使用HttpClientBuilder时获取"ClassNotFoundException"

Question

老程序员,Java新手.我试图运行我认为非常常见的示例代码,在网络上的许多地方类似,HttpClient httpClient = HttpClientBuilder.create().build()抛出一个异常,我无法弄清楚为什么.我正在使用HttpClient 4.3.

import java.io.IOException;
import org.apache.http.HttpEntity;
import org.apache.http.HttpResponse;
import org.apache.http.client.HttpClient;
import org.apache.http.client.methods.HttpPost;
import org.apache.http.entity.StringEntity;
import org.apache.http.impl.client.HttpClientBuilder;
import org.apache.http.util.EntityUtils;

public class ATest{

   public static void main(String[] args) throws Exception {
      String strURL  = "http://192.9.10.11/cgi-bin/echo";
      String message = "hello world";
      // next line throwsClassNotFoundException, why?
      HttpClient httpClient = HttpClientBuilder.create().build();
      HttpPost   httpPost   = new  HttpPost(strURL);
      httpPost.setEntity(new StringEntity(message));
      HttpResponse response = httpClient.execute(httpPost);
      try {
         System.out.println(response.getStatusLine());
         HttpEntity entity = response.getEntity();
         // do something useful with the response body
         // and ensure it is fully consumed
         EntityUtils.consume(entity);
      } finally {
         response.close();
      }
   }
}

Answer 1

Java VM附带了很多类,但没有org.apache.http.*.

你必须帮助Java虚拟机,就像你帮GCC在C或C++使用链接二进制代码-lxxx,并LD_LIBRARY_PATH与类路径概念.java -cp <path>:<path>:<path>指定所需类的位置(如Unix下的二进制文件.so).

org.apache.http.*课程放在一个罐子里.你必须将这个jar路径指定为cp <path>spec.

apache http client 4.3 delivery中包含的jar 位于lib目录中:

• HttpClient的-4.3.jar
• httpmime-4.3.jar
• 流利-HC-4.3.jar
• HttpClient的缓存-4.3.jar
• 的HttpCore-4.3.jar
• 共享记录-1.1.3.jar
• 公地编解码器1.6.jar

如果你的代码只是一个样本,你不需要全部,我建议commons-logging-1.1.3.jar和httpclient-4.3.jar