java - NoClassDefFoundError - Eclipse - Apache HTTPClient

Question

我正在尝试从 eclipse juno( jetty 网络服务器)运行一个简单的基于 REST 的应用程序(稍后将部署在谷歌应用引擎上)

这是我的代码:

package co.suhas.live;

import java.io.IOException;
import javax.servlet.http.*;

import org.apache.http.HttpResponse;
import org.apache.http.client.HttpClient;
import org.apache.http.client.methods.HttpGet;
import org.apache.http.impl.client.DefaultHttpClient;

@SuppressWarnings("serial")
public class AppServlet extends HttpServlet {
public void doGet(HttpServletRequest req, HttpServletResponse resp)
        throws IOException {
    resp.setContentType("text/plain");
    resp.getWriter().println("Hello, world");

    HttpClient httpclient = new DefaultHttpClient();
    HttpGet httpget = new HttpGet(
            "http://www.google.com/search?q=google");

    HttpResponse response = httpclient.execute(httpget);

    resp.getWriter().println(response.toString());
    }
}

我已将 Apache HTTP Client jar 文件添加到 BUILD PATH。

包括:

commons-codec-1.6.jar
commons-logging-1.1.1.jar
fluent-hc-4.2.3.jar
httpclient-4.2.3.jar
httpclient-cache-4.2.3.jar
httpcore-4.2.2.jar
httpmime-4.2.3.jar

但是当我在 localhost 上运行时出现这个错误:

HTTP ERROR 500

Problem accessing /app. Reason:

org/apache/http/client/methods/HttpUriRequest

Caused by:

java.lang.NoClassDefFoundError: org/apache/http/client/methods/HttpUriRequest
at java.lang.Class.getDeclaredConstructors0(Native Method)
at java.lang.Class.privateGetDeclaredConstructors(Class.java:2404)
at java.lang.Class.getConstructor0(Class.java:2714)
at java.lang.Class.newInstance0(Class.java:343)
at java.lang.Class.newInstance(Class.java:325)
at org.mortbay.jetty.servlet.Holder.newInstance(Holder.java:153)
at org.mortbay.jetty.servlet.ServletHolder.initServlet(ServletHolder.java:428)
at org.mortbay.jetty.servlet.ServletHolder.getServlet(ServletHolder.java:339)
at org.mortbay.jetty.servlet.ServletHolder.handle(ServletHolder.java:487)
at org.mortbay.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1166)
at com.google.appengine.api.socket.dev.DevSocketFilter.doFilter(DevSocketFilter.java:74)
at org.mortbay.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1157)
at com.google.appengine.tools.development.ResponseRewriterFilter.doFilter(ResponseRewriterFilter.java:123)
at org.mortbay.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1157)
at com.google.appengine.tools.development.HeaderVerificationFilter.doFilter(HeaderVerificationFilter.java:34)
at org.mortbay.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1157)
at com.google.appengine.api.blobstore.dev.ServeBlobFilter.doFilter(ServeBlobFilter.java:61)
at org.mortbay.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1157)
at com.google.apphosting.utils.servlet.TransactionCleanupFilter.doFilter(TransactionCleanupFilter.java:43)
at org.mortbay.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1157)
at com.google.appengine.tools.development.StaticFileFilter.doFilter(StaticFileFilter.java:125)
at org.mortbay.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1157)
at com.google.appengine.tools.development.BackendServersFilter.doFilter(BackendServersFilter.java:97)
at org.mortbay.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1157)
at org.mortbay.jetty.servlet.ServletHandler.handle(ServletHandler.java:388)
at org.mortbay.jetty.security.SecurityHandler.handle(SecurityHandler.java:216)
at org.mortbay.jetty.servlet.SessionHandler.handle(SessionHandler.java:182)
at org.mortbay.jetty.handler.ContextHandler.handle(ContextHandler.java:765)
at org.mortbay.jetty.webapp.WebAppContext.handle(WebAppContext.java:418)
at com.google.appengine.tools.development.DevAppEngineWebAppContext.handle(DevAppEngineWebAppContext.java:94)
at org.mortbay.jetty.handler.HandlerWrapper.handle(HandlerWrapper.java:152)
at com.google.appengine.tools.development.JettyContainerService$ApiProxyHandler.handle(JettyContainerService.java:383)
at org.mortbay.jetty.handler.HandlerWrapper.handle(HandlerWrapper.java:152)
at org.mortbay.jetty.Server.handle(Server.java:326)
at org.mortbay.jetty.HttpConnection.handleRequest(HttpConnection.java:542)
at org.mortbay.jetty.HttpConnection$RequestHandler.headerComplete(HttpConnection.java:923)
at org.mortbay.jetty.HttpParser.parseNext(HttpParser.java:547)
at org.mortbay.jetty.HttpParser.parseAvailable(HttpParser.java:212)
at org.mortbay.jetty.HttpConnection.handle(HttpConnection.java:404)
at org.mortbay.io.nio.SelectChannelEndPoint.run(SelectChannelEndPoint.java:409)
at org.mortbay.thread.QueuedThreadPool$PoolThread.run(QueuedThreadPool.java:582)

我做错了什么？

Answer 1

从 Eclipse 插件的角度来看。我遇到了同样的问题，并通过以下步骤解决了这个问题:

1. 将 lib 文件夹添加到根目录。
2. 添加jar文件
3. 打开 MANIFEST.MF 文件，转到运行时选项卡
4. 将项目添加到类路径
5. 转到构建选项卡
6. 将文件添加到输出