Android Practical Development - Kotlin Tutorial (Introduction - Login Function Implementation 3.3)

In the previous article we used the components we learned earlier、Layout knowledge successfully builds a login interface,And it simply implements the logical judgment before the login function,Today we will learn how to implement the login function in detail,具体来说,How should we implement data requests and callbacks with the server.

Network request environment configuration

AndroidThe network requests we commonly useRetrofit+Okhttpway to request the interface.
首先,Let's configure the dependency library,在我们Moudle项目的build.gradle文件新增依赖库.

 implementation 'com.squareup.retrofit2:retrofit:2.0.2'
 implementation 'com.squareup.okhttp3:okhttp:3.1.2'
 implementation 'com.squareup.retrofit2:converter-gson:2.0.2'

第一个是retrofit的依赖包,第二个是okhttp框架包,Usually used in conjunction with the first one,第三个是gson包,用来将jsonThe entity object or list corresponding to the data conversion.

其次,新建一个APIConfiguration interface file namingApiProtocol,Used to view and manage all interfaces,内容格式如下：

  interface ApiProtocol {
    
     @POST("/smartbackstage/appUser/loginTest")
     @FormUrlEncoded
      fun submitLogin(@Field("userId") userId: String?,@Field("password") password: String?): Call<ResponseBody>
}

这里我们新增了一个submitLogin的接口,Specify its request method as Post请求,and the corresponding serverAPI为/smartbackstage/appUser/loginTest,Specify two request parameters at the same timeuserId和password.

最后,我们需要在AndroidManifest.xmlAdded network request permission to the file.

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="com.test.ktolin.application">
    <application
        android:allowBackup="true"
        android:icon="@mipmap/ic_launcher"
        android:label="@string/app_name"
        android:roundIcon="@mipmap/ic_launcher_round"
        android:supportsRtl="true"
        android:theme="@style/Theme.KtolinApplication">
        <activity
            android:name=".LoginActivity"
            android:exported="true">
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />

                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
        </activity>
        <activity
            android:name=".MainActivity"
            android:exported="true"></activity>
    </application>
    <uses-permission android:name="android.permission.INTERNET" />
    <uses-permission android:name="android.permission.ACCESS_NETWORK_STATE" />
</manifest>

登录请求

After the network request environment is set up,Let's try to complete the data request function of the login module,In the previous article, we completed a simple non-null verification of the login interface username and password,After the verification is completed, the corresponding value can be passed into the interface,Next we create a login request method.

 private fun requestLogin(userId:String,password:String) {
    
        val retrofit = Retrofit.Builder()
            .baseUrl("http://192.168.1.196:8443/") // 设置 网络请求 Url
            .addConverterFactory(GsonConverterFactory.create()) //设置使用Gson解析(记得加入依赖)
            .build()
        val request = retrofit.create(ApiProtocol::class.java)
        val call= request.submitLogin(userId,password)
        call.enqueue(object :Callback<ResponseBody> {
    
            override fun onResponse(call: Call<ResponseBody>, response: Response<ResponseBody>) {
    
                println("请求成功")
                val result = response.body().string()
                System.out.println(result)
                val entity:ResponseEntity= Gson().fromJson(result, ResponseEntity::class.java)
                Toast.makeText(this@LoginActivity, "登录成功！", Toast.LENGTH_SHORT).show()
            }

            override fun onFailure(call: Call<ResponseBody>, throwable: Throwable) {
    
                println("请求失败")
                println(throwable.message)
            }
        })
    }

这里baseUrlYou need to fill in the corresponding server host address,request.submitLogin(userId,password)After the specified interface request is successfulonResponse方法中返回结果,After the request failsonFailure中返回结果,请求成功后,We need to convert the obtained result to the corresponding entity object.

请求结果：

 {
    "msg":"操作成功","code":200}

We start by creating an entity object structure,如下：

class ResponseEntity {
    
    /*返回结果提示*/
    var msg :String?=null
    /*返回码*/
    var code:Int=0
    /*返回内容*/
    var data=null
}

通过Gosnlibrary we can returnJsonThe format result is converted to the corresponding entity class object

val entity:ResponseEntity= Gson().fromJson(result, ResponseEntity::class.java)

至此,We basically implemented a complete login module.