聊聊HttpClient的close

HttpClient的close"/>

聊聊HttpClient的close

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本文主要研究一下HttpClient的close

CloseableHttpClient

org/apache/http/impl/client/CloseableHttpClient.java

@Contract(threading = ThreadingBehavior.SAFE)
public abstract class CloseableHttpClient implements HttpClient, Closeable {@Overridepublic <T> T execute(final HttpHost target, final HttpRequest request,final ResponseHandler<? extends T> responseHandler, final HttpContext context)throws IOException, ClientProtocolException {Args.notNull(responseHandler, "Response handler");final CloseableHttpResponse response = execute(target, request, context);try {final T result = responseHandler.handleResponse(response);final HttpEntity entity = response.getEntity();EntityUtils.consume(entity);return result;} catch (final ClientProtocolException t) {// Try to salvage the underlying connection in case of a protocol exceptionfinal HttpEntity entity = response.getEntity();try {EntityUtils.consume(entity);} catch (final Exception t2) {// Log this exception. The original exception is more// important and will be thrown to the caller.this.log.warn("Error consuming content after an exception.", t2);}throw t;} finally {response.close();}}//......
}

CloseableHttpClient声明实现HttpClient, Closeable接口

InternalHttpClient

org/apache/http/impl/client/InternalHttpClient.java

@Contract(threading = ThreadingBehavior.SAFE_CONDITIONAL)
@SuppressWarnings("deprecation")
class InternalHttpClient extends CloseableHttpClient implements Configurable {private final Log log = LogFactory.getLog(getClass());private final ClientExecChain execChain;private final HttpClientConnectionManager connManager;private final HttpRoutePlanner routePlanner;private final Lookup<CookieSpecProvider> cookieSpecRegistry;private final Lookup<AuthSchemeProvider> authSchemeRegistry;private final CookieStore cookieStore;private final CredentialsProvider credentialsProvider;private final RequestConfig defaultConfig;private final List<Closeable> closeables;public InternalHttpClient(final ClientExecChain execChain,final HttpClientConnectionManager connManager,final HttpRoutePlanner routePlanner,final Lookup<CookieSpecProvider> cookieSpecRegistry,final Lookup<AuthSchemeProvider> authSchemeRegistry,final CookieStore cookieStore,final CredentialsProvider credentialsProvider,final RequestConfig defaultConfig,final List<Closeable> closeables) {super();Args.notNull(execChain, "HTTP client exec chain");Args.notNull(connManager, "HTTP connection manager");Args.notNull(routePlanner, "HTTP route planner");this.execChain = execChain;this.connManager = connManager;this.routePlanner = routePlanner;this.cookieSpecRegistry = cookieSpecRegistry;this.authSchemeRegistry = authSchemeRegistry;this.cookieStore = cookieStore;this.credentialsProvider = credentialsProvider;this.defaultConfig = defaultConfig;this.closeables = closeables;}//......@Overridepublic void close() {if (this.closeables != null) {for (final Closeable closeable: this.closeables) {try {closeable.close();} catch (final IOException ex) {this.log.error(ex.getMessage(), ex);}}}}    
}    

InternalHttpClient继承了CloseableHttpClient，其构造器要求传入closeables，它实现了close方法，它主要是遍历closeables，挨个执行close

HttpClientBuilder

org/apache/http/impl/client/HttpClientBuilder.java

public class HttpClientBuilder {private List<Closeable> closeables;private boolean connManagerShared;//....../*** For internal use.*/protected void addCloseable(final Closeable closeable) {if (closeable == null) {return;}if (closeables == null) {closeables = new ArrayList<Closeable>();}closeables.add(closeable);}public CloseableHttpClient build() {//......List<Closeable> closeablesCopy = closeables != null ? new ArrayList<Closeable>(closeables) : null;if (!this.connManagerShared) {if (closeablesCopy == null) {closeablesCopy = new ArrayList<Closeable>(1);}final HttpClientConnectionManager cm = connManagerCopy;if (evictExpiredConnections || evictIdleConnections) {final IdleConnectionEvictor connectionEvictor = new IdleConnectionEvictor(cm,maxIdleTime > 0 ? maxIdleTime : 10, maxIdleTimeUnit != null ? maxIdleTimeUnit : TimeUnit.SECONDS,maxIdleTime, maxIdleTimeUnit);closeablesCopy.add(new Closeable() {@Overridepublic void close() throws IOException {connectionEvictor.shutdown();try {connectionEvictor.awaitTermination(1L, TimeUnit.SECONDS);} catch (final InterruptedException interrupted) {Thread.currentThread().interrupt();}}});connectionEvictor.start();}closeablesCopy.add(new Closeable() {@Overridepublic void close() throws IOException {cm.shutdown();}});}//......return new InternalHttpClient(execChain,connManagerCopy,routePlannerCopy,cookieSpecRegistryCopy,authSchemeRegistryCopy,defaultCookieStore,defaultCredentialsProvider,defaultRequestConfig != null ? defaultRequestConfig : RequestConfig.DEFAULT,closeablesCopy);}
}    

HttpClientBuilder定义了addCloseable方法用于添加closeable，不过是protected；而build方法在connManagerShared参数为false的时候(默认)会创建closeablesCopy，创建Closeable去关闭HttpClientConnectionManager并添加到closeablesCopy中；

在开启evictExpiredConnections或者evictIdleConnections的时候会创建IdleConnectionEvictor，然后创建关闭connectionEvictor的Closeable添加到closeablesCopy中

最后将这些closeablesCopy传递给InternalHttpClient的构造器

小结

HttpClient(CloseableHttpClient)的close方法会关闭一系列的Closeable，这些Closeable在HttpClientBuilder的build方法会构建好然后传递给InternalHttpClient；默认情况下这些closeable包括HttpClientConnectionManager的关闭、IdleConnectionEvictor的关闭。