Retrofit là gì? Những kiến thức cần nắm về Retrofit trong Android

// retrofit
implementation 'com.squareup.retrofit2:retrofit:2.1.0'
implementation 'com.squareup.retrofit2:converter-gson:2.1.0'

// Junit
testImplementation("org.junit.jupiter:junit-jupiter-api:5.0.0")
testRuntime("org.junit.jupiter:junit-jupiter-engine:5.0.0")
// to run JUnit 3/4 tests:
testImplementation("junit:junit:4.12")
testRuntime("org.junit.vintage:junit-vintage-engine:4.12.0")

package com.huongdancode.java.retrofitgerrit;

public class Change {
    String subject;

    public String getSubject() {
        return subject;
    }

    public void setSubject(String subject) {
        this.subject = subject;
    }
}

package com.huongdancode.java.retrofitgerrit;

import java.util.List;

import retrofit2.Call;
import retrofit2.http.GET;
import retrofit2.http.Query;

public interface GerritAPI {

    @GET("changes/")
    Call<List<Change>> loadChanges(@Query("q") String status);
}

package com.huongdancode.java.retrofitgerrit;

import java.util.List;

import com.google.gson.Gson;
import com.google.gson.GsonBuilder;

import retrofit2.Call;
import retrofit2.Callback;
import retrofit2.Response;
import retrofit2.Retrofit;
import retrofit2.converter.gson.GsonConverterFactory;

public class Controller implements Callback<List<Change>> {

    static final String BASE_URL = "https://git.eclipse.org/r/";

    public void start() {
        Gson gson = new GsonBuilder()
                .setLenient()
                .create();

        Retrofit retrofit = new Retrofit.Builder()
                .baseUrl(BASE_URL)
                .addConverterFactory(GsonConverterFactory.create(gson))
                .build();

        GerritAPI gerritAPI = retrofit.create(GerritAPI.class);

        Call<List<Change>> call = gerritAPI.loadChanges("status:open");
        call.enqueue(this);

    }

    @Override
    public void onResponse(Call<List<Change>> call, Response<List<Change>> response) {
        if(response.isSuccessful()) {
            List<Change> changesList = response.body();
            changesList.forEach(change -> System.out.println(change.subject));
        } else {
            System.out.println(response.errorBody());
        }
    }

    @Override
    public void onFailure(Call<List<Change>> call, Throwable t) {
        t.printStackTrace();
    }
}

package com.huongdancode.java.retrofitgerrit;

public class Main {

    public static void main(String[] args) {
        Controller controller = new Controller();
        controller.start();
    }
}

implementation 'com.squareup.retrofit2:retrofit:2.1.0'
implementation 'com.squareup.retrofit2:converter-simplexml:2.1.0'

<?xml version="1.0" encoding="UTF-8"?>
<rss version="2.0">
<channel>
    <title>Eclipse and Android Information</title>
    <link>https://www.huongdancode.com</link>
    <description>Eclipse and Android Information</description>
    <language>en</language>
    <copyright>Creative Commons Attribution-NonCommercial-ShareAlike 3.0 Germany (CC BY-NC-SA 3.0)</copyright>
    <pubDate>Tue, 03 May 2016 11:46:11 +0200</pubDate>
<item>
    <title>Android user interface testing with Espresso - Tutorial</title>
    <description> This tutorial describes how to test Android applications with the Android Espresso testing framework.</description>
    <link>https://www.huongdancode.com/tutorials/AndroidTestingEspresso/article.html</link>
    <author>minhvu@huongdancode.com (minh vu)</author>
    <guid>https://www.huongdancode.com/tutorials/AndroidTestingEspresso/article.html</guid>
</item>
<item>
    <title>Using the Gradle build system in the Eclipse IDE - Tutorial</title>
    <description>This article describes how to use the Gradle tooling in Eclipse</description>
    <link>https://www.huongdancode.com/tutorials/EclipseGradle/article.html</link>
    <author>minhvu@huongdancode.com (minh vu)</author>
    <guid>https://www.huongdancode.com/tutorials/EclipseGradle/article.html</guid>
</item>
<item>
    <title>Unit tests with Mockito - Tutorial</title>
    <description>This tutorial explains testing with the Mockito framework for writting software tests.</description>
    <link>https://huongdancode.com/tutorials/Mockito/article.html</link>
    <author>minhvu@huongdancode.com (minh vu)</author>
    <guid>https://www.huongdancode.com/tutorials/Mockito/article.html</guid>
</item>
</channel>
</rss>

package com.huongdancode.java.retrofitxml;

import org.simpleframework.xml.Element;
import org.simpleframework.xml.Root;

@Root(name = "item", strict = false)
public class Article {

    @Element(name = "title")
    private String title;

    @Element(name = "link")
    private String link;

    public String getTitle() {
        return title;
    }

    public void setTitle(String title) {
        this.title = title;
    }

    public String getLink() {
        return link;
    }

    public void setLink(String link) {
        this.link = link;
    }
}

package com.huongdancode.java.retrofitxml;

import java.util.List;

import org.simpleframework.xml.Element;
import org.simpleframework.xml.ElementList;
import org.simpleframework.xml.Path;
import org.simpleframework.xml.Root;

@Root(name="rss", strict=false)
public class RSSFeed {

    @Element(name="title")
    @Path("channel")
    private String channelTitle;

    @ElementList(name="item", inline=true)
    @Path("channel")
    private List<Article> articleList;

    public String getChannelTitle() {
        return channelTitle;
    }

    public void setChannelTitle(String channelTitle) {
        this.channelTitle = channelTitle;
    }

    public List<Article> getArticleList() {
        return articleList;
    }

    public void setArticleList(List<Article> articleList) {
        this.articleList = articleList;
    }


}

package com.huongdancode.java.retrofitxml;

import retrofit2.Call;
import retrofit2.http.GET;

public interface huongdancodeAPI {

    @GET("article.rss")
    Call<RSSFeed> loadRSSFeed();
}

package com.huongdancode.java.retrofitxml;

import retrofit2.Call;
import retrofit2.Callback;
import retrofit2.Response;
import retrofit2.Retrofit;
import retrofit2.converter.simplexml.SimpleXmlConverterFactory;

public class Controller implements Callback<RSSFeed> {

    static final String BASE_URL = "http://huongdancode.com/";

    public void start() {
        Retrofit retrofit = new Retrofit.Builder().baseUrl(BASE_URL)
                .addConverterFactory(SimpleXmlConverterFactory.create()).build();

        huongdancodeAPI huongdancodeAPI = retrofit.create(huongdancodeAPI.class);

        Call<RSSFeed> call = huongdancodeAPI.loadRSSFeed();
        call.enqueue(this);
    }

    @Override
    public void onResponse(Call<RSSFeed> call, Response<RSSFeed> response) {
        if (response.isSuccessful()) {
            RSSFeed rss = response.body();
            System.out.println("Channel title: " + rss.getChannelTitle());
            rss.getArticleList().forEach(
                    article -> System.out.println("Title: " + article.getTitle() + " Link: " + article.getLink()));
        } else {
            System.out.println(response.errorBody());
        }
    }

    @Override
    public void onFailure(Call<RSSFeed> call, Throwable t) {
        t.printStackTrace();
    }
}

package com.huongdancode.java.retrofitxml;

public class Application {

    public static void main(String[] args) {
        Controller ctrl = new Controller();
        ctrl.start();
    }

}