jsp-servlet mysql 增删改查

2019-06-18 10:36:39 80 阅读 AI 写同款 · GEO 优化AI 选题数据监测一键分发 ›

基于mysql的servlet+jsp增删改查操作（代码）接着上一篇，环境配置好以后，就要开始开发了，在使用servlet+jsp开发的项目时候，必然会有操作数据库的时候，这篇文章我就总结一下。注：在开始写代码之前，我们必须要准备jar包，连接池工具，连接池配置文件，新建五个包，分别是bean,servlet,service,dao,还有你的连接池工具包查询操作 bean:创建实体类对象，所有的字段和数据类型都必须和数据库里一一对应， packag... 阅读详情

org.apache.jasper.JasperException: An exception occurred processing JSP page /index.jsp at line 124

121: <form action="ModifyServlet" method="post">
122: <table>
123: <tr>
124: <td class="pink">User</td><td><input type="text" name="name" value=<%=student.getName()%> > </td>
125: <td><input type="hidden" name="id" value=<%=student.getID()%> > </td>
126: </tr>
127: <tr>

Stacktrace:
org.apache.jasper.servlet.JspServletWrapper.handleJspException(JspServletWrapper.java:521)
org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:430)
org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:313)
org.apache.jasper.servlet.JspServlet.service(JspServlet.java:260)
javax.servlet.http.HttpServlet.service(HttpServlet.java:723)

root cause
java.lang.NullPointerException
org.apache.jsp.index_jsp._jspService(index_jsp.java:179)
org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:70)
javax.servlet.http.HttpServlet.service(HttpServlet.java:723)
org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:388)
org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:313)
org.apache.jasper.servlet.JspServlet.service(JspServlet.java:260)
javax.servlet.http.HttpServlet.service(HttpServlet.java:723)

代码如下：
<%
com.bift.Student student=(com.bift.Student)session.getAttribute("student");
%>
<div class="fd1">
<div class="fd_box">
<div class="tm_box"></div>
<div class="denglu_box">
<h1>Idol Community</h1>
<form action="ModifyServlet" method="post">
<table>
<tr>
<td class="pink">User：</td><td><input type="text" name="name" value=<%=student.getName()%> > </td>
<td><input type="hidden" name="id" value=<%=student.getID()%> > </td>
</tr>
<tr>
<td class="pink">Password:</td><td><input type="password" name="password" class="ttext"></td>
</tr>
<tr>
<td>sex:</td><td>
<%
if (student.getSex()!=null){
if (student.getSex().equals("F")){
%>
<input type="radio" name="sex" value="F" checked>女
<input type="radio" name="sex" value="M">男
<%
}else{
%>
<input type="radio" name="sex" value="F" >女
<input type="radio" name="sex" value="M" checked>男
<%
}}
%> --%>
</td>
</tr>
<tr>

student：
package com.bift;

public class Student {
private int id;
private String name;
private String password;
private String sex;
private String hobby;
private int flag;
public void setFlag(int flag){
this.flag=flag;
}
public int getFlag(){
return this.flag;
}
public void setID(int id){
this.id=id;
}
public int getID(){
return this.id;
}
public void setName(String name){
this.name=name;
}
public String getName(){
return this.name;
}
public void setPassword(String password){
this.password=password;
}
public String getPassword(){
return this.password;
}
public void setSex(String sex){
this.sex=sex;
}
public String getSex(){
return this.sex;
}
public void setHobby(String hobby){
this.hobby=hobby;
}
public String getHobby(){
return this.hobby;
}

}

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