我想尝试一下javabean的连接数据库,于是写了如下这个beanpackage com.mybean;
import java.sql.*;
import java.io.*;
public class TaoTiSelect
{
//声明变量
String sDBDriver="com.microsoft.jdbc.sqlserver.SQLServerDriver"; //数据库驱动
String sConnStr="jdbc:microsoft:sqlserver://localhost:1433;DatabaseName=db_netExam,sa,sa"; //使用桥对数据库连接
Connection conn=null;
ResultSet rs=null; //加载驱动
public void TaoTiSelect()
{
try{
Class.forName(sDBDriver);
}
catch(java.lang.ClassNotFoundException e)
{
System.err.println(e.getMessage());
}
} //数据插入
public void executeInsert(String sql)
{
try
{
conn=DriverManager.getConnection(sConnStr);
Statement stmt=conn.createStatement();
stmt.executeUpdate(sql);
}
catch(SQLException ex)
{
System.err.println(ex.getMessage());
}
} //数据查询
public ResultSet executeQuery(String sql)
{
rs=null;
try
{
conn=DriverManager.getConnection(sConnStr);
Statement stmt=conn.createStatement(ResultSet.TYPE_SCROLL_SENSITIVE,ResultSet.CONCUR_UPDATABLE);
rs=stmt.executeQuery(sql);
}
catch(SQLException ex)
{
System.err.println(ex.getMessage());
}
return rs; } //数据删除
public void executeDelete(String sql)
{
try
{
conn=DriverManager.getConnection(sConnStr);
Statement stmt=conn.createStatement();
stmt.executeUpdate(sql);
}
catch(SQLException ex)
{
System.err.println(ex.getMessage());
}
}
}然后用了一个jsp调用它:
<%@ page contentType="text/html; charset=gb2312" language="java" import="java.sql.*,com.mybean.*,java.io.*" errorPage="" %>
<html>
<body> <jsp:useBean id="ni" scope="page" class="com.mybean.TaoTiSelect"/>
<%
TaoTiSelect tts=new TaoTiSelect();
ResultSet rst=null;
rst=tts.executeQuery("select * from tb_Lesson");
while(rst.next()) {%> 您的第一个字段内容为:<%=rst.getString(1)%> 您的第二个字段内容为:<%=rst.getString(2)%> <% }
%></body>
</html> 其中,javabean是这样:WEB-INF/classes/com/mybean/TaoTiSelect.class不知道为什么有错误,如下:HTTP Status 500 - --------------------------------------------------------------------------------type Exception reportmessage description The server encountered an internal error () that prevented it from fulfilling this request.exception org.apache.jasper.JasperException: An exception occurred processing JSP page /abc.jsp at line 129:
10:
11: rst=tts.executeQuery("select * from tb_Lesson");
12: while(rst.next())
13:
14: {
15:
Stacktrace:
org.apache.jasper.servlet.JspServletWrapper.handleJspException(JspServletWrapper.java:505)
org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:416)
org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:342)
org.apache.jasper.servlet.JspServlet.service(JspServlet.java:267)
javax.servlet.http.HttpServlet.service(HttpServlet.java:717)
root cause java.lang.NullPointerException
org.apache.jsp.abc_jsp._jspService(abc_jsp.java:77)
org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:70)
javax.servlet.http.HttpServlet.service(HttpServlet.java:717)
org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:374)
org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:342)
org.apache.jasper.servlet.JspServlet.service(JspServlet.java:267)
javax.servlet.http.HttpServlet.service(HttpServlet.java:717)
note The full stack trace of the root cause is available in the Apache Tomcat/6.0.20 logs.
--------------------------------------------------------------------------------Apache Tomcat/6.0.20
import java.sql.*;
import java.io.*;
public class TaoTiSelect
{
//声明变量
String sDBDriver="com.microsoft.jdbc.sqlserver.SQLServerDriver"; //数据库驱动
String sConnStr="jdbc:microsoft:sqlserver://localhost:1433;DatabaseName=db_netExam,sa,sa"; //使用桥对数据库连接
Connection conn=null;
ResultSet rs=null; //加载驱动
public void TaoTiSelect()
{
try{
Class.forName(sDBDriver);
}
catch(java.lang.ClassNotFoundException e)
{
System.err.println(e.getMessage());
}
} //数据插入
public void executeInsert(String sql)
{
try
{
conn=DriverManager.getConnection(sConnStr);
Statement stmt=conn.createStatement();
stmt.executeUpdate(sql);
}
catch(SQLException ex)
{
System.err.println(ex.getMessage());
}
} //数据查询
public ResultSet executeQuery(String sql)
{
rs=null;
try
{
conn=DriverManager.getConnection(sConnStr);
Statement stmt=conn.createStatement(ResultSet.TYPE_SCROLL_SENSITIVE,ResultSet.CONCUR_UPDATABLE);
rs=stmt.executeQuery(sql);
}
catch(SQLException ex)
{
System.err.println(ex.getMessage());
}
return rs; } //数据删除
public void executeDelete(String sql)
{
try
{
conn=DriverManager.getConnection(sConnStr);
Statement stmt=conn.createStatement();
stmt.executeUpdate(sql);
}
catch(SQLException ex)
{
System.err.println(ex.getMessage());
}
}
}然后用了一个jsp调用它:
<%@ page contentType="text/html; charset=gb2312" language="java" import="java.sql.*,com.mybean.*,java.io.*" errorPage="" %>
<html>
<body> <jsp:useBean id="ni" scope="page" class="com.mybean.TaoTiSelect"/>
<%
TaoTiSelect tts=new TaoTiSelect();
ResultSet rst=null;
rst=tts.executeQuery("select * from tb_Lesson");
while(rst.next()) {%> 您的第一个字段内容为:<%=rst.getString(1)%> 您的第二个字段内容为:<%=rst.getString(2)%> <% }
%></body>
</html> 其中,javabean是这样:WEB-INF/classes/com/mybean/TaoTiSelect.class不知道为什么有错误,如下:HTTP Status 500 - --------------------------------------------------------------------------------type Exception reportmessage description The server encountered an internal error () that prevented it from fulfilling this request.exception org.apache.jasper.JasperException: An exception occurred processing JSP page /abc.jsp at line 129:
10:
11: rst=tts.executeQuery("select * from tb_Lesson");
12: while(rst.next())
13:
14: {
15:
Stacktrace:
org.apache.jasper.servlet.JspServletWrapper.handleJspException(JspServletWrapper.java:505)
org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:416)
org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:342)
org.apache.jasper.servlet.JspServlet.service(JspServlet.java:267)
javax.servlet.http.HttpServlet.service(HttpServlet.java:717)
root cause java.lang.NullPointerException
org.apache.jsp.abc_jsp._jspService(abc_jsp.java:77)
org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:70)
javax.servlet.http.HttpServlet.service(HttpServlet.java:717)
org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:374)
org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:342)
org.apache.jasper.servlet.JspServlet.service(JspServlet.java:267)
javax.servlet.http.HttpServlet.service(HttpServlet.java:717)
note The full stack trace of the root cause is available in the Apache Tomcat/6.0.20 logs.
--------------------------------------------------------------------------------Apache Tomcat/6.0.20
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500报错都是服务器方面的事,看你:
10:
11: rst=tts.executeQuery("select * from tb_Lesson");
12: while(rst.next())
13:
14: {
15:
这里出错了,
还有你贴出来的错误其实不是真正的错误所在,是你的服务器端出错了,你应该看看后台有什么错误信息
希望能帮到你