IntelliJ IDEA 2017.2.4 Build #IC-172.4155.36, built on September 12, 2017 JRE: 1.8.0_152-release-915-b11 amd64 JVM: OpenJDK 64-Bit Server VM by JetBrains s.r.o Windows 10 10.0
public class WordCountMapper extends Mapper<LongWritable,Text,Text,IntWritable> { private final static IntWritable one = new IntWritable(1); private Text word = new Text();
@Override protected void map(LongWritable key, Text value, Context context) throws IOException, InterruptedException { StringTokenizer itr = new StringTokenizer(value.toString()); while (itr.hasMoreTokens()){ word.set(itr.nextToken()); context.write(word,one); } } }
@Override public List<Cookie> loadForRequest(HttpUrl url) { List<Cookie> cookies = cookieStore.get(url); return cookies != null ? cookies : new ArrayList<Cookie>(); } }) .build(); //为请求添加CookieJar。
至于实现，也非常简单，就是一个Builder模式。具体实现就不做过多的介绍了。
构造request对象
构建request对象的代码如下所示：
1
Request request = new Request.Builder().get().url("url").build();
/** Ready async calls in the order they'll be run. */ //这个队列代表准备好的异步请求 private final Deque<AsyncCall> readyAsyncCalls = new ArrayDeque<>();
/** Running asynchronous calls. Includes canceled calls that haven't finished yet. */ //这个队列代表正在运行的异步请求 private final Deque<AsyncCall> runningAsyncCalls = new ArrayDeque<>();
/** Running synchronous calls. Includes canceled calls that haven't finished yet. */ //这个队列代表正在运行的同步请求。 private final Deque<RealCall> runningSyncCalls = new ArrayDeque<>(); private int maxRequests = 64; private int maxRequestsPerHost = 5; synchronized void enqueue(AsyncCall call) { if (runningAsyncCalls.size() < maxRequests && runningCallsForHost(call) < maxRequestsPerHost) { runningAsyncCalls.add(call); executorService().execute(call); } else { readyAsyncCalls.add(call); } }
private void promoteCalls() { if (runningAsyncCalls.size() >= maxRequests) return; // Already running max capacity. if (readyAsyncCalls.isEmpty()) return; // No ready calls to promote.
for (Iterator<AsyncCall> i = readyAsyncCalls.iterator(); i.hasNext(); ) { AsyncCall call = i.next();
if (runningCallsForHost(call) < maxRequestsPerHost) { i.remove(); runningAsyncCalls.add(call); executorService().execute(call); }
if (runningAsyncCalls.size() >= maxRequests) return; // Reached max capacity. } }
** * A concrete interceptor chain that carries the entire interceptor chain: all application * interceptors, the OkHttp core, all network interceptors, and finally the network caller. */ public final class RealInterceptorChain implements Interceptor.Chain { private final List<Interceptor> interceptors; private final StreamAllocation streamAllocation; private final HttpCodec httpCodec; private final RealConnection connection; private final int index; private final Request request; private int calls;
public Response proceed(Request request, StreamAllocation streamAllocation, HttpCodec httpCodec, RealConnection connection) throws IOException { if (index >= interceptors.size()) throw new AssertionError();
calls++;
// If we already have a stream, confirm that the incoming request will use it. if (this.httpCodec != null && !this.connection.supportsUrl(request.url())) { throw new IllegalStateException("network interceptor " + interceptors.get(index - 1) + " must retain the same host and port"); }
// If we already have a stream, confirm that this is the only call to chain.proceed(). if (this.httpCodec != null && calls > 1) { throw new IllegalStateException("network interceptor " + interceptors.get(index - 1) + " must call proceed() exactly once"); }
// Call the next interceptor in the chain. RealInterceptorChain next = new RealInterceptorChain( interceptors, streamAllocation, httpCodec, connection, index + 1, request); Interceptor interceptor = interceptors.get(index); Response response = interceptor.intercept(next);
// Confirm that the next interceptor made its required call to chain.proceed(). if (httpCodec != null && index + 1 < interceptors.size() && next.calls != 1) { throw new IllegalStateException("network interceptor " + interceptor + " must call proceed() exactly once"); }
// Confirm that the intercepted response isn't null. if (response == null) { throw new NullPointerException("interceptor " + interceptor + " returned null"); }
// Attach the prior response if it exists. Such responses never have a body. if (priorResponse != null) { response = response.newBuilder() .priorResponse(priorResponse.newBuilder() .body(null) .build()) .build(); }
Request followUp = followUpRequest(response);
if (followUp == null) { if (!forWebSocket) { streamAllocation.release(); } return response; } closeQuietly(response.body());
if (!sameConnection(response, followUp.url())) { streamAllocation.release(); streamAllocation = new StreamAllocation( client.connectionPool(), createAddress(followUp.url()), callStackTrace); } else if (streamAllocation.codec() != null) { throw new IllegalStateException("Closing the body of " + response + " didn't close its backing stream. Bad interceptor?"); }
RequestBody body = userRequest.body(); if (body != null) { MediaType contentType = body.contentType(); if (contentType != null) { requestBuilder.header("Content-Type", contentType.toString()); }
long contentLength = body.contentLength(); if (contentLength != -1) { requestBuilder.header("Content-Length", Long.toString(contentLength)); requestBuilder.removeHeader("Transfer-Encoding"); } else { requestBuilder.header("Transfer-Encoding", "chunked"); requestBuilder.removeHeader("Content-Length"); } }
if (userRequest.header("Host") == null) { requestBuilder.header("Host", hostHeader(userRequest.url(), false)); }
if (userRequest.header("Connection") == null) { requestBuilder.header("Connection", "Keep-Alive"); }
// If we add an "Accept-Encoding: gzip" header field we're responsible for also decompressing // the transfer stream. boolean transparentGzip = false; if (userRequest.header("Accept-Encoding") == null && userRequest.header("Range") == null) { transparentGzip = true; requestBuilder.header("Accept-Encoding", "gzip"); }
List<Cookie> cookies = cookieJar.loadForRequest(userRequest.url()); if (!cookies.isEmpty()) { requestBuilder.header("Cookie", cookieHeader(cookies)); }
if (userRequest.header("User-Agent") == null) { requestBuilder.header("User-Agent", Version.userAgent()); }
if (cache != null) { cache.trackResponse(strategy); }
if (cacheCandidate != null && cacheResponse == null) { closeQuietly(cacheCandidate.body()); // The cache candidate wasn't applicable. Close it. }
// If we're forbidden from using the network and the cache is insufficient, fail. if (networkRequest == null && cacheResponse == null) { return new Response.Builder() .request(chain.request()) .protocol(Protocol.HTTP_1_1) .code(504) .message("Unsatisfiable Request (only-if-cached)") .body(Util.EMPTY_RESPONSE) .sentRequestAtMillis(-1L) .receivedResponseAtMillis(System.currentTimeMillis()) .build(); }
// If we don't need the network, we're done. if (networkRequest == null) { return cacheResponse.newBuilder() .cacheResponse(stripBody(cacheResponse)) .build(); }
Response networkResponse = null; try { networkResponse = chain.proceed(networkRequest); } finally { // If we're crashing on I/O or otherwise, don't leak the cache body. if (networkResponse == null && cacheCandidate != null) { closeQuietly(cacheCandidate.body()); } }
// If we have a cache response too, then we're doing a conditional get. if (cacheResponse != null) { if (networkResponse.code() == HTTP_NOT_MODIFIED) { Response response = cacheResponse.newBuilder() .headers(combine(cacheResponse.headers(), networkResponse.headers())) .sentRequestAtMillis(networkResponse.sentRequestAtMillis()) .receivedResponseAtMillis(networkResponse.receivedResponseAtMillis()) .cacheResponse(stripBody(cacheResponse)) .networkResponse(stripBody(networkResponse)) .build(); networkResponse.body().close();
// Update the cache after combining headers but before stripping the // Content-Encoding header (as performed by initContentStream()). cache.trackConditionalCacheHit(); cache.update(cacheResponse, response); return response; } else { closeQuietly(cacheResponse.body()); } }
// We need the network to satisfy this request. Possibly for validating a conditional GET. boolean doExtensiveHealthChecks = !request.method().equals("GET"); HttpCodec httpCodec = streamAllocation.newStream(client, doExtensiveHealthChecks); RealConnection connection = streamAllocation.connection();
long sentRequestMillis = System.currentTimeMillis(); httpCodec.writeRequestHeaders(request);
Response.Builder responseBuilder = null; if (HttpMethod.permitsRequestBody(request.method()) && request.body() != null) { // If there's a "Expect: 100-continue" header on the request, wait for a "HTTP/1.1 100 // Continue" response before transmitting the request body. If we don't get that, return what // we did get (such as a 4xx response) without ever transmitting the request body. if ("100-continue".equalsIgnoreCase(request.header("Expect"))) { httpCodec.flushRequest(); responseBuilder = httpCodec.readResponseHeaders(true); }
if (responseBuilder == null) { // Write the request body if the "Expect: 100-continue" expectation was met. Sink requestBodyOut = httpCodec.createRequestBody(request, request.body().contentLength()); BufferedSink bufferedRequestBody = Okio.buffer(requestBodyOut); request.body().writeTo(bufferedRequestBody); bufferedRequestBody.close(); } else if (!connection.isMultiplexed()) { // If the "Expect: 100-continue" expectation wasn't met, prevent the HTTP/1 connection from // being reused. Otherwise we're still obligated to transmit the request body to leave the // connection in a consistent state. streamAllocation.noNewStreams(); } }
httpCodec.finishRequest();
if (responseBuilder == null) { responseBuilder = httpCodec.readResponseHeaders(false); }
<manifest> <uses-permission android:name="android.permission.INTERNET" /> <!-- Include next permission if you want to allow UIL to cache images on SD card --> <uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" /> ... <application android:name="YourApplication"> ... </application> </manifest>
networkDeniedDownloader = new NetworkDeniedImageDownloader(downloader);//不允许访问网络的图片下载器。 slowNetworkDownloader = new SlowNetworkImageDownloader(downloader);//慢网络情况下的图片下载器。
public final class SimpleBitmapDisplayer implements BitmapDisplayer { @Override public void display(Bitmap bitmap, ImageAware imageAware, LoadedFrom loadedFrom) { imageAware.setImageBitmap(bitmap); } }
final class DisplayBitmapTask implements Runnable {
... private final Bitmap bitmap; private final String imageUri; private final ImageAware imageAware; private final String memoryCacheKey; private final BitmapDisplayer displayer; private final ImageLoadingListener listener; private final ImageLoaderEngine engine; private final LoadedFrom loadedFrom;
//主要用于判断imageView是否被重用，被重用返回true，否则返回false private boolean isViewReused() { String currentCacheKey = engine.getLoadingUriForView(imageAware); // Check whether memory cache key (image URI) for current ImageAware is actual. // If ImageAware is reused for another task then current task should be cancelled. boolean imageAwareWasReused = !memoryCacheKey.equals(currentCacheKey); if (imageAwareWasReused) { L.d(LOG_TASK_CANCELLED_IMAGEAWARE_REUSED, memoryCacheKey); return true; } return false; }
public static DiskLruCache open(File directory, int appVersion, int valueCount, long maxSize) throws IOException { if (maxSize <= 0) { throw new IllegalArgumentException("maxSize <= 0"); } if (valueCount <= 0) { throw new IllegalArgumentException("valueCount <= 0"); }
// If a bkp file exists, use it instead. File backupFile = new File(directory, JOURNAL_FILE_BACKUP); if (backupFile.exists()) { File journalFile = new File(directory, JOURNAL_FILE); // If journal file also exists just delete backup file. if (journalFile.exists()) { backupFile.delete(); } else { renameTo(backupFile, journalFile, false); } }
