这是一个简单的测试应用程序，我正在使用它来帮助更好地了解在Eclipse中创建动态Web应用程序。我已经看过许多名字相似的帖子，但是，它们都没有帮助，我仍然不知道为什么它不起作用。
错误是：
HTTP Status 500 – Internal Server Error
Type Exception Report
Message Error instantiating servlet class LoginCheck
Description The server encountered an unexpected condition that prevented it from fulfilling the request.
Exception
javax.servlet.ServletException: Error instantiating servlet class LoginCheck
org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:494)
org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:104)
org.apache.catalina.valves.AccessLogValve.invoke(AccessLogValve.java:1025)
org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:445)
org.apache.coyote.http11.AbstractHttp11Processor.process(AbstractHttp11Processor.java:1137)
org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java:637)
org.apache.tomcat.util.net.JIoEndpoint$SocketProcessor.run(JIoEndpoint.java:319)
java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1152)
java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:622)
org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61)
java.lang.Thread.run(Thread.java:748)
Root Cause
java.lang.UnsupportedClassVersionError: LoginCheck : Unsupported major.minor version 52.0 (unable to load class LoginCheck)
org.apache.catalina.loader.WebappClassLoaderBase.findClassInternal(WebappClassLoaderBase.java:3255)
org.apache.catalina.loader.WebappClassLoaderBase.findClass(WebappClassLoaderBase.java:1420)
org.apache.catalina.loader.WebappClassLoaderBase.loadClass(WebappClassLoaderBase.java:1924)
org.apache.catalina.loader.WebappClassLoaderBase.loadClass(WebappClassLoaderBase.java:1798)
org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:494)
org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:104)
org.apache.catalina.valves.AccessLogValve.invoke(AccessLogValve.java:1025)
org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:445)
org.apache.coyote.http11.AbstractHttp11Processor.process(AbstractHttp11Processor.java:1137)
org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java:637)
org.apache.tomcat.util.net.JIoEndpoint$SocketProcessor.run(JIoEndpoint.java:319)
java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1152)
java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:622)
org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61)
java.lang.Thread.run(Thread.java:748)
Note The full stack trace of the root cause is available in the server logs.
Apache Tomcat/7.0.94
login.jsp
<%@ page language="java" contentType="text/html; charset=UTF-8" pageEncoding="UTF-8"%>
<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<title>Login Page</title>
</head>
<body>
<form method="post" action="LoginCheck">
<table>
<tr>
<td>User Name</td>
<td><input type="text" name="uname"></td>
</tr>
<tr>
<td>Password</td>
<td><input type="password" name="password"></td>
</tr>
<tr>
<td></td>
<td><input type="submit" value="login"></td>
</tr>
</table>
</form>
</body>
</html>
LoginCheck.java
import java.io.IOException;
import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
@WebServlet("/LoginCheck")
public class LoginCheck extends HttpServlet {
private static final long serialVersionUID = 1L;
public LoginCheck() {
super();
}
protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
String uname = request.getParameter("uname");
String password = request.getParameter("password");
if (uname.equals("1") && password.equals("1"))
{
response.sendRedirect("member.jsp");
}
else
{
response.sendRedirect("error.jsp");
}
}
}
web.xml
<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns="http://java.sun.com/xml/ns/javaee" xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_3_0.xsd" id="WebApp_ID" version="3.0">
<display-name>test</display-name>
<welcome-file-list>
<welcome-file>login.jsp</welcome-file>
</welcome-file-list>
</web-app>
不支持的主要/次要版本错误通常是由于编译器（JDK）和运行时环境版本（JRE）不同而发生的。因此，请确保您使用的是JDK + JRE的相同/兼容版本。