开始本博客之前，请先阅读： Retrofit请求数据对错误以及网络异常的处理
实际开发经常有这种情况，比如登录请求，接口返回的
假如服务器返回的是统一数据格式：
public class Response<T> {
public int state;
public String message;
public T data;}
网络异常导致的登录失败，在使用Retrofit+RxJava请求时都会直接调用subscribe的onError事件；
密码错误导致的登录失败，在使用Retrofit+RxJava请求时都会调用subscribe的onNext事件；
无论是异常还是错误，都要在subscribe里面处理异常信息，如下代码：
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APIWrapper.getInstance().login(
"username" ,
"password" ) .subscribe(
new Observer<Response<User>>() {
@Override public void onCompleted () { }
@Override public void onError (Throwable e) { }
@Override public void onNext (Response<User> data) {
if (data.state ==
1001 ){ }
else if (data.state ==
1002 ){ } } });
现在我希望在发生任何错误的情况下，都会调用onError事件，并且由model来处理错误信息。那么，此时我们就应该有一个ExceptionEngine来处理事件流中的错误信息了。
在正常情况下，我们获取网络数据的流程通常如下：
请求接口->解析数据->更新ＵＩ
整个数据请求过程都是发生在Rx中的工作流之中。当有异常产生的时候，我们要尽量不在ui层里面进行判断，换句话说，我们没有必要去告诉ui层具体的错误信息，只需要让他弹出一个信息（Toast或者Dialog）展示我们给它的信息就行。
请求接口和数据解析都可能出错，所以在这两层进行错误处理。为了更好的解耦，我们通过拦截器拦截错误，然后根据错误类型分发信息。
数据解析层的拦截器
这个拦截器主要是为了获取具体的错误信息，分发给上层的UI，给用户以提示，增强用户体验。
public Observable<Weather>
getWeather (String cityName){
return weatherService.getWeather(cityName) .map(
new ServerResponseFunc<Weather>()) .onErrorResumeNext(
new HttpResponseFunc<Weather>()); }
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private class ServerResponseFunc <T > implements Func1 <Response <T >, T > { @Override
public T call(Response<T> reponse) {
if (reponse.state !=
0 ) {
throw new ServerException(reponse.state,reponse.message); }
return reponse.data; } }
所以整个逻辑是这样的：
所以在前三步的过程中，只要发生异常(服务器返回的错误也抛出了)都会抛出，这时候就触发了RxJava的OnError事件。
处理onError事件的拦截器
这个拦截器主要是将异常信息转化为用户”能看懂”的友好提示。
private class HttpResponseFunc <T > implements Func1 <Throwable , Observable <T >> { @Override
public Observable<T> call(Throwable throwable) {
return Observable.error(ExceptionEngine.handleException(throwable)); } }
两个拦截器以前使用，代码如下：
public Observable<Weather>
getWeather (String cityName){
return weatherService.getWeather(cityName) .map(
new ServerResponseFunc<Weather>()) .onErrorResumeNext(
new HttpResponseFunc<Weather>()); }
调用：
APIWrapper.getInstance().getWeather(
"北京" ) .subscribe(
new SampleProgressObserver<Weather>(MainActivity.
this ) {
@Override public void onNext (WeatherBean weatherBean) { tv.setText(weatherBean.toString()); } });
相关类：
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public
class RxSubscriber <T > extends ErrorSubscriber <T > {@Override public void onStart() {
super .onStart(); DialogHelper.showProgressDlg(context,
"正在加载数据" ); }
@Override public void onCompleted() { DialogHelper.stopProgressDlg(); }
@Override protected void onError(ApiException ex) { DialogHelper.stopProgressDlg(); Toast.makeText(context, ex.message, Toast.LENGTH_SHORT).show(); }
@Override public void onNext(T t) { }}public
abstract class ErrorSubscriber <T > extends Observer <T > {@Override public void onError(Throwable e) {
if (e instanceof ApiException){ onError((ApiException)e); }
else { onError(
new ApiException(e,
123 )); } }
/** * 错误回调 */ protected abstract void onError(ApiException ex);}
处理异常的驱动器
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package com.sanniuben.net;
import android.net.ParseException;
import com.google.gson.JsonParseException;
import org.json.JSONException;
import java.net.ConnectException;
import retrofit2.adapter.rxjava.HttpException;
/** * Created by Lzx on 2016/7/11. */ public class ExceptionEngine {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 ;
public static ApiException
handleException (Throwable e){ ApiException ex;
if (e
instanceof HttpException){ HttpException httpException = (HttpException) e; ex =
new ApiException(e, ERROR.HTTP_ERROR);
switch (httpException.code()){
case UNAUTHORIZED:
case FORBIDDEN:
case NOT_FOUND:
case REQUEST_TIMEOUT:
case GATEWAY_TIMEOUT:
case INTERNAL_SERVER_ERROR:
case BAD_GATEWAY:
case SERVICE_UNAVAILABLE:
default : ex.message =
"网络错误" ;
break ; }
return ex; }
else if (e
instanceof ServerException){ ServerException resultException = (ServerException) e; ex =
new ApiException(resultException, resultException.code); ex.message = resultException.message;
return ex; }
else if (e
instanceof JsonParseException || e
instanceof JSONException || e
instanceof ParseException){ ex =
new ApiException(e, ERROR.PARSE_ERROR); ex.message =
"解析错误" ;
return ex; }
else if (e
instanceof ConnectException){ ex =
new ApiException(e, ERROR.NETWORD_ERROR); ex.message =
"连接失败" ;
return ex; }
else { ex =
new ApiException(e, ERROR.UNKNOWN); ex.message =
"未知错误" ;
return ex; } }}
/** * 约定异常 */ public class ERROR {/** * 未知错误 */ public static final int UNKNOWN =
1000 ;
/** * 解析错误 */ public static final int PARSE_ERROR =
1001 ;
/** * 网络错误 */ public static final int NETWORD_ERROR =
1002 ;
/** * 协议出错 */ public static final int HTTP_ERROR =
1003 ;}
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public class ApiException extends Exception {public int code;
public String message;
public ApiException (Throwable throwable,
int code) {
super (throwable);
this .code = code; }}
public class ServerException extends RuntimeException {public int code;
public String message;}
DialogHelper.java
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public class DialogHelper {/** * 通用Dialog * */ public interface OnOkClickListener {abstract void onOkClick(); }
/** * Listener */ public interface OnCancelClickListener {abstract void onCancelClick(); }
private static AlertDialog mDialog;
public static void showDialog (Context context, String title, String content,
final OnOkClickListener listenerYes,
final OnCancelClickListener listenerNo) { showDialog(context, context.getString(android.R.string.ok), context.getString(android.R.string.cancel), title, content, listenerYes, listenerNo); }
public static void showDialog (Context context, String ok, String cancel, String title, String content,
final OnOkClickListener listenerYes,
final OnCancelClickListener listenerNo) { AlertDialog.Builder builder =
new AlertDialog.Builder(context); builder.setMessage(content); builder.setTitle(title); builder.setPositiveButton(ok,
new DialogInterface.OnClickListener() {
public void onClick (DialogInterface dialog,
int which) {
if (listenerYes !=
null ) { listenerYes.onOkClick(); } mDialog =
null ; } }); builder.setNegativeButton(cancel,
new DialogInterface.OnClickListener() {
public void onClick (DialogInterface dialog,
int which) {
if (listenerNo !=
null ) { listenerNo.onCancelClick(); } mDialog =
null ; } }); builder.setCancelable(
false ); mDialog = builder.create();
if (!mDialog.isShowing()) mDialog.show(); }
public static void showDialog (Context context,
int ok,
int cancel,
int title,
int content,
final OnOkClickListener listenerYes,
final OnCancelClickListener listenerNo) { showDialog(context, context.getString(ok), context.getString(cancel), context.getString(title), context.getString(content), listenerYes, listenerNo); }
static ProgressDialog progressDlg =
null ;
/** * 启动进度条 * * @param strMessage 进度条显示的信息 * @param // 当前的activity */ public static void showProgressDlg (Context ctx, String strMessage) {
if (
null == progressDlg) {
if (ctx ==
null )
return ; progressDlg =
new ProgressDialog(ctx); progressDlg.setProgressStyle(ProgressDialog.STYLE_SPINNER); progressDlg.setMessage(strMessage); progressDlg.setIndeterminate(
false ); progressDlg.setCancelable(
true ); progressDlg.show(); } }
public static void showProgressDlg (Context ctx) { showProgressDlg(ctx,
"" ); }
/** * 结束进度条 */ public static void stopProgressDlg () {
if (
null != progressDlg && progressDlg.isShowing()) { progressDlg.dismiss(); progressDlg =
null ; }
if (
null != dialog && dialog.isShowing()) { dialog.dismiss(); dialog =
null ; } }
private static Dialog dialog;
public static void showDialogForLoading (Context context, String msg,
boolean cancelable) {
if (
null == dialog) {
if (
null == context)
return ; View view = LayoutInflater.from(context).inflate(R.layout.layout_loading_dialog,
null ); TextView loadingText = (TextView)view.findViewById(R.id.loading_tip_text); loadingText.setText(msg); dialog =
new Dialog(context, R.style.loading_dialog_style); dialog.setCancelable(cancelable); dialog.setCanceledOnTouchOutside(cancelable); dialog.setContentView(view,
new LinearLayout.LayoutParams(LinearLayout.LayoutParams.MATCH_PARENT, LinearLayout.LayoutParams.MATCH_PARENT)); Activity activity = (Activity) context;
if (activity.isFinishing())
return ; dialog.show(); } }}
可能本博客也不是最好的解决方案，如果有更好的想法，我愿与你互相交流！
代码参考：https://github.com/122627018/Retorfit_RxJava_Exception
分享： Retrofit+RxJava错误预处理
看到bobo_wang的文章，不仅感觉有受益匪浅，这里做下介绍。
首先定义如下Transformer转换器。
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public static <T> Observable.Transformer<Response<T>, T> sTransformer() {
return responseObservable -> responseObservable.map(tResponse -> {
if (!tResponse.success)
throw new RuntimeException(tResponse.code);
return tResponse.data; }).onErrorResumeNext(
new HttpResponseFunc<>()); }
public static <T> Observable.Transformer<T, T> switchSchedulers() {
return observable -> observable.subscribeOn(Schedulers.io()) .observeOn(AndroidSchedulers.mainThread()); }
private static class HttpResponseFunc <T > implements Func1 <Throwable , Observable <T >> { @Override
public Observable<T> call(Throwable throwable) {
return Observable.error(
new Throwable(throwable)); } }
调用：
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public void login (View v){ apiservice.login(name,pwd) .compose(Transformers.sTransformer()) .compose(Transformers.switchSchedulers()) .subscribe(subscriber);}
private Subscriber<UserModel> subscriber =
new Subscriber<UserModel>() {
@Override public void onCompleted () { }
@Override public void onError (Throwable e) { }
@Override public void onNext (UserModel model) { } };
接口：
@FormUrlEncoded @POST("interface?login" ) Observable<Response<UserModel>> login(@Field("name" ) String name,@Field("pwd" ) String pwd) ;
最后再来点干货。
Transformer 和 Func 处理的区别
如上的处理，定义了 一个 sTransformer 和一个 HttpResponseFunc,
public void login (View v){ apiservice.login(name,pwd) .compose(Transformers.switchSchedulers()) .map(
new TransFuc<UserModel>()) .onErrorReturn(
new HttpResponseFunc<>()) .subscribe(subscriber);}
public static class TransFuc <T > implements Func1 <Response <T >, T > { @Override
public T call(Response<T> tResponse) {
if (!tResponse.success)
throw new RuntimeException(tResponse.code);
return tResponse.data; } }
Transformer作用于整个流，Func1是一个操作符,作用于数据项。
不规范数据的处理
有时候服务器返回的数据并不是十分规范的,比如
{
"success" :
true ,
"status" :
"1" ,
"data" : { } }
错误时时这样的
{
"success" :
false ,
"status" :
"0" ,
"data" :
"371" }
这时候如果我么用泛型处理
public class Response<T> {
public boolean success;
public String status;
public T data;}
针对这种数据,我们的泛型该怎么写成了问题,错误的时候是String,正确的时候是Bean?
如果我们直接写成JavaBean,那么我们会得到一个错误,LinkedTreeMap cannot be cast to xxx
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public static Observable
. Transformer
< String , UserModel
> trans() {
return stringObservable
-> stringObservable
. map (s
-> { Response parseJson
= GsonUtil
. parseJson(s, Response
. class);
if (
null == parseJson) { throw
new RuntimeException(
"null == parseJson" ); }
if (PatternsUtil
. isNum(parseJson
. data . toString())) { throw
new RuntimeException(parseJson
. data . toString()); }
return GsonUtil
. parseJson(s, UserModel
. class); })
. onErrorResumeNext(
new HttpResponseFunc
<> ()); }
使用就变成了如下这样
public void login(View v){ apiservice
.login (name,pwd)
.compose (Transformers
.switchSchedulers ())
.compose (Transformers
.trans ())
.subscribe (subscriber)}
封装的越来越简介了，用到实际项目吧！
