type Exception reportmessage java.lang.NullPointerExceptiondescription The server encountered an internal error that prevented it from fulfilling this request.exceptionorg.apache.jasper.JasperException: java.lang.NullPointerException
org.apache.jasper.servlet.JspServletWrapper.handleJspException(JspServletWrapper.java:549)
org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:470)
org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:391)
org.apache.jasper.servlet.JspServlet.service(JspServlet.java:335)
javax.servlet.http.HttpServlet.service(HttpServlet.java:725)
org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52)
root causejava.lang.NullPointerException
org.apache.jsp.words_005flist_jsp._jspService(words_005flist_jsp.java:118)
org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:70)
javax.servlet.http.HttpServlet.service(HttpServlet.java:725)
org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:432)
org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:391)
org.apache.jasper.servlet.JspServlet.service(JspServlet.java:335)
javax.servlet.http.HttpServlet.service(HttpServlet.java:725)
org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52)
note The full stack trace of the root cause is available in the Apache Tomcat/8.0.12 logs.这个是异常,
import java.util.*;
import java.sql.*;
import java.text.*;public class words extends mysql_db
{
//定义成员变量
private int WordsID;
private String WordsTitle;
private String WordsContent;
private String WordsTime;
private int UserID;
private String strSql;
//时间格式
private SimpleDateFormat timeFormatter;
public words()
{
this.WordsID = 0;
this.WordsTitle = "";
this.WordsContent ="";
this.UserID = 0;
timeFormatter = new SimpleDateFormat("yyyy-MM-dd hh:mm:ss");
this.WordsTime = timeFormatter.format(new java.util.Date());
this.strSql = "";
}
/*添加留言记录*/
public boolean add_words()
{
this.strSql = "insert into words ";
this.strSql = this.strSql + "(";
this.strSql = this.strSql + "this.WordsTitle,";
this.strSql = this.strSql + "this.WordsContent,";
this.strSql = this.strSql + "this.WordsTime,";
this.strSql = this.strSql + "this.UserID";
this.strSql = this.strSql + ")";
this.strSql = this.strSql + "values(";
this.strSql = this.strSql + "'" + this.WordsTitle + "',";
this.strSql = this.strSql + "'" + this.WordsContent + "',";
this.strSql = this.strSql + "'" + this.WordsTime + "',";
this.strSql = this.strSql + "'" + this.UserID + "'";
this.strSql = this.strSql + ")"; boolean isAdd = super.exeSql(this.strSql);
return isAdd;
}
/*获取某条留言信息 by WordsID*/
public boolean init()
{
this.strSql = "select * from 'words' where WordsID=";
this.strSql = this.strSql +"'"+ this.WordsID+"'";
try
{
ResultSet rs = super.exeSqlQuery(strSql);
if (rs.next())
{
this.WordsID = rs.getInt("WordsID");
this.WordsTitle = rs.getString("WordsTitle");
this.WordsContent = rs.getString("WordsContent");
this.WordsTime = rs.getString("WordsTime");
this.UserID = rs.getInt("UserID");
return true;
}
else
{
return false;
}
}
catch(Exception ex)
{
System.out.println(ex.toString());
return false;
}
}
/*显示所有留言*/
public ResultSet show_all_words()
{
this.strSql = "select * from 'words'";
ResultSet rs = null; try
{
rs = super.exeSqlQuery(this.strSql);
}
catch(Exception ex)
{
System.out.println(ex.toString());
}
return rs;
}
/*设置成员变量WordsID的值*/
public void setWordsID(int WordsID)
{
this.WordsID = WordsID;
}
/*获取成员变量WordsID的值*/
public int getWordsID()
{
return this.WordsID;
}
/*设置成员变量WordsTitle的值*/
public void setWordsTitle(String WordsTitle)
{
this.WordsTitle = WordsTitle;
}
/*获取成员变量WordsTitle的值*/
public String getWordsTitle()
{
return this.WordsTitle;
}
/*设置成员变量WordsContent的值*/
public void setWordsContent(String WordsContent)
{
this.WordsContent = WordsContent;
}
/*获取成员变量WordsTitle的值*/
public String getWordsContent()
{
return this.WordsContent;
}
/*设置成员变量WordsTime的值*/
public void setWordsTime(String WordsTime)
{
this.WordsTime = WordsTime;
}
/*获取成员变量WordsTime的值*/
public String getWordsTime()
{
return this.WordsTime;
}
/*设置成员变量UserID的值*/
public void setUserID(int UserID)
{
this.UserID = UserID;
}
/*获取成员变量UserID的值*/
public int getUserID()
{
return this.UserID;
}
}
这是words.java文件,