圖片

JSP:

 <div id = "main">
          <form action = "${pageContext.request.contextPath}/loginServlet" method="get">
              <table>
                 <tr>
                    <td><span>使用者名稱:</span></td>
                    <td><input type="text" name="username"/></td>
                 </tr>
                 <tr>
                    <td><span>密&nbsp;&nbsp;&nbsp;&nbsp;碼:</span></td>
                    <td><input type="text" name="password"/></td>
                 </tr>
                 <tr>
                    <td><input type="submit" value="登入" name="sub"/></td>
                 </tr>
              </table>
          </form>
      </div>

Servlet:

package com.syh.servlet;


import java.io.IOException;


import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;


import com.syh.pojo.User;
import com.syh.service.UserService;


public class LoginServlet extends HttpServlet{


@Override
protected void doGet(HttpServletRequest req, HttpServletResponse resp)
throws ServletException, IOException {
doPost(req, resp);
}
@Override
protected void doPost(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {

//獲取從jsp頁面傳過來的資料
String username = request.getParameter("username");
String password = request.getParameter("password");

//獲取service物件，用來處理邏輯事務
UserService service = new UserService();

User user = new User();
user = service.findSimpleUser(username);
if(password != null && password != "" && password.equals(user.getPassword())){
HttpSession session = request.getSession();
session.setAttribute("user", user);
request.getRequestDispatcher("/success.jsp").forward(request, response);
}else{
request.getRequestDispatcher("/error.jsp").forward(request, response);
}
}
}

Service:

package com.syh.service;


import com.syh.dao.UserDao;
import com.syh.pojo.User;


public class UserService {


UserDao dao = new UserDao();


public User findSimpleUser(String username) {
return dao.findSimpleUser(username);
}


}

dao:

package com.syh.dao;


import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;


import com.syh.pojo.User;
import com.syh.utils.DataSourseUtil;


public class UserDao {


private DataSourseUtil util = null;
public User findSimpleUser(String username) {
String sql = "select * from user where  username = ?";
Map<String ,Object> map = new HashMap<String , Object>();
List<Object> params = new ArrayList<Object>();
params.add(username);
util = new DataSourseUtil();
map = util.findSample(sql, params);
if(map != null){
User user  = new User();
user.setUsername((String)map.get("username"));
user.setPassword((String)map.get("password"));
return user;
}

return null;
}


}

Util:

package com.syh.utils;


import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.ResultSetMetaData;
import java.sql.SQLException;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;


public class DataSourseUtil {



private static String name = "root";
private static String password = "123456";
private static String url = "jdbc:mysql://localhost:3306/test";
private final static String Driver = "com.mysql.jdbc.Driver";

private static Connection coon = null;
private PreparedStatement statement = null;
private ResultSet result = null;

static{
try {
Class.forName(Driver);
coon = DriverManager.getConnection(url, name, password);
} catch (Exception e) {
e.printStackTrace();
}
}

//增刪改
public boolean addDeleteModify(String sql , List<Object> params){
boolean flag = false;
int rows = -1;//表示受影響的行數
try{
this.statement = coon.prepareStatement(sql);
int index = 1;
int len = params.size();
if (params != null && !params.isEmpty()){
for(int i = 0 ; i < len ; i++){
statement.setObject(index++, params.get(i));
}
}
   rows = statement.executeUpdate();
   flag = rows > 0 ? true : false;
}catch(Exception ex){
ex.printStackTrace();
}
return flag;
}
//查詢 單一查詢
public Map<String ,Object> findSample(String sql , List<Object> params){
Map<String ,Object> map = new HashMap<String , Object>();
try{
this.statement = coon.prepareStatement(sql);
int index = 1;
int len = params.size();
if (params != null && !params.isEmpty()){
for(int i = 0 ; i < len ; i++){
statement.setObject(index++, params.get(i));
}
}
result = statement.executeQuery();
ResultSetMetaData rsmd =  result.getMetaData();//獲取列名
int count = rsmd.getColumnCount();
System.out.println(result.getRow());
while(result.next()){
for(int i = 0 ; i < count ; i++ ){
String key = rsmd.getColumnName(i + 1);//獲取第i個列名
Object value = result.getObject(key);//通過列名來獲取對應的值
map.put(key, value);
}
}
return map;
}catch(Exception ex){
ex.printStackTrace();
return null;
}
}



public List<Map<String,Object>> findMany(String sql , List<Object> params){
//Map<String , Object> 儲存的沒行資料
List<Map<String , Object>> list = new ArrayList<Map<String , Object>>();
try{
this.statement = coon.prepareStatement(sql);
int index = 1;
int len = params.size();
if (params != null && !params.isEmpty()){
for(int i = 0 ; i < len ; i++){
statement.setObject(index++, params.get(i));
}
}
result = statement.executeQuery();
ResultSetMetaData rsmd =  result.getMetaData();//獲取列名
int count = rsmd.getColumnCount();//共有多少列
while(result.next()){
Map<String ,Object> map = new HashMap<String , Object>();
for(int i = 0 ; i < count ; i++ ){
String key = rsmd.getColumnName(i + 1);//獲取第i個列名
Object value = result.getObject(key);//通過列名來獲取對應的值
map.put(key, value);
}
list.add(map);
}
return list;
}catch(Exception ex){
ex.printStackTrace();
return null;
}
}


public void closeConnection(){
if(coon != null){
try {
coon.close();
} catch (SQLException e) {
e.printStackTrace();
}
}

if(statement != null){
try {
statement.close();
} catch (SQLException e) {
e.printStackTrace();
}
}


if(result != null){
try {
result.close();
} catch (SQLException e) {
e.printStackTrace();
}
}





}





}

web.xml:

<?xml version="1.0" encoding="UTF-8"?>
<web-app version="2.5" 
xmlns="http://java.sun.com/xml/ns/javaee" 
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" 
xsi:schemaLocation="http://java.sun.com/xml/ns/javaee 
http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd">
  <display-name></display-name>
  <welcome-file-list>
    <welcome-file>index.jsp</welcome-file>
  </welcome-file-list>
  
  
  <servlet>
     <servlet-name>LoginServlet</servlet-name>
     <servlet-class>com.syh.servlet.LoginServlet</servlet-class>
  </servlet>
  
  <servlet-mapping>
     <servlet-name>LoginServlet</servlet-name>
     <url-pattern>/loginServlet</url-pattern>
  </servlet-mapping>
  
  

</web-app>