严重 [http-nio-8080-exec-4] org.apache.catalina.core.StandardWrapperValve.invoke

[Immer_L6]

问题如上，严重 [http-nio-8080-exec-4] org.apache.catalina.core.StandardWrapperValve.invoke Servlet.service() for servlet [PrepareAndExecuteServlet] in context with path [] threw exception 这个报错调了好久，就是出不来，有没有小伙伴遇到过的

[Immer_L6]

有没有小伙伴来分享一下思路啊

[yjsl__]

Tomcat自己会开新线程的，求高人解决

package question;

import java.util.HashMap;
import java.util.Map;

public class Tests {

	public static void main(String[] args) {
		ActionContext.getInstance().setRequest(1);
		ActionContext.getInstance().setRequest(2);
		
		new Thread() {
		    @Override
		    public void run() {
		    	ActionContext.getInstance().setRequest(3);
		    }
		}.start();
	}
}

class ActionContext {
	private ThreadLocal<Map<String, Object>> threadLocal = new ThreadLocal<>();

	private ActionContext() {
		Map<String, Object> map = new HashMap<>();
		threadLocal.set(map);
	}

	private static ActionContext instance = new ActionContext();

	public static ActionContext getInstance() {
		return instance;
	}

	public void setRequest(Object request) {
		Map<String, Object> map = threadLocal.get();
		System.out.println(map);
		map.put("request", request);
	}

	public void setResponse(Object response) {
		threadLocal.get().put("response", response);
	}

}

Exception in thread "Thread-0" java.lang.NullPointerException at question.ActionContext.setRequest(Tests.java:38) at question.Tests$1.run(Tests.java:15)

[Immer_L6]

首先感谢这位小伙伴的回答，这个问题已经解决

[Immer_L6]

具体解决方法可移步到我的博客文章地址https://blog.csdn.net/Immer_L6/article/details/80411084

[Immer_L6]

[yjsl__]

ActionContext19行空指针

[Immer_L6]

空指针的话，我debug了好久，看不出来哪里有问题

[Immer_L6]

package com.gem.struts.core;

import com.gem.fruit.util.StringUtil;

import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;
import java.util.*;

/**
 * 中央控制器
 */
@WebServlet(name = "PrepareAndExecuteServlet", urlPatterns = "*.action")
public class PrepareAndExecuteServlet extends HttpServlet {

    private ActionMapper mapper = new ActionMapper();

    @Override
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        request.setCharacterEncoding("utf-8");
        response.setCharacterEncoding("utf-8");
        response.setContentType("text/html;charset=utf-8");

        ActionContext.getInstance().setRequest(request);
        ActionContext.getInstance().setResponse(response);

        //获取统一 request 参数 保存在 Map 中去
        Map<String, String> paramsMap = showParams(request);

        String servletPath = request.getServletPath();
        if (StringUtil.isNoEmpty(servletPath)) {
            String path = servletPath.substring(1);
            int index = path.lastIndexOf(".action");
            path = path.substring(0, index);
            //获取 path 所对应的 action 类 实例对象
            Object actionObj = mapper.getMap().get(path);
            //回调set方法 将对象的
            invokeSetMethod(actionObj, paramsMap);
            if (actionObj != null) {
                ReflectUtil.invokeMethod(actionObj, "execute");
            } else {
                response.sendRedirect("error.jsp");
            }
        }
    }


    @Override
    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        doPost(request, response);
    }

    private void invokeSetMethod(Object actionObj, Map<String, String> params) {
        Set<String> keySet = params.keySet();
        Iterator<String> iterator = keySet.iterator();
        while (iterator.hasNext()) {
            String propertyName = iterator.next();
            String propertyValue = params.get(propertyName);
            String setMethodName = "set" + propertyName.substring(0, 1).toUpperCase() + propertyName.substring(1);
            ReflectUtil.invokeMethod(actionObj, setMethodName, propertyValue);
        }

    }

    private Map<String, String> showParams(HttpServletRequest request) {
        Map<String, String> params = new HashMap<>();
        Enumeration<String> parameterNames = request.getParameterNames();

        while (parameterNames.hasMoreElements()) {
            String paramName = parameterNames.nextElement();
            String paramValue = request.getParameter(paramName);
            params.put(paramName, paramValue);
        }
        return params;
    }
}

这里是我 PrepareAndExecuteServlet 页面

[Immer_L6]

引用 2 楼 yjsl__ 的回复:

ActionContext19行空指针

空指针的话，我debug了好久，看不出来哪里有问题……

[yjsl__]

ActionContext.getInstance().setRequest(request);没获取到ActionContext的实例对象

[Immer_L6]

引用 6 楼 yjsl__ 的回复:

ActionContext.getInstance().setRequest(request);没获取到ActionContext的实例对象

package com.gem.struts.core;

import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.util.HashMap;
import java.util.Map;

public class ActionContext {
    private ThreadLocal<Map<String,Object>> threadLocal = new ThreadLocal<>();
    private ActionContext() {
        Map<String,Object> map = new HashMap<>();
        threadLocal.set(map);
    }
    private static ActionContext instance = new ActionContext();
    public static ActionContext getInstance() {
        return instance;
    }
    public void setRequest(HttpServletRequest request) {
        threadLocal.get().put("request",request);
    }
    public void setResponse(HttpServletResponse response) {
        threadLocal.get().put("response",response);
    }
    public HttpServletRequest getRequest() {
        return (HttpServletRequest) threadLocal.get().get("request");
    }
    public HttpServletResponse getResponse() {
        return (HttpServletResponse) threadLocal.get().get("response");
    }
}

[Immer_L6]

这是debug设置 return instance 上的断点 不知道这样有没有获取到 我这里访问的是 preIndex.action 它会加载数据库中数据 并以每页5条的数据显示出来