学习Servlet时运行报错，如何解决？
JSP页面错误：
type Exception report
message Error instantiating servlet class com.rl.servlet.ServeltDemo1
description The server encountered an internal error that prevented it from fulfilling this request.
exception
javax.servlet.ServletException: Error instantiating servlet class com.rl.servlet.ServeltDemo1
org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:502)
org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:79)
org.apache.catalina.valves.AbstractAccessLogValve.invoke(AbstractAccessLogValve.java:616)
org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:522)
org.apache.coyote.http11.AbstractHttp11Processor.process(AbstractHttp11Processor.java:1095)
org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java:672)
org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1500)
org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.run(NioEndpoint.java:1456)
java.util.concurrent.ThreadPoolExecutor.runWorker(Unknown Source)
java.util.concurrent.ThreadPoolExecutor$Worker.run(Unknown Source)
org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61)
java.lang.Thread.run(Unknown Source)
root cause
java.lang.IllegalAccessException: Class org.apache.catalina.core.DefaultInstanceManager can not access a member of class com.rl.servlet.ServeltDemo1 with modifiers ""
sun.reflect.Reflection.ensureMemberAccess(Unknown Source)
java.lang.Class.newInstance(Unknown Source)
org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:502)
org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:79)
org.apache.catalina.valves.AbstractAccessLogValve.invoke(AbstractAccessLogValve.java:616)
org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:522)
org.apache.coyote.http11.AbstractHttp11Processor.process(AbstractHttp11Processor.java:1095)
org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java:672)
org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1500)
org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.run(NioEndpoint.java:1456)
java.util.concurrent.ThreadPoolExecutor.runWorker(Unknown Source)
java.util.concurrent.ThreadPoolExecutor$Worker.run(Unknown Source)
org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61)
java.lang.Thread.run(Unknown Source)
note The full stack trace of the root cause is available in the Apache Tomcat/8.0.32 logs.
控制台报错：
严重: Allocate exception for servlet helloServlet
java.lang.IllegalAccessException: Class org.apache.catalina.core.DefaultInstanceManager can not access a member of class com.rl.servlet.ServeltDemo1 with modifiers ""
at sun.reflect.Reflection.ensureMemberAccess(Unknown Source)
at java.lang.Class.newInstance(Unknown Source)
at org.apache.catalina.core.DefaultInstanceManager.newInstance(DefaultInstanceManager.java:119)
at org.apache.catalina.core.StandardWrapper.loadServlet(StandardWrapper.java:1102)
at org.apache.catalina.core.StandardWrapper.allocate(StandardWrapper.java:828)
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:135)
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:106)
at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:502)
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:141)
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:79)
at org.apache.catalina.valves.AbstractAccessLogValve.invoke(AbstractAccessLogValve.java:616)
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:88)
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:522)
at org.apache.coyote.http11.AbstractHttp11Processor.process(AbstractHttp11Processor.java:1095)
at org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java:672)
at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1500)
at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.run(NioEndpoint.java:1456)
at java.util.concurrent.ThreadPoolExecutor.runWorker(Unknown Source)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(Unknown Source)
at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61)
at java.lang.Thread.run(Unknown Source)
**实现类代码**：
class ServeltDemo1 implements Servlet {
@Override
public void init(ServletConfig arg0) throws ServletException {
System.out.println("相应请求");
System.out.println("Servlet组件被创建了");
}
@Override
public void service(ServletRequest request, ServletResponse response)
throws ServletException, IOException {
response.getOutputStream().write("<font color = 'red'>Hello Servlet</font>".getBytes());
}
@Override
public void destroy() {
System.out.println("Servlet销毁了");
}
}
web.xml代码：
<?xml version="1.0" encoding="UTF-8"?>
<!-- 设置Servlet名称 -->
helloServlet
<!-- 具体的Servlet类 -->
com.rl.servlet.ServeltDemo1
helloServlet
/hello
实现类添加public
实现类代码：
public class ServeltDemo1 implements Servlet {
@Override
public void init(ServletConfig arg0) throws ServletException {
System.out.println("相应请求");
System.out.println("Servlet组件被创建了");
}
@Override
public void service(ServletRequest request, ServletResponse response)
throws ServletException, IOException {
response.getOutputStream().write("Hello Servlet".getBytes());
}
@Override
public void destroy() {
System.out.println("Servlet销毁了");
}
应该是servlet的编写有问题，导致容器无法成功实例化，仔细检查一下代码，或者贴出代码让大家看看。
实现类代码：
package com.rl.servlet;
import java.io.IOException;
import javax.servlet.Servlet;
import javax.servlet.ServletConfig;
import javax.servlet.ServletException;
import javax.servlet.ServletRequest;
import javax.servlet.ServletResponse;
class ServeltDemo1 implements Servlet {
/**
* 执行时机：当Servlet实例被创建的时候被调用，做初始化工作
* ServletConfig：Servlet的配置对象，初始化的时候可以进行配置
*/
@Override
public void init(ServletConfig arg0) throws ServletException {
System.out.println("相应请求");
System.out.println("Servlet组件被创建了");
}
/**
* 执行时机：当一个请求来请求当前的Servlet的时候被调用
* 处理当前的Servlet的业务逻辑并且把响应返回给浏览器
*/
@Override
public void service(ServletRequest request, ServletResponse response)
throws ServletException, IOException {
response.getOutputStream().write("<font color = 'red'>Hello Servlet</font>".getBytes());
}
/**
* 执行时机：是Servlet的实例对象被销毁的时候
* 做一些收尾或清理工作
*/
@Override
public void destroy() {
System.out.println("Servlet销毁了");
}
/**
* 获得ServletConfig的配置对象
*/
@Override
public ServletConfig getServletConfig() {
return null;
}
/**
* 获得当前Servlet的一些属性信息（了解）
*/
@Override
public String getServletInfo() {
return null;
}
}
web.xml代码：
<?xml version="1.0" encoding="UTF-8"?>
<!-- 设置Servlet名称 -->
helloServlet
<!-- 具体的Servlet类 -->
com.rl.servlet.ServeltDemo1
<!-- 指定要映射的Servlet的名字 -->
helloServlet
<!-- Servlet的具体映射路径 -->
/hello