httpclient绕过证书验证进行HTTPS请求

http请求是我们常用的一种web应用的应用层协议，但是由于它的不安全性，现在正在逐渐向https协议过渡。https协议是在http的基础上进行了隧道加密，加密方式有SSL和TLS两种。当server用https协议进行数据交换后，client请求server时会对server的证书进行校验，如果server端证书为四大证书机构颁发的证书或者其授权机构颁发的证书，则允许进一步请求，否则会警告证书不受信任。更多信息可参考https://www.cnblogs.com/handsomeBoys/p/6556336.html

当用httpclient进行请求https，会提示找不到有效的证书（unable to find valid certification path to requested target）

出现这种情况就是server端的证书不被信任，可以通过重写一个类继承DefaultHttpClient类,代码如下：

 import org.apache.http.conn.ClientConnectionManager;
 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 javax.net.ssl.SSLContext;
 import javax.net.ssl.TrustManager;
 import javax.net.ssl.X509TrustManager;
 import java.security.cert.CertificateException;
 import java.security.cert.X509Certificate;

 public class SSLClient extends DefaultHttpClient {
     public SSLClient() throws Exception{
         super();
         SSLContext ctx = SSLContext.getInstance("TLS");
         X509TrustManager tm = new X509TrustManager() {
             @Override
             public void checkClientTrusted(X509Certificate[] chain,
                                            String authType) throws CertificateException {
             }
             @Override
             public void checkServerTrusted(X509Certificate[] chain,
                                            String authType) throws CertificateException {
             }
             @Override
             public X509Certificate[] getAcceptedIssuers() {
                 return null;
             }
         };
         ctx.init(null, new TrustManager[]{tm}, null);
         SSLSocketFactory ssf = new SSLSocketFactory(ctx,SSLSocketFactory.ALLOW_ALL_HOSTNAME_VERIFIER);
         ClientConnectionManager ccm = this.getConnectionManager();
         SchemeRegistry sr = ccm.getSchemeRegistry();
         sr.register(new Scheme("https", 443, ssf));
     }
 }

然后在进行https请求创建HttpClient对象时用这个类的构造器创建对象就可以实现https请求，例如：

 import org.apache.http.Header;
 import org.apache.http.HttpResponse;
 import org.apache.http.client.methods.HttpGet;
 import org.apache.http.impl.client.CloseableHttpClient;

 public class RestApi {

     public static String getCsrf(){
         String csrfToken = "";
         try {
             CloseableHttpClient client = new SSLClient();
             String url = "https://10.67.19.186";
             HttpGet get = new HttpGet(url);
             HttpResponse response = client.execute(get);
             Header setCookidHeader = response.getFirstHeader("Set-Cookie");
             csrfToken = setCookidHeader.getValue().split(";")[0].split("=")[1];
         } catch (Exception e) {
             e.printStackTrace();
         }
         return csrfToken;
     }