大家帮我看看这个错误，谢谢

Question

at org.apache.catalina.loader.WebappClassLoader.loadClass(WebappClassLoader.java:1358)
at org.apache.catalina.loader.WebappClassLoader.loadClass(WebappClassLoader.java:1204)
at java.lang.ClassLoader.loadClassInternal(ClassLoader.java:320)
at java.lang.Class.forName0(Native Method)
at java.lang.Class.forName(Class.java:169)
at com.buy.bean.comm.database.DBConnect.getConnection(DBConnect.java:10)
at com.buy.bean.coin.OrderSelectBean.selectOrder(OrderSelectBean.java:84)
at org.apache.jsp.COIN.oder_jsp._jspService(oder_jsp.java:220)
at org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:70)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:803)
at org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:393)
at org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:320)
at org.apache.jasper.servlet.JspServlet.service(JspServlet.java:266)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:803)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:290)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:230)
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:175)
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:128)
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:104)
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:109)
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:261)
at org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:844)
at org.apache.coyote.http11.Http11Protocol$Http11ConnectionHandler.process(Http11Protocol.java:581)
at org.apache.tomcat.util.net.JIoEndpoint$Worker.run(JIoEndpoint.java:447)
at java.lang.Thread.run(Thread.java:619)
no get connection! throws Exception
2011-3-31 22:23:22 org.apache.catalina.core.StandardWrapperValve invoke
严重: Servlet.service() for servlet jsp threw exception
java.lang.NullPointerException
at com.buy.bean.coin.OrderSelectBean.selectOrder(OrderSelectBean.java:85)
at org.apache.jsp.COIN.oder_jsp._jspService(oder_jsp.java:220)
at org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:70)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:803)
at org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:393)
at org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:320)
at org.apache.jasper.servlet.JspServlet.service(JspServlet.java:266)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:803)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:290)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:230)
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:175)
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:128)
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:104)
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:109)
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:261)
at org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:844)
at org.apache.coyote.http11.Http11Protocol$Http11ConnectionHandler.process(Http11Protocol.java:581)
at org.apache.tomcat.util.net.JIoEndpoint$Worker.run(JIoEndpoint.java:447)
at java.lang.Thread.run(Thread.java:619)

Answer 1

java.lang.NullPointerException
at com.buy.bean.coin.OrderSelectBean.selectOrder(OrderSelectBean.java:85)
这不是写的很清楚吗？？？在这里出现了空指针异常，处理一下就可以了

Answer 2

package com.buy.bean.coin;import java.sql.Connection;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;import com.buy.bean.comm.database.DBConnect;public class OrderSelectBean {
String s_year = "1700", s_month = "1", s_day = "1", e_year = "2099",
e_month = "1", e_day = "1", status = "0", num = null; public OrderSelectBean() { } public void setS_year(String sYear) {
s_year = sYear;
} public void setS_month(String sMonth) {
s_month = sMonth;
} public void setS_day(String sDay) {
s_day = sDay;
} public void setE_year(String eYear) {
e_year = eYear;
} public void setE_month(String eMonth) {
e_month = eMonth;
} public void setE_day(String eDay) {
e_day = eDay;
} public void setStatus(String status) {
this.status = status;
} public void setNum(String num) {
this.num = num;
} public StringBuffer selectOrder(String userID) {
String type1 = null;
int j = Integer.parseInt(status);
switch (j) {
case 0 :
type1 = "any";break;
case 1 :
type1 = "dealing";break;
case 2 :
type1 = "success";break;
case 3 :
type1 = "fail";break;
}

String s_date = s_year + "-" + s_month + "-" + s_day;
String e_date = e_year + "-" + e_month + "-" + e_day;

String condition;

if(num!=null){
condition = "select orderid,type,price,datetime,productname from buy.order where USERID='"+userID+"' and  orderid="+num+"";
    
}else{
condition = "select orderid,type,price,datetime,productname from buy.order where USERID='"+userID+"' and  datetime<='"+e_date+"' and datetime >='"+s_date+"'";
if(j !=0){
condition += "and type ='"+type1+"'";
}
}

ResultSet rs = null;
Statement sql = null;
String num,status,c_date,p_date,cabi,coin,name,date;
StringBuffer buffer = new StringBuffer("");
try {
Connection conn = DBConnect.getConnection();
sql = conn.createStatement();
rs = sql.executeQuery(condition);
int i = 1;

buffer.append("<table width="+"100%"+" border="+"0"+"" +
" cellpadding="+"0"+" cellsacing="+"1"+">");
buffer.append("<tr align="+"center"+">");
buffer.append("<td width="+"150"+"height ="+"25"+" class="+
"cal_td2"+">订单号</td>");
buffer.append("<td width="+"180"+"height ="+"25"+" class="+
"cal_td2"+">订单状态</td>");
buffer.append("<td width="+"150"+"height ="+"25"+" class="+
"cal_td2"+">金额</td>");
buffer.append("<td width="+"150"+"height ="+"25"+" class="+
"cal_td2"+">订单创建时间</td>");
buffer.append("<td width="+"150"+"height ="+"25"+" class="+
"cal_td2"+">订购商品名称</td>");
buffer.append("</tr>");
while(rs.next()){
buffer.append("<tr align="+"center"+">");
num = rs.getString(1);

status = rs.getString(2);
buffer.append("<td width="+"150"+"height ="+"20"+" class="+
"cal_td06"+">"+status+"</td>");
coin = rs.getString(3);
buffer.append("<td width="+"150"+"height ="+"20"+" class="+
"cal_td06"+">"+coin+"</td>");
date = rs.getString(4);
buffer.append("<td width="+"150"+"height ="+"20"+" class="+
"cal_td06"+">"+date+"</td>");
name = rs.getString(5);
buffer.append("<td width="+"150"+"height ="+"20"+" class="+
"cal_td06"+">"+name+"</td>");

buffer.append("</tr>");
i++;

}
buffer.append("</table>");

rs.close();
sql.close();
conn.close();
} catch (SQLException ex) {
return new StringBuffer("查询错误");
} return buffer;
}}

Answer 3

 Servlet.service() for servlet jsp threw exception
异常