高手来帮我看看是哪错了

Question

<%@ page contentType="text/html;charset=GB2312" %>
<%@ page import="java.sql.ResultSet,user.user_operation,
 java.sql.SQLException"%>
<%//-------接收输入参数------------
   int sysuser_role=0;
   ResultSet rs=null;
try{
        sysuser_role=Integer.parseInt(request.getParameter("sysuser_role"));
    }catch(Exception e){}
    String sysuser_password=request.getParameter("sysuser_password");
    String sysuser_name=request.getParameter("sysuser_name");
    String certCode=request.getParameter("certCode");
    //------查询数据库------
user_operation uop=new user_operation();
rs=uop.getUserOne(sysuser_name,sysuser_password,sysuser_role);
int rowCount=0;
try{
rs.next();
rowCount=1;
}catch(SQLException e){}
if(rowCount!=0&&certCode.equals((String)session.getAttribute("certCode"))){
//------通过检查------
session.setAttribute("sysuser_id",rs.getString("sysuser_id"));
response.sendRedirect("\\index.jsp");
}else{
response.sendRedirect("\\login.jsp");
}
%>
错误信息：
严重: Servlet.service() for servlet jsp threw exception
java.lang.IllegalStateException: getOutputStream() has already been called for this response
at org.apache.catalina.connector.Response.getWriter(Response.java:604)
at org.apache.catalina.connector.ResponseFacade.getWriter(ResponseFacade.java:198)
at org.apache.jasper.runtime.JspWriterImpl.initOut(JspWriterImpl.java:125)
at org.apache.jasper.runtime.JspWriterImpl.flushBuffer(JspWriterImpl.java:118)
at org.apache.jasper.runtime.PageContextImpl.release(PageContextImpl.java:186)
at org.apache.jasper.runtime.JspFactoryImpl.internalReleasePageContext(JspFactoryImpl.java:118)
at org.apache.jasper.runtime.JspFactoryImpl.releasePageContext(JspFactoryImpl.java:77)
at org.apache.jsp.makeCertPic_jsp._jspService(makeCertPic_jsp.java:77)
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:233)
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:102)
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:109)
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:263)
at org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:844)
at org.apache.coyote.http11.Http11Protocol$Http11ConnectionHandler.process(Http11Protocol.java:584)
at org.apache.tomcat.util.net.JIoEndpoint$Worker.run(JIoEndpoint.java:447)
at java.lang.Thread.run(Thread.java:619)
java.lang.NullPointerException
at java.util.Properties$LineReader.readLine(Properties.java:418)
at java.util.Properties.load0(Properties.java:337)
at java.util.Properties.load(Properties.java:325)
at db.dbconn.getPropertyFromFile(dbconn.java:59)
at db.dbconn.getDBConn(dbconn.java:21)
at user.user_operation.getUserOne(user_operation.java:331)
at org.apache.jsp.checkLogin_jsp._jspService(checkLogin_jsp.java:69)
at org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:70)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:803)
at org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:393)
at org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:320)
at org.apache.jasper.servlet.JspServlet.service(JspServlet.java:266)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:803)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:290)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:233)
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:175)
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:128)
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:102)
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:109)
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:263)
at org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:844)
at org.apache.coyote.http11.Http11Protocol$Http11ConnectionHandler.process(Http11Protocol.java:584)
at org.apache.tomcat.util.net.JIoEndpoint$Worker.run(JIoEndpoint.java:447)
at java.lang.Thread.run(Thread.java:619)
java.lang.NullPointerException
at java.util.Properties$LineReader.readLine(Properties.java:418)
at java.util.Properties.load0(Properties.java:337)
at java.util.Properties.load(Properties.java:325)
at db.dbconn.getPropertyFromFile(dbconn.java:59)
at db.dbconn.getDBConn(dbconn.java:22)
at user.user_operation.getUserOne(user_operation.java:331)
at org.apache.jsp.checkLogin_jsp._jspService(checkLogin_jsp.java:69)
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:233)
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:102)
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:109)
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:263)
at org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:844)
at org.apache.coyote.http11.Http11Protocol$Http11ConnectionHandler.process(Http11Protocol.java:584)
at org.apache.tomcat.util.net.JIoEndpoint$Worker.run(JIoEndpoint.java:447)
at java.lang.Thread.run(Thread.java:619)
java.lang.NullPointerException
at java.util.Properties$LineReader.readLine(Properties.java:418)
at java.util.Properties.load0(Properties.java:337)
at java.util.Properties.load(Properties.java:325)
at db.dbconn.getPropertyFromFile(dbconn.java:59)
at db.dbconn.getDBConn(dbconn.java:23)
at user.user_operation.getUserOne(user_operation.java:331)
at org.apache.jsp.checkLogin_jsp._jspService(checkLogin_jsp.java:69)
at org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:70)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:803)
at org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:393)
at org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:320)
at org.apache.jasper.servlet.JspServlet.service(JspServlet.java:266)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:803)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:290)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:233)
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:175)
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:128)
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:102)
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:109)
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:263)
at org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:844)
at org.apache.coyote.http11.Http11Protocol$Http11ConnectionHandler.process(Http11Protocol.java:584)
at org.apache.tomcat.util.net.JIoEndpoint$Worker.run(JIoEndpoint.java:447)
at java.lang.Thread.run(Thread.java:619)

Answer 1

type Exception reportmessagedescription 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:541)
org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:435)
org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:320)
org.apache.jasper.servlet.JspServlet.service(JspServlet.java:266)
javax.servlet.http.HttpServlet.service(HttpServlet.java:803)
root causejava.lang.NullPointerException
org.apache.jsp.checkLogin_jsp._jspService(checkLogin_jsp.java:72)
org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:70)
javax.servlet.http.HttpServlet.service(HttpServlet.java:803)
org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:393)
org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:320)
org.apache.jasper.servlet.JspServlet.service(JspServlet.java:266)
javax.servlet.http.HttpServlet.service(HttpServlet.java:803)
note The full stack trace of the root cause is available in the Apache Tomcat/6.0.14 logs.

Answer 2

java.lang.NullPointerException
at java.util.Properties$LineReader.readLine(Properties.java:418)
at java.util.Properties.load0(Properties.java:337)
at java.util.Properties.load(Properties.java:325)
at db.dbconn.getPropertyFromFile(dbconn.java:59)
at db.dbconn.getDBConn(dbconn.java:21)
看看你的dbconn的59行，空指针咯

Answer 3

看看你的.properties 文件有问题没

Answer 4

方便的话把导入的类 发一下
<%@ page import="java.sql.ResultSet,user.user_operation,
java.sql.SQLException"%>

Answer 5

空指针
properties文件有问题

Answer 6

java.lang.NullPointerException
at java.util.Properties$LineReader.readLine(Properties.java:418)
at java.util.Properties.load0(Properties.java:337)
at java.util.Properties.load(Properties.java:325)
at db.dbconn.getPropertyFromFile(dbconn.java:59)  ///查看一下，为什么抛空指针异常
at db.dbconn.getDBConn(dbconn.java:23)

Answer 7

<%@ page contentType="text/html;charset=GB2312" %>
<%@ page import="java.sql.ResultSet,user.user_operation,
java.sql.SQLException"%>
<%//-------接收输入参数------------
  int sysuser_role=0;
  ResultSet rs=null;
try{
    sysuser_role=Integer.parseInt(request.getParameter("sysuser_role"));
}catch(Exception e){
e.printStackTrace();
}
  String sysuser_password=request.getParameter("sysuser_password");
  String sysuser_name=request.getParameter("sysuser_name");
  String certCode=request.getParameter("certCode");
  //------查询数据库------
user_operation uop=new user_operation();
rs=uop.getUserOne(sysuser_name,sysuser_password,sysuser_role);
int rowCount=0;
try{
    if(rs.next()){//这样判断rs.next()返回的是个boolean
          rowCount=1;
    }
}catch(SQLException e){
     e.printStackTrace();
}
if(rowCount!=0&&certCode.equals((String)session.getAttribute("certCode"))){
//------通过检查------
session.setAttribute("sysuser_id",rs.getString("sysuser_id"));
response.sendRedirect("\\index.jsp");//好像网址url是/这个斜杠吧？文件路径是这个\ 。
}else{
response.sendRedirect("\\login.jsp");//好像网址url是/这个斜杠吧？文件路径是这个\ 。
}
%>

Answer 8

java.lang.NullPointerException
at java.util.Properties$LineReader.readLine(Properties.java:418)
at java.util.Properties.load0(Properties.java:337)
at java.util.Properties.load(Properties.java:325)
at db.dbconn.getPropertyFromFile(dbconn.java:59)
空指针
文件有问题 

Answer 9

package user;
import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.Statement;
import util.stringUtil;
import db.dbconn;
/**
 * 用户类
 */
public class user_operation {
    /**
     * 功能:判断自动生成的角色是否已经生成用户
     * 输入:foreign_id为教师表或学生表中的ID号,sysuser_role为用户角色
     * 输出:返回0表未生成,返回1表已生成,返回3表未知
     * 说明:只要有sysuser表中可查到记录,即表示已经生成
     */
    public int isAutoGenOK(long foreign_id,int sysuser_role){
        if(foreign_id==0||sysuser_role==0||sysuser_role==1||sysuser_role==2)
        //用户角色为1表系统管理员,为2表教务人员,这两种角色手工生成,所以不为自动生成
            return 3;
        String sqlString=null;//SQL语句字符串
        ResultSet rs=null;//结果记录集
        dbconn dbconnOBject=new dbconn();//数据库连接对象
        Connection dbconn=dbconnOBject.getDBConn();//得到数据库连接
        if(dbconn==null) return 3;//连接失败
        sqlString="select * from sysuser where foreign_id=? and sysuser_role=?";
        try{
            PreparedStatement preSQLSelect=dbconn.prepareStatement(sqlString);
            preSQLSelect.setLong(1,foreign_id);
            preSQLSelect.setInt(2,sysuser_role);
            rs=preSQLSelect.executeQuery();
            if(rs.next()) return 1;
            else return 0;
          }catch(Exception e){
            System.out.print(e);
            return 3;
          }   
    }
    public int isAdminGenOK(long foreign_id,int sysuser_role){
        if(foreign_id==0||sysuser_role==0)
            return 3;
        String sqlString=null;//SQL语句字符串
        ResultSet rs=null;//结果记录集
        dbconn dbconnOBject=new dbconn();//数据库连接对象
        Connection dbconn=dbconnOBject.getDBConn();//得到数据库连接
        if(dbconn==null) return 3;//连接失败
        sqlString="select * from sysuser where foreign_id=? and sysuser_role=?";
        try{
            PreparedStatement preSQLSelect=dbconn.prepareStatement(sqlString);
            preSQLSelect.setLong(1,foreign_id);
            preSQLSelect.setInt(2,sysuser_role);
            rs=preSQLSelect.executeQuery();
            if(rs.next()) return 1;
            else return 0;
          }catch(Exception e){
            System.out.print(e);
            return 3;
          }   
    }
    /**
     * 功能：生成老师用户
     */
    public String genTeacherUser(String teacher_id[]){
        String returnString=new String("");
        String sqlString=null;//SQL语句字符串
        ResultSet rs=null;//结果记录集
        ResultSet rs1=null;//另一结果记录集
        Statement sql=null;//SQL语句对象
        dbconn dbconnOBject=new dbconn();//数据库连接对象
        Connection dbconn=dbconnOBject.getDBConn();//得到数据库连接
        if(dbconn==null) return returnString;//连接失败
        try{
            sqlString="select * from teacher";
            System.out.println(teacher_id.length);
            int j=0;//加长SQL语句的次数
            if(teacher_id.length!=0){//生成部分教师用户
                for(int i=0;i<teacher_id.length;i++)
                    if(teacher_id[i]!=null&&teacher_id[i].length()!=0&&!teacher_id[i].equalsIgnoreCase("null")){
                        if(j==0)
                            {sqlString=sqlString+" where teacher_id="+teacher_id[i];j++;}
                        else
                            sqlString=sqlString+" or teacher_id="+teacher_id[i];
                    }
                
            }
            sql=dbconn.createStatement(ResultSet.TYPE_SCROLL_SENSITIVE, ResultSet.CONCUR_READ_ONLY);
            rs=sql.executeQuery(sqlString);
            while(rs.next()){
                sqlString="select * from sysuser where foreign_id=" +
                 rs.getLong("teacher_id")+" and sysuser_role=3";
                sql=dbconn.createStatement(ResultSet.TYPE_SCROLL_SENSITIVE, ResultSet.CONCUR_READ_ONLY);
                rs1=sql.executeQuery(sqlString);
                if(!rs1.next()){//不存在插入，存在则不做事
                    sqlString="insert into sysuser(sysuser_name,sysuser_password,sysuser_role" +
                     ",foreign_id) values(?,?,3,?)";
                    PreparedStatement preSQLUpdate=dbconn.prepareStatement(sqlString);
                    preSQLUpdate.setString(1,rs.getString("teacher_name"));
                    preSQLUpdate.setString(2,"111111");
                    preSQLUpdate.setLong(3,rs.getLong("teacher_id"));
                    preSQLUpdate.executeUpdate();
                    returnString=returnString+"生成教师"+rs.getString("teacher_name")+"用户成功！<BR>";
                }else
                    returnString=returnString+"教师"+rs.getString("teacher_name")+"用户已经生成，不必再生成！<BR>";
                rs1.close();
            }
        }catch(Exception e){
            System.out.print(e);
        }
        return returnString;
    }
    
    /**
     * 功能：生成学生用户
     */
    public String genStudentUser(String student_id[]){
        String returnString=new String("");
        String sqlString=null;//SQL语句字符串
        ResultSet rs=null;//结果记录集
        ResultSet rs1=null;//另一结果记录集
        Statement sql=null;//SQL语句对象
        dbconn dbconnOBject=new dbconn();//数据库连接对象
        Connection dbconn=dbconnOBject.getDBConn();//得到数据库连接
        if(dbconn==null) return returnString;//连接失败
        try{
            sqlString="select * from student";
            System.out.println(student_id.length);
            int j=0;//加长SQL语句的次数
            if(student_id.length!=0){//生成部分教师用户
                for(int i=0;i<student_id.length;i++)
                    if(student_id[i]!=null&&student_id[i].length()!=0&&!student_id[i].equalsIgnoreCase("null")){
                        if(j==0)
                            {sqlString=sqlString+" where student_id="+student_id[i];j++;}
                        else
                            sqlString=sqlString+" or student_id="+student_id[i];
                    }
                
            }
            sql=dbconn.createStatement(ResultSet.TYPE_SCROLL_SENSITIVE, ResultSet.CONCUR_READ_ONLY);
            rs=sql.executeQuery(sqlString);
            while(rs.next()){
                sqlString="select * from sysuser where foreign_id=" +
                 rs.getLong("student_id")+" and sysuser_role=4";
                sql=dbconn.createStatement(ResultSet.TYPE_SCROLL_SENSITIVE, ResultSet.CONCUR_READ_ONLY);
                rs1=sql.executeQuery(sqlString);
                if(!rs1.next()){//不存在插入，存在则不做事
                    sqlString="insert into sysuser(sysuser_name,sysuser_password,sysuser_role" +
                     ",foreign_id) values(?,?,4,?)";
                    PreparedStatement preSQLUpdate=dbconn.prepareStatement(sqlString);
                    preSQLUpdate.setString(1,rs.getString("student_name"));
                    preSQLUpdate.setString(2,"111111");
                    preSQLUpdate.setLong(3,rs.getLong("student_id"));
                    preSQLUpdate.executeUpdate();
                    returnString=returnString+"生成学生"+rs.getString("student_name")+"用户成功！<BR>";
                }else
                    returnString=returnString+"学生"+rs.getString("student_name")+"用户已经生成，不必再生成！<BR>";
                rs1.close();
            }
        }catch(Exception e){
            System.out.print(e);
        }
        return returnString;
    }
    /**
     * 得到管理用户记录集,系统管理员和教务管理员是管理用户
     */
    public ResultSet getAdminUsers(){
        String sqlString=null;//SQL语句字符串
        Statement sql=null;//SQL语句对象
        ResultSet rs=null;//结果记录集
        dbconn dbconnOBject=new dbconn();//数据库连接对象
        Connection dbconn=dbconnOBject.getDBConn();//得到数据库连接
        if(dbconn==null) return null;//连接失败
        try{
           //-------查询出数据------------
           sqlString="select * from sysuser where sysuser_role=1 or sysuser_role=2"; 
           sql=dbconn.createStatement(ResultSet.TYPE_SCROLL_SENSITIVE, ResultSet.CONCUR_READ_ONLY);
           rs=sql.executeQuery(sqlString);
           return rs;
        }catch(Exception e){
           System.out.print(e);
           return null;
        } 
    }

Answer 10

/**
     * 功能：生成管理用户
     * 输入:参数teacher_id为生成管理用户的教师ID,只有教师能成为管理用户,role_id为分配的角色
     */
    public String genAdminUser(int teacher_id,int role_id){
        String returnString=new String("");
        String sqlString=null;//SQL语句字符串
        ResultSet rs=null;//结果记录集
        ResultSet rs1=null;//另一结果记录集
        Statement sql=null;//SQL语句对象
        dbconn dbconnOBject=new dbconn();//数据库连接对象
        Connection dbconn=dbconnOBject.getDBConn();//得到数据库连接
        if(dbconn==null||teacher_id==0||role_id==0) return returnString;//连接失败
        try{
            sqlString="select * from teacher where teacher_id="+teacher_id;
            sql=dbconn.createStatement(ResultSet.TYPE_SCROLL_SENSITIVE, ResultSet.CONCUR_READ_ONLY);
            rs=sql.executeQuery(sqlString);
            while(rs.next()){
                sqlString="select * from sysuser where foreign_id=" +
                 rs.getLong("teacher_id")+" and sysuser_role="+role_id;
                sql=dbconn.createStatement(ResultSet.TYPE_SCROLL_SENSITIVE, ResultSet.CONCUR_READ_ONLY);
                rs1=sql.executeQuery(sqlString);
                if(!rs1.next()){//不存在插入，存在则不做事
                    sqlString="insert into sysuser(sysuser_name,sysuser_password,sysuser_role" +
                     ",foreign_id) values(?,?,"+role_id+",?)";
                    System.out.println(sqlString);
                    PreparedStatement preSQLUpdate=dbconn.prepareStatement(sqlString);
                    preSQLUpdate.setString(1,rs.getString("teacher_name"));
                    preSQLUpdate.setString(2,"111111");
                    preSQLUpdate.setLong(3,rs.getLong("teacher_id"));
                    preSQLUpdate.executeUpdate();
                    returnString=returnString+"生成管理用户"+rs.getString("teacher_name")+"用户成功！<BR>";
                }else
                    returnString=returnString+rs.getString("teacher_name")+"管理用户已经生成，不必再生成！<BR>";
                rs1.close();
            }
        }catch(Exception e){
            System.out.print(e);
        }
        return returnString;
    }
    /**
     * 得到一条用户记录
     */
    public ResultSet getUserByPrimKey(int sysuser_id){
        String sqlString=null;//SQL语句字符串
        Statement sql=null;//SQL语句对象
        ResultSet rs=null;//结果记录集
        dbconn dbconnOBject=new dbconn();//数据库连接对象
        Connection dbconn=dbconnOBject.getDBConn();//得到数据库连接
        if(dbconn==null||sysuser_id==0) return null;//连接失败
        try{
           //-------查询出数据------------
           sqlString="select * from sysuser where sysuser_id="+sysuser_id; 
           sql=dbconn.createStatement(ResultSet.TYPE_SCROLL_SENSITIVE, ResultSet.CONCUR_READ_ONLY);
           rs=sql.executeQuery(sqlString);
           return rs;
        }catch(Exception e){
           System.out.print(e);
           return null;
        } 
    }
    /**
     * 根据用户表的外键和角色得到用户ID号
     */
    public long getUserId(int foreign_id,int sysuser_role){
        if(foreign_id==0||sysuser_role==0) return 0;
        String sqlString=null;//SQL语句字符串
        Statement sql=null;//SQL语句对象
        ResultSet rs=null;//结果记录集
        dbconn dbconnOBject=new dbconn();//数据库连接对象
        Connection dbconn=dbconnOBject.getDBConn();//得到数据库连接
        if(dbconn==null) return 0;//连接失败
        try{
           //-------查询出数据------------
           sqlString="select * from sysuser where foreign_id="+foreign_id+
              " and sysuser_role="+sysuser_role; 
           //System.out.println(sqlString);
           sql=dbconn.createStatement(ResultSet.TYPE_SCROLL_SENSITIVE, ResultSet.CONCUR_READ_ONLY);
           rs=sql.executeQuery(sqlString);
           if(rs.next())
               return rs.getLong("sysuser_id");
           else
               return 0;
        }catch(Exception e){
           e.printStackTrace();
           return 0;
        }            
    }
    /**
     * 更新系统用户信息
     */
    public int update_sysuser(int user_id,String user_name,String user_password,int user_role){
        if(user_role==0||user_id==0) return 0;
        String sqlString=null;//SQL语句字符串
        Statement sql=null;//SQL语句对象
        ResultSet rs=null;//结果记录集
        dbconn dbconnOBject=new dbconn();//数据库连接对象
        Connection dbconn=dbconnOBject.getDBConn();//得到数据库连接
        //--------输入参数编码转换-------
        stringUtil stringCode=new stringUtil();
        user_name=stringCode.codeToString(user_name.trim());
        user_password=stringCode.codeToString(user_password.trim());
        if(dbconn==null) return 0;//连接失败
        try{
           //-------查询出数据------------
           sqlString="update sysuser set sysuser_name='" + user_name +
     "',sysuser_password='"+user_password+"',sysuser_role="+
     user_role+" where sysuser_id="+user_id;
           //System.out.println(sqlString);
           sql=dbconn.createStatement(ResultSet.TYPE_SCROLL_SENSITIVE, ResultSet.CONCUR_READ_ONLY);
           return sql.executeUpdate(sqlString);         
        }catch(Exception e){
           e.printStackTrace();
           return 0;
        }
    }
    /**
     * 删除一条用户记录
     */
    public int deleteUserByPrimKey(int sysuser_id){
        String sqlString=null;//SQL语句字符串
        Statement sql=null;//SQL语句对象
        ResultSet rs=null;//结果记录集
        dbconn dbconnOBject=new dbconn();//数据库连接对象
        Connection dbconn=dbconnOBject.getDBConn();//得到数据库连接
        if(dbconn==null||sysuser_id==0) return 0;//连接失败
        try{
           //-------查询出数据------------
           sqlString="delete from sysuser where sysuser_id="+sysuser_id; 
           sql=dbconn.createStatement(ResultSet.TYPE_SCROLL_SENSITIVE, ResultSet.CONCUR_READ_ONLY);
           return sql.executeUpdate(sqlString);
        }catch(Exception e){
           System.out.print(e);
           return 0;
        } 
    }
    /**
     * 得到一条用户记录
     */
    public ResultSet getUserOne(String sysuser_name,String sysuser_password,int sysuser_role){
        String sqlString=null;//SQL语句字符串
        Statement sql=null;//SQL语句对象
        ResultSet rs=null;//结果记录集
        dbconn dbconnOBject=new dbconn();//数据库连接对象
        Connection dbconn=dbconnOBject.getDBConn();//得到数据库连接
        if(dbconn==null) return null;//连接失败
        //--------输入参数编码转换-------
        stringUtil stringCode=new stringUtil();
        sysuser_name=stringCode.codeToString(sysuser_name.trim());
        sysuser_password=stringCode.codeToString(sysuser_password.trim());
        try{
           //-------查询出数据------------
           sqlString="select * from sysuser where sysuser_name=? and sysuser_password=? and sysuser_role=?"; 
           PreparedStatement preSQLSelect=dbconn.prepareStatement(sqlString);
           preSQLSelect.setString(1,sysuser_name);
           preSQLSelect.setString(2,sysuser_password);
           preSQLSelect.setInt(3,sysuser_role);
           rs=preSQLSelect.executeQuery();
           System.out.println("select * from sysuser where sysuser_name='"+sysuser_name+"' and sysuser_password='"+ sysuser_password+"' and sysuser_role="+sysuser_role);
           return rs;
        }catch(Exception e){
           System.out.print(e);
           return null;
        } 
    }
}

Answer 11

package db;
import java.sql.Connection;
import java.sql.DriverManager;
import java.io.InputStream;
import java.util.Properties;
/**
 * 数据库连接类
 */
public class dbconn {
    String driverName=null;//数据库驱动名
String connString=null;//连接字符串
String userName=null;//用户名
String password=null;//密码
String propertyFileName=null;//.properties文件名称
public dbconn() {
}
public Connection getDBConn()
{//得到数据库连接对象
    this.setPropertyFileName("/dbconn.properties");
    driverName=this.getPropertyFromFile("driverName");
connString=this.getPropertyFromFile("connString");
userName=this.getPropertyFromFile("userName");
password=this.getPropertyFromFile("password");
if(driverName==null||connString==null||userName==null) return null;
try{
Connection connDBObject=null;
Class.forName(driverName);
return DriverManager.getConnection(connString,userName,password);
}catch(Exception e){
e.printStackTrace();
return null;
}
}
public String getConnString() {
return connString;
}
public String getDriverName() {
return driverName;
}
public String getPassword() {
return password;
}
public String getUserName() {
return userName;
}
public void setPropertyFileName(String propertyFileName) {
this.propertyFileName = propertyFileName;
}
public String getPropertyFileName() {
return propertyFileName;
}
public String getPropertyFromFile(String refName)
{//从.properties文件中得到refName属性的值
if(this.getPropertyFileName()==null) return new String("");
try{
InputStream fin = getClass().getResourceAsStream(this.getPropertyFileName());
Properties props = new Properties();
props.load(fin);
return (String)props.getProperty(refName);
}catch(Exception e){
    e.printStackTrace();
return new String("");
}
}
}

Answer 12

try{
rs.next();
rowCount=1;
}catch(SQLException e){}将以上部分改为
try{
if(rs.next()){
rowCount=1;
}
}catch(SQLException e){}

Answer 13

this.setPropertyFileName("/dbconn.properties");你这用绝对路径能找到文件？？？

Answer 14

你所有方法里面的
dbconn dbconnOBject=new dbconn();//数据库连接对象
  Connection dbconn=dbconnOBject.getDBConn();//得到数据库连接
都是新new的，所以里面的值是没有的，要么你就把那些变量都定义为static的，或者你每次都set一下那个properties文件的路径