这是我参与2022首次更文挑战的第20天，活动详情查看：2022首次更文挑战
简介
在Android应用中，如果不是单机的话，应该都有请求后端接口API的情况，本篇文章就介绍下Retrofit在Android中如何进行使用的
相关代码
我们以一个简单的登录接口为例
完整代码GitHub上有：github.com/lw124392545…
仅做代码参考，目前数据监控上传是有了，但界面这些还很粗糙，没有完善
相关的依赖引入
首先我们在工程中引入相关的依赖：
implementation 'com.squareup.okhttp3:okhttp:4.5.0'
implementation 'com.squareup.retrofit2:retrofit:2.9.0'
implementation 'com.squareup.retrofit2:converter-gson:2.9.0'
复制代码相关的手机权限开启
需要在文件中开启网络权限：
<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="com.example.selfgrowth">
<uses-permission android:name="android.permission.INTERNET"/>
<application
......
</application>
</manifest>
复制代码配置Retrofit Client
Client的相关配置：单例，配置基于OKHTTP，Gson序列化;OKHTTP中添加了请求拦截器
@Data
public class RetrofitClient {
private static final RetrofitClient instance = new RetrofitClient();
private final Retrofit retrofit = new Retrofit.Builder()
.baseUrl(HttpConfig.ADDRESS) //基础url,其他部分在GetRequestInterface里
.client(httpClient())
.addConverterFactory(GsonConverterFactory.create()) //Gson数据转换器
.build();
public static RetrofitClient getInstance() {
return instance;
}
private OkHttpClient httpClient() {
return new OkHttpClient.Builder()
.addInterceptor(new AccessTokenInterceptor())
.connectTimeout(20, TimeUnit.SECONDS)
.build();
}
}
复制代码配置通用的请求拦截器
比如在请求中，带上Authorization等
public class AccessTokenInterceptor implements Interceptor {
@NonNull
@Override
public Response intercept(@NonNull Chain chain) throws IOException {
if (UserCache.getInstance().getToken() == null) {
return chain.proceed(chain.request());
}
Request original = chain.request();
Request.Builder requestBuilder = original.newBuilder()
.addHeader("Authorization", UserCache.getInstance().getToken());
Request request = requestBuilder.build();
return chain.proceed(request);
}
}
复制代码Retrofit接口定义
登录请求的接口定义：
public interface UserApi {
/**
* 用户登录
**/
@POST("auth/user/login")
Call<ApiResponse> login(@Body LoginUser user);
}
复制代码Retrofit Request具体请求编写
我们首先定义一个抽象类，在其中持有我们的RetrofitClient全局类，在其中发起请求，由于Android UI的形式，请求是异步的
public abstract class Request {
final Retrofit retrofit;
public Request() {
this.retrofit = RetrofitClient.getInstance().getRetrofit();
}
/**
* 发送网络请求(异步)
* @param call call
*/
void sendRequest(Call<ApiResponse> call, Consumer<? super Object> success, Consumer<? super Object> failed) {
call.enqueue(new Callback<ApiResponse>() {
@Override
public void onResponse(Call<ApiResponse> call, Response<ApiResponse> response) {
if (response.code() != 200) {
Log.w("Http Response", "请求响应错误");
failed.accept(response.raw().message());
return;
}
if (response.body() == null || response.body().getData() == null) {
success.accept(null);
return;
}
Object res = response.body().getData();
if (String.valueOf(res).isEmpty()) {
success.accept(null);
return;
}
success.accept(res);
}
@Override
public void onFailure(Call<ApiResponse> call, Throwable t) {
System.out.println("GetOutWarehouseList->onFailure(MainActivity.java): "+t.toString() );
}
});
}
}
复制代码如上所示，请求成功就执行success相关的逻辑，失败则执行failed相关的逻辑
登录请求的具体逻辑如下：构造Retrofit Interface，发起请求
public class UserRequest extends Request {
public void login(LoginUser user, Consumer<? super Object> success, Consumer<? super Object> failed) {
UserApi request = retrofit.create(UserApi.class);
Call<ApiResponse> call = request.login(user);
sendRequest(call, success, failed);
}
}
复制代码Android UI中进行调动
使用示例如下，点击一个登录按钮后触发
public class LoginFragment extends Fragment {
private final UserRequest userRequest = new UserRequest();
@Nullable
@Override
public View onCreateView(@NonNull LayoutInflater inflater, @Nullable ViewGroup container, @Nullable Bundle savedInstanceState) {
View rootView = inflater.inflate(R.layout.fragment_login, container, false);
Button loginButton = rootView.findViewById(R.id.login_button);
loginButton.setOnClickListener(view -> {
EditText email = rootView.findViewById(R.id.login_email_edit);
EditText password = rootView.findViewById(R.id.login_password_edit);
final LoginUser user = LoginUser.builder()
.email(email.getText().toString())
.password(password.getText().toString())
.build();
// 获取相关的用户名和密码后，调用登录接口
userRequest.login(user, (token) -> {
UserCache.getInstance().initUser(email.getText().toString(), token.toString());
final SharedPreferences preferences = requireContext().getSharedPreferences("userInfo", Context.MODE_PRIVATE);
final SharedPreferences.Editor edit = preferences.edit();
edit.putString("username", email.getText().toString());
edit.putString("password", password.getText().toString());
edit.apply();
Snackbar.make(view, "登录成功:" + token.toString(), Snackbar.LENGTH_LONG)
.setAction("Action", null).show();
}, failedMessage -> {
Snackbar.make(view, "登录失败:" + failedMessage, Snackbar.LENGTH_LONG)
.setAction("Action", null).show();
});
});
return rootView;
}
@Override
public void onActivityCreated(@Nullable Bundle savedInstanceState) {
super.onActivityCreated(savedInstanceState);
final SharedPreferences preferences = getActivity().getSharedPreferences("userInfo", Activity.MODE_PRIVATE);
final String userName = preferences.getString("username", "");
final String password = preferences.getString("password", "");
final EditText emailEdit = getView().findViewById(R.id.login_email_edit);
final EditText passwordEdit = getView().findViewById(R.id.login_password_edit);
emailEdit.setText(userName);
passwordEdit.setText(password);
}
}
复制代码总结
本篇文章中介绍了如Android学习中如何使用Retrofit发起网络请求
但由于吃初学，虽然感觉能用，但有点繁琐，不知道在实际的Android开发中，网络请求的最近实践是怎么样的，如果有的话，大佬可以在评论区告知下，感谢