相对于httpurlconnection ，httpclient更加丰富，也更加强大，当中apache有两个项目都是httpclient。一个是commonts包下的，这个是通用的，更专业的是org.apache.http.包下的。所以我一般用后者；
httpclient能够处理长连接，保存会话，重连接，以及请求过滤器，连接重用等等...
以下是測试代码（所有总结来自官方文档。以及翻译）
需要下载核心包：httpclient-4.3.4.jar ，也可在官网下载：http://hc.apache.org/downloads.cgi
/**
* HTTP认证：
*
* HTTPclient支持http标准认证，也支持其它认证，如NTLM和SPNEGO。
*/
private static void test17(){ //最简单的明文username password认证。
UsernamePasswordCredentials creds = new UsernamePasswordCredentials("user", "pwd");
System.out.println(creds.getUserPrincipal().getName());
System.out.println(creds.getPassword()); /**
* NTCredentials是微软的windows系统使用的一种凭据。包括username、password，还包括一系列其它的属性。
* 比方用户所在的域名。在Microsoft Windows的网络环境中，同一个用户能够属于不同的域，所以他也就有不同的凭据。
* workstation:本机的计算机名
*/
NTCredentials ntcreds = new NTCredentials("user", "pwd", "workstation", "domain");
System.out.println(ntcreds.getUserPrincipal().getName());//输出 DOMAIN/user
System.out.println(ntcreds.getPassword()); } /**
* 凭证提供者（CredentialsProvider）内含一套特定的凭证，需要哪种凭证时，CredentialsProvider就能获得相应的凭证。
* 获取凭证的时候，能够模糊的指定主机名、port号、realm和认证方案。
* CredentialsProvider会筛选出一个最佳匹配方案。
*/
private static void test18() { CredentialsProvider credsProvider = new BasicCredentialsProvider(); credsProvider.setCredentials(new AuthScope("somehost",AuthScope.ANY_PORT),
new UsernamePasswordCredentials("u1", "p1"));
credsProvider.setCredentials(new AuthScope("somehost", 8080),
new UsernamePasswordCredentials("u2", "p2"));
credsProvider.setCredentials(new AuthScope("otherhost", 8080,AuthScope.ANY_REALM, "ntlm"),
new UsernamePasswordCredentials("u3", "p3")); System.out.println(credsProvider.getCredentials(new AuthScope(
"somehost", 80, "realm", "basic")));
System.out.println(credsProvider.getCredentials(new AuthScope(
"somehost", 8080, "realm", "basic")));
System.out.println(credsProvider.getCredentials(new AuthScope(
"otherhost", 8080, "realm", "basic")));
System.out.println(credsProvider.getCredentials(new AuthScope(
"otherhost", 8080, null, "ntlm"))); /**
* 输出：
* [principal: u1]
[principal: u2]
null
[principal: u3]
*/
} private static void test19() throws ClientProtocolException, IOException { // CloseableHttpClient httpclient = HttpClients.createDefault();
// HttpClientContext context = HttpClientContext.create();
//
// HttpHost targetHost = new HttpHost("webservice.webxml.com.cn", 80, "http");
//
// //认证提供者
// CredentialsProvider credsProvider = new BasicCredentialsProvider();
// credsProvider.setCredentials(new AuthScope(targetHost.getHostName(),targetHost.getPort()),
// new UsernamePasswordCredentials("root", "root"));
//
// //基础认证缓存
// AuthCache authCache = new BasicAuthCache();
//
// context.setCredentialsProvider(credsProvider);
// context.setAuthCache(authCache);
//
// HttpGet httpget = new HttpGet("/WebServices/MobileCodeWS.asmx/getDatabaseInfo");
//
// CloseableHttpResponse response = httpclient.execute(targetHost,httpget, context);
//
// AuthState proxyAuthState = context.getProxyAuthState();
//
// System.out.println("Proxy auth state: " + proxyAuthState.getState());
// System.out.println("Proxy auth scheme: "+ proxyAuthState.getAuthScheme());
// System.out.println("Proxy auth credentials: "+ proxyAuthState.getCredentials());
// AuthState targetAuthState = context.getTargetAuthState();
// System.out.println("Target auth state: " + targetAuthState.getState());
// System.out.println("Target auth scheme: "+ targetAuthState.getAuthScheme());
// System.out.println("Target auth credentials: "+ targetAuthState.getCredentials());
/**
* Proxy auth state: UNCHALLENGED
Proxy auth scheme: null
Proxy auth credentials: null
Target auth state: UNCHALLENGED
Target auth scheme: null
Target auth credentials: null
*/
} /**
* HttpClientContext 设置抢先认证 和 认证提供者：
*
* 在HTTP中。基本认证是一种用来同意Web浏览器或其它客户端程序在请求时提供以username和口令形式的凭证。
*
* 一般http basic认证，首先登录server。 然后server会返回401码让客户端输入username和password，客户端把usernamepassword进行BASE64加密。
*
* 最后把加密后的username和password发送给server进行验证。
*
* 抢先验证则省略了前几部，直接发送BASE64位密文，进行验证。但存在风险，慎用。
*/
private static void test20() throws ClientProtocolException, IOException { HttpClientContext context = HttpClientContext.create();
CloseableHttpClient httpclient = HttpClients.createDefault();
//配置主机 。 port可任意填写
HttpHost targetHost = new HttpHost("webservice.webxml.com.cn", 80, "http");
//认证提供者
CredentialsProvider credsProvider = new BasicCredentialsProvider(); credsProvider.setCredentials(
new AuthScope(targetHost.getHostName(),targetHost.getPort()),
new UsernamePasswordCredentials("username", "password")); AuthCache authCache = new BasicAuthCache(); BasicScheme basicAuth = new BasicScheme();
authCache.put(targetHost, basicAuth); //提前填充认证信息缓存到上下文中，这样，以这个上下文运行的方法。就会使用抢先认证。 可能会出错
context.setAuthCache(authCache);
context.setCredentialsProvider(credsProvider); HttpGet httpget = new HttpGet("/WebServices/MobileCodeWS.asmx/getDatabaseInfo"); CloseableHttpResponse response = httpclient.execute(targetHost,httpget, context);
try {
HttpEntity entity = response.getEntity();
String result = EntityUtils.toString(entity);
System.out.println(result); } finally {
response.close();
}
} /**
* NTLM连接认证：
*
* windows提供的一套安全、复杂的、有状态的协议。
*
* 相比Basic和Digest认证。NTLM认证要明显需要很多其它的计算开销，性能影响也比較大。 *
* 也就是说，NTLM连接一旦建立，用户的身份就会在其整个生命周期和它相关联。
*/
private static void test21() throws ClientProtocolException, IOException { // 确保使用同一个上下文
HttpClientContext context = HttpClientContext.create();
CloseableHttpClient httpclient = HttpClients.createDefault(); CredentialsProvider credsProvider = new BasicCredentialsProvider();
//构建具体nt认证信息：NTCredentials 參数1：username 2：password 3：本机名 3：domain域
credsProvider.setCredentials(new AuthScope("somehost",AuthScope.ANY_PORT) ,
new NTCredentials("username", "password", "myworkstation", "domain")); context.setCredentialsProvider(credsProvider); HttpHost target = new HttpHost("somehost", 80, "http"); HttpGet httpget = new HttpGet("/"); CloseableHttpResponse response1 = httpclient.execute(target, httpget, context); try {
HttpEntity entity1 = response1.getEntity();
System.out.println(EntityUtils.toString(entity1,"GB2312"));
} finally {
response1.close();
} HttpPost httppost = new HttpPost("/");
httppost.setEntity(new StringEntity("lots and lots of data"));
CloseableHttpResponse response2 = httpclient.execute(target, httppost, context);
try {
HttpEntity entity2 = response2.getEntity();
} finally {
response2.close();
} }
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