servlet+JDBC实现登录 增删查改 分页显示

本人是初学者，网上的搜了一下基本很少有详细的讲解，所以自己亲自动手做了下，把遇到的一些问题也说明了一下，希望对和我一样的菜鸟有所帮助，共同进步。

本案例没有添加AJAX以及JS验证，只是简单的功能实现。实现方法有不合理之处请大神指教，小弟不胜感激。

运行环境：Eclipse Java EE IDE for Web Developers Mars Release (4.5.0)

apache-tomcat-8.0.22

jdk-7u17-windows-i586

SQL2008 R2

需要添加的JAR包sqljdbc4.jar

表结构：

CREATE TABLE [dbo].[users](

[id] [int] IDENTITY(1,1) NOT FOR REPLICATION NOT NULL,

[name] [varchar](50) ,

[password] [varchar](50) ,

[sex] [varchar](50)

)

项目文件结构：



业务逻辑为登录成功直接分页显示所有结果，和修改删除功能。注册成功同样是直接显示此界面。。比较简单哈哈

运行结果如下：



实体类User.java

package com.wu.entity;

public class User {

private int id;

private String name;

private String password;

private String sex;

public int getid(){

return id;

}

public void setid(int id){

this.id=id;

}

public String getname(){

return name;

}

public void setname(String name){

this.name=name;

}

public String getpassword(){

return password;

}

public void setpassword(String password){

this.password=password;

}

public String getsex(){

return sex;

}

public void setsex(String sex){

this.sex=sex;

}

}

创建数据库连接sqlutil.java

package com.wu.util;

import java.sql.Connection;

import java.sql.DriverManager;

public class sqlutil {

private static Connection conn;

public static Connection getconn() {

String url="jdbc:sqlserver://localhost:1433;databaseName=test";

String username="sa";

String password="6321194";

try{

Class.forName("com.microsoft.sqlserver.jdbc.SQLServerDriver");

conn=DriverManager.getConnection(url, username, password);

}catch(Exception e){

e.printStackTrace();

return null;

}

return conn;

}

}

创建UserDao接口

package com.wu.dao;

import java.sql.SQLException;

import com.wu.entity.User;

public interface UserDao {

boolean checkLogin(User user) throws Exception; //登录验证

int adduser(User user) throws Exception; //添加用户

User serchforid(int id) throws SQLException; //根据ID查找用户

int delet(int id) throws SQLException; //删除用户

int update(int id,User user) throws SQLException; //修改用户信息

}

实现方法：UserDaoimpl.java

package com.wu.dao;

import java.sql.Connection;

import java.sql.PreparedStatement;

import java.sql.ResultSet;

import java.sql.SQLException;

import java.util.ArrayList;

import java.util.List;

import com.wu.entity.User;

import com.wu.util.sqlutil;

public class UserDaoimpl implements UserDao{

private Connection conn=null;

private PreparedStatement pstmt = null;

private ResultSet rs=null;

@Override

public boolean checkLogin(User user) throws Exception {

conn = sqlutil.getconn();

String sql="select * from users where name=? and password=?";

pstmt=conn.prepareStatement(sql);

pstmt.setString(1, user.getname());

pstmt.setString(2, user.getpassword());

rs=pstmt.executeQuery();

if(rs.next()){

return true;

}

return false;

}

@Override

public int adduser(User user) throws Exception {

conn=sqlutil.getconn();

String sql="insert into users(name,password,sex) values(?,?,?)";

pstmt=conn.prepareStatement(sql);

pstmt.setString(1, user.getname());

pstmt.setString(2, user.getpassword());

pstmt.setString(3, user.getsex());

int row=pstmt.executeUpdate();

return row;

}

@Override

public User serchforid(int id) throws SQLException {

User user=new User();

conn=sqlutil.getconn();

String sql="select * from users where id=?";

pstmt=conn.prepareStatement(sql);

pstmt.setInt(1, id);

rs=pstmt.executeQuery();

while(rs.next()){

user.setid(rs.getInt("id"));

user.setname(rs.getString("name"));

user.setpassword(rs.getString("password"));

user.setsex(rs.getString("sex"));

}

System.out.print(user.getsex());

return user;

}

@Override

public int delet(int id) throws SQLException {

conn=sqlutil.getconn();

String sql="delete from users where id=?";

pstmt=conn.prepareStatement(sql);

pstmt.setInt(1, id);

int row=pstmt.executeUpdate();

return row;

}

@Override

public int update(int id,User user) throws SQLException {

conn=sqlutil.getconn();

String sql="update users set name=?,password=?,sex=? where id=?";

pstmt=conn.prepareStatement(sql);

pstmt.setString(1, user.getname());

pstmt.setString(2, user.getpassword());

pstmt.setString(3, user.getsex());

pstmt.setInt(4, id);

int row=pstmt.executeUpdate();

return row;

}

}

PageDao接口

package com.wu.dao;

import java.sql.SQLException;

import java.util.List;

import com.wu.entity.User;

public interface PageDao {

int maxPage(int rowsperpage) throws SQLException; //总共页数

List<User> getsearch(User user,int rowsperpage,int nowpage) throws Exception; //根据每页记录数，当前页码返回记录集

}

实现方法PageDaoimpl.java

package com.wu.dao;

import java.sql.Connection;

import java.sql.PreparedStatement;

import java.sql.ResultSet;

import java.sql.SQLException;

import java.sql.Statement;

import java.util.ArrayList;

import java.util.List;

import com.wu.entity.User;

import com.wu.util.sqlutil;

public class PageDaoimpl implements PageDao{

private Connection conn=null;

private PreparedStatement pstmt=null;

private ResultSet rs=null;

@Override

public int maxPage(int rowsperpage) throws SQLException {

conn = sqlutil.getconn();

String sql="select count(id) from users";

Statement stmt = conn.createStatement();

rs=stmt.executeQuery(sql);

int maxrecord = 0;

if(rs.next()){

maxrecord=rs.getInt(1);

System.out.print("啊啊啊");

}

int maxpage=(maxrecord+rowsperpage-1)/rowsperpage;

return maxpage;

}

@Override

public List<User> getsearch(User user,int rowsperpage,int nowpage) throws Exception {

int page=rowsperpage*(nowpage-1);

List<User> list=new ArrayList<User>();

conn=sqlutil.getconn();

String sql="select top "+rowsperpage+" * from users where id not in (select top "+page+" id from users) order by id asc";
//这里注意不要使用？通配符，不然会报错

pstmt=conn.prepareStatement(sql);

rs=pstmt.executeQuery();

while(rs.next()){

User user2 = new User();

user2.setid(rs.getInt("id"));

user2.setname(rs.getString("name"));

user2.setpassword(rs.getString("password"));

user2.setsex(rs.getString("sex"));

list.add(user2);

}

return list;

}

}

控制层：

delet.java

package com.wu.servlet;

import java.io.IOException;

import java.sql.SQLException;

import javax.servlet.ServletException;

import javax.servlet.annotation.WebServlet;

import javax.servlet.http.HttpServlet;

import javax.servlet.http.HttpServletRequest;

import javax.servlet.http.HttpServletResponse;

import com.wu.dao.UserDao;

import com.wu.dao.UserDaoimpl;

@WebServlet("/delet")

public class delet extends HttpServlet {

private static final long serialVersionUID = 1L;

public delet() {

super();

// TODO Auto-generated constructor stub

}

protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {

doPost(request,response);

}

protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {

int id=Integer.parseInt(request.getParameter("id").toString());

UserDao userdao=new UserDaoimpl();

int d=0;

try {

d=userdao.delet(id);

} catch (SQLException e) {

e.printStackTrace();

}

if(d>0){

request.getRequestDispatcher("cg.jsp").forward(request, response);

}else{

request.getRequestDispatcher("error.jsp").forward(request, response);

}

}

}

登陆验证loginservlet.java

package com.wu.servlet;

import java.io.IOException;

import javax.servlet.ServletException;

import javax.servlet.annotation.WebServlet;

import javax.servlet.http.HttpServlet;

import javax.servlet.http.HttpServletRequest;

import javax.servlet.http.HttpServletResponse;

import com.wu.dao.UserDao;

import com.wu.dao.UserDaoimpl;

import com.wu.entity.User;

@WebServlet("/loginservlet")

public class loginservlet extends HttpServlet {

private static final long serialVersionUID = 1L;

public loginservlet() {

super();

// TODO Auto-generated constructor stub

}

protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {

// TODO Auto-generated method stub

}

protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {

String username = request.getParameter("username");

String password = request.getParameter("password");

User user=new User();

user.setname(username);

user.setpassword(password);

boolean b = false;

UserDao userdao=new UserDaoimpl();

try {

b= userdao.checkLogin(user);

} catch (Exception e) {

e.printStackTrace();

}

if (b==true){

request.getRequestDispatcher("/shall").forward(request, response);

}else{request.getRequestDispatcher("/error.jsp").forward(request, response); }

}

}