Retrofit2系列：简单的Get请求

完整源码见: https://github.com/androidzhangjin/Retrofit2Demo

Postman调试接口

• url地址：https://api.github.com/search/commits
• 默认的http头部Accept，因为不能直接编辑它的值，所以不勾选，新建一个Accept。值为application/vnd.github.cloak-preview。
  
• Get请求参数q,值为repo:square/retrofit merge:false sort:author-date-desc
  
• 发送后的效果：
  
  具体的json数据很长，就不粘贴了。自己用postman跑下，就有了。

开始撸代码

• 网络权限

 <uses-permission android:name="android.permission.INTERNET"/>

• retrofit2.7.2中包含了okhttp3.14.7，需要增加java8编译配置，免得2.7.2版本编译失败。

android {
    compileSdkVersion 30
    buildToolsVersion "30.0.3"

    defaultConfig {
        ...
    }

    buildTypes {
      ...
    }

	// 增加java8的配置 
    compileOptions {
        sourceCompatibility JavaVersion.VERSION_1_8
        targetCompatibility JavaVersion.VERSION_1_8
    }
}

• 导入retrofit2依赖，不需要再导入okhttp了。

    implementation 'com.squareup.retrofit2:retrofit:2.7.2'
    implementation 'com.squareup.retrofit2:converter-gson:2.7.2'

• 从Postman中复制json数据，粘贴到GsonFormat插件，生成ResponseBean.java，接近1400行代码，就不贴了，看上面的github地址吧。
• 新建接口GithubApiService.java,代码如下：

public interface GithubApiService {
    @GET("search/commits")
    Call<ResponseBean> getReposCommits(@Header("Accept") String authorization, @Query("q") String para);
}

• MainActivity.java中初始化Retrofit、发送请求：

public class MainActivity extends AppCompatActivity {

    private static final String TAG = "xxx";
    public static final String BASE_URL = "https://api.github.com/";
    private static Retrofit retrofit = null;

    private final static String REPO_PATH = "repo:square/retrofit merge:false sort:author-date-desc";
    private final static String HEADER_AUTH = "application/vnd.github.cloak-preview";

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        connectAndGetApiData();
    }

    public void connectAndGetApiData(){
        if (retrofit == null) {
            retrofit = new Retrofit.Builder()
                    .baseUrl(BASE_URL)
                    .addConverterFactory(GsonConverterFactory.create())
                    .build();
        }

        GithubApiService commitApiService = retrofit.create(GithubApiService.class);

        Call<ResponseBean> call = commitApiService.getReposCommits(HEADER_AUTH,REPO_PATH);

        call.enqueue(new Callback<ResponseBean>() {
            @Override
            public void onResponse(Call<ResponseBean> call, Response<ResponseBean> response) {
                List<ResponseBean.ItemsBean> commits = response.body().getItems();
                Log.d(TAG, "Number of commits received: " + commits.size());
            }

            @Override
            public void onFailure(Call<ResponseBean> call, Throwable throwable) {
                Log.e(TAG, throwable.toString());
            }
        });
    }
}

运行结果，logcat截图，搞定。