文章目录
（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
（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)
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
