!.enqueue(object : SingleCallback<Result<List<User>>>() {
            override fun onSuccess(response: Result<List<User>>) {
                if (response.data != null && (response.data?.size ?: 0 > 0)) {
                    mUserList.addAll(response.data!!)
                    rvUserData.adapter?.notifyDataSetChanged()
                }
            }
        })
        //请求文章接口
        var api1 = HttpHelper.getApi()
        api1!!.getArticle("1", "60")!!.enqueue(object : SingleCallback<Result<Article>>() {
            override fun onSuccess(response: Result<Article>) {
                if (response.data != null && response.data?.datas != null && response.data?.datas?.size ?: 0 > 0) {
                    mArticleList.addAll(response.data?.datas!!)
                    rvArticleData.adapter?.notifyDataSetChanged()
                }
            }
        })
    }
}

ArticleAdapter.kt

  class ArticleAdapter(var mContext: Context, var mList: List<ArticleData>) :
    RecyclerView.Adapter<ArticleAdapter.ViewHolder>() {
    class ViewHolder(view: View) : RecyclerView.ViewHolder(view) {
        var mTvArticle: TextView = view.tv_article
    }

    override fun onCreateViewHolder(parent: ViewGroup, viewType: Int): ViewHolder {
        return ViewHolder(
            LayoutInflater.from(parent.context).inflate(
                R.layout.item_article,
                parent,
                false
            )
        )
    }

    override fun getItemCount(): Int {
        return mList.size
    }

    override fun onBindViewHolder(holder: ViewHolder, position: Int) {
        holder.mTvArticle.text = mList[position].title
        //设置点击事件，Lambda 表达式用着真的很舒服
        holder.mTvArticle.setOnClickListener {
            Toast.makeText(
                mContext,
                mList[position].title,
                Toast.LENGTH_SHORT
            ).show()
        }
    }

UserAdapter.kt

class UserAdapter(var mList: List<User>) :
    RecyclerView.Adapter<UserAdapter.ViewHolder>() {
    class ViewHolder(view: View) : RecyclerView.ViewHolder(view) {
        var mTvUser: TextView = view.tv_user
    }

    private var mUserClickListener: OnUserClickListener? = null
    //设置点击事件回调，具体的实现在回调中定义
    interface OnUserClickListener {
        fun click(text: String?)
    }

    fun setOnUserClickListener(onUserClickListener: OnUserClickListener) {
        this.mUserClickListener = onUserClickListener
    }

    override fun onCreateViewHolder(parent: ViewGroup, viewType: Int): ViewHolder {
        return ViewHolder(
            LayoutInflater.from(parent.context).inflate(
                R.layout.item_user,
                parent,
                false
            )
        )
    }

    override fun getItemCount(): Int {
        return mList.size
    }

    override fun onBindViewHolder(holder: ViewHolder, position: Int) {
        holder.mTvUser.text = mList[position].name
        holder.mTvUser.setOnClickListener {
            mUserClickListener!!.click(mList[position].name)
        }
    }

到此为止，Kotlin+Retrofit+Recyclerview的用法就介绍到这里了，功能的效果图如开头展示，代码已上传到码云，地址：https://gitee.com/fjjxxy/kotlin_retrofit.git，有疑惑的欢迎扫描下方二维码添加我微信，我们共同进步！最后，祝大家身体健康，万事如意，谢谢大家的支持与阅读！

Kotlin+Retrofit+Recyclerview的使用以及示例代码

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