页面提示如下:
type Exception reportdescription The server encountered an internal error () that prevented it from fulfilling this request.exception
org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:292)
org.apache.jasper.servlet.JspServlet.service(JspServlet.java:236)
javax.servlet.http.HttpServlet.service(HttpServlet.java:802)root cause java.lang.NullPointerException
org.apache.jsp.lab1_jsp._jspService(lab1_jsp.java:63)
org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:94)
javax.servlet.http.HttpServlet.service(HttpServlet.java:802)
org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:324)
org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:292)
org.apache.jasper.servlet.JspServlet.service(JspServlet.java:236)
javax.servlet.http.HttpServlet.service(HttpServlet.java:802)note The full stack trace of the root cause is available in the Apache Tomcat/5.0.27 logs.
我编写的连接数据库的代码如下:
/* condb.java 3.27.2006
Bean to connect database */package condb;
import java.sql.*;public class condb
{
String strDBDriver="sun.jdbc.odbc.JdbcOdbcDriver";
String strDBUrl="jdbc:odbc:CRM";
private Connection conn=null;
private Statement stmt=null;
ResultSet rs=null;
//<!--注册数据库驱动程序-->
public condb()
{
try
{
Class.forName(strDBDriver);
}
//异常处理
catch(java.lang.ClassNotFoundException e)
{
System.err.println("condb():"+e.getMessage());
}
}
//<!--建立数据库连接及定义数据查询-->
public ResultSet executeQuery(String sql)
{
rs=null;
try
{
conn=DriverManager.getConnection(strDBUrl,"sa","");//创建数据库连接对象
stmt=conn.createStatement();
rs=stmt.executeQuery(sql);
}
catch(SQLException ex)
{
System.err.println("aq.executeQuery:"+ex.getMessage());
}
return rs;
}
//<!--定义数据操作-->
public void executeUpdate(String sql)
{
stmt=null;
rs=null;
try
{
conn=DriverManager.getConnection(strDBUrl,"sa","");
stmt=conn.createStatement();
stmt.executeQuery(sql);
stmt.close();
conn.close();
}
catch(SQLException ex)
{
System.err.println("aq.executeQuery:"+ex.getMessage());
}
}
//<!--关闭数据库连接-->
public void closeStmt()
{
try
{
stmt.close();
}
catch(SQLException e)
{
e.printStackTrace();
}
}
public void closeConn()
{
try
{
conn.close();
}
catch(SQLException e)
{
e.printStackTrace();
}
}
}
我用一段代码测试的
<jsp:useBean id="db" scope="page" class="condb.condb"/>
<%
String sql="select * from User";
ResultSet rs=db.executeQuery(sql);
if(rs.next())
{
String getUserNAME=rs.getString("UserName");
out.println(getUserNAME);
rs.close();
}
实在不知道怎么搞的了!谢谢大家帮忙啦!
type Exception reportdescription The server encountered an internal error () that prevented it from fulfilling this request.exception
org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:292)
org.apache.jasper.servlet.JspServlet.service(JspServlet.java:236)
javax.servlet.http.HttpServlet.service(HttpServlet.java:802)root cause java.lang.NullPointerException
org.apache.jsp.lab1_jsp._jspService(lab1_jsp.java:63)
org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:94)
javax.servlet.http.HttpServlet.service(HttpServlet.java:802)
org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:324)
org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:292)
org.apache.jasper.servlet.JspServlet.service(JspServlet.java:236)
javax.servlet.http.HttpServlet.service(HttpServlet.java:802)note The full stack trace of the root cause is available in the Apache Tomcat/5.0.27 logs.
我编写的连接数据库的代码如下:
/* condb.java 3.27.2006
Bean to connect database */package condb;
import java.sql.*;public class condb
{
String strDBDriver="sun.jdbc.odbc.JdbcOdbcDriver";
String strDBUrl="jdbc:odbc:CRM";
private Connection conn=null;
private Statement stmt=null;
ResultSet rs=null;
//<!--注册数据库驱动程序-->
public condb()
{
try
{
Class.forName(strDBDriver);
}
//异常处理
catch(java.lang.ClassNotFoundException e)
{
System.err.println("condb():"+e.getMessage());
}
}
//<!--建立数据库连接及定义数据查询-->
public ResultSet executeQuery(String sql)
{
rs=null;
try
{
conn=DriverManager.getConnection(strDBUrl,"sa","");//创建数据库连接对象
stmt=conn.createStatement();
rs=stmt.executeQuery(sql);
}
catch(SQLException ex)
{
System.err.println("aq.executeQuery:"+ex.getMessage());
}
return rs;
}
//<!--定义数据操作-->
public void executeUpdate(String sql)
{
stmt=null;
rs=null;
try
{
conn=DriverManager.getConnection(strDBUrl,"sa","");
stmt=conn.createStatement();
stmt.executeQuery(sql);
stmt.close();
conn.close();
}
catch(SQLException ex)
{
System.err.println("aq.executeQuery:"+ex.getMessage());
}
}
//<!--关闭数据库连接-->
public void closeStmt()
{
try
{
stmt.close();
}
catch(SQLException e)
{
e.printStackTrace();
}
}
public void closeConn()
{
try
{
conn.close();
}
catch(SQLException e)
{
e.printStackTrace();
}
}
}
我用一段代码测试的
<jsp:useBean id="db" scope="page" class="condb.condb"/>
<%
String sql="select * from User";
ResultSet rs=db.executeQuery(sql);
if(rs.next())
{
String getUserNAME=rs.getString("UserName");
out.println(getUserNAME);
rs.close();
}
实在不知道怎么搞的了!谢谢大家帮忙啦!
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type Exception reportmessage description The server encountered an internal error () that prevented it from fulfilling this request.exception org.apache.jasper.JasperException: Unable to compile class for JSPAn error occurred at line: 4 in the jsp file: /confirm.jsp
Generated servlet error:
Exeception cannot be resolved or is not a type
org.apache.jasper.compiler.DefaultErrorHandler.javacError(DefaultErrorHandler.java:84)
org.apache.jasper.compiler.ErrorDispatcher.javacError(ErrorDispatcher.java:328)
org.apache.jasper.compiler.JDTCompiler.generateClass(JDTCompiler.java:397)
org.apache.jasper.compiler.Compiler.compile(Compiler.java:288)
org.apache.jasper.compiler.Compiler.compile(Compiler.java:267)
org.apache.jasper.compiler.Compiler.compile(Compiler.java:255)
org.apache.jasper.JspCompilationContext.compile(JspCompilationContext.java:556)
org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:293)
org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:291)
org.apache.jasper.servlet.JspServlet.service(JspServlet.java:241)
javax.servlet.http.HttpServlet.service(HttpServlet.java:802)
note The full stack trace of the root cause is available in the Apache Tomcat/5.5.9 logs.
--------------------------------------------------------------------------------
java connbean 这样做没问题啊
package useBean;import java.sql.*;public class Link_db{
private static Connection con=null;
private Statement state=null;
private ResultSet rs=null;
/***************************************************
*method name: init()<br>
*method function: Set up DataBase Statement<br>
*return value: void<br>
*method function: no<br>
*amend: crazyadept<br>
* 2004/8/2<br>
****************************************************/
public void init(Connection con){
try{
state=Link_db.con.createStatement();
}catch(Exception e){
System.out.println("init");
System.out.println(e.getMessage());
}
}
/***************************************************
*method name: close()<br>
*method function: close DataBase Connection<br>
*return value: void<br>
*method function: no<br>
*amend: crazyadept<br>
* 2004/7/28<br>
****************************************************/
public void close(){
try{
if (rs !=null){
rs.close();
rs=null;
}
}catch(Exception e){
System.out.println("rs");
System.out.println(e.getMessage());
}
try{
if(state!=null){
state.close();
state=null;
}
}catch(Exception e){
System.out.println("state");
System.out.println(e.getMessage());
}
try{
if(con!=null){
con.close();
state=null;
}
}catch(Exception e){
System.out.println("close");
System.out.println(e.getMessage());
}
}
/***************************************************
*method name: select()<br>
*method function: select DataBase data<br>
*return value: int<br>
* k=-10; on word<br>
* k=0; on record<br>
* k=-1; have exception <br>
* k>0; it is ok<br>
*parameter explain: no<br>
*amend: crazyadept<br>
* 2004/8/2<br>
****************************************************/
public int select(String sql){
int k=-10;
this.init(Link_db.getCon());
try{
k=0;
rs=state.executeQuery(sql);
if(rs.next()){
k=k+1;
}
}catch(Exception e){
k=-1;
System.out.println("select");
System.out.println(e.getMessage());
this.close();
}
this.close();
return k;
}
/***************************************************
*method name: update()<br>
*method function: updata,insert,delete<br>
*return value: int<br>
* k=-10; on work <br>
* k=0; on insert data<br>
* k=-1; hava exception<br>
* k>0; work is ok<br>
*parameter explain: no<br>
*amend: crazyadept<br>
* 2004/8/2<br>
****************************************************/
public int update(String sql){
int k=-10;
this.init(Link_db.getCon());
try{
k=0;
k=state.executeUpdate(sql);
}catch(Exception e){
k=-1;
System.out.println("update");
System.out.println(e.getMessage());
}
this.close();
return k;
} /***************************************************
*method name: getCon()<br>
*method function: get DataBase Connection<br>
*return value: Connection<br>
* con; return DataBase Connection<br>
*parameter explain: no<br>
*amend: crazyadept<br>
* 2004/8/2
****************************************************/
public static synchronized Connection getCon(){
try{
Class.forName("sun.jdbc.odbc.JdbcOdbcDriver");
con=DriverManager.getConnection("jdbc:odbc:CRM","sa","");
}catch(Exception e){
System.out.println("getCon");
System.out.println(e.getMessage());
}
return con;
}
/***************************************************
*method name: chStr()<br>
*method function: change coding<br>
*return value: String<br>
* return Chainese<br>
*parameter explain: str<br>
*amend: crazyadept<br>
* 2004/8/2<br>
****************************************************/
public String chStr(String str){
if(str==null){
str="";
}else{
try{
str=(new String(str.getBytes("iso-8859-1"),"GB2312")).trim();
}catch(Exception e){
System.out.println("chStr");
System.out.println(e.getMessage());
}
}
return str;
}}