httpclient org.apache.http.NoHttpResponseException: host:端口 failed to respond 错误原因和解决方法

原因：httpclient 之前与服务端建立的链接已经失效（例如：tomcat 默认的keep-alive timeout ：20s），再次从连接池拿该失效链接进行请求时，就会保存。

解决方法：官方链接：http://hc.apache.org/httpcomponents-client-ga/tutorial/html/connmgmt.html#d5e659

上面官方链接的2.6 解决方法的代码如果报错，可能是自己的httpclient版本 不适用。自己用的是httpclient 4.0.1，使用以下代码绿色代码：

import com.google.api.client.http.ByteArrayContent;
import com.google.api.client.http.GenericUrl;
import com.google.api.client.http.HttpBackOffUnsuccessfulResponseHandler;
import com.google.api.client.http.HttpContent;
import com.google.api.client.http.HttpHeaders;
import com.google.api.client.http.HttpRequest;
import com.google.api.client.http.HttpRequestFactory;
import com.google.api.client.http.HttpResponse;
import com.google.api.client.http.HttpStatusCodes;
import com.google.api.client.http.HttpTransport;
import com.google.api.client.http.apache.ApacheHttpTransport;
import com.google.api.client.util.BackOff;
import java.io.IOException;
import java.io.InputStream;
import java.net.ProxySelector;
import java.util.Map;
import java.util.Timer;
import java.util.TimerTask;
import java.util.concurrent.TimeUnit;
import javax.annotation.PreDestroy;
import lombok.Data;
import lombok.extern.slf4j.Slf4j;
import org.apache.http.HeaderElement;
import org.apache.http.HeaderElementIterator;
import org.apache.http.HttpHost;
import org.apache.http.conn.ClientConnectionManager;
import org.apache.http.conn.ConnectionKeepAliveStrategy;
import org.apache.http.conn.params.ConnManagerParams;
import org.apache.http.conn.params.ConnPerRouteBean;
import org.apache.http.conn.scheme.PlainSocketFactory;
import org.apache.http.conn.scheme.Scheme;
import org.apache.http.conn.scheme.SchemeRegistry;
import org.apache.http.conn.ssl.SSLSocketFactory;
import org.apache.http.impl.client.DefaultHttpClient;
import org.apache.http.impl.client.DefaultHttpRequestRetryHandler;
import org.apache.http.impl.conn.ProxySelectorRoutePlanner;
import org.apache.http.impl.conn.tsccm.ThreadSafeClientConnManager;
import org.apache.http.message.BasicHeaderElementIterator;
import org.apache.http.params.BasicHttpParams;
import org.apache.http.params.HttpConnectionParams;
import org.apache.http.params.HttpParams;
import org.apache.http.protocol.HTTP;
import org.apache.http.protocol.HttpContext;

/**
* @author Li Sheng
*/
@Slf4j
public class HttpClientUtils {

private static HttpRequestFactory requestFactory;
private static HttpTransport httpTransport;
private static final String CONTENT_TYPE_JSON = "application/json";

private static final int CACHE_SIZE = 4096;

static {

HttpParams params = new BasicHttpParams();
HttpConnectionParams.setStaleCheckingEnabled(params, false);
HttpConnectionParams.setSocketBufferSize(params, 245760); // 8k(8192) * 30
ConnManagerParams.setMaxTotalConnections(params, 400);
ConnManagerParams.setMaxConnectionsPerRoute(params, new ConnPerRouteBean(200));

SchemeRegistry registry = new SchemeRegistry();
registry.register(new Scheme("http", PlainSocketFactory.getSocketFactory(), 80));
registry.register(new Scheme("https", SSLSocketFactory.getSocketFactory(), 443));
ClientConnectionManager connectionManager = new ThreadSafeClientConnManager(params, registry);

DefaultHttpClient defaultHttpClient = new DefaultHttpClient(connectionManager, params);
defaultHttpClient.setHttpRequestRetryHandler(new DefaultHttpRequestRetryHandler(0, false));
defaultHttpClient
.setRoutePlanner(new ProxySelectorRoutePlanner(registry, ProxySelector.getDefault()));

ConnectionKeepAliveStrategy connectionKeepAliveStrategy = new ConnectionKeepAliveStrategy() {
@Override
public long getKeepAliveDuration(org.apache.http.HttpResponse httpResponse,
HttpContext httpContext) {
return 20 * 1000; // 20 seconds,because tomcat default keep-alive timeout is 20s
}
};
defaultHttpClient.setKeepAliveStrategy(connectionKeepAliveStrategy);

httpTransport = new ApacheHttpTransport(defaultHttpClient);

requestFactory = httpTransport.createRequestFactory();

}

@Data
public static class PostParam {

private Integer connectTimeoutMills;  // 可选,默认 20s
private Integer readTimeoutMills;  // 可选，默认 20s
private Map<String, String> headers; // 可选
private String url; //必填
private String postJson; //必填
private Boolean readResponseData; //必填：是否需要读取数据。如果不需要返回结果,设置 false
private BackOff backOff; //可选,重试机制策略
private String authorization; //可选

public PostParam(String url, String postJson, boolean readResponseData) {
this.url = url;
this.postJson = postJson;
this.readResponseData = readResponseData;
}
}

public static String postWithJson(PostParam postParam) {
GenericUrl genericUrl = new GenericUrl(postParam.getUrl());
HttpContent httpContent = ByteArrayContent.fromString(null, postParam.getPostJson());
HttpResponse httpResponse = null;
try {
HttpRequest httpRequest = requestFactory.buildPostRequest(genericUrl, httpContent);
if (postParam.getConnectTimeoutMills() != null) {
httpRequest.setConnectTimeout(postParam.getConnectTimeoutMills());
}
if (postParam.getReadTimeoutMills() != null) {
httpRequest.setReadTimeout(postParam.getReadTimeoutMills());
}
if (postParam.getBackOff() != null) {
httpRequest.setUnsuccessfulResponseHandler(
new HttpBackOffUnsuccessfulResponseHandler(postParam.getBackOff()));
}

HttpHeaders httpHeaders = new HttpHeaders();
httpHeaders.setContentType(CONTENT_TYPE_JSON);
Map<String, String> headers = postParam.getHeaders();
if (headers != null && headers.size() > 0) {
headers.forEach(httpHeaders::set);
}
if (postParam.getAuthorization() != null && !postParam.equals("")) {
httpHeaders.setAuthorization(postParam.getAuthorization());
}

httpRequest.setHeaders(httpHeaders);
httpResponse = httpRequest.execute();
if (httpResponse.getStatusCode() != HttpStatusCodes.STATUS_CODE_OK) {
log.error("http status not 200. param:{},status:{},msg:{}", postParam,
httpResponse.getStatusCode(), httpResponse.getStatusMessage());
return null;
}
Boolean readResponseData = postParam.getReadResponseData();
if (readResponseData != null && readResponseData) {
InputStream inputStream = httpResponse.getContent();
if (inputStream != null) {
StringBuffer out = new StringBuffer();
byte[] b = new byte[CACHE_SIZE];
for (int n; (n = inputStream.read(b)) != -1; ) {
out.append(new String(b, 0, n));
}
return out.toString();
}
}
} catch (Exception e) {
log.error("post exception,param:{}", postParam, e);
} finally {
try {
if (httpResponse != null) {
httpResponse.disconnect();
}
} catch (Exception e) {
log.error("httpResponse disconnect exception", e);
}
}
return null;
}

@PreDestroy
public static void destory() {
try {
log.info("httpTransport shutdown now....");
httpTransport.shutdown();
} catch (IOException e) {
log.error("shut down httpTransport exception", e);
}
}

}

如果想使用上面的 HttpClientUtils，必须引入 google-httpclient:

　　<dependency>
<groupId>com.google.http-client</groupId>
<artifactId>google-http-client</artifactId>
<version>1.22.0</version>
</dependency>