HttpClient 访问 https 网站

利用 Apache HttpClient 访问 https 的写法略有差异，但可信证书库的位置、作用等于java完全相同。下面测试在 OracleJDK 下进行。

$ wget http://mirror.bit.edu.cn/apache//httpcomponents/httpclient/binary/httpcomponents-client-4.5.3-bin.tar.gz
$ tar xzvf httpcomponents-client-4.5.3-bin.tar.gz
$ keytool -delete -keystore /usr/java/jdk1.8.0_131/jre/lib/security/cacerts -alias 12306 -storepass changeit

删除 JDK 可信证书库中的 12306 条目是为了下面的测试。

HttpClientSSL.java 类的写法参考了 这个官方例子。

import java.io.File;

import org.apache.http.util.EntityUtils;
import org.apache.http.HttpEntity;
import org.apache.http.client.methods.CloseableHttpResponse;
import org.apache.http.impl.client.CloseableHttpClient;
import org.apache.http.client.methods.HttpGet;
import org.apache.http.impl.client.HttpClients;

public class HttpClientSSL {

  public final static void main(String[] args) throws Exception {
    if(args.length==0) {
        System.out.println("Please enter URL.");
    return;
    }
    CloseableHttpClient httpclient = HttpClients.createDefault();
    try {
      HttpGet httpget = new HttpGet(args[0]);

      System.out.println("Executing request " + httpget.getRequestLine());

      CloseableHttpResponse response = httpclient.execute(httpget);
      try {
        HttpEntity entity = response.getEntity();

        System.out.println("----------------------------------------");
        System.out.println(response.getStatusLine());
        EntityUtils.consume(entity);
      } finally {
        response.close();
      }
    } finally {
      httpclient.close();
    }
  }
}

编译执行：

$ javac -cp ".:/opt/https/httpcomponents-client-4.5.3/lib/*" HttpClientSSL.java       (编译)
$ java -cp ".:/opt/https/httpcomponents-client-4.5.3/lib/*" HttpClientSSL https://cn.bing.com    (正常执行)
----------------------------------------
HTTP/1.1 200 OK
$ java -cp ".:/opt/https/httpcomponents-client-4.5.3/lib/*" HttpClientSSL https://kyfw.12306.cn   (报错)
$ java -Djavax.net.ssl.trustStore=trust.jks -cp ".:/opt/https/httpcomponents-client-4.5.3/lib/*" HttpClientSSL https://kyfw.12306.cn            (正常执行)

HttpClient 的可信证书库规则与纯 Java 编程相同。