package JavaBean;
import java.sql.*;
import java.io.PrintWriter;
public class DB_conn{
private Connection conn=null;
public Statement sm=null;
private PrintWriter out = null;
public void connectDB(){
try{
Class.forName("sun.jdbc.odbc.JdbcOdbcDriver").newInstance();
conn=DriverManager.getConnection("jdbc:odbc:shop","sa","");
sm=conn.createStatement();
}
catch(Exception e){
out.print("数据库连接失败!");
}
}
public void closeDB(){
try{
if(sm!=null)
{
sm.close();
}
conn.close();
}
catch(Exception e){
out.println("数据库关闭失败!");
}
}
}package JavaBean;
public class user{
private int userid;
private String username;
private String pwd;
private String email;
private int gender;
private String strgender;
private String tel;
public int getuserid() {
return userid;
}
public void setuserid(int id) {
this.userid=id;
}
public String getusername() {
return username;
}
public void setusername(String username) {
this.username=username;
}
public String getpwd() {
return pwd;
}
public void setpwd(String pwd) {
this.pwd=pwd;
}
public String getemail() {
return email;
}
public void setemail(String email) {
this.email=email;
}
public int getgender() {
return gender;
}
public void setgender(int gender) {
this.gender=gender;
}
public String getstrgender(){
if (gender == 0)
strgender="女";
else
strgender="男";
return strgender;
}
public String gettel() {
return tel;
}
public void settel(String tel) {
this.tel=tel;
}
}
package JavaBean;
import java.io.*;
import java.sql.*;
import java.util.*;
import JavaBean.user;
import JavaBean.DB_conn;
public class DB_user
{
DB_conn conn=new DB_conn();
public void add(user us)
{
conn.connectDB();
try{
String sql="insert into userinfo(user_name,pwd,"
+ "email,gender,tel) values('" + us.getusername()
+ "','" + us.getpwd() + "','" + us.getemail()
+ "','" + us.getgender() + "','" + us.gettel()
+ "')";
conn.sm.executeUpdate(sql);
}
catch(Exception e){
System.out.println("执行失败!");
}
finally{
conn.closeDB();
}
}
public void update(user us)
{
conn.connectDB();
try {
String sql = "update userinfo set user_name='"
+ us.getusername() + "',pwd='"
+ us.getpwd() + "',email='"
+ us.getemail() + "',gender='"
+ us.getgender() + "',tel='"
+ us.gettel() + "' where user_id='"
+ us.getuserid() + "'"; conn.sm.executeUpdate(sql);
}
catch (Exception e) {
System.out.println("执行失败!");
}
finally {
conn.closeDB();
}
}
public user get(String username, String password)
{
conn.connectDB();
ResultSet rs = null;
try {
String sql = "select * from userinfo where user_name = '"
+ username + "' and pwd='" + password + "'";
rs = conn.sm.executeQuery(sql);
user us = null;
if (rs.next())
{
us = new user();
us.setuserid(rs.getInt("user_id"));
us.setusername(rs.getString("username"));
us.setpwd(rs.getString("pwd"));
us.setemail(rs.getString("email"));
us.setgender(rs.getInt("gender"));
us.settel(rs.getString("tel"));
return us;
}
return us;
}
catch (Exception e) {
System.out.println(e);
return null;
} finally {
conn.closeDB();
}
}
}
package Servlet;
import java.io.*;
import java.sql.*;
import javax.servlet.*;
import javax.servlet.http.*;
import JavaBean.user;
import JavaBean.DB_user;
public class LoginServlet extends javax.servlet.http.HttpServlet implements javax.servlet.Servlet
{
public LoginServlet()
{
super();
}
protected void doPost(HttpServletRequest request,HttpServletResponse response) throws ServletException, IOException
{
response.setContentType("text/html;charset=GB2312");
String username=request.getParameter("logname");
String password=request.getParameter("logpwd");
DB_user dbuser = new DB_user();
user us=dbuser.get(username,password);
if(us!=null)
{
request.getSession(true).setAttribute("username",username);
try{
request.getRequestDispatcher("index.jsp").forward(request,response);
}
catch(Exception e){
System.out.println(e);
}
}
else
{
request.setAttribute("error", "用户名与密码不匹配,请重试!");
try{
request.getRequestDispatcher("Login.jsp").forward(request,response);
}
catch(Exception e){
System.out.println(e);
}
}
}
}
HTTP Status 500 - --------------------------------------------------------------------------------type Exception reportmessage description The server encountered an internal error () that prevented it from fulfilling this request.exception java.lang.NullPointerException
JavaBean.DB_conn.connectDB(DB_conn.java:15)
JavaBean.DB_user.get(DB_user.java:54)
Servlet.LoginServlet.doPost(LoginServlet.java:20)
javax.servlet.http.HttpServlet.service(HttpServlet.java:710)
javax.servlet.http.HttpServlet.service(HttpServlet.java:803)
note The full stack trace of the root cause is available in the Apache Tomcat/5.5.23 logs.
--------------------------------------------------------------------------------Apache Tomcat/5.5.23
import java.sql.*;
import java.io.PrintWriter;
public class DB_conn{
private Connection conn=null;
public Statement sm=null;
private PrintWriter out = null;
public void connectDB(){
try{
Class.forName("sun.jdbc.odbc.JdbcOdbcDriver").newInstance();
conn=DriverManager.getConnection("jdbc:odbc:shop","sa","");
sm=conn.createStatement();
}
catch(Exception e){
out.print("数据库连接失败!");
}
}
public void closeDB(){
try{
if(sm!=null)
{
sm.close();
}
conn.close();
}
catch(Exception e){
out.println("数据库关闭失败!");
}
}
}package JavaBean;
public class user{
private int userid;
private String username;
private String pwd;
private String email;
private int gender;
private String strgender;
private String tel;
public int getuserid() {
return userid;
}
public void setuserid(int id) {
this.userid=id;
}
public String getusername() {
return username;
}
public void setusername(String username) {
this.username=username;
}
public String getpwd() {
return pwd;
}
public void setpwd(String pwd) {
this.pwd=pwd;
}
public String getemail() {
return email;
}
public void setemail(String email) {
this.email=email;
}
public int getgender() {
return gender;
}
public void setgender(int gender) {
this.gender=gender;
}
public String getstrgender(){
if (gender == 0)
strgender="女";
else
strgender="男";
return strgender;
}
public String gettel() {
return tel;
}
public void settel(String tel) {
this.tel=tel;
}
}
package JavaBean;
import java.io.*;
import java.sql.*;
import java.util.*;
import JavaBean.user;
import JavaBean.DB_conn;
public class DB_user
{
DB_conn conn=new DB_conn();
public void add(user us)
{
conn.connectDB();
try{
String sql="insert into userinfo(user_name,pwd,"
+ "email,gender,tel) values('" + us.getusername()
+ "','" + us.getpwd() + "','" + us.getemail()
+ "','" + us.getgender() + "','" + us.gettel()
+ "')";
conn.sm.executeUpdate(sql);
}
catch(Exception e){
System.out.println("执行失败!");
}
finally{
conn.closeDB();
}
}
public void update(user us)
{
conn.connectDB();
try {
String sql = "update userinfo set user_name='"
+ us.getusername() + "',pwd='"
+ us.getpwd() + "',email='"
+ us.getemail() + "',gender='"
+ us.getgender() + "',tel='"
+ us.gettel() + "' where user_id='"
+ us.getuserid() + "'"; conn.sm.executeUpdate(sql);
}
catch (Exception e) {
System.out.println("执行失败!");
}
finally {
conn.closeDB();
}
}
public user get(String username, String password)
{
conn.connectDB();
ResultSet rs = null;
try {
String sql = "select * from userinfo where user_name = '"
+ username + "' and pwd='" + password + "'";
rs = conn.sm.executeQuery(sql);
user us = null;
if (rs.next())
{
us = new user();
us.setuserid(rs.getInt("user_id"));
us.setusername(rs.getString("username"));
us.setpwd(rs.getString("pwd"));
us.setemail(rs.getString("email"));
us.setgender(rs.getInt("gender"));
us.settel(rs.getString("tel"));
return us;
}
return us;
}
catch (Exception e) {
System.out.println(e);
return null;
} finally {
conn.closeDB();
}
}
}
package Servlet;
import java.io.*;
import java.sql.*;
import javax.servlet.*;
import javax.servlet.http.*;
import JavaBean.user;
import JavaBean.DB_user;
public class LoginServlet extends javax.servlet.http.HttpServlet implements javax.servlet.Servlet
{
public LoginServlet()
{
super();
}
protected void doPost(HttpServletRequest request,HttpServletResponse response) throws ServletException, IOException
{
response.setContentType("text/html;charset=GB2312");
String username=request.getParameter("logname");
String password=request.getParameter("logpwd");
DB_user dbuser = new DB_user();
user us=dbuser.get(username,password);
if(us!=null)
{
request.getSession(true).setAttribute("username",username);
try{
request.getRequestDispatcher("index.jsp").forward(request,response);
}
catch(Exception e){
System.out.println(e);
}
}
else
{
request.setAttribute("error", "用户名与密码不匹配,请重试!");
try{
request.getRequestDispatcher("Login.jsp").forward(request,response);
}
catch(Exception e){
System.out.println(e);
}
}
}
}
HTTP Status 500 - --------------------------------------------------------------------------------type Exception reportmessage description The server encountered an internal error () that prevented it from fulfilling this request.exception java.lang.NullPointerException
JavaBean.DB_conn.connectDB(DB_conn.java:15)
JavaBean.DB_user.get(DB_user.java:54)
Servlet.LoginServlet.doPost(LoginServlet.java:20)
javax.servlet.http.HttpServlet.service(HttpServlet.java:710)
javax.servlet.http.HttpServlet.service(HttpServlet.java:803)
note The full stack trace of the root cause is available in the Apache Tomcat/5.5.23 logs.
--------------------------------------------------------------------------------Apache Tomcat/5.5.23
解决方案 »
免费领取超大流量手机卡,每月29元包185G流量+100分钟通话, 中国电信官方发货