Android 使用kotlin Retrofit2 + Dagger2完成网络请求跟依赖注入组合使用

文章目录

- （一）引入依赖
- （二）基本概念
- - Dagger中的基本概念：
  - Retrofit介绍
- （三）Dagger2 @Module 和 @Provides 和 @Component +@Inject
- （四）Retrofit2 创建数据类Bean跟Service服务
- （五）使用Retrofit跟Dagger2

（一）引入依赖

implementation 'com.google.dagger:dagger:2.21'
kapt 'com.google.dagger:dagger-compiler:2.21'
implementation 'com.squareup.retrofit2:retrofit:2.0.2'
implementation("com.squareup.retrofit2:converter-gson:2.3.0")

注： dagger-compiler要使用kapt插件

plugins {
    id 'org.jetbrains.kotlin.kapt'
}

（二）基本概念

Dagger中的基本概念：

Provides提供依赖的方法撒谎给你添加的注解，provide方法需要包含在Module中
Module专门提供依赖，类似工厂模式
Component它是一个桥梁，一端是目标类，另一端是目标所依赖的实例，它也是注入器，负责把目标类所依赖类的实例注入到目标类中，同时它也管理Module。（先从Module中找依赖，再从Inject找构造函数)
Scope自定义注解，用于标示作用域，随意命名，对应即可
Inject是用来标注依赖和被依赖的构造函数

Retrofit介绍

Retrofit介绍：
它是一个RESTful的HTTP网络请求框架（基于OkHttp），它基于OkHttp，通过注解配置网络请求参数，能够支持多种数据的解析和序列化，如Gson、Json、XML、Protobuf
优点：

功能强大，支持同步 & 异步、支持多种数据的解析 & 序列化格式、支持RxJava
简洁易用：通过注解配置网络请求参数，采用大量设计模式简化使用
可扩展性好：功能模块高度封装、解耦彻底

在这里插入图片描述

（三）Dagger2 @Module 和 @Provides 和 @Component +@Inject

定义Module类跟Component抽象接口

@Module
class NetworkModule {
    @Provides
    fun getRetrofit(): Retrofit? {
        return Retrofit.Builder()
                .addConverterFactory(GsonConverterFactory.create())
                .baseUrl(BASE_URL)
                .build()
    }
    companion object {
        const val BASE_URL = "http://api.k780.com/"
    }
}


@Component(modules = [NetworkModule::class])
interface MyComponent {
    fun inject(regesiteActivity: RegesiteActivity)
}

在活动Activity中定义一个retrofit变量，标注@Inject注解表明这是需要被注入的变量，注意不要定义成val不可变类型

    @Inject
    lateinit var retrofit: Retrofit

然后在活动中进行注入，需要在View创建之后使用，DaggerMyComponent会在构建rebuild之后生成

DaggerMyComponent.create().inject(this)

在这里插入图片描述
如果依赖正确但是没有生成，检查下依赖是否正确，或者在gradle.properties中添加一行配置：

kapt.incremental.apt = false

（四）Retrofit2 创建数据类Bean跟Service服务

public interface Service {
    @GET("?app=weather.today&weaid=成都&appkey=46951&sign=b2f1992fc55dfd5ae70895f60ab3a86d&format=json")
    Call<FeatureBean> getFeatureBean();

    @GET("?")
    Call<FeatureBean> getFeature(@Query("app") String app, @Query("weaid") String city,
                                              @Query("appkey") String key, @Query("sign") String sign,
                                              @Query("format") String format);
}

public class FeatureBean {

    private String success;
    private Result result;
    public void setSuccess(String success) {
        this.success = success;
    }
    public String getSuccess() {
        return success;
    }

    public void setResult(Result result) {
        this.result = result;
    }
    public Result getResult() {
        return result;
    }

}

public class Result {

    private String weaid;
    private String days;
    private String week;
    private String cityno;
    private String citynm;
    private String cityid;
    private String temperature;
    private String temperature_curr;
    private String humidity;
    private String aqi;
    private String weather;
    private String weather_curr;
    private String weather_icon;
    private String weather_icon1;
    private String wind;
    private String winp;
    private String temp_high;
    private String temp_low;
    private String temp_curr;
    private String humi_high;
    private String humi_low;
    private String weatid;
    private String weatid1;
    private String windid;
    private String winpid;
    private String weather_iconid;
    public void setWeaid(String weaid) {
        this.weaid = weaid;
    }
    public String getWeaid() {
        return weaid;
    }

    public void setWeek(String week) {
        this.week = week;
    }
    public String getWeek() {
        return week;
    }

    public String getDays() {
        return days;
    }

    public void setDays(String days) {
        this.days = days;
    }

    public void setHumidity(String humidity) {
        this.humidity = humidity;
    }

    public void setCityno(String cityno) {
        this.cityno = cityno;
    }
    public String getCityno() {
        return cityno;
    }

    public void setCitynm(String citynm) {
        this.citynm = citynm;
    }
    public String getCitynm() {
        return citynm;
    }

    public void setCityid(String cityid) {
        this.cityid = cityid;
    }
    public String getCityid() {
        return cityid;
    }

    public void setTemperature(String temperature) {
        this.temperature = temperature;
    }
    public String getTemperature() {
        return temperature;
    }

    public void setTemperature_curr(String temperature_curr) {
        this.temperature_curr = temperature_curr;
    }
    public String getTemperature_curr() {
        return temperature_curr;
    }

    public void setAqi(String aqi) {
        this.aqi = aqi;
    }
    public String getAqi() {
        return aqi;
    }

    public void setWeather(String weather) {
        this.weather = weather;
    }
    public String getWeather() {
        return weather;
    }

    public void setWeather_curr(String weather_curr) {
        this.weather_curr = weather_curr;
    }
    public String getWeather_curr() {
        return weather_curr;
    }

    public void setWeather_icon(String weather_icon) {
        this.weather_icon = weather_icon;
    }
    public String getWeather_icon() {
        return weather_icon;
    }

    public void setWeather_icon1(String weather_icon1) {
        this.weather_icon1 = weather_icon1;
    }
    public String getWeather_icon1() {
        return weather_icon1;
    }

    public void setWind(String wind) {
        this.wind = wind;
    }
    public String getWind() {
        return wind;
    }

    public void setWinp(String winp) {
        this.winp = winp;
    }
    public String getWinp() {
        return winp;
    }

    public void setTemp_high(String temp_high) {
        this.temp_high = temp_high;
    }
    public String getTemp_high() {
        return temp_high;
    }

    public void setTemp_low(String temp_low) {
        this.temp_low = temp_low;
    }
    public String getTemp_low() {
        return temp_low;
    }

    public void setTemp_curr(String temp_curr) {
        this.temp_curr = temp_curr;
    }
    public String getTemp_curr() {
        return temp_curr;
    }

    public void setHumi_high(String humi_high) {
        this.humi_high = humi_high;
    }
    public String getHumi_high() {
        return humi_high;
    }

    public void setHumi_low(String humi_low) {
        this.humi_low = humi_low;
    }
    public String getHumi_low() {
        return humi_low;
    }

    public void setWeatid(String weatid) {
        this.weatid = weatid;
    }
    public String getWeatid() {
        return weatid;
    }

    public void setWeatid1(String weatid1) {
        this.weatid1 = weatid1;
    }
    public String getWeatid1() {
        return weatid1;
    }

    public void setWindid(String windid) {
        this.windid = windid;
    }
    public String getWindid() {
        return windid;
    }

    public void setWinpid(String winpid) {
        this.winpid = winpid;
    }
    public String getWinpid() {
        return winpid;
    }

    public void setWeather_iconid(String weather_iconid) {
        this.weather_iconid = weather_iconid;
    }
    public String getWeather_iconid() {
        return weather_iconid;
    }

    @Override
    public String toString() {
        return "Result{" +
                "weaid='" + weaid + '\'' +
                ", days='" + days + '\'' +
                ", week='" + week + '\'' +
                ", cityno='" + cityno + '\'' +
                ", citynm='" + citynm + '\'' +
                ", cityid='" + cityid + '\'' +
                ", temperature='" + temperature + '\'' +
                ", temperature_curr='" + temperature_curr + '\'' +
                ", humidity='" + humidity + '\'' +
                ", aqi='" + aqi + '\'' +
                ", weather='" + weather + '\'' +
                ", weather_curr='" + weather_curr + '\'' +
                ", weather_icon='" + weather_icon + '\'' +
                ", weather_icon1='" + weather_icon1 + '\'' +
                ", wind='" + wind + '\'' +
                ", winp='" + winp + '\'' +
                ", temp_high='" + temp_high + '\'' +
                ", temp_low='" + temp_low + '\'' +
                ", temp_curr='" + temp_curr + '\'' +
                ", humi_high='" + humi_high + '\'' +
                ", humi_low='" + humi_low + '\'' +
                ", weatid='" + weatid + '\'' +
                ", weatid1='" + weatid1 + '\'' +
                ", windid='" + windid + '\'' +
                ", winpid='" + winpid + '\'' +
                ", weather_iconid='" + weather_iconid + '\'' +
                '}';
    }
}

（五）使用Retrofit跟Dagger2

没有注入的话需要先进行注入：

DaggerMyComponent.create().inject(this)

val callback  = retrofit.create(Service::class.java)
                        .getFeature("weather.today", "成都", "46951", "b2f1992fc55dfd5ae70895f60ab3a86d", "json")
val execute : Response<FeatureBean>? = callback?.execute()
val featureBean = execute?.body()
val result = featureBean?.result
println("返回结果：" + result?.toString())

注意：
（1）Unresolved reference: DaggerMyComponent
解决：在gradle.properties中添加

kapt.incremental.apt = false

（2）Kotlin 使用 Retrofit 报 Unresolved reference: GsonConverterFactory

原因是依赖有问题，converter-gson不适用kapt，修改成正确的依赖即可：

implementation 'com.squareup.retrofit2:retrofit:2.0.2'
implementation("com.squareup.retrofit2:converter-gson:2.3.0")

（3）IllegalArgumentException: Unable to create converter for class com.example.weatherapp.network.FeatureBean for method Service.getFeature

出现这个问题的原因是因为缺少ConverterFactory，所以要addConverterFactory

Retrofit.Builder()
                .addConverterFactory(GsonConverterFactory.create())//这一行
                .baseUrl(BASE_URL)
                .build()

参考文档：
https://blog.csdn.net/rjgcszlc/article/details/78364689
https://zhuanlan.zhihu.com/p/595569731
https://www.jianshu.com/p/f79003a5e6ba
https://blog.csdn.net/lu202032/article/details/129217818

好了，到这就写完了，更新不易，还望老铁们点个追更