XUtils3代码详解--http

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() {
           @OverridepublicvoidonSuccess(Stringresult) {
               Toast.makeText(x.app(), result, Toast.LENGTH_LONG).show();
           }

           @OverridepublicvoidonError(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();
           }

           @OverridepublicvoidonCancelled(CancelledExceptioncex) {
               Toast.makeText(x.app(), "cancelled", Toast.LENGTH_LONG).show();
           }

           @OverridepublicvoidonFinished() {

           }
       });

// 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() {
        @OverridepublicvoidonSuccess(Stringresult) {
            Toast.makeText(x.app(), result, Toast.LENGTH_LONG).show();
        }

        @OverridepublicvoidonError(Throwableex, booleanisOnCallback) {
            Toast.makeText(x.app(), ex.getMessage(), Toast.LENGTH_LONG).show();
        }

        @OverridepublicvoidonCancelled(CancelledExceptioncex) {
            Toast.makeText(x.app(), "cancelled", Toast.LENGTH_LONG).show();
        }

        @OverridepublicvoidonFinished() {

        }
    });


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() {

    privateboolean hasError =false;
    privateString result =null;

    @OverridepublicbooleanonCache(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.
    }

    @OverridepublicvoidonSuccess(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;
    }

    @OverridepublicvoidonError(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// ...
        }
    }

    @OverridepublicvoidonCancelled(CancelledExceptioncex) {
        Toast.makeText(x.app(), "cancelled", Toast.LENGTH_LONG).show();
    }

    @OverridepublicvoidonFinished() {
        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
*/
 Callback.Cancelable get(RequestParams entity, Callback.CommonCallback callback);
/**
     * 异步POST请求
*/
 Callback.Cancelable post(RequestParams entity, Callback.CommonCallback callback);
/**
     * 异步请求
*/
 Callback.Cancelable request(HttpMethod method, RequestParams entity, Callback.CommonCallback callback);


/**
     * 同步GET请求
 T getSync(RequestParams entity, Class resultType) throws Throwable;
/**
     * 同步POST请求
     */
 T postSync(RequestParams entity, Class resultType) throws Throwable;

/**
     * 同步请求
     */
 T requestSync(HttpMethod method, RequestParams entity, Class resultType) throws Throwable;

/**
     * 同步请求
     */
 T requestSync(HttpMethod method, RequestParams entity, Callback.TypedCallback 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  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 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 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>>>
DOWNLOAD_TASK = new HashMap>>>(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 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) callback;
    }
    if (callback instanceof Callback.PrepareCallback) {
        this.prepareCallback = (Callback.PrepareCallback) callback;
    }
    if (callback instanceof Callback.ProgressCallback) {
        this.progressCallback = (Callback.ProgressCallback) 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 task)
Override
public  T getSync(RequestParams entity, Class resultType) throws Throwable {
    return requestSync(HttpMethod.GET, entity, resultType);
}

@Override
public  T postSync(RequestParams entity, Class resultType) throws Throwable {
    return requestSync(HttpMethod.POST, entity, resultType);
}

@Override
public  T requestSync(HttpMethod method, RequestParams entity, Class resultType) throws Throwable {
    DefaultSyncCallback callback = new DefaultSyncCallback(resultType);
    return requestSync(method, entity, callback);
}

@Override
public  T requestSync(HttpMethod method, RequestParams entity, Callback.TypedCallback callback) throws Throwable {
    entity.setMethod(method);
    HttpTask task = new HttpTask(entity, null, callback);
    return x.task().startSync(task);
}
  • TaskControllerImpl.startSync( AbsTask 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 startSync(AbsTask 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 implements Callback.TypedCallback {

    private final Class resultType;

    public DefaultSyncCallback(Class 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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