总结学了 j2ee 一月半后的项目情况(3)

源码：

1、用户 CRUD servlet 

package fafa.shop.controller;
import java.io.IOException;
import java.util.ArrayList;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import fafa.shop.service.User;
import fafa.shop.service.UserModel;
@SuppressWarnings("serial")
public class UserServ extends HttpServlet {
    public void doGet(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        request.setCharacterEncoding("GBK") ;
            UserModel us = new UserModel() ;        
        String type= request.getParameter("type");
        if (type.equals("add")){
            String uid = null ; 
            String username = request.getParameter("username") ;
            String password = request.getParameter("password") ;
            String email = request.getParameter("email") ;
            User user = new User(uid, username, password, email) ;
            if (us.insertUser(user)){
                ArrayList<User> all = us.getAll() ;
                request.setAttribute("user", all) ;
                request.getRequestDispatcher("/index.jsp").forward(request, response) ;
            }else{
                request.setAttribute("error", "用户添加失败") ;
                request.getRequestDispatcher("/index.jsp").forward(request, response) ;
            }
        }else if (type.equals("mod")){
            String uid = request.getParameter("uid") ;
            ArrayList<User> all = us.getOne(uid) ;
            if (all != null){
                request.setAttribute("user", all) ;
                request.getRequestDispatcher("/WEB-INF/update.jsp").forward(request, response) ;
            }else {
                request.setAttribute("error", "用户不存在！！！") ;
                request.getRequestDispatcher("/WEB-INF/update.jsp").forward(request, response) ;
            }

        }else if (type.equals("update")){
            String uid = request.getParameter("uid") ;
            String username = request.getParameter("username") ;
            String password = request.getParameter("password") ;
            String email = request.getParameter("email") ;
            User user = new User(uid, username, password, email) ;
            if (us.updateUser(user)){
                request.setAttribute("updateSuccess", "数据更新成功！") ;
                request.getRequestDispatcher("/index.jsp").forward(request, response) ;
            }else{
                request.setAttribute("updateError", "数据更新失败！") ;
                request.getRequestDispatcher("/index.jsp").forward(request, response) ;
            }
        }else if (type.equals("del")){
            String uid = request.getParameter("uid") ;
            
            if (us.delUser(uid)){
                request.setAttribute("delSuccess", "数据删除成功！") ;
                request.getRequestDispatcher("/index.jsp").forward(request, response) ;
            }else{
                request.setAttribute("delError", "数据删除失败！") ;
                request.getRequestDispatcher("/index.jsp").forward(request, response) ;
            }
        }
        
    }
    public void doPost(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        this.doGet(request, response) ;
    }

}

2、user bean 类 

package fafa.shop.service;

public class User {
    private String uid ;
    private String username ;
    private String password ;
    private String email ;
    
    public User() {
        super();
    }
    public User(String uid ,String username, String password, String email) {
        super();
        this.uid = uid ;
        this.username = username;
        this.password = password;
        this.email = email;
    }
    public String getUid() {
        return uid;
    }
    public void setUid(String uid) {
        this.uid = uid;
    }
    public String getUsername() {
        return username;
    }
    public void setUsername(String username) {
        this.username = username;
    }
    public String getPassword() {
        return password;
    }
    public void setPassword(String password) {
        this.password = password;
    }
    public String getEmail() {
        return email;
    }
    public void setEmail(String email) {
        this.email = email;
    }
}

3、userModel 类 和 数据库连接类 

package fafa.shop.service;

import java.sql.*;
import java.util.ArrayList;

import fafa.shop.util.DBUtil;

public class UserModel {
    private Connection conn = null ;
    private PreparedStatement ps = null ;
    private ResultSet rs = null ;
    
    //插入用户
    public boolean insertUser(User user){
        boolean flag = false ;
        try {
            this.conn = DBUtil.getConnection() ;
            String sql = "INSERT INTO user(uid,username,password,email) VALUES(?,?,?,?)" ;
            this.ps = this.conn.prepareStatement(sql) ;
            this.ps.setString(1, null) ;
            this.ps.setString(2, user.getUsername()) ;
            this.ps.setString(3, user.getPassword()) ;
            this.ps.setString(4, user.getEmail()) ;
            this.ps.executeUpdate() ;
            flag = true ;
        } catch (Exception e) {
            e.printStackTrace();
        }finally{
            try {
                this.conn.close() ;
            } catch (SQLException e) {
                e.printStackTrace();
            }
            try {
                this.ps.close();
            } catch (SQLException e) {
                e.printStackTrace();
            } 
        }
        
        return flag ;
    }
    
    //取得所有用户
    public ArrayList<User> getAll(){
        ArrayList<User> all = new ArrayList<User>() ;
        try {
            this.conn = DBUtil.getConnection() ;
            String sql = "SELECT uid, username, password, email FROM user" ;
            this.ps = this.conn.prepareStatement(sql) ;
            this.rs = this.ps.executeQuery() ;
            while(this.rs.next()){
                User user = new User() ;
                user.setUid(rs.getString("uid")) ;
                user.setUsername(rs.getString("username")) ;
                user.setPassword(rs.getString("password")) ;
                user.setEmail(rs.getString("email")) ;
                all.add(user) ;
            }
            
        } catch (Exception e) {
            e.printStackTrace();
        }finally{
            try {
                this.conn.close() ;
                this.ps.close() ;
                this.rs.close() ;
            } catch (SQLException e) {
                e.printStackTrace();
            }
        }

        return all ;
    }
    
    //取一条数据
    public ArrayList<User> getOne(String uid){
        ArrayList<User> all = new ArrayList<User>() ;
        try {
            this.conn = DBUtil.getConnection() ;
            String sql = "SELECT uid, username, password, email FROM user WHERE uid=?" ;
            this.ps = this.conn.prepareStatement(sql) ;
            this.ps.setString(1, uid) ;
            this.rs = this.ps.executeQuery() ;
            while(this.rs.next()){
                User user = new User() ;
                user.setUid(rs.getString("uid")) ;
                user.setUsername(rs.getString("username")) ;
                user.setPassword(rs.getString("password")) ;
                user.setEmail(rs.getString("email")) ;
                all.add(user) ;
            }
            
        } catch (Exception e) {
            e.printStackTrace();
        }finally{
            try {
                this.conn.close() ;
                this.ps.close() ;
                this.rs.close() ;
            } catch (SQLException e) {
                e.printStackTrace();
            }
        }
        return all ;
    }
    
    //更新数据
    public boolean updateUser(User user){
        boolean flag = false ;
        try {
            this.conn = DBUtil.getConnection() ;
            String sql = "UPDATE user SET username=?, password=?, email=? WHERE uid=?" ;
            this.ps = this.conn.prepareStatement(sql) ;
            this.ps.setString(1, user.getUsername()) ;
            this.ps.setString(2, user.getPassword()) ;
            this.ps.setString(3, user.getEmail()) ;
            this.ps.setString(4, user.getUid()) ;
            this.ps.executeUpdate() ;
            flag = true ;
        } catch (Exception e) {
            e.printStackTrace();
        }finally{
            try {
                this.conn.close() ;
            } catch (SQLException e) {
                e.printStackTrace();
            }
            try {
                this.ps.close();
            } catch (SQLException e) {
                e.printStackTrace();
            } 
        }
        return flag ;
    }
    
    //删除用户
    public boolean delUser(String uid){
        boolean flag = false ;
        try {
            this.conn = DBUtil.getConnection() ;
            String sql = "DELETE FROM user WHERE uid=?" ;
            this.ps = this.conn.prepareStatement(sql) ;
            this.ps.setInt(1, Integer.parseInt(uid)) ;
            this.ps.executeUpdate() ;
            flag = true ;
        } catch (Exception e) {
            e.printStackTrace();
        }finally{
            try {
                this.conn.close() ;
            } catch (SQLException e) {
                e.printStackTrace();
            }
            try {
                this.ps.close();
            } catch (SQLException e) {
                e.printStackTrace();
            } 
        }
        return flag ;
    }
}

package fafa.shop.util;

import java.sql.*;

public class DBUtil {
    private static final String DBDRIVER = "org.gjt.mm.mysql.Driver" ;
    private static final String DBURL = "jdbc:mysql://localhost:3306/test" ;
    private static final String DBUSER = "root" ;
    private static final String DBPASS = "123456" ;
    
    private static Connection conn = null ;
    
    //外部取得连接
    public static Connection getConnection() throws Exception {
        Class.forName(DBDRIVER) ;
        conn = DriverManager.getConnection(DBURL, DBUSER, DBPASS) ;
        return conn ;
    }
    
    //关闭连接
    public static void close(ResultSet rs, Statement ps, Connection ct){
        try {
            if (rs!=null){
                rs.close() ;
            }
        } catch (SQLException e) {
            e.printStackTrace();
        }
        try {
            if (ps!=null){
                ps.close() ;
            }
        } catch (SQLException e) {
            e.printStackTrace();
        }
        try {
            if (ct!=null){
                ct.close() ;
            }
        } catch (SQLException e) {
            e.printStackTrace();
        }
    }
}

 这样就完成成了数据的CRUD ，我现在是初学者啊，没办法只能这样练练手，希望能更快上手.

本来是使用三种数据库 oracle、mssql 、mysql 完成的。

以上还少了功能：分页、上传文件、支付、 等等。

当然现在很多企业也不再会这样写代码了，基本都是用框架了。所以下面的学习中心转移到框架  和 基础加深了。