最近事比较多，距离上次写文章已通过去了一个月了。上一篇文章Retrofit全攻略——基础篇介绍了Retrofit的基础用法，这篇文章介绍点进阶的用法。css

打印网络日志

在开发阶段，为了方便调试，咱们须要查看网络日志。由于Retrofit2.0+底层是采用的OKHttp请求的。能够给OKHttp设置拦截器，用来打印日志。
首先能够在app/build.gradle中添加依赖，这是官方的日志拦截器。java

compile 'com.squareup.okhttp3:logging-interceptor:3.3.0'

而后在代码中设置：json

public static Retrofit getRetrofit() { //若是mRetrofit为空 或者服务器地址改变 从新建立 if (mRetrofit == null) { OkHttpClient httpClient; OkHttpClient.Builder builder=new OkHttpClient.Builder(); //阶段分为开发和发布阶段，当前为开发阶段设置拦截器 if (BuildConfig.DEBUG) { HttpLoggingInterceptor logging = new HttpLoggingInterceptor(); //设置拦截器级别 logging.setLevel(HttpLoggingInterceptor.Level.BODY); builder.addInterceptor(logging); } httpClient=builder.build(); //构建Retrofit mRetrofit = new Retrofit.Builder() //配置服务器路径 .baseUrl(mServerUrl) //返回的数据经过Gson解析 .addConverterFactory(GsonConverterFactory.create()) //配置回调库，采用RxJava .addCallAdapterFactory(RxJavaCallAdapterFactory.create()) //设置OKHttp模板 .client(httpClient) .build(); } return mRetrofit; }

当处于开发阶段的时候，设置监听日志的拦截器。拦截有4个级别，分别是api

BODY
HEADERS
BASIC
NONE

其中BODY输出的日志是最全的。bash

添加相同的请求参数

为了更好的管理迭代版本，通常每次发起请求的时候都传输当前程序的版本号到服务器。
有些项目咱们每次还会传用户id，token令牌等相同的参数。
若是在每一个请求的接口都添加这些参数太繁琐。Retrofit能够经过拦截器添加相同的请求参数，无需再每一个接口添加了。服务器

步骤一，本身拦截器微信

public class CommonInterceptor implements Interceptor { @Override public Response intercept(Interceptor.Chain chain) throws IOException { Request oldRequest = chain.request(); // 添加新的参数 HttpUrl.Builder authorizedUrlBuilder = oldRequest.url() .newBuilder() .scheme(oldRequest.url().scheme()) .host(oldRequest.url().host()) .addQueryParameter("device_type", "1") .addQueryParameter("version", BuildConfig.VERSION_NAME) .addQueryParameter("token", PreUtils.getString(R.string.token)) .addQueryParameter("userid", PreUtils.getString(R.string.user_id)); // 新的请求 Request newRequest = oldRequest.newBuilder() .method(oldRequest.method(), oldRequest.body()) .url(authorizedUrlBuilder.build()) .build(); return chain.proceed(newRequest); } }

实现原理就是拦截以前的请求，添加完参数，再传递新的请求。这个位置我添加了四个公共的参数。
而后再Retrofit初始化的时候配置。网络

if (mRetrofit == null) { OkHttpClient httpClient; OkHttpClient.Builder builder=new OkHttpClient.Builder(); //添加公共参数 builder.addInterceptor(new CommonInterceptor()); httpClient=builder.build(); //构建Retrofit mRetrofit = new Retrofit.Builder() //.... .client(httpClient) .build(); }

处理约定错误

除了常见的404，500等异常，网络请求中咱们每每还会约定些异常，好比token失效，帐号异常等等。app

以token失效为例，每次请求咱们都须要验证是否失效，若是在每一个接口都处理一遍错误就有点太繁琐了。ide

咱们能够统一处理下错误。

步骤一，Retrofit初始化时添加自定义转化器

mRetrofit = new Retrofit.Builder() //配置服务器路径 baseUrl(mServerUrl) //配置回调库，采用RxJava .addCallAdapterFactory(RxJavaCallAdapterFactory.create()) //配置转化库，默认是Gson，这里修改了。 .addConverterFactory(ResponseConverterFactory.create()) .client(httpClient) .build();

步骤二建立ResponseConverterFactory

步骤一 ResponseConverterFactory这个类是须要咱们本身建立的。

public class ResponseConverterFactory extends Converter.Factory { /** * Create an instance using a default {@link Gson} instance for conversion. Encoding to JSON and * decoding from JSON (when no charset is specified by a header) will use UTF-8. */ public static ResponseConverterFactory create() { return create(new Gson()); } /** * Create an instance using {@code gson} for conversion. Encoding to JSON and * decoding from JSON (when no charset is specified by a header) will use UTF-8. */ public static ResponseConverterFactory create(Gson gson) { return new ResponseConverterFactory(gson); } private final Gson gson; private ResponseConverterFactory(Gson gson) { if (gson == null) throw new NullPointerException("gson == null"); this.gson = gson; } @Override public Converter<ResponseBody, ?> responseBodyConverter(Type type, Annotation[] annotations, Retrofit retrofit) { // TypeAdapter<?> adapter = gson.getAdapter(TypeToken.get(type)); return new GsonResponseBodyConverter<>(gson, type); } @Override public Converter<?, RequestBody> requestBodyConverter(Type type, Annotation[] parameterAnnotations, Annotation[] methodAnnotations, Retrofit retrofit) { TypeAdapter<?> adapter = gson.getAdapter(TypeToken.get(type)); return new GsonRequestBodyConverter<>(gson, adapter); } }

这里面咱们自定义了请求和响应时解析JSON的转换器——GsonRequestBodyConverter和GsonResponseBodyConverter。

其中GsonRequestBodyConverter 负责处理请求时传递JSON对象的格式，不须要额外处理任何事，直接使用默认的GSON解析。代码我直接贴出来：

final class GsonRequestBodyConverter<T> implements Converter<T, RequestBody> { private static final MediaType MEDIA_TYPE = MediaType.parse("application/json; charset=UTF-8"); private static final Charset UTF_8 = Charset.forName("UTF-8"); private final Gson gson; private final TypeAdapter<T> adapter; GsonRequestBodyConverter(Gson gson, TypeAdapter<T> adapter) { this.gson = gson; this.adapter = adapter; } @Override public RequestBody convert(T value) throws IOException { Buffer buffer = new Buffer(); Writer writer = new OutputStreamWriter(buffer.outputStream(), UTF_8); JsonWriter jsonWriter = gson.newJsonWriter(writer); adapter.write(jsonWriter, value); jsonWriter.close(); return RequestBody.create(MEDIA_TYPE, buffer.readByteString()); } }

GsonResponseBodyConverter负责把响应的数据转换成JSON格式，这个咱们须要处理一下。

public class GsonResponseBodyConverter<T> implements Converter<ResponseBody, T> { private final Gson gson; private final Type type; GsonResponseBodyConverter(Gson gson, Type type) { this.gson = gson; this.type = type; } @Override public T convert(ResponseBody value) throws IOException { String response = value.string(); try { Log.i("YLlibrary", "response>>> "+response); //ResultResponse 只解析result字段 BaseInfo baseInfo = gson.fromJson(response, BaseInfo.class); if (baseInfo.getHeader().getCode().equals("1")) { //正确 return gson.fromJson(response, type); } else { //ErrResponse 将msg解析为异常消息文本 错误码能够本身指定. throw new ResultException(-1024, baseInfo,response); } } finally { } } }

这种状况只是应用于后台接口数据统一的状况。好比咱们项目的格式是这样的

{
          header : {"message":"token失效","code":"99"} data : {} }

当code值是1的时候，表示正确，其它数字表示错误。只有正确的时候data才会有内容。

这里我用BaseInfo解析这个JSON：

public class BaseInfo { /** * header : {"message":"用户名或密码错误","code":"0"} * data : {} */ private HeaderBean header; public HeaderBean getHeader() { return header; } public void setHeader(HeaderBean header) { this.header = header; } public static class HeaderBean { /** * message : 用户名或密码错误 * code : 0 */ private String message; private String code; public String getMessage() { return message; } public void setMessage(String message) { this.message = message; } public String getCode() { return code; } public void setCode(String code) { this.code = code; } } }

服务器返回的数据实体对象所有继承BaseInfo 只是data内容不同。

ResultException这个类用于捕获服务器约定的错误类型

/** * 这个类用于捕获服务器约定的错误类型 */ public class ResultException extends RuntimeException { private int errCode = 0; private BaseInfo info; private String response; public ResultException(int errCode, BaseInfo info,String response) { super(info.getHeader().getMessage()); this.info=info; this.errCode = errCode; this.response=response; } public String getResponse() { return response; } public void setResponse(String response) { this.response = response; } public int getErrCode() { return errCode; } public BaseInfo getBaseInfo(){ return info; } }

最后定义Retrofit处理异常的代码

public abstract class AbsAPICallback<T> extends Subscriber<T> { //对应HTTP的状态码 private static final int UNAUTHORIZED = 401; private static final int FORBIDDEN = 403; private static final int NOT_FOUND = 404; private static final int REQUEST_TIMEOUT = 408; private static final int INTERNAL_SERVER_ERROR = 500; private static final int BAD_GATEWAY = 502; private static final int SERVICE_UNAVAILABLE = 503; private static final int GATEWAY_TIMEOUT = 504; //出错提示 private final String networkMsg; private final String parseMsg; private final String unknownMsg; protected AbsAPICallback(String networkMsg, String parseMsg, String unknownMsg) { this.networkMsg = networkMsg; this.parseMsg = parseMsg; this.unknownMsg = unknownMsg; } public AbsAPICallback(){ networkMsg="net error(联网失败)"; parseMsg="json parser error(JSON解析失败)"; unknownMsg="unknown error(未知错误)"; } ProgressBar progressBar; public AbsAPICallback(ProgressBar progressBar){ this(); this.progressBar=progressBar; } @Override public void onError(Throwable e) { Throwable throwable = e; //获取最根源的异常 while(throwable.getCause() != null){ e = throwable; throwable = throwable.getCause(); } ApiException ex; if (e instanceof HttpException){ //HTTP错误 HttpException httpException = (HttpException) e; ex = new ApiException(e, httpException.code()); switch(httpException.code()){ case UNAUTHORIZED: case FORBIDDEN: // onPermissionError(ex); //权限错误，须要实现 // break; case NOT_FOUND: case REQUEST_TIMEOUT: case GATEWAY_TIMEOUT: case INTERNAL_SERVER_ERROR: case BAD_GATEWAY: case SERVICE_UNAVAILABLE: default: ex.setDisplayMessage(networkMsg); //均视为网络错误 onNetError(ex); break; } } else if (e instanceof ResultException){ //服务器返回的错误 ResultException resultException = (ResultException) e; onResultError(resultException); } else if (e instanceof JsonParseException || e instanceof JSONException || e instanceof ParseException){ ex = new ApiException(e, ApiException.PARSE_ERROR); ex.setDisplayMessage(parseMsg); //均视为解析错误 onNetError(ex); } else { ex = new ApiException(e, ApiException.UNKNOWN); ex.setDisplayMessage(unknownMsg); //未知错误 onNetError(ex); } } static long time; protected void onNetError(ApiException e){ long currentTime=System.currentTimeMillis(); if(currentTime-time>3000){ //防止连续反馈 time=currentTime; UIUtils.showToast("网络加载失败"); } e.printStackTrace(); onApiError(e); } /** * 错误回调 */ protected void onApiError(ApiException ex){ Log.i("YLLibrary","onApiError"); if(progressBar!=null) UIUtils.runOnUiThread(new Runnable() { @Override public void run() { progressBar.setVisibility(View.GONE); progressBar=null; } }); } // /** // * 权限错误，须要实现从新登陆操做 // */ // protected void onPermissionError(ApiException ex){ // ex.printStackTrace(); // } /** * 服务器返回的错误 */ protected synchronized void onResultError(ResultException ex){ // if(ex.getErrCode()== XApplication.API_ERROR){ // UIUtils.getContext().onApiError(); //能够用来处理Token失效 // return ; // } if(ConstantValue.TOKEN_ERROR.equals(ex.getBaseInfo().getHeader().getCode()) &&!TextUtils.isEmpty(PreUtils.getString(R.string.token))){ //验证token是否为空是为了防止连续两次请求 PreUtils.putString(R.string.user_id,null); PreUtils.putString(R.string.token,null); PreUtils.putString(R.string.orgDistrict,null); if(BaseActivity.runActivity!=null){ Intent intent = new Intent(UIUtils.getContext(), LoginActivity.class); if(BaseActivity.runActivity instanceof MainActivity){ MainActivity activity= (MainActivity) BaseActivity.runActivity; int tabIndex=activity.getCurrentTab(); //activity.switchCurrentTab(0); activity.startActivityForResult(intent,tabIndex+10); }else { BaseActivity.runActivity.startActivity(intent); } } } Log.i("YLLibrary","resultError"); if(ex.getBaseInfo()!=null&&!TextUtils.isEmpty(ex.getBaseInfo().getHeader().getMessage())) UIUtils.showToast(ex.getBaseInfo().getHeader().getMessage()); ApiException apiException = new ApiException(ex, ex.getErrCode()); onApiError(apiException); } @Override public void onCompleted() { Log.i("YLLibrary","onCompleted"); if(progressBar!=null) UIUtils.runOnUiThread(new Runnable() { @Override public void run() { progressBar.setVisibility(View.GONE); progressBar=null; } }); } }

实际接口请求的代码，使用自定义异常回调的类——AbsAPICallback就能够统一处理异常:

ApiRequestManager.createApi().problemDetail(dataBean.getId())
                .compose(ApiRequestManager.<QuestionDetailInfo>applySchedulers())
                .subscribe(new AbsAPICallback<QuestionDetailInfo>() { @Override public void onNext(QuestionDetailInfo baseInfo) { fillData(baseInfo); } });

Retrofit全攻略——进阶篇

打印网络日志

添加相同的请求参数

处理约定错误