问题描述
bean的使用一直不行，希望大家给我看一下我的测试jsp哪些地方不对！！javabean如下：名是DBClass.javapackagebean;importjava.io.*;importjava.util.*;importjava.sql.*;publicclassDBClass{privateStringdriver;privateStringurl;privateStringusername;privateStringpassword;privateConnectionconnection;privateStatementstatement;privateStringmessage;publicDBClass(){driver="com.mysql.jdbc.Driver";url="com:mysql://localhost:3306/bookshop";username="root";password="mysql5";connection=null;statement=null;message="";}publicDBClass(Stringdriver,Stringurl,Stringusername,Stringpassword){this.driver=driver;this.url=url;this.username=username;this.password=password;connection=null;statement=null;message="";}publicStringgetDriver(){returndriver;}publicvoidsetDriver(Stringdriver){this.driver=driver;}publicStringgetUrl(){returnurl;}publicvoidsetUrl(Stringurl){this.url=url;}publicStringgetUsername(){returnusername;}publicvoidsetUsername(Stringusername){this.username=username;}publicStringgetPassword(){returnpassword;}publicvoidsetPassword(Stringpassword){this.password=password;}publicConnectiongetConnection(){returnconnection;}publicvoidsetConnection(Connectionconnection){this.connection=connection;}publicStatementgetStatement(){returnstatement;}publicvoidsetStatement(){this.statement=statement;}publicStringgetMessage(){returnmessage;}publicvoidsetMessage(Stringmessage){this.message=message;}//连接数据库publicvoidconnect(){try{Class.forName(driver);connection=DriverManager.getConnection(url+"?user="+username+"&password="+password);statement=connection.createStatement();}catch(ClassNotFoundExceptioncnfe){message="connection:"+cnfe;}catch(SQLExceptionsqle){message="executeQuery:"+sqle;}}//执行SQL查询并返回结果publicResultSetexecuteQuery(Stringquery){ResultSetresultset=null;try{resultset=statement.executeQuery(query);}catch(SQLExceptionsqle){message="executeQuery:"+sqle;}returnresultset;}//执行数据库更新操作publicvoidexecuteUpdate(Stringcommand){try{statement.executeUpdate(command);}catch(SQLExceptionsqle){message="executeUpdate:"+sqle;}}//关闭数据库连接publicvoidcloseConnection(){try{connection.close();}catch(SQLExceptionsqle){message="closeConnection:"+sqle;}}}测试的jsp<%@pagelanguage="java"contentType="text/html;charset=gb2312"%><%@pageimport="java.util.*,bean.DBClass,java.sql.*,java.io.*"%><%DBClassdb=newDBClass("com.mysql.jdbc.Driver","jdbc:mysql://localhost/bookshop","root","mysql5");db.connect();Stringsql="selcet*frombook";ResultSetrs=db.executeQuery(sql);while(rs.next()){out.print("getString(1)");}db.closeConnection();%>
解决方案
解决方案二：
有没有测试过javabean正确不？？while(rs.next()){out.print(rs.getString(1));}
解决方案三：
引用1楼wlf2131的回复:
有没有测试过javabean正确不？？while(rs.next()){out.print(rs.getString(1));}
提示while这个地方出错
解决方案四：
错误：typeExceptionreportmessagedescriptionTheserverencounteredaninternalerror()thatpreventeditfromfulfillingthisrequest.exceptionorg.apache.jasper.JasperException:java.lang.NullPointerExceptionorg.apache.jasper.servlet.JspServletWrapper.handleJspException(JspServletWrapper.java:534)org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:457)org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:391)org.apache.jasper.servlet.JspServlet.service(JspServlet.java:334)javax.servlet.http.HttpServlet.service(HttpServlet.java:722)rootcausejava.lang.NullPointerExceptionorg.apache.jsp.testmysql_jsp._jspService(testmysql_jsp.java:70)org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:70)javax.servlet.http.HttpServlet.service(HttpServlet.java:722)org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:419)org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:391)org.apache.jasper.servlet.JspServlet.service(JspServlet.java:334)javax.servlet.http.HttpServlet.service(HttpServlet.java:722)noteThefullstacktraceoftherootcauseisavailableintheApacheTomcat/7.0.12logs.
解决方案五：
引用1楼wlf2131的回复:
有没有测试过javabean正确不？？while(rs.next()){out.print(rs.getString(1));}
我把引号去掉之后的错误：HTTPStatus500---------------------------------------------------------------------------------typeExceptionreportmessagedescriptionTheserverencounteredaninternalerror()thatpreventeditfromfulfillingthisrequest.exceptionorg.apache.jasper.JasperException:AnexceptionoccurredprocessingJSPpage/testmysql.jspatline1310:11:ResultSetrs=db.executeQuery(sql);12:13:while(rs.next()){14:out.print(getString(1));15:}16:db.closeConnection();Stacktrace:org.apache.jasper.servlet.JspServletWrapper.handleJspException(JspServletWrapper.java:553)org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:457)org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:391)org.apache.jasper.servlet.JspServlet.service(JspServlet.java:334)javax.servlet.http.HttpServlet.service(HttpServlet.java:722)rootcausejava.lang.NullPointerExceptionorg.apache.jsp.testmysql_jsp._jspService(testmysql_jsp.java:70)org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:70)javax.servlet.http.HttpServlet.service(HttpServlet.java:722)org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:419)org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:391)org.apache.jasper.servlet.JspServlet.service(JspServlet.java:334)javax.servlet.http.HttpServlet.service(HttpServlet.java:722)noteThefullstacktraceoftherootcauseisavailableintheApacheTomcat/7.0.12logs.--------------------------------------------------------------------------------ApacheTomcat/7.0.12
解决方案六：
10:11:ResultSetrs=db.executeQuery(sql);12:13:while(rs.next()){14:out.print(getString(1));15:}16:db.closeConnection();14：要用rs.getString(1);
解决方案七：
引用5楼wlf2131的回复:
10:11:ResultSetrs=db.executeQuery(sql);12:13:while(rs.next()){14:out.print(getString(1));15:}16:db.closeConnection();14：要用rs.getString(1);
这是改了之后的错误：HTTPStatus500---------------------------------------------------------------------------------typeExceptionreportmessagedescriptionTheserverencounteredaninternalerror()thatpreventeditfromfulfillingthisrequest.exceptionorg.apache.jasper.JasperException:AnexceptionoccurredprocessingJSPpage/testmysql.jspatline1310:11:ResultSetrs=db.executeQuery(sql);12:13:while(rs.next()){14:out.print(rs.getString(1));15:}16:db.closeConnection();Stacktrace:org.apache.jasper.servlet.JspServletWrapper.handleJspException(JspServletWrapper.java:553)org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:457)org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:391)org.apache.jasper.servlet.JspServlet.service(JspServlet.java:334)javax.servlet.http.HttpServlet.service(HttpServlet.java:722)rootcausejava.lang.NullPointerExceptionorg.apache.jsp.testmysql_jsp._jspService(testmysql_jsp.java:70)org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:70)javax.servlet.http.HttpServlet.service(HttpServlet.java:722)org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:419)org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:391)org.apache.jasper.servlet.JspServlet.service(JspServlet.java:334)javax.servlet.http.HttpServlet.service(HttpServlet.java:722)noteThefullstacktraceoftherootcauseisavailableintheApacheTomcat/7.0.12logs.--------------------------------------------------------------------------------ApacheTomcat/7.0.12