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本文主要研究一下HttpClient的close
CloseableHttpClient
org/apache/http/impl/client/CloseableHttpClient.java
代码语言：javascript复制@Contract(threading = ThreadingBehavior.SAFE)
public abstract class CloseableHttpClient implements HttpClient, Closeable {
@Override
public <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 exception
final 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
代码语言：javascript复制@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;
}
//......
@Override
public 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
代码语言：javascript复制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() {
@Override
public 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() {
@Override
public 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。
