Encapsulate a set of project network request framework from 0

Preface

Android Make a network request , Usually by Retrofit coordination RxJava To achieve . It should be noted that , In the project , It is impossible to directly use the framework naked in every request place , Instead, you must have encapsulated a layer of the framework in your own project , What is actually used is the layer of encapsulation .
This article will introduce a packaging scheme , You can use... In a project . There must be some shortcomings in this scheme , Please criticize and correct .

Knowledge used

Kotlin、Retrofit,RxJava,OkHttp

Introduction to the steps

1.api Introduce

Use the opening of Hongyang great God here api, Link here . Login only api that will do , Other api In the same way .

url：https://www.wanandroid.com/user/login
 Method ：POST
 Parameters ：username,password

Here is a good interface testing tool Apipost, Let me test the login interface

It returns response It's made up of three parts , Namely data,errorCode,errorMsg. I pasted the results

{
    
	"data": {
    
		"admin": false,
		"chapterTops": [],
		"coinCount": 10,
		"collectIds": [],
		"email": "",
		"icon": "",
		"id": 130077,
		"nickname": "LJH111",
		"password": "",
		"publicName": "LJH111",
		"token": "",
		"type": 0,
		"username": "LJH111"
	},
	"errorCode": 0,
	"errorMsg": ""
}

2. Create project

Create a kotlin project , Complete the necessary preparations
① Dependency import
stay app Modular gradle Import in file retrofit and rxjava Dependence

// Import retrofit
implementation 'com.squareup.retrofit2:retrofit:2.3.0'
implementation 'com.squareup.retrofit2:converter-gson:2.3.0'//ConverterFactory Of Gson Dependency package 
implementation 'com.squareup.retrofit2:converter-scalars:2.3.0'//ConverterFactory Of String Dependency package 
implementation("com.squareup.okhttp3:okhttp:4.9.1")
implementation 'com.squareup.retrofit2:adapter-rxjava2:2.3.0'

// Import rxjava
compile 'io.reactivex.rxjava2:rxandroid:2.0.1'
compile "io.reactivex.rxjava2:rxjava:2.0.8"

② Turn on network permissions
（1） First, create a new one xml file , Pictured

The content is

<?xml version="1.0" encoding="utf-8"?>
<network-security-config>
    <base-config cleartextTrafficPermitted="true" />
</network-security-config>

（2） And then find Menifest file
stay application Set such a property in the tag

（3） then , stay menifest Open network permissions in

The content is

<!-- network right -->
<uses-permission android:name="android.permission.INTERNET" />
<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />
<uses-permission android:name="android.permission.READ_EXTERNAL_STORAGE" />

3. newly build response Template class

be-all response There's one thing in common , It consists of three parts , Namely data,errorCode,errorMsg. There is only data The type of is uncertain , But you can use generics to represent .
So you can use a common template class to receive all Response

/** * Created by didiwei on 2022/4/20 * desc:  All requested template classes  */
data class ResponseModel<T>(val data: T,
                         val errorCode: String?,
                         val errorMsg: String?)

data Just use generics

4. When the new login is successful , Back to data Template class

When the login is successful , Back to json as follows

{
    
	"data": {
    
		"admin": false,
		"chapterTops": [],
		"coinCount": 10,
		"collectIds": [],
		"email": "",
		"icon": "",
		"id": 130077,
		"nickname": "LJH111",
		"password": "",
		"publicName": "LJH111",
		"token": "",
		"type": 0,
		"username": "LJH111"
	},
	"errorCode": 0,
	"errorMsg": ""
}

Because data Is different api, It may be different , So it's best to use a class to distinguish different data. Here, when the login is successful , Back to data I say so

/** * Created by didiwei on 2022/4/20 * desc:  When the login is successful , Back to response Medium data Template class of  */
data class LoginSuccessResData(val admin: Boolean,
                               val chapterTops: List<*>,
                               val coinCount: Int,
                               val collectIds: List<*>,
                               val email: String?,
                               val icon: String?,
                               val id: String?,
                               val nickname: String?,
                               val password: String?,
                               val publicName: String?,
                               val token: String?,
                               val type: Int,
                               val username: String?)

5. Customize RxJava The operator

The normal logic should be like this , When the request is successful , hold data Throw it to UI, When the request fails , hold errorMsg Throw it to UI. So we can customize RxJava The operator , When the data returns , Yes Response To accomplish such a function .

/** * Created by didiwei on 2022/4/20 * desc: RxJava Custom operators for , For stripping data and errorMsg */
abstract class RxJavaInterceptor<T> : Observer<ResponseModel<T>> {
    
    abstract fun success(data: T?)
    abstract fun failure(errorMsg: String?)

    override fun onSubscribe(d: Disposable?) {
    
        // You can get a load here dialog Of start, Don't forget to finish the request （ Success or failure ） Let this dialog disappear 
    }

    override fun onNext(t: ResponseModel<T>?) {
    
        if(t?.data != null){
    
            // Request succeeded 
            success(t?.data)
        }else{
    
            // Failure 
            failure(t?.errorMsg)
        }
    }

    override fun onError(e: Throwable?) {
    
        failure(e?.message)
    }

    override fun onComplete() {
    
        // You can add dialog The disappearance of 
    }

}

There's a caveat , First RxJavaInterceptor Class is an abstract class , Inside success and failure Is an abstract method , When called, implement . Secondly, it is still a generic class , Applicable to all model

6. Interface for writing requests

/** * Created by didiwei on 2022/4/20 * desc:  About user login   Registered api */
interface UserService {
    
    /** * desc  Login interface  * * url：https://www.wanandroid.com/user/login *  Method ：POST *  Parameters ：username,password */
    @POST("/user/login")
    @FormUrlEncoded
    fun loginAction(@Field("username")username: String?,
                    @Field("password")password: String?)
        :Observable<ResponseModel<LoginSuccessResData>>
}

Notice that its return value is Observable type , As the observed , Flow to the observer （RxJava Knowledge ）

7. Create instantiation service Class

/** * Created by didiwei on 2022/4/20 * desc:  This class is a singleton class , Used to create Service Example  */
class ApiClient {
    
    private object Holder{
    
        val instance = ApiClient()
    }

    companion object{
    
        val INSTANCE = Holder.instance
    }

    fun <T> createRetrofit(retrofitInterface: Class<T>) : T{
    
        // establish okhttp
        val mOkHttpClient = OkHttpClient().newBuilder()
            .readTimeout(10000, TimeUnit.SECONDS)// Read timeout 
            .connectTimeout(10000, TimeUnit.SECONDS)// Connection timeout 
            .writeTimeout(10000, TimeUnit.SECONDS)// Write the timeout 
            .build()

        // establish retrofit
        val retrofit: Retrofit = Retrofit.Builder()
            .baseUrl("https://www.wanandroid.com")
            .client(mOkHttpClient)
            .addCallAdapterFactory(RxJava2CallAdapterFactory.create())
            .addConverterFactory(GsonConverterFactory.create())
            .build()
        
        // return 
        return retrofit.create(retrofitInterface)
    }
}

8. So when we use it , That's how it works

For example, add a login button , Then register its click event

class MainActivity : AppCompatActivity() {
    
    override fun onCreate(savedInstanceState: Bundle?) {
    
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_main)

        val userLoginBtn: Button = findViewById<Button>(R.id.userLoginBtn)
        userLoginBtn.setOnClickListener(onClickListener)
    }

    private val onClickListener = View.OnClickListener {
    
        when(it.id){
    
            R.id.userLoginBtn ->{
    
                val userName = "LJH111"
                val userPwd = "123456"

                ApiClient.INSTANCE.createRetrofit(UserService::class.java)
                        .loginAction(userName,userPwd)
                        .subscribeOn(Schedulers.io())
                        .observeOn(AndroidSchedulers.mainThread())
                        .subscribe(object : RxJavaInterceptor<LoginSuccessResData>(){
    
                            override fun success(data: LoginSuccessResData?) {
    
                                Log.v("ljh"," The request is successful , Back to data by ：${data}")
                            }

                            override fun failure(errorMsg: String?) {
    
                                Log.v("ljh"," request was aborted , The error message is :${errorMsg}")
                            }
                        })
            }
        }
    }
}

effect

If you change it to the wrong user name or password , The effect is this

thus , We have completed the encapsulation of network request rules