1. 依赖包
<dependency>
<groupId>org.apache.httpcomponents</groupId>
<artifactId>httpclient</artifactId>
<version>4.4.1</version>
</dependency>
2. 代码
import org.apache.http.*;
import org.apache.http.client.HttpRequestRetryHandler;
import org.apache.http.client.config.RequestConfig;
import org.apache.http.client.entity.UrlEncodedFormEntity;
import org.apache.http.client.methods.CloseableHttpResponse;
import org.apache.http.client.methods.HttpGet;
import org.apache.http.client.methods.HttpPost;
import org.apache.http.client.protocol.HttpClientContext;
import org.apache.http.client.utils.URIBuilder;
import org.apache.http.config.Registry;
import org.apache.http.config.RegistryBuilder;
import org.apache.http.conn.routing.HttpRoute;
import org.apache.http.conn.socket.ConnectionSocketFactory;
import org.apache.http.conn.socket.LayeredConnectionSocketFactory;
import org.apache.http.conn.socket.PlainConnectionSocketFactory;
import org.apache.http.conn.ssl.SSLConnectionSocketFactory;
import org.apache.http.entity.ContentType;
import org.apache.http.entity.StringEntity;
import org.apache.http.impl.client.CloseableHttpClient;
import org.apache.http.impl.client.HttpClients;
import org.apache.http.impl.conn.PoolingHttpClientConnectionManager;
import org.apache.http.message.BasicNameValuePair;
import org.apache.http.util.EntityUtils;
import javax.net.ssl.SSLException;
import javax.net.ssl.SSLHandshakeException;
import java.io.IOException;
import java.io.InterruptedIOException;
import java.net.URI;
import java.net.UnknownHostException;
import java.util.ArrayList;
import java.util.List;
import java.util.Map;
public class HttpClientUtil {
// org.apache.http.impl.client.CloseableHttpClient
private static CloseableHttpClient httpclient = null;
// 这里就直接默认固定了,因为以下三个参数在新建的method中仍然可以重新配置并被覆盖.
static final int connectionRequestTimeout = 5000;// ms毫秒,从池中获取链接超时时间
static final int connectTimeout = 5000;// ms毫秒,建立链接超时时间
static final int socketTimeout = 30000;// ms毫秒,读取超时时间
// 总配置,主要涉及是以下两个参数,如果要作调整没有用到properties会比较后麻烦,但鉴于一经粘贴,随处可用的特点,就不再做依赖性配置化处理了.
// 而且这个参数同一家公司基本不会变动.
static final int maxTotal = 500;// 最大总并发,很重要的参数
static final int maxPerRoute = 100;// 每路并发,很重要的参数
// 正常情况这里应该配成MAP或LIST
// 细化配置参数,用来对每路参数做精细化处理,可以管控各ip的流量,比如默认配置请求baidu:80端口最大100个并发链接,
static final String detailHostName = "http://www.baidu.com";// 每个细化配置之ip(不重要,在特殊场景很有用)
static final int detailPort = 80;// 每个细化配置之port(不重要,在特殊场景很有用)
static final int detailMaxPerRoute = 100;// 每个细化配置之最大并发数(不重要,在特殊场景很有用)
private static CloseableHttpClient getHttpClient() {
if (null == httpclient) {
synchronized (HttpClientUtil.class) {
if (null == httpclient) {
httpclient = init();
}
}
}
return httpclient;
}
/**
* 链接池初始化 这里最重要的一点理解就是. 让CloseableHttpClient 一直活在池的世界里, 但是HttpPost却一直用完就消掉.
* 这样可以让链接一直保持着.
*/
private static CloseableHttpClient init() {
CloseableHttpClient newHttpclient;
// 设置连接池
ConnectionSocketFactory plainsf = PlainConnectionSocketFactory.getSocketFactory();
LayeredConnectionSocketFactory sslsf = SSLConnectionSocketFactory.getSocketFactory();
Registry<ConnectionSocketFactory> registry = RegistryBuilder.<ConnectionSocketFactory>create().register("http", plainsf).register("https", sslsf).build();
PoolingHttpClientConnectionManager cm = new PoolingHttpClientConnectionManager(registry);
// 将最大连接数增加
cm.setMaxTotal(maxTotal);
// 将每个路由基础的连接增加
cm.setDefaultMaxPerRoute(maxPerRoute);
// 细化配置开始,其实这里用Map或List的for循环来配置每个链接,在特殊场景很有用.
// 将每个路由基础的连接做特殊化配置,一般用不着
HttpHost httpHost = new HttpHost(detailHostName, detailPort);
// 将目标主机的最大连接数增加
cm.setMaxPerRoute(new HttpRoute(httpHost), detailMaxPerRoute);
// 细化配置结束
// 请求重试处理
HttpRequestRetryHandler httpRequestRetryHandler = (exception, executionCount, context) -> {
if (executionCount >= 2) {// 如果已经重试了2次，就放弃
return false;
}
if (exception instanceof NoHttpResponseException) {// 如果服务器丢掉了连接，那么就重试
return true;
}
if (exception instanceof SSLHandshakeException) {// 不要重试SSL握手异常
return false;
}
if (exception instanceof InterruptedIOException) {// 超时
return false;
}
if (exception instanceof UnknownHostException) {// 目标服务器不可达
return false;
}
if (exception instanceof SSLException) {// SSL握手异常
return false;
}
HttpClientContext clientContext = HttpClientContext.adapt(context);
HttpRequest request = clientContext.getRequest();
// 如果请求是幂等的，就再次尝试
return !(request instanceof HttpEntityEnclosingRequest);
};
// 配置请求的超时设置
RequestConfig requestConfig = RequestConfig.custom().setConnectionRequestTimeout(connectionRequestTimeout).setConnectTimeout(connectTimeout).setSocketTimeout(socketTimeout).build();
newHttpclient = HttpClients.custom().setConnectionManager(cm).setDefaultRequestConfig(requestConfig).setRetryHandler(httpRequestRetryHandler).build();
return newHttpclient;
}
public static String doGet(String url, Map<String, String> param) {
// 创建Httpclient对象
CloseableHttpClient httpclient = getHttpClient();
String resultString = "";
CloseableHttpResponse response = null;
try {
// 创建uri
URIBuilder builder = new URIBuilder(url);
if (param != null) {
for (String key : param.keySet()) {
builder.addParameter(key, param.get(key));
}
}
URI uri = builder.build();
// 创建http GET请求
HttpGet httpGet = new HttpGet(uri);
// 执行请求
response = httpclient.execute(httpGet);
// 判断返回状态是否为200
if (response.getStatusLine().getStatusCode() == 200) {
resultString = EntityUtils.toString(response.getEntity(), "UTF-8");
}
} catch (Exception e) {
e.printStackTrace();
} finally {
try {
if (response != null) {
response.close();
}
httpclient.close();
} catch (IOException e) {
e.printStackTrace();
}
}
return resultString;
}
public static String doGet(String url) {
return doGet(url, null);
}
public static String doPost(String url, Map<String, String> param) {
// 创建Httpclient对象
CloseableHttpClient httpClient = getHttpClient();
CloseableHttpResponse response = null;
String resultString = "";
try {
// 创建Http Post请求
HttpPost httpPost = new HttpPost(url);
// 创建参数列表
if (param != null) {
List<NameValuePair> paramList = new ArrayList<>();
for (String key : param.keySet()) {
paramList.add(new BasicNameValuePair(key, param.get(key)));
}
// 模拟表单
UrlEncodedFormEntity entity = new UrlEncodedFormEntity(paramList, "utf-8");
httpPost.setEntity(entity);
}
// 执行http请求
response = httpClient.execute(httpPost);
resultString = EntityUtils.toString(response.getEntity(), "utf-8");
} catch (Exception e) {
e.printStackTrace();
} finally {
try {
response.close();
} catch (IOException e) {
e.printStackTrace();
}
}
return resultString;
}
public static String doPost(String url) {
return doPost(url, null);
}
public static String doPostJson(String url, String json) {
// 创建Httpclient对象
CloseableHttpClient httpClient = getHttpClient();
CloseableHttpResponse response = null;
String resultString = "";
try {
// 创建Http Post请求
HttpPost httpPost = new HttpPost(url);
// 创建请求内容
StringEntity entity = new StringEntity(json, ContentType.APPLICATION_JSON);
httpPost.setEntity(entity);
// 执行http请求
response = httpClient.execute(httpPost);
resultString = EntityUtils.toString(response.getEntity(), "utf-8");
} catch (Exception e) {
e.printStackTrace();
} finally {
try {
response.close();
} catch (IOException e) {
e.printStackTrace();
}
}
return resultString;
}
}
