【发布时间】：2020-02-05 21:02:49
【问题描述】：
“java”目录中有我的servlet：
@WebServlet("HelloWebServlet")
public class HelloWebServlet extends HttpServlet {
private HttpServletRequest request;
private String title = "Servlet test app";
public void doPost(HttpServletRequest req, HttpServletResponse resp) {
doGet(req, resp);
} // end: doPost()
private void sendHead(HttpServletResponse resp) {
try {
PrintWriter writer = resp.getWriter();
resp.setCharacterEncoding("UTF-8");
resp.setContentType("text/html; charset=utf-8");
writer.println("<HTML>");
writer.println("<HEAD>");
writer.println("<meta charset=\"UTF-8\">");
writer.println("<TITLE>" + title + "</TITLE>");
writer.println("</HEAD>");
writer.println("<BODY>");
} catch (Exception e) {
throw new Error(e);
}
} // END: sendHead()
private void sendFlooter(HttpServletResponse resp) {
try {
PrintWriter writer = resp.getWriter();
writer.println("</BODY>");
writer.println("</HTML>");
} catch (Exception e) {
throw new Error(e);
}
} // END: sendHead()
public void doGet(HttpServletRequest req, HttpServletResponse resp) {
this.request = req;
try {
sendHead(resp);
PrintWriter writer = resp.getWriter();
writer.println("<CENTER>");
writer.println("<FORM>");
writer.println("<H1>Input your request</H1>");
writer.println("<INPUT TYPE=\"submit\" value=\"" + "Send" + "\" />");
writer.println("</FORM>");
writer.println("</CENTER>");
sendFlooter(resp);
} catch (Exception e) {
throw new Error(e);
}
} // END: doGet()
} //END: class HelloWebServlet
有web.xml文件：
<?xml version="1.0" encoding="UTF-8"?>
<web-app
xmlns="http://xmlns.jcp.org/xml/ns/javaee"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://xmlns.jcp.org/xml/ns/javaee
http://xmlns.jcp.org/xml/ns/javaee/web-app_4_0.xsd"
version="4.0">
<display-name>Servlet test app</display-name>
<servlet-mapping>
<servlet-name>HelloWebServlet</servlet-name>
<url-pattern>/hello</url-pattern>
</servlet-mapping>
</web-app>
还有 index.html 文件：
<html>
<head>
<meta charset="UTF-8">
<title>Request from servlet</title>
</head>
<body>
<form action="./hello" method="POST">
<center>
<h1>Send request</h1>
<form>
<input NAME="Request" TYPE="submit" VALUE="Request from servlet"/>
</form>
</center>
</form>
</center>
</body>
</html>
当我的 servlet 类在“java”目录中时，它可以完美运行。但是，如果我尝试将其移动到某个包中，例如在 HelloWebApp 的第一行添加“package info.bhrigu.spring.test.servlets”：
package info.bhrigu.spring.test.servlets; // <------- now in the package!
@WebServlet("HelloWebServlet")
public class HelloWebServlet extends HttpServlet {
private static ArrayList<String> text;
...
并将 web.xml 更改为：
<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns="http://xmlns.jcp.org/xml/ns/javaee"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://xmlns.jcp.org/xml/ns/javaee
http://xmlns.jcp.org/xml/ns/javaee/web-app_4_0.xsd" version="4.0">
<description>Servlet test app</description>
<display-name>Servlet test app</display-name>
<servlet>
<servlet-name>HelloWebServlet</servlet-name>
<servlet-class>info.bhrigu.spring.test.servlets.HelloWebServlet</servlet-class>
</servlet>
<servlet-mapping>
<servlet-name>HelloWebServlet</servlet-name>
<url-pattern>/hello</url-pattern>
</servlet-mapping>
</web-app>
然后我从 tomcat 收到该类丢失的消息：
HTTP Status 500 – Internal Server Error
Type Exception Report
Message Error instantiating servlet class [info.bhrigu.spring.test.servlets.HelloWebServlet]
Description The server encountered an unexpected condition that prevented it from fulfilling the request.
Exception
javax.servlet.ServletException: Error instantiating servlet class [info.bhrigu.spring.test.servlets.HelloWebServlet] org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:526)
org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:92)
org.apache.catalina.valves.AbstractAccessLogValve.invoke(AbstractAccessLogValve.java:678)
org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:343)
org.apache.coyote.http11.Http11Processor.service(Http11Processor.java:408)
org.apache.coyote.AbstractProcessorLight.process(AbstractProcessorLight.java:66)
org.apache.coyote.AbstractProtocol$ConnectionHandler.process(AbstractProtocol.java:860)
org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1589)
org.apache.tomcat.util.net.SocketProcessorBase.run(SocketProcessorBase.java:49)
java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149)
java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624)
org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61)
java.lang.Thread.run(Thread.java:748)
Root Cause
java.lang.ClassNotFoundException: info.bhrigu.spring.test.servlets.HelloWebServlet
如何为某个包中的servlet编写正确的配置？
【问题讨论】：
-
你是不是把你的java源文件放到java/info/bhrigu/spring/test/servlets目录下，编译好的class文件在WEB-INF/classes/info/bhrigu/spring/test/servlets ?
-
你是如何编译这个的？例如，Maven 有一个定义的位置来放置您的类和 HTML/JSP 文件，以便以正确的方式打包它。其他构建环境的工作方式类似。
-
@Selaron 是的，问题是我将我的类文件保存在 /classes 文件夹中而没有竞争路径。谢谢。
-
@stdunbar 我用 JAR 插件编译它（就像一个普通的 jar），但我自己创建内部文件结构。可以在 Maven 中实现。
标签： java tomcat servlets web.xml