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Rxjava + Retrofit 你需要掌握的几个经典技巧

时间:2017-03-16 15:13:15      阅读:415      评论:0      收藏:0      [点我收藏+]

标签:src   服务   转义符   返回   tcl   ons   compose   ram   throws   

本文出处 :Tamic
文/ http://blog.csdn.net/sk719887916/article/details/52132106

Rxjava +Rterofit 需要掌握的几个技巧

技术分享

RXjava入门和详解请移步 比较有名的《RxJAVA详解》,这里继续前篇一些列的介绍一些容易忽略的技巧.

Retrofit+RxJava结合系列请阅读:


取消订阅

一般我们在视图消亡后,无需RxJava再执行,可以直接取消订阅

  if (!subscription.isUnsubscribed()) {
        subscription.unsubscribe();
    }

 observable.unsubscribeOn(Schedulers.io());

可用在activity的 onDestroy(), Fragment的 onDestroyView()中调用

还有种场景是借助rxJava请求网络数据,需要网络返回后保存数据并更新UI,这种情况视图已经消亡了必定会导致rxJava出错,导致App闪退,这种我们可以判断前的activity/view是否为空,并是否已showing,如果
两者都不存在,即可无须更新UI。只处理保存数据即可。

订阅问题

需要UI绘制后再进行订阅的场景,防止阻塞UI,我们需要延迟订阅执行。

立即订阅;

observable
               .subscribeOn(Schedulers.io())
               .observeOn(AndroidSchedulers.mainThread())
               .subscribe(action);

延迟订阅

observable.delay(2, TimeUnit.SECONDS)
               .subscribeOn(Schedulers.io())
               .observeOn(AndroidSchedulers.mainThread())
               .subscribe(action);

基础ApiService

通常我们写接口会有以下定义,增加一个api就必须写一个方法

public interface MyApi {

@GET("app.php")
Observable<SouguBean> getSougu(@Query("name") String name);

@GET("/getWeather")
Observable<ResponseBody> getWeather(@QueryMap Map<String, String> maps);
}

很多时候每新增一个接口就要写一个api,是不是有很好的方法代替这种情况。

@GET()
<T> Observable<ResponseBody> get(
        @Url String url,
        @QueryMap Map<String, T> maps);

我们可以定义一个通用的getApi,将url动态传入,返回Modle定义为ResponseBody, 并将实际参数定义为泛型,不管是更改url,还是服务端返回类型,包括参数个数都可以完美适配,这种方式技术不到位的千万别用,因为Retrofit明确说明接口必须要给定明确类型,悠着点哈!

上层进行通用组装时就可以这样子:

   public <T> T get(String url, Map<String, T> maps, BaseSubscriber<ResponseBody> subscriber) {
return (T) apiManager.get(url, maps)
.compose(schedulersTransformer)
.compose(handleErrTransformer())
.subscribe(subscriber);
}

看不懂?看不懂不算奇怪,源码可以去文章末尾下载研究,这里只是列举了一下。这种方式很适合从HttpClent迁移到Retrofit带来接口适配问题,一用一个准啊…

基础Subscriber

很多时候我们需要借用RxJava开启多个observable去读取网络,这是我们对不同Subscriber处理起来比较麻烦,因此统一对Subscriber对网络返回进行处理和, 有无网络做判断,甚至可以根据需求显示加载进度等
构建抽象的BaseSubscribe类,只处理start()onCompleted() ,上层处理时只处理onError()onNext()

 /**
    * BaseSubscriber
    * Created by Tamic on 2016-7-15.
    */
   public abstract class BaseSubscriber<T> extends Subscriber<T> {

       private BaseActivity context;

       public BaseSubscriber(BaseActivity context) {
           this.context = context;
       }

       @Override
       public void onStart() {
           super.onStart();

           if (!NetworkUtil.isNetworkAvailable(context)) {

               Toast.makeText(context, "当前网络不可用,请检查网络情况", Toast.LENGTH_SHORT).show();
              // 一定好主动调用下面这一句
               onCompleted();

               return;
           }
           // 显示进度条
           showLoadingProgress();
       }

       @Override
       public void onCompleted() {
          //关闭等待进度条
          closeLoadingProgress();

       }


   }

这样我们上层调用时只关心成功和失败即可无需关心网络情况

observable.subscribeOn(Schedulers.io())
               .observeOn(AndroidSchedulers.mainThread())
               .subscribe(new BaseSubscriber<ResponseBody>(MainActivity.this) {

                @Override
                public void onError(Throwable e) {
                   Toast.makeText(MainActivity.this, e.getMessage(), Toast.LENGTH_LONG).show();
                }

                @Override
                public void onNext(ResponseBody responseBody) {
                    Toast.makeText(MainActivity.this, responseBody.toString(), Toast.LENGTH_LONG).show();
                }
            });
 );

如果想对Error错误统一处理,也可以在BaseSubscriber处理onError(), 然后在callback上层,具体看自己项目情况。

/**
  * 网络返回基类 支持泛型
  * Created by Tamic on 2016-06-06.
 */

public class BaseResponse<T> {

  private int code;
  private String msg;
  private T data;

 public int getCode() {
     return code;
 }

public void setCode(int code) {
    this.code = code;
}

public String getMsg() {
    return msg;
}

public void setMsg(String msg) {
    this.msg = msg;
}

public T getData() {
    return data;
}

public void setData(T data) {
    this.data = data;
}

public boolean isOk() {
    return code == 0;
}

}

如果对成功结果进行处理,则可以将 ResonseBody 加入泛型.
Response 一般是包含Code,msg, Data的,在这里你可以中级判断code来进行业务分发,代码很简单具体看文章结尾源码即可 如果你觉得目前的返回判断麻烦,也可以定义Respons基类。

我们在onNext() 只需统一判断状态码即可

 @Override
  public void onNext(BaseResponse<IpResult> responseBody) {

        if (responseBody.isOk()) {

          IpResult ip = responseBody.getData();
          Toast.makeText(MainActivity.this, ip.toString(), Toast.LENGTH_LONG).show();
            }

}

错误结果问题

通过RX的 Func1来进行对原始的Throwable 进行包装转换

我们将原来Throwable 强转成自定义的 ResponeThrowable;

private static class HttpResponseFunc《T》 implements Func1《Throwable, Observable《T》》 {
    @Override public Observable<T> call(Throwable t) {
        return Observable.error(ExceptionHandle.handleException(t));
    }
}

ResponeThrowable

public static class ResponeThrowable extends Exception {
    public int code;
    public String message;

    public ResponeThrowable(Throwable throwable, int code) {
        super(throwable);
        this.code = code;

    }
}

我们已经处理好强转工作后 继续讲 Func1加到Observable 中:

因此这样用observable提供的onErrorResumeNext 则可以将你自定义的Func1 关联到错误处理类中:

  ((Observable) observable).onErrorResumeNext(new HttpResponseFunc<T>());

很可能你感觉有点不理解,这前提你需要了解RxJava的转义符和操 Observable.Transformer
还有Func1

这样我们对服务器返回的错误状态进行了自我的处理,再稍加翻译下便可以达到用户看懂的语言

这个类我参考一叶扁舟同学的案列,我再次做了改进:

ExceptionHandle 错误处理驱动

public class ExceptionHandle {

 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 ResponeThrowable handleException(Throwable e) {
    ResponeThrowable ex;
    if (e instanceof HttpException) {
        HttpException httpException = (HttpException) e;
        ex = new ResponeThrowable(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 ResponeThrowable(resultException, resultException.code);
        ex.message = resultException.message;
        return ex;
    } else if (e instanceof JsonParseException
            || e instanceof JSONException
            || e instanceof ParseException) {
        ex = new ResponeThrowable(e, ERROR.PARSE_ERROR);
        ex.message = "解析错误";
        return ex;
    } else if (e instanceof ConnectException) {
        ex = new ResponeThrowable(e, ERROR.NETWORD_ERROR);
        ex.message = "连接失败";
        return ex;
    } else if (e instanceof javax.net.ssl.SSLHandshakeException) {
        ex = new ResponeThrowable(e, ERROR.SSL_ERROR);
        ex.message = "证书验证失败";
        return ex;
    }
    else {
        ex = new ResponeThrowable(e, ERROR.UNKNOWN);
        ex.message = "未知错误";
        return ex;
    }
}


/**
 * 约定异常
 */
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;

    /**
     * 证书出错
     */
    public static final int SSL_ERROR = 1005;
}

public static class ResponeThrowable extends Exception {
    public int code;
    public String message;

    public ResponeThrowable(Throwable throwable, int code) {
        super(throwable);
        this.code = code;

    }
}

public class ServerException extends RuntimeException {
    public int code;
    public String message;
}

}

接着可以在 BaseSubscriber中处理异常拉

public abstract class BaseSubscriber<T> extends Subscriber<T> {

private Context context;


public BaseSubscriber(Context context) {
    this.context = context;
}

@Override
public void onError(Throwable e) {
    Log.e("Tamic", e.getMessage());
    // todo error somthing

    if(e instanceof ExceptionHandle.ResponeThrowable){
        onError((ExceptionHandle.ResponeThrowable)e);
    } else {
        onError(new ExceptionHandle.ResponeThrowable(e, ExceptionHandle.ERROR.UNKNOWN));
    }
 }
}

最后上层调用就是这样了:

RetrofitClient.getInstance(MainActivity.this).createBaseApi().getData(new BaseSubscriber(MainActivity.this) {

                @Override
                public void onError(ResponeThrowable e) {
                   // 处理翻译后异常。
                    Log.e("Tamic", e.code + " "+ e.message);
                    Toast.makeText(MainActivity.this, e.message, Toast.LENGTH_LONG).show();

                }

                @Override
                public void onNext(IpResult responseBody) {
                    Toast.makeText(MainActivity.this, responseBody.toString(), Toast.LENGTH_LONG).show();
                }
            }, "21.22.11.33");

缓存问题

有时候需要在无网络时增加缓存功能,因此给Retrofit加入基础拦截器,来处理缓存问题

/**
    * BaseInterceptor
    * Created by Tamic on 2016-7-15.
    */
public class BaseInterceptor implements Interceptor{
    private Map<String, String> headers;
    private Context context;
    public BaseInterceptor(Map<String, String> headers, Context context) {
        this.headers = headers;
        this.context = context;
    }

    @Override
    public Response intercept(Chain chain) throws IOException {

        Request.Builder builder = chain.request()
                .newBuilder();
        builder.cacheControl(CacheControl.FORCE_CACHE).url(chain.request().url())
        .build();

        if (!NetworkUtil.isNetworkAvailable(context)) {

            ((Activity)context).runOnUiThread(new Runnable() {
                @Override
                public void run() {
                    Toast.makeText(context, "当前无网络!", Toast.LENGTH_SHORT).show();
                }
            });
        }
        if (headers != null && headers.size() > 0) {
            Set<String> keys = headers.keySet();
            for (String headerKey : keys) {
                builder.addHeader(headerKey, headers.get(headerKey)).build();
            }
        }

        if (NetworkUtil.isNetworkAvailable(context)) {
            int maxAge = 60; // read from cache for 60 s
            builder
                    .removeHeader("Pragma")
                    .addHeader("Cache-Control", "public, max-age=" + maxAge)
                    .build();
        } else {
            int maxStale = 60 * 60 * 24 * 14; // tolerate 2-weeks stale
            builder
                    .removeHeader("Pragma")
                    .addHeader("Cache-Control", "public, only-if-cached, max-stale=" + maxStale)
                    .build();
        }
        return chain.proceed(builder.build());

    }
}

okHttpClient加入拦截器

       okHttpClient = new OkHttpClient.Builder()

            .addInterceptor(new BaseInterceptor(headers, context))
            .connectTimeout(DEFAULT_TIMEOUT, TimeUnit.SECONDS)
            .build();

Retrofit 加入okhttpClient

retrofit = new Retrofit.Builder()
                .client(okHttpClient)
                .baseUrl(url)
                .build();

如果你不想用okhttp自带的缓存策略,因为这需要服务端配合处理缓存请求头,不然会抛出: HTTP 504 Unsatisfiable Request (only-if-cached)

除了以上修改 Request.cacheControl的方式实现缓存,也可以自定义一个Cahe策略用来实现本地硬缓存。

构建CaheManager,用Url对应Json实现,此类非常简单,你可以自己实现,时间策略可自我加入扩展
在BaseSubscriber进行网络判断,加载缓存数据返回妥妥的;

 @Override
 public void onStart() {
    super.onStart();

    Toast.makeText(context, "http is start", Toast.LENGTH_SHORT).show();

    // todo some common as show loadding  and check netWork is NetworkAvailable
    // if  NetworkAvailable no !   must to call onCompleted
    if (!NetworkUtil.isNetworkAvailable(context)) {
        Toast.makeText(context, "无网络", Toast.LENGTH_SHORT).show();

        if (isNeedCahe) {
            Toast.makeText(context, "无网络,已智能读取缓存!", Toast.LENGTH_SHORT).show();
            IpResult ipResult = new Gson().fromJson(CaheManager.getjson(url), IpResult.class);
            onNext((T) ipResult);
        }
        onCompleted();
    }

}

常规问题归总

1 url被转义

   http://api.myapi.com/http%3A%2F%2Fapi.mysite.com%2Fuser%2Flist

请将@path改成@url

   public interface APIService { 
    @GET Call<Users> getUsers(@Url String url);}

或者:

  public interface APIService {
    @GET("{fullUrl}")
    Call<Users> getUsers(@Path(value = "fullUrl", encoded = true) String fullUrl);
}

2Method方法找不到

java.lang.IllegalArgumentException: Method must not be null

请指定具体请求类型@get @post等

   public interface APIService { 

   @GET Call<Users> getUsers(@Url String url);
}

3Url编码不对,@fieldMap parameters must be use FormUrlEncoded

如果用fieldMap加上FormUrlEncoded编码

@POST()
@FormUrlEncoded
Observable<ResponseBody> executePost(
        @FieldMap Map<String, Object> maps);

上层需要转换将自己的map转换为FieldMap

 @FieldMap(encoded = true) Map<String, Object> parameters,

4 paht和url一起使用

Using @Path and @Url paramers together with retrofit2

java.lang.IllegalArgumentException: @Path parameters may not be used with @Url. (parameter #4

如果你是这样的:

 @GET
Call<DataResponse> getOrder(@Url String url,
 @Path("id") int id);

请在你的url指定占位符.url:

www.myAPi.com/{Id}

总结


接着上次的介绍,笔者进行新框架开发novate已快接近尾声,估计本月就能和大家见面,敬请继续关注!

封装https://github.com/Tamicer/RetrofitClient
源 码https://github.com/Tamicer/Novate

Rxjava + Retrofit 你需要掌握的几个经典技巧

标签:src   服务   转义符   返回   tcl   ons   compose   ram   throws   

原文地址:http://blog.csdn.net/sk719887916/article/details/52132106

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