Amazon Credentials Method not found

问题:

So my next problem with this code. It seemse to not be finding a method and my eyes are untrained. Any help available on this?

package packeging;

import java.io.IOException;
import java.io.PrintWriter;
import java.util.Calendar;
import java.util.Date;

import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import com.amazonaws.HttpMethod;
import com.amazonaws.auth.BasicAWSCredentials;
import com.amazonaws.services.s3.AmazonS3;
import com.amazonaws.services.s3.AmazonS3Client;
import com.amazonaws.auth.BasicAWSCredentials;
import org.apache.http.*;
/**
 * Servlet implementation class Hashtastic
 */
@WebServlet("/Hashtastic")
public class Hashtastic extends HttpServlet {
    private static final long serialVersionUID = 1L;
    private final static String BUCKET_NAME = "idlatestingbucket";//http://s3.amazonaws.com/THESISDB/techy.jpg
    private final static String FILE_NAME = "TestPicture/wallpaper-264411.png";
    private final static String ACCESS_KEY = "Fakepass";
    private final static String SECRET_KEY = "Fakekey";
    /**
     * Default constructor. 
     */
    public Hashtastic() {
        // TODO Auto-generated constructor stub
    }

    /**
     * @see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse response)
     */
    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        // TODO Auto-generated method stub
         PrintWriter out = response.getWriter();
          Calendar cal = Calendar.getInstance();
         cal.add(Calendar.SECOND, 1000);
         Date expDate = cal.getTime();
         out.println(expDate+"\n");

         BasicAWSCredentials cre = new BasicAWSCredentials(ACCESS_KEY, SECRET_KEY);
        AmazonS3 s3 = new AmazonS3Client(cre);
        String url = s3.generatePresignedUrl(BUCKET_NAME, FILE_NAME, expDate, HttpMethod.GET).toString();
        out.println(url);
         out.close();
    }

    /**
     * @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse response)
     */
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        // TODO Auto-generated method stub
    }

}

I am getting this 500 error. It says that it is missing a method. I have the jar in my lib and plugins for eclipse.

description The server encountered an internal error () that prevented it from fulfilling this request.

exception 

javax.servlet.ServletException: Servlet execution threw an exception


root cause 

java.lang.NoSuchMethodError: org.apache.http.impl.conn.tsccm.ThreadSafeClientConnManager: method <init>()V not found
    com.amazonaws.http.ConnectionManagerFactory.createThreadSafeClientConnManager(ConnectionManagerFactory.java:26)
    com.amazonaws.http.HttpClientFactory.createHttpClient(HttpClientFactory.java:83)
    com.amazonaws.http.AmazonHttpClient.<init>(AmazonHttpClient.java:116)
    com.amazonaws.AmazonWebServiceClient.<init>(AmazonWebServiceClient.java:60)
    com.amazonaws.services.s3.AmazonS3Client.<init>(AmazonS3Client.java:291)
    com.amazonaws.services.s3.AmazonS3Client.<init>(AmazonS3Client.java:273)
    packeging.Hashtastic.doGet(Hashtastic.java:48)
    javax.servlet.http.HttpServlet.service(HttpServlet.java:621)
    javax.servlet.http.HttpServlet.service(HttpServlet.java:722)


note The full stack trace of the root cause is available in the Apache Tomcat/7.0.27 logs.

Any help?

回答1:

This could happen if you have the wrong version of the httpclient jar in your classpath, or if you have more than one version of that jar in your classpath (e.g. having both httpclient-4.0.1.jar and httpclient-4.1.1.jar).

It could also be caused by another jar containing a different version of the same class. For example, I know that gwt-dev.jar contains a version of ThreadSafeClientConnManager. If this is the case, the problem could probably be solved by adjusting the build path order to put httpclient.jar before gwt-dev.jar (or the other jar causing problem).

回答2:

From experience with this exact same Exception, the chances are fairly good that it is caused by gwt-dev appearing before aws-java-sdk in your classpath and due to gwt-dev containing a conflicting (in terms of classloading) version of org.apache.http.impl.conn.tsccm.ThreadSafeClientConnManager

If you happen to be using Maven, re-order your dependencies as follows and perhaps add a warning to fellow maintainers on the significance of the ordering.

<dependency>
   <groupId>com.amazonaws</groupId>
   <artifactId>aws-java-sdk</artifactId>
   <version>1.3.26</version>
</dependency>

<dependency>
  <groupId>com.google.gwt</groupId>
  <artifactId>gwt-dev</artifactId>
  <version>2.3.0</version>
</dependency>