大佬求教，刚开始接触java

HTTP Status 500 -

type Exception report

message

description The server encountered an internal error () that prevented it from fulfilling this request.

exception

org.apache.jasper.JasperException: java.lang.NullPointerException
	org.apache.jasper.servlet.JspServletWrapper.handleJspException(JspServletWrapper.java:541)
	org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:435)
	org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:320)
	org.apache.jasper.servlet.JspServlet.service(JspServlet.java:266)
	javax.servlet.http.HttpServlet.service(HttpServlet.java:803)

root cause

java.lang.NullPointerException
	org.apache.jsp.homepage_jsp._jspService(homepage_jsp.java:214)
	org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:70)
	javax.servlet.http.HttpServlet.service(HttpServlet.java:803)
	org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:393)
	org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:320)
	org.apache.jasper.servlet.JspServlet.service(JspServlet.java:266)
	javax.servlet.http.HttpServlet.service(HttpServlet.java:803)

note The full stack trace of the root cause is available in the Apache Tomcat/6.0.13 logs.

你看下后台Controller转到jsp的时候；

homeData没有设值成功

homepage.jsp 文件调用的对象是空值，导致页面报错

homeData是空值，检查一下后台代码

如有需要可以学习一下（0检查学习JSP+在线视频教学平台项目实训）：https://edu.csdn.net/course/detail/3462

你这个是javabean呀，要看数据库操作的代码

org.apache.jasper.JasperException: An exception occurred processing JSP page /homepage.jsp at line 155

152: 	               <%
153: 	               HomeData homeData=(HomeData)request.getAttribute("homeData");
154: 	               
155: 	               for(int i=0;i<homeData.getGoodList().size();i++){
156: 	                 Goods goods=homeData.getGoodList().get(i);
157: 	               
158: 	                %>

public class HomeData {
    /*
    private int curPage;
    private int totalPage;
    public static int numForOnePage=8;
    private ArrayList<Goods> goodList;
    private int kind;//kind==0表示不分类，全部查询
    private String keyword;
    */
    private int numForOnePage=8;
    private int curPage;
    private int kind;
    private String keyword;
    private int totalPage;
    private  ArrayList<Goods> goodList;
    public HomeData(int curPage, int kind, String keyword) {
        super();
        this.curPage = curPage;
        this.kind = kind;
        this.keyword = keyword;
    }
    public HomeData() {
        super();
    }
    public int getCurPage() {
        return curPage;
    }
    public void setCurPage(int curPage) {
        this.curPage = curPage;
    }
    public int getTotalPage() {
        return totalPage;
    }
    public void setTotalPage(int totalPage) {
        this.totalPage = totalPage;
    }
    public int getNumForOnePage() {
        return numForOnePage;
    }
    public void setNumForOnePage(int numForOnePage) {
        this.numForOnePage = numForOnePage;
    }
    public ArrayList<Goods> getGoodList() {
        return goodList;
    }
    public void setGoodList(ArrayList<Goods> goodList) {
        this.goodList = goodList;
    }
    public int getKind() {
        return kind;
    }
    public void setKind(int kind) {
        this.kind = kind;
    }
    public String getKeyword() {
        return keyword;
    }
    public void setKeyword(String keyword) {
        this.keyword = keyword;
    }
    
    
}

您好，我是有问必答小助手，你的问题已经有小伙伴为您解答了问题，您看下是否解决了您的问题，可以追评进行沟通哦~

如果有您比较满意的答案 / 帮您提供解决思路的答案，可以点击【采纳】按钮，给回答的小伙伴一些鼓励哦～～

ps:问答VIP仅需29元，即可享受5次/月 有问必答服务，了解详情>>>https://vip.csdn.net/askvip?utm_source=1146287632

你homeData首先不判断非空，直接调用他的get方法，可不就报空指针了