XUtils3代码详解--http

作者: carrey001 | 来源:发表于2016-06-13 18:19 被阅读1405次

    这是xutils3 源码分析的第二篇。

    第一篇超级传送门:xutils3详解一


    官方访问网络用法:

    复杂版本:

    /** 
    * 自定义实体参数类请参考: 
    * 请求注解 {@link org.xutils.http.annotation.HttpRequest} 
    * 请求注解处理模板接口 {@link org.xutils.http.app.ParamsBuilder} 
    * * 需要自定义类型作为callback的泛型时, 参考: 
    * 响应注解 {@link org.xutils.http.annotation.HttpResponse} 
    * 响应注解处理模板接口 {@link org.xutils.http.app.ResponseParser} 
    * * 示例: 查看 org.xutils.sample.http 包里的代码 
    */
    BaiduParams params =newBaiduParams();
    params.wd ="xUtils";// 有上传文件时使用multipart表单, 否则上传原始文件流.
    // params.setMultipart(true);// 上传文件方式 1
    // params.uploadFile = new File("/sdcard/test.txt");// 上传文件方式 2
    // params.addBodyParameter("uploadFile", new File("/sdcard/test.txt"));
    Callback.Cancelable cancelable = x.http().get(params, 
    /** * 1. callback的泛型: 
    * callback参数默认支持的泛型类型参见{@link org.xutils.http.loader.LoaderFactory}, 
    * 例如: 指定泛型为File则可实现文件下载, 使用params.setSaveFilePath(path)指定文件保存的全路径. 
    * 默认支持断点续传(采用了文件锁和尾端校验续传文件的一致性). 
    * 其他常用类型可以自己在LoaderFactory中注册, 
    * 也可以使用{@link org.xutils.http.annotation.HttpResponse} 
    * 将注解HttpResponse加到自定义返回值类型上, 实现自定义ResponseParser接口来统一转换. 
    * 如果返回值是json形式, 那么利用第三方的json工具将十分容易定义自己的ResponseParser. 
    * 如示例代码{@link org.xutils.sample.http.BaiduResponse}, 可直接使用BaiduResponse作为 
    * callback的泛型. 
    * * 2. callback的组合: 
    * 可以用基类或接口组合个种类的Callback, 见{@link org.xutils.common.Callback}. 
    * 例如: 
    * a. 组合使用CacheCallback将使请求检测缓存或将结果存入缓存(仅GET请求生效). 
    * b. 组合使用PrepareCallback的prepare方法将为callback提供一次后台执行耗时任务的机会, 
    * 然后将结果给onCache或onSuccess. 
    * c. 组合使用ProgressCallback将提供进度回调.
    * ...(可参考{@link org.xutils.image.ImageLoader} 
    * 或 示例代码中的 {@link org.xutils.sample.download.DownloadCallback}) 
    * * 3. 请求过程拦截或记录日志: 参考 {@link org.xutils.http.app.RequestTracker} 
    * * 4. 请求Header获取: 参考 {@link org.xutils.http.app.RequestInterceptListener} 
    * * 5. 其他(线程池, 超时, 重定向, 重试, 代理等): 参考 {@link org.xutils.http.RequestParams} 
    * 
    **/
      newCallback.CommonCallback<String>() { 
          @Override
          public void onSuccess(Stringresult) { 
            Toast.makeText(x.app(), result, Toast.LENGTH_LONG).show(); 
          } 
          @Override
          public void onError(Throwableex, booleanisOnCallback) { 
              //Toast.makeText(x.app(), ex.getMessage(), Toast.LENGTH_LONG).show();
              if (ex instanceofHttpException) { // 网络错误
                  HttpException httpEx = (HttpException) ex; 
                  int responseCode = httpEx.getCode(); 
                  String responseMsg = httpEx.getMessage();
                   String errorResult = httpEx.getResult();
                   // ... 
              } else {
               // 其他错误//
                 ... 
              } 
              Toast.makeText(x.app(), ex.getMessage(), Toast.LENGTH_LONG).show(); 
            } 
            @Override
            public void onCancelled(CancelledExceptioncex) { 
                Toast.makeText(x.app(), "cancelled", Toast.LENGTH_LONG).show();
               }
         @Override
          public void onFinished() { } 
        });
    // cancelable.cancel(); // 取消请求
    

    简单版本:

    RequestParams params =newRequestParams("https://www.baidu.com/s"); 
    params.setSslSocketFactory(...); // 设置ssl 
    params.addQueryStringParameter("wd", "xUtils"); 
    x.http().get(params, newCallback.CommonCallback<String>() { 
      @Override
      public void onSuccess(Stringresult) { 
      Toast.makeText(x.app(), result, Toast.LENGTH_LONG).show(); 
      } 
      @Override
      public void onError(Throwableex, booleanisOnCallback) { 
      Toast.makeText(x.app(), ex.getMessage(), Toast.LENGTH_LONG).show();
      } 
      @Override
      public void onCancelled(CancelledExceptioncex) { 
      Toast.makeText(x.app(), "cancelled", Toast.LENGTH_LONG).show(); 
      } 
      @Override
      public void onFinished() { }
     });
    带有缓存的请求示例:
    BaiduParams params =newBaiduParams();
    params.wd ="xUtils";
    // 默认缓存存活时间, 单位:毫秒.(如果服务没有返回有效的max-age或Expires)params.setCacheMaxAge(1000*60);
    Callback.Cancelable cancelable // 使用CacheCallback, xUtils将为该请求缓存数据.
              = x.http().get(params, newCallback.CacheCallback<String>() { 
              privateboolean hasError =false;
              privateString result =null; 
              @Override
              public boolean onCache(Stringresult) {
               // 得到缓存数据, 缓存过期后不会进入这个方法.
              // 如果服务端没有返回过期时间, 参考params.setCacheMaxAge(maxAge)方法.
               ////* 客户端会根据服务端返回的 header 中 max-age 或 expires 来确定本地缓存是否给 onCache 方法.
              // 如果服务端没有返回 max-age 或 expires, 那么缓存将一直保存, 除非这里自己定义了返回false的
            // 逻辑, 那么xUtils将请求新数据, 来覆盖它.
            //// * 如果信任该缓存返回 true, 将不再请求网络;
            // 返回 false 继续请求网络, 但会在请求头中加上ETag, Last-Modified等信息,
            // 如果服务端返回304, 则表示数据没有更新, 不继续加载数据.
            //this.result = result; returnfalse;   
              // true: 信任缓存数据, 不在发起网络请求; false不信任缓存数据.
            } 
            @Override
            public void onSuccess(Stringresult) { 
              // 注意: 如果服务返回304或 onCache 选择了信任缓存, 这里将不会被调用,
              // 但是 onFinished 总会被调用.
              this.result = result; 
            } 
            @Override
            public void onError(Throwableex, booleanisOnCallback) {
             hasError =true;
             Toast.makeText(x.app(), ex.getMessage(), Toast.LENGTH_LONG).show();
             if (ex instanceofHttpException) {
                 // 网络错误
                HttpException httpEx = (HttpException) ex;
                 int responseCode = httpEx.getCode();
                 String responseMsg = httpEx.getMessage();
                 String errorResult = httpEx.getResult();
             // ... 
            } else {  
           // 其他错误
            // ...
             }
         }
           @Override
            public void onCancelled(CancelledExceptioncex) {   
                Toast.makeText(x.app(), "cancelled", Toast.LENGTH_LONG).show();
            }
           @Override
            public void onFinished() {
                 if (!hasError && result !=null) {
                   // 成功获取数据
                  Toast.makeText(x.app(), result, Toast.LENGTH_LONG).show();
                   }
             }
        });
    
    

    源码查看:

    首先还是入口:http相关的接口和实现类。HttpManager和HttpManagerImpl
    接口很简单。定义了三个异步请求和四个同步请求的方法签名。

    /** 
    * Created by wyouflf on 15/6/17. 
    * http请求接口
    */
    public interface HttpManager {
    /** * 异步GET请求*/
    <T> Callback.Cancelable get(RequestParams entity, Callback.CommonCallback<T> callback);
    /** * 异步POST请求*/
    <T> Callback.Cancelable post(RequestParams entity, Callback.CommonCallback<T> callback);
    /** * 异步请求*/
    <T> Callback.Cancelable request(HttpMethod method, RequestParams entity, Callback.CommonCallback<T> callback);
    /** * 同步GET请求*/
    <T> T getSync(RequestParams entity, Class<T> resultType) throws Throwable;
    /** * 同步POST请求 */
    <T> T postSync(RequestParams entity, Class<T> resultType) throws Throwable;
    /** * 同步请求 */
    <T> T requestSync(HttpMethod method, RequestParams entity, Class<T> resultType) throws Throwable;
    /** * 同步请求 */
    <T> T requestSync(HttpMethod method, RequestParams entity, Callback.TypedCallback<T> callback) throws Throwable;
    }
    
    

    先看异步的一些实现方法:
    HttpManagerImpl: 看源码我们得知。异步请求最后都会调用到这个方法:request(···)。在这个方法中发现 会new一个HttpTask 并放到线程池中运行。在上一篇博客可以知道 x.task().start(task) 其实就是调用task的doBackground方法。

    @Override
    public <T> Callback.Cancelable request(HttpMethod method, RequestParams entity, Callback.CommonCallback<T> callback) { 
    entity.setMethod(method);
    Callback.Cancelable cancelable = null;
     if (callback instanceof Callback.Cancelable) {
     cancelable = (Callback.Cancelable) callback;
    } 
    HttpTask<T> task = new HttpTask<T>(entity, cancelable, callback); 
    return x.task().start(task);
    }
    
    

    我们继续跟进来查看HttpTask:* 我们发现httpTask 中有哦很多成员变量。 作者代码注释的也比较清楚。

    
    /** 
    * Created by wyouflf on 15/7/23. 
    * http 请求任务
    */
    public class HttpTask<ResultType> extends AbsTask<ResultType> implements ProgressHandler {// 请求相关
    private RequestParams params;
    private UriRequest request;
    private RequestWorker requestWorker;
    private final Executor executor;
    private final Callback.CommonCallback<ResultType> callback;
    // 缓存控制
    private Object rawResult = null;
    private final Object cacheLock = new Object();
    private volatile Boolean trustCache = null;
    // 扩展callback
    private Callback.CacheCallback<ResultType> cacheCallback;
    private Callback.PrepareCallback prepareCallback;
    private Callback.ProgressCallback progressCallback;
    private RequestInterceptListener requestInterceptListener;
    // 文件下载线程数限制
    private Type loadType;
    private final static int MAX_FILE_LOAD_WORKER = 3;
    private final static AtomicInteger sCurrFileLoadCount = new AtomicInteger(0);
    // 文件下载任务
    private static final HashMap<String, WeakReference<HttpTask<?>>>DOWNLOAD_TASK = new HashMap<String, WeakReference<HttpTask<?>>>(1);
    private static final PriorityExecutor HTTP_EXECUTOR = new PriorityExecutor(5, true);
    private static final PriorityExecutor CACHE_EXECUTOR = new PriorityExecutor(5, true);
    }
    
    • HttpTask构造函数中,先用了两个断言来确保params 和callback 不为空。并赋值给成员变量。 判断是哪个callback 并赋值给想应的callback。初始化tracker 日志跟踪系统。初始化线程池 executor.
    public HttpTask(RequestParams params, Callback.Cancelable cancelHandler, Callback.CommonCallback<ResultType> callback) { 
    super(cancelHandler);
     assert params != null;
     assert callback != null;
     // set params & callback
     this.params = params;
     this.callback = callback;
     if (callback instanceof Callback.CacheCallback) {
     this.cacheCallback = (Callback.CacheCallback<ResultType>) callback;
     } 
    if (callback instanceof Callback.PrepareCallback) { 
    this.prepareCallback = (Callback.PrepareCallback) callback;
     }
     if (callback instanceof Callback.ProgressCallback) { 
    this.progressCallback = (Callback.ProgressCallback<ResultType>) callback; 
    } 
    if (callback instanceof RequestInterceptListener) { 
    this.requestInterceptListener = (RequestInterceptListener) callback;
     } 
    // init tracker {
     RequestTracker customTracker = params.getRequestTracker();
     if (customTracker == null) {
     if (callback instanceof RequestTracker) {
    customTracker = (RequestTracker) callback;
     } else {
     customTracker = UriRequestFactory.getDefaultTracker();
     } 
    }
     if (customTracker != null) {
     tracker = new RequestTrackerWrapper(customTracker);
     } 
    }
     // init executor
     if (params.getExecutor() != null) {
     this.executor = params.getExecutor();
     } else { 
    if (cacheCallback != null) {
     this.executor = CACHE_EXECUTOR;
    } else { 
    this.executor = HTTP_EXECUTOR;
     } 
    }
    }
    
    • doBackground 方法: 异步请求的最主要的方法。 我把这个方法截断了。 这部分主要是做一些准备工作。比如说 初始化,缓存等。
    @Override
    @SuppressWarnings("unchecked")
    protected ResultType doBackground() throws Throwable {
     if (this.isCancelled()) {
      throw new Callback.CancelledException("cancelled before request");
     }
     // 初始化请求参数 
     ResultType result = null; 
     resolveLoadType();
     request = createNewRequest();
     checkDownloadTask();
     // retry 初始化
     boolean retry = true;
     int retryCount = 0;
     Throwable exception = null;
     HttpRetryHandler retryHandler = this.params.getHttpRetryHandler();
     if (retryHandler == null) {
      retryHandler = new HttpRetryHandler();
      }
     retryHandler.setMaxRetryCount(this.params.getMaxRetryCount());
     if (this.isCancelled()) {
      throw new Callback.CancelledException("cancelled before request"); 
     } 
     // 检查缓存
     Object cacheResult = null;
     if (cacheCallback != null && HttpMethod.permitsCache(params.getMethod())) { 
     // 尝试从缓存获取结果, 并为请求头加入缓存控制参数.
     try {
      clearRawResult(); LogUtil.d("load cache: " + this.request.getRequestUri());
     rawResult = this.request.loadResultFromCache();
      } catch (Throwable ex) {
      LogUtil.w("load disk cache error", ex);
    
     }
      if (this.isCancelled()) {
     clearRawResult();
     throw new Callback.CancelledException("cancelled before request");
     }
      if (rawResult != null) {
        if (prepareCallback != null) {
          try {
             cacheResult = prepareCallback.prepare(rawResult);
           } catch (Throwable ex) {
             cacheResult = null;
             LogUtil.w("prepare disk cache error", ex);
           } finally {
              clearRawResult();
           }
         } else {
         cacheResult = rawResult;   
      }
       if (this.isCancelled()) {
         throw new Callback.CancelledException("cancelled before request");
        } 
        if (cacheResult != null) {
           // 同步等待是否信任缓存
           this.update(FLAG_CACHE, cacheResult); 
            while (trustCache == null) {
                 synchronized (cacheLock) {
                           try {
                                     cacheLock.wait();
                                  } catch (Throwable ignored) {
                                   }
                 }
               } 
            // 处理完成 
          if (trustCache) {
                 return null;
           }
         }
        }
      } 
      if (trustCache == null) {
           trustCache = false;
         } 
      if (cacheResult == null) {
         this.request.clearCacheHeader();
       }
    
    • 发请求的代码: 请求代码中主要就是重试机子和发送机制。字段retry 是控制重试的开关。请求正常则retry一直为false。否则异常处理代码块里编写有重试的规则。在代码里面发送请求的是对象RequestWorker的run();方法。所有我们去看看RequestWorker对象。
     // 发起请求
     retry = true;
     while (retry) {
       retry = false;
       try {
           if (this.isCancelled()) {
             throw new Callback.CancelledException("cancelled before request");
             } 
          // 由loader发起请求, 拿到结果. 
          this.request.close(); 
          // retry 前关闭上次请求 
          try {
               clearRawResult();
               // 开始请求工作 
                LogUtil.d("load: " + this.request.getRequestUri()); 
                requestWorker = new RequestWorker();
               if (params.isCancelFast()) {
                   requestWorker.start();
                   requestWorker.join();
                } else {
                requestWorker.run();
               } 
              if (requestWorker.ex != null) {
                       throw requestWorker.ex;
              }
             rawResult = requestWorker.result;
             } catch (Throwable ex) {
               clearRawResult();
               if (this.isCancelled()) {
                   throw new Callback.CancelledException("cancelled during request");
                 } else {
               throw ex;
               }
           }
           if (prepareCallback != null) { 
              if (this.isCancelled()) { 
                      throw new Callback.CancelledException("cancelled before request");
               }
             try {
                 result = (ResultType) prepareCallback.prepare(rawResult);
             } finally {
               clearRawResult();
             } 
            } else { 
              result = (ResultType) rawResult;
            }
             // 保存缓存 
            if (cacheCallback != null && HttpMethod.permitsCache(params.getMethod())) {
               this.request.save2Cache();
             }
            if (this.isCancelled()) { 
                  throw new Callback.CancelledException("cancelled after request");
             }
           } catch (HttpRedirectException redirectEx) {
                 retry = true;
                  LogUtil.w("Http Redirect:" + params.getUri());
           } catch (Throwable ex) {
               if (this.request.getResponseCode() == 304) {
                 // disk cache is valid.
                 return null;
               } else {
               exception = ex;
               if (this.isCancelled() && !(exception instanceof Callback.CancelledException)) {
                   exception = new Callback.CancelledException("canceled by user");
                 }
               retry = retryHandler.retryRequest(exception, ++retryCount, this.request);
               }
              } 
            } 
          if (exception != null && result == null && !trustCache) {
                 throw exception; 
          } 
          return result;
      }
    
    • RequestWorker: 是HttpTask的内部类 ,主要的功能是请求发送和加载数据线程. 内部run()方法分析:
      • 下载另作处理
      • 请求前回调 requestInterceptListener.beforeRequest(request);
      • 请求 this.result = request.loadResult(); 得到结果
      • 请求后回调 requestInterceptListener.afterRequest(request);
      • http重定向类的异常处理。
    /** 
    * 请求发送和加载数据线程. 
    * 该线程被join到HttpTask的工作线程去执行. 
    * 它的主要作用是为了能强行中断请求的链接过程; 
    * 并辅助限制同时下载文件的线程数. 
    * but: 
    * 创建一个Thread约耗时2毫秒, 优化? 
    */
    private final class RequestWorker extends Thread { 
     /*private*/ Object result;
     /*private*/ Throwable ex;
     private RequestWorker() { }
     public void run() { 
        try {
           if (File.class == loadType) {
               while (sCurrFileLoadCount.get() >= MAX_FILE_LOAD_WORKER && !HttpTask.this.isCancelled()) {
                 synchronized (sCurrFileLoadCount) {
                     try {
                         sCurrFileLoadCount.wait(100);
                          } catch (Throwable ignored) { }
                     } 
                  }
               sCurrFileLoadCount.incrementAndGet();
               }
             if (HttpTask.this.isCancelled()) {
                   throw new Callback.CancelledException("cancelled before request");
               }
             // intercept response 
            if (requestInterceptListener != null) { 
                  requestInterceptListener.beforeRequest(request);
             }
             try {
                 this.result = request.loadResult();
               } catch (Throwable ex) {
                   this.ex = ex;
               } 
            // intercept response
           if (requestInterceptListener != null) { 
                  requestInterceptListener.afterRequest(request);
             }
           if (this.ex != null) {
                 throw this.ex;
             } 
          } catch (Throwable ex) {
               this.ex = ex;
               if (ex instanceof HttpException) {
                     HttpException httpEx = (HttpException) ex;
                     int errorCode = httpEx.getCode();
                     if (errorCode == 301 || errorCode == 302) {
                           RedirectHandler redirectHandler = params.getRedirectHandler();
                           if (redirectHandler != null) {
                               try {
                                     RequestParams redirectParams = redirectHandler.getRedirectParams(request);
                                     if (redirectParams != null) {
                                       if (redirectParams.getMethod() == null) { 
                                            redirectParams.setMethod(params.getMethod());
                                         }
                                     // 开始重定向请求
                                     HttpTask.this.params = redirectParams;
                                     HttpTask.this.request = createNewRequest(); 
                                     this.ex = new HttpRedirectException(errorCode, httpEx.getMessage(), httpEx.getResult());
                                   }
                                   } catch (Throwable throwable) {
                                                        this.ex = ex; 
                                   } 
                                } 
                              } 
                            } 
                          } finally {
                              if (File.class == loadType) {
                                 synchronized (sCurrFileLoadCount) { 
                                              sCurrFileLoadCount.decrementAndGet();   
                                              sCurrFileLoadCount.notifyAll();
                                   } 
                                }
                             } 
      }
    }
    

    同步的一些实现方法:

    • **HttpManagerImpl: ** 最终都会内部调用到requestSync(···)的方法。 在这个方法中 我们可以发现 。作者也创建了一个HttpTask。并调用了x.task().startSync(task);的方法。这个方法我们task的实现类发现实际调用的是 TaskControllerImpl.startSync( AbsTask<T> task)
    Override 
    public <T> T getSync(RequestParams entity, Class<T> resultType) throws Throwable {
       return requestSync(HttpMethod.GET, entity, resultType);
      }
    @Override
     public <T> T postSync(RequestParams entity, Class<T> resultType) throws Throwable {
     return requestSync(HttpMethod.POST, entity, resultType);
    }
    @Override
    public <T> T requestSync(HttpMethod method, RequestParams entity, Class<T> resultType) throws Throwable {
     DefaultSyncCallback<T> callback = new DefaultSyncCallback<T>(resultType);
     return requestSync(method, entity, callback);
    }
    @Override
    public <T> T requestSync(HttpMethod method, RequestParams entity, Callback.TypedCallback<T> callback) throws Throwable { 
    entity.setMethod(method);
     HttpTask<T> task = new HttpTask<T>(entity, null, callback);
     return x.task().startSync(task);
    }
    
    
    • TaskControllerImpl.startSync( AbsTask<T> task) 找到这个方法我们发现 调用的是AbsTask的四个方法。onWaiting onStarted doBackground onSuccess 我们知道其实就是httpTask的这个四个方法。通过字面意思我们也可以知道就是 等待,开始,子线程运行和成功四个方法。
    @Override
    public <T> T startSync(AbsTask<T> task) throws Throwable {
     T result = null;
     try {
       task.onWaiting();
       task.onStarted();
       result = task.doBackground();
       task.onSuccess(result);
       } catch (Callback.CancelledException cex) {
           task.onCancelled(cex);
       } catch (Throwable ex) { 
            task.onError(ex, false);
             throw ex;
       } finally {
           task.onFinished();
       }
     return result;
    }
    
    • HttpTask的这四个方法: 在onSuccess方法中出现一个callback。回溯到TaskControllerImpl,我们发现了这个callback。它为外部传递的。外部没有传递的化。有个默认的DefaultSyncCallback。
    @Override
    protected void onWaiting() { 
      if (tracker != null) {
         tracker.onWaiting(params);
       }
     if (progressCallback != null) {
         progressCallback.onWaiting();
       }
    }
    @Override
    protected void onStarted() {
       if (tracker != null) {
         tracker.onStart(params);
       }
       if (progressCallback != null) {
           progressCallback.onStarted();
       }
    }
    @Override
    protected void onSuccess(ResultType result) {
       if (tracker != null) {
           tracker.onSuccess(request, result);
        }
       if (result != null) {
         callback.onSuccess(result);
        }
    }
    
    • DefaultSyncCallback: 此对象传递一个泛型。此泛型就为onSuccess 中返回的结果。 需要再构建DefaultSyncCallback对象时候传递。
    private class DefaultSyncCallback<T> implements Callback.TypedCallback<T> {
     private final Class<T> resultType;
     public DefaultSyncCallback(Class<T> resultType) {
     this.resultType = resultType;
     }
     @Override
     public Type getLoadType() {
       return resultType;
       }
     @Override
     public void onSuccess(T result) { }
     @Override
     public void onError(Throwable ex, boolean isOnCallback) { } 
    @Override
     public void onCancelled(CancelledException cex) { }
     @Override
     public void onFinished() { }
    }
    

    从task的onwaiting 可以得到。同步请求会一直等待 直到请求返回 或者请求超时。

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