java NoClassDefFoundError 和 Netty
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NoClassDefFoundError and Netty
提问by Dmytro Leonenko
First to say I'm n00b in Java. I can understand most concepts but in my situation I want somebody to help me. I'm using JBoss Netty to handle simple http request and using MemCachedClient check existence of client ip in memcached.
首先说我是 Java 中的 n00b。我可以理解大多数概念，但在我的情况下，我希望有人帮助我。我正在使用 JBoss Netty 处理简单的 http 请求，并使用 MemCachedClient 检查 memcached 中客户端 ip 的存在。
import org.jboss.netty.channel.ChannelHandler;
import static org.jboss.netty.handler.codec.http.HttpHeaders.*;
import static org.jboss.netty.handler.codec.http.HttpHeaders.Names.*;
import static org.jboss.netty.handler.codec.http.HttpResponseStatus.*;
import static org.jboss.netty.handler.codec.http.HttpVersion.*;
import com.danga.MemCached.*;
import java.util.List;
import java.util.Map;
import java.util.Map.Entry;
import java.util.Set;
import org.jboss.netty.buffer.ChannelBuffer;
import org.jboss.netty.buffer.ChannelBuffers;
import org.jboss.netty.channel.ChannelFuture;
import org.jboss.netty.channel.ChannelFutureListener;
import org.jboss.netty.channel.ChannelHandlerContext;
import org.jboss.netty.channel.ExceptionEvent;
import org.jboss.netty.channel.MessageEvent;
import org.jboss.netty.channel.SimpleChannelUpstreamHandler;
import org.jboss.netty.handler.codec.http.Cookie;
import org.jboss.netty.handler.codec.http.CookieDecoder;
import org.jboss.netty.handler.codec.http.CookieEncoder;
import org.jboss.netty.handler.codec.http.DefaultHttpResponse;
import org.jboss.netty.handler.codec.http.HttpChunk;
import org.jboss.netty.handler.codec.http.HttpChunkTrailer;
import org.jboss.netty.handler.codec.http.HttpRequest;
import org.jboss.netty.handler.codec.http.HttpResponse;
import org.jboss.netty.handler.codec.http.HttpResponseStatus;
import org.jboss.netty.handler.codec.http.QueryStringDecoder;
import org.jboss.netty.util.CharsetUtil;
/**
* @author <a href="http://www.jboss.org/netty/">The Netty Project</a>
* @author Andy Taylor ([email protected])
* @author <a href="http://gleamynode.net/">Trustin Lee</a>
*
* @version $Rev: 2368 $, $Date: 2010-10-18 17:19:03 +0900 (Mon, 18 Oct 2010) $
*/
@SuppressWarnings({"ALL"})
public class HttpRequestHandler extends SimpleChannelUpstreamHandler {
private HttpRequest request;
private boolean readingChunks;
/** Buffer that stores the response content */
private final StringBuilder buf = new StringBuilder();
protected MemCachedClient mcc = new MemCachedClient();
private static SockIOPool poolInstance = null;
static {
// server list and weights
String[] servers =
{
"lcalhost:11211"
};
//Integer[] weights = { 3, 3, 2 };
Integer[] weights = {1};
// grab an instance of our connection pool
SockIOPool pool = SockIOPool.getInstance();
// set the servers and the weights
pool.setServers(servers);
pool.setWeights(weights);
// set some basic pool settings
// 5 initial, 5 min, and 250 max conns
// and set the max idle time for a conn
// to 6 hours
pool.setInitConn(5);
pool.setMinConn(5);
pool.setMaxConn(250);
pool.setMaxIdle(21600000); //1000 * 60 * 60 * 6
// set the sleep for the maint thread
// it will wake up every x seconds and
// maintain the pool size
pool.setMaintSleep(30);
// set some TCP settings
// disable nagle
// set the read timeout to 3 secs
// and don't set a connect timeout
pool.setNagle(false);
pool.setSocketTO(3000);
pool.setSocketConnectTO(0);
// initialize the connection pool
pool.initialize();
// lets set some compression on for the client
// compress anything larger than 64k
//mcc.setCompressEnable(true);
//mcc.setCompressThreshold(64 * 1024);
}
@Override
public void messageReceived(ChannelHandlerContext ctx, MessageEvent e) throws Exception {
HttpRequest request = this.request = (HttpRequest) e.getMessage();
if(mcc.get(request.getHeader("X-Real-Ip")) != null)
{
HttpResponse response = new DefaultHttpResponse(HTTP_1_1, OK);
response.setHeader("X-Accel-Redirect", request.getUri());
ctx.getChannel().write(response).addListener(ChannelFutureListener.CLOSE);
}
else {
sendError(ctx, NOT_FOUND);
}
}
private void writeResponse(MessageEvent e) {
// Decide whether to close the connection or not.
boolean keepAlive = isKeepAlive(request);
// Build the response object.
HttpResponse response = new DefaultHttpResponse(HTTP_1_1, OK);
response.setContent(ChannelBuffers.copiedBuffer(buf.toString(), CharsetUtil.UTF_8));
response.setHeader(CONTENT_TYPE, "text/plain; charset=UTF-8");
if (keepAlive) {
// Add 'Content-Length' header only for a keep-alive connection.
response.setHeader(CONTENT_LENGTH, response.getContent().readableBytes());
}
// Encode the cookie.
String cookieString = request.getHeader(COOKIE);
if (cookieString != null) {
CookieDecoder cookieDecoder = new CookieDecoder();
Set<Cookie> cookies = cookieDecoder.decode(cookieString);
if(!cookies.isEmpty()) {
// Reset the cookies if necessary.
CookieEncoder cookieEncoder = new CookieEncoder(true);
for (Cookie cookie : cookies) {
cookieEncoder.addCookie(cookie);
}
response.addHeader(SET_COOKIE, cookieEncoder.encode());
}
}
// Write the response.
ChannelFuture future = e.getChannel().write(response);
// Close the non-keep-alive connection after the write operation is done.
if (!keepAlive) {
future.addListener(ChannelFutureListener.CLOSE);
}
}
@Override
public void exceptionCaught(ChannelHandlerContext ctx, ExceptionEvent e)
throws Exception {
e.getCause().printStackTrace();
e.getChannel().close();
}
private void sendError(ChannelHandlerContext ctx, HttpResponseStatus status) {
HttpResponse response = new DefaultHttpResponse(HTTP_1_1, status);
response.setHeader(CONTENT_TYPE, "text/plain; charset=UTF-8");
response.setContent(ChannelBuffers.copiedBuffer(
"Failure: " + status.toString() + "\r\n",
CharsetUtil.UTF_8));
// Close the connection as soon as the error message is sent.
ctx.getChannel().write(response).addListener(ChannelFutureListener.CLOSE);
}
}
When I try to send request like http://127.0.0.1:8090/1/2/3I'm getting
当我尝试发送像http://127.0.0.1:8090/1/2/3这样的请求时，我得到了
java.lang.NoClassDefFoundError: com/danga/MemCached/MemCachedClient
at httpClientValidator.server.HttpRequestHandler.<clinit>(HttpRequestHandler.java:66)
I believe it's not related to classpath. May be it's related to context in which mcc doesn't exist. Any help appreciated
我相信它与类路径无关。可能与 mcc 不存在的上下文有关。任何帮助表示赞赏
EDIT: Original code http://docs.jboss.org/netty/3.2/xref/org/jboss/netty/example/http/snoop/package-summary.htmlI've modified some parts to fit my needs.
编辑：原始代码http://docs.jboss.org/netty/3.2/xref/org/jboss/netty/example/http/snoop/package-summary.html我修改了一些部分以满足我的需要。
采纳答案by mtraut
Why do you think this is not classpath related? That's the kind of error you get when the jar you need is not available. How do you start your app?
为什么你认为这与类路径无关？当您需要的 jar 不可用时，您会遇到这种错误。你如何启动你的应用程序？
EDIT
编辑
Sorry - i loaded and tried the java_memcached-release_2.5.2 bundle in eclipse and found no issue so far. Debugging the class loading revealed nothing unusual. I can't help besides some more hints to double check:
抱歉 - 我在 eclipse 中加载并尝试了 java_memcached-release_2.5.2 包，到目前为止没有发现任何问题。调试类加载没有发现任何异常。除了一些要仔细检查的提示外，我无能为力：
- make sure your download is correct. download and unpack again. (are the com.schooner.* classes available?)
- make sure you use > java 1.5
- make sure your classpath is correct and complete. The example you have shown does not include netty. Where is it.
- I'm not familiar with interactions stemming from adding a classpath to the manifest. Maybe revert to plain style, add all jars needed (memcached, netty, yours) to the classpath and reference the main class to start, not a startable jar file
- 确保您的下载正确。再次下载并解压。（com.schooner.* 课程是否可用？）
- 确保您使用 > java 1.5
- 确保您的类路径正确且完整。您展示的示例不包括 netty。它在哪里。
- 我不熟悉因向清单添加类路径而产生的交互。也许恢复到普通样式，将所有需要的 jar（memcached、netty、你的）添加到类路径并引用主类来启动，而不是一个可启动的 jar 文件
