HttpClient4.x可以自带维持会话功能，只要使用同一个HttpClient且未关闭连接，则可以使用相同会话来访问其他要求登录验证的服务（见TestLogin()方法中的“执行get请求”部分）。
如果需要使用HttpClient池，并且想要做到一次登录的会话供多个HttpClient连接使用，就需要自己保存会话信息。因为客户端的会话信息是保存在cookie中的（JSESSIONID），所以只需要将登录成功返回的cookie复制到各个HttpClient使用即可。使用Cookie的方法有两种，可以自己使用CookieStore来保存（见TestCookieStore()方法），也可以通过HttpClientContext上下文来维持（见TestContext()方法）。
package com.sunbin.httpSession; import java.io.IOException;import java.util.ArrayList;import java.util.HashMap;import java.util.Iterator;import java.util.List;import java.util.Map;import java.util.Map.Entry; import org.apache.http.HeaderIterator;import org.apache.http.HttpEntity;import org.apache.http.HttpResponse;import org.apache.http.NameValuePair;import org.apache.http.ParseException;import org.apache.http.client.CookieStore;import org.apache.http.client.config.CookieSpecs;import org.apache.http.client.entity.UrlEncodedFormEntity;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.config.Registry;import org.apache.http.config.RegistryBuilder;import org.apache.http.cookie.CookieSpecProvider;import org.apache.http.impl.client.BasicCookieStore;import org.apache.http.impl.client.CloseableHttpClient;import org.apache.http.impl.client.HttpClients;import org.apache.http.impl.cookie.BasicClientCookie;import org.apache.http.impl.cookie.BestMatchSpecFactory;import org.apache.http.impl.cookie.BrowserCompatSpecFactory;import org.apache.http.message.BasicNameValuePair;import org.apache.http.util.EntityUtils;import org.junit.Test; public class TestHttpClient { ??// 创建CookieStore实例 ?static CookieStore cookieStore = null; ?static HttpClientContext context = null; ?String loginUrl = "http://127.0.0.1:8080/CwlProClient/j_spring_security_check"; ?String testUrl = "http://127.0.0.1:8080/CwlProClient/account/querySubAccount.action"; ?String loginErrorUrl = "http://127.0.0.1:8080/CwlProClient/login/login.jsp"; ??@Test ?public void testLogin() throws Exception { ???System.out.println("----testLogin"); ????// // 创建HttpClientBuilder ???// HttpClientBuilder httpClientBuilder = HttpClientBuilder.create(); ???// // HttpClient ???// CloseableHttpClient client = httpClientBuilder.build(); ???// 直接创建client ???CloseableHttpClient client = HttpClients.createDefault(); ????HttpPost httpPost = new HttpPost(loginUrl); ???Map parameterMap = new HashMap(); ???parameterMap.put("j_username", "sunb012"); ???parameterMap.put("j_password", "sunb012"); ???UrlEncodedFormEntity postEntity = new UrlEncodedFormEntity( ???????getParam(parameterMap), "UTF-8"); ???httpPost.setEntity(postEntity); ???System.out.println("request line:" + httpPost.getRequestLine()); ???try { ?????// 执行post请求 ?????HttpResponse httpResponse = client.execute(httpPost); ?????String location = httpResponse.getFirstHeader("Location") ?????????.getValue(); ?????if (location != null && location.startsWith(loginErrorUrl)) { ???????System.out.println("----loginError"); ?????} ?????printResponse(httpResponse); ??????// 执行get请求 ?????System.out.println("----the same client"); ?????HttpGet httpGet = new HttpGet(testUrl); ?????System.out.println("request line:" + httpGet.getRequestLine()); ?????HttpResponse httpResponse1 = client.execute(httpGet); ?????printResponse(httpResponse1); ???????// cookie store ?????setCookieStore(httpResponse); ?????// context ?????setContext(); ???} catch (IOException e) { ?????e.printStackTrace(); ???} finally { ?????try { ???????// 关闭流并释放资源 ???????client.close(); ?????} catch (IOException e) { ???????e.printStackTrace(); ?????} ???} ?} ??@Test ?public void testContext() throws Exception { ???System.out.println("----testContext"); ???// 使用context方式 ???CloseableHttpClient client = HttpClients.createDefault(); ???HttpGet httpGet = new HttpGet(testUrl); ???System.out.println("request line:" + httpGet.getRequestLine()); ???try { ?????// 执行get请求 ?????HttpResponse httpResponse = client.execute(httpGet, context); ?????System.out.println("context cookies:" ?????????+ context.getCookieStore().getCookies()); ?????printResponse(httpResponse); ???} catch (IOException e) { ?????e.printStackTrace(); ???} finally { ?????try { ???????// 关闭流并释放资源 ???????client.close(); ?????} catch (IOException e) { ???????e.printStackTrace(); ?????} ???} ?} ??@Test ?public void testCookieStore() throws Exception { ???System.out.println("----testCookieStore"); ???// 使用cookieStore方式 ???CloseableHttpClient client = HttpClients.custom() ???????.setDefaultCookieStore(cookieStore).build(); ???HttpGet httpGet = new HttpGet(testUrl); ???System.out.println("request line:" + httpGet.getRequestLine()); ???try { ?????// 执行get请求 ?????HttpResponse httpResponse = client.execute(httpGet); ?????System.out.println("cookie store:" + cookieStore.getCookies()); ?????printResponse(httpResponse); ???} catch (IOException e) { ?????e.printStackTrace(); ???} finally { ?????try { ???????// 关闭流并释放资源 ???????client.close(); ?????} catch (IOException e) { ???????e.printStackTrace(); ?????} ???} ?} ??public static void printResponse(HttpResponse httpResponse) ?????throws ParseException, IOException { ???// 获取响应消息实体 ???HttpEntity entity = httpResponse.getEntity(); ???// 响应状态 ???System.out.println("status:" + httpResponse.getStatusLine()); ???System.out.println("headers:"); ???HeaderIterator iterator = httpResponse.headerIterator(); ???while (iterator.hasNext()) { ?????System.out.println("\t" + iterator.next()); ???} ???// 判断响应实体是否为空 ???if (entity != null) { ?????String responseString = EntityUtils.toString(entity); ?????System.out.println("response length:" + responseString.length()); ?????System.out.println("response content:" ?????????+ responseString.replace("\r\n", "")); ???} ?} ??public static void setContext() { ???System.out.println("----setContext"); ???context = HttpClientContext.create(); ???Registry<CookieSpecProvider> registry = RegistryBuilder ???????.<CookieSpecProvider> create() ???????.register(CookieSpecs.BEST_MATCH, new BestMatchSpecFactory()) ???????.register(CookieSpecs.BROWSER_COMPATIBILITY, ???????????new BrowserCompatSpecFactory()).build(); ???context.setCookieSpecRegistry(registry); ???context.setCookieStore(cookieStore); ?} ??public static void setCookieStore(HttpResponse httpResponse) { ???System.out.println("----setCookieStore"); ???cookieStore = new BasicCookieStore(); ???// JSESSIONID ???String setCookie = httpResponse.getFirstHeader("Set-Cookie") ???????.getValue(); ???String JSESSIONID = setCookie.substring("JSESSIONID=".length(), ???????setCookie.indexOf(";")); ???System.out.println("JSESSIONID:" + JSESSIONID); ???// 新建一个Cookie ???BasicClientCookie cookie = new BasicClientCookie("JSESSIONID", ???????JSESSIONID); ???cookie.setVersion(0); ???cookie.setDomain("127.0.0.1"); ???cookie.setPath("/CwlProClient"); ???// cookie.setAttribute(ClientCookie.VERSION_ATTR, "0"); ???// cookie.setAttribute(ClientCookie.DOMAIN_ATTR, "127.0.0.1"); ???// cookie.setAttribute(ClientCookie.PORT_ATTR, "8080"); ???// cookie.setAttribute(ClientCookie.PATH_ATTR, "/CwlProWeb"); ???cookieStore.addCookie(cookie); ?} ??public static List<NameValuePair> getParam(Map parameterMap) { ???List<NameValuePair> param = new ArrayList<NameValuePair>(); ???Iterator it = parameterMap.entrySet().iterator(); ???while (it.hasNext()) { ?????Entry parmEntry = (Entry) it.next(); ?????param.add(new BasicNameValuePair((String) parmEntry.getKey(), ?????????(String) parmEntry.getValue())); ???} ???return param; ?}}httpclient 登录成功后返回的cookie值访问下一页面
原文地址：https://www.cnblogs.com/zhimingxin/p/8472245.html