//本文主要實現學員日誌管理功能，表單以及前端等樣式程式碼省略，主要servlet方法實現的功能的如下：

package com.softeem.dao;

import java.util.List;

public interface BaseDAO<T> {
	
	public boolean save(T t);
	
	public boolean delete(T t);
	
	public boolean update(T t);
	
	public T findById(int id);
	
	public T findProperty(T t); 
	
	public List<T> findByProperties(T t);
	
	public List<T> findAll();
}
 

package com.softeem.servlet;

import java.io.IOException;
import java.util.List;

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.softeem.dao.impl.DailyDAO;
import com.softeem.dto.Daily;
import com.softeem.dto.Student;

@WebServlet("/daily")
public class DailyServlet extends HttpServlet{

	@Override
	protected void doGet(HttpServletRequest req, HttpServletResponse resp)
			throws ServletException, IOException {
		doPost(req,resp);
	}
	
	@Override
	protected void doPost(HttpServletRequest req, HttpServletResponse resp)
			throws ServletException, IOException {
		String flag = req.getParameter("flag");
		switch(flag){
		case "add":
			submit(req,resp);
			break;
		case "modify":
			modify(req,resp);
			break;
		case "queryAll":
			queryAll(req,resp);
			break;
		case "queryById":
			queryById(req,resp);
			break;
		}
	}

	private void queryById(HttpServletRequest req, HttpServletResponse resp) {
		// TODO Auto-generated method stub
		
	}

	private void queryAll(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
		//從session中取出當前使用者
		Student stu = getSession(req);
		if(stu!=null){
			//查詢當前學生的日誌
			Daily d = new Daily();
			d.setStudent(stu);
			DailyDAO dao = new DailyDAO();
			List<Daily> list = dao.findByProperties(d);
			//將日誌集合快取到request中
			req.setAttribute("list", list);
			req.getRequestDispatcher("dailyList.jsp").forward(req, resp);
			
		}else{
			req.setAttribute("error", "你還沒有登入，請登入再試！");
			req.getRequestDispatcher("login.jsp").forward(req, resp);
		}
		
	}

	private void modify(HttpServletRequest req, HttpServletResponse resp) {
		// TODO Auto-generated method stub
		
	}

	private void submit(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
		
		//從session中取出學生物件,有資料代表已經登入
		Student stu = getSession(req);
		if(stu!=null){
			String content = req.getParameter("content");
			Daily daily = new Daily();
			daily.setContent(content);
			daily.setStudent(stu);
		
			DailyDAO dao = new DailyDAO();
			if(dao.save(daily)){
				//成功後直接跳轉到列表頁面，顯示日誌列表
				resp.sendRedirect("daily?flag=queryAll");
			}else{
				//失敗
			}
			
		}else{
			req.setAttribute("error", "你還沒有登入，請登入再試！");
			req.getRequestDispatcher("login.jsp").forward(req, resp);
		}
		
	}
	
	//從session中獲取快取的當前登入學生資訊
		private Student getSession(HttpServletRequest request){
			Object obj = request.getSession().getAttribute("user");
			return obj != null?(Student)obj:null;
		}
	
}
 

package com.softeem.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.softeem.dao.impl.StudentDAO;
import com.softeem.dto.Student;
import com.softeem.encrypt.MD5;

@WebServlet("/login")
public class LoginServlet extends HttpServlet{

	private static final long serialVersionUID = 1L;
	
	public LoginServlet() {
		super();
	}
	
	@Override
	protected void doGet(HttpServletRequest request, HttpServletResponse response)
			throws ServletException, IOException {
		doPost(request, response);
	}
	
	@Override
	protected void doPost(HttpServletRequest request, HttpServletResponse response)
			throws ServletException, IOException {
		//獲取表單資料（賬號，密碼）
		String sno = request.getParameter("username");
		String pass = request.getParameter("password");
		
		Student stu = new Student();
		stu.setSno(sno);
		stu.setPassword(pass);
		
		StudentDAO dao = new StudentDAO();
		stu = dao.findProperty(stu);
		//對提交的密碼加密
//		MD5 md5 = new MD5();
//		pass = md5.getMD5ofStr(pass);
		if(stu != null){
			if(stu.getPassword().equals(pass)){
				//成功
				//將登入的學生資訊儲存到session中
				request.getSession().setAttribute("user", stu);
				response.sendRedirect("index.jsp");
			}else{
				//密碼錯誤
				request.setAttribute("error", "密碼錯誤");
			    request.getRequestDispatcher("login.jsp").forward(request, response);
			}
		}else{
			//學號錯誤
			request.setAttribute("error", "學號錯誤");
			request.getRequestDispatcher("login.jsp").forward(request, response);
		}
	}
}
 

package com.softeem.utils;



import java.io.IOException;
import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;
import java.util.List;
import java.util.Properties;

import org.apache.tomcat.dbcp.dbcp2.BasicDataSource;





/**
 * DBCP資料庫連線工具類
 * 依賴
 * 1.mysql驅動
 * 2.dbcp相關外掛
 * @author mrchai
 *
 */
public class DBUtils {

	//連線資料庫基本屬性
	private static String driverClass="com.mysql.jdbc.Driver";
	private static String url="jdbc:mysql://127.0.0.1:3306/oa";
	private static String username="root";
	private static String password="123456";
	//連線池屬性
	private static int initSize=10;
	private static int maxSize=50;
	private static int maxIdle=30;
	private static long maxWait=10000;
	//資料來源
	private static BasicDataSource bds;
	
	//初始化資料來源配置
	static{
		init();
	}
	
	public static void init(){
		try {
			//建立資料來源物件
			bds = new BasicDataSource();
			//載入屬性檔案，獲取屬性資訊
			Properties props = new Properties();
			props.load(DBUtils.class.getResourceAsStream("jdbc.properties"));
			driverClass = props.getProperty("driver");
			url = props.getProperty("url");
			username = props.getProperty("user");
			password = props.getProperty("password");
			
			initSize = Integer.parseInt(props.getProperty("initSize"));
			maxSize = Integer.parseInt(props.getProperty("maxSize"));
			maxIdle = Integer.parseInt(props.getProperty("maxIdle"));
			maxWait = Long.parseLong(props.getProperty("maxWait"));
			
			//設定驅動類路徑
			bds.setDriverClassName(driverClass);
			//設定url
			bds.setUrl(url);
			//設定使用者名稱
			bds.setUsername(username);
			//設定密碼
			bds.setPassword(password);
			
			//設定初始連線數
			bds.setInitialSize(initSize);
			//設定最大連線
			bds.setMaxTotal(maxSize);
			//設定最大閒置連線數
			bds.setMaxIdle(maxIdle);
			//等待獲取連線的最大時間(MS)
			bds.setMaxWaitMillis(maxWait);
		} catch (Exception e) {
			e.printStackTrace();
		}
	}
	
	//獲取連線
	public static Connection getConn(){
		try {
			if(bds == null || bds.isClosed()){
				init();
			}
			return bds.getConnection();
		} catch (SQLException e) {
			e.printStackTrace();
		}
		return null;
	}
	
	//封裝資源回收的方法
	public static void close(ResultSet rs,Statement stat,Connection conn){
	
		try {
			if(rs != null) rs.close();
			if(stat != null) stat.close();
			if(conn != null)conn.close();
		} catch (SQLException e) {
			e.printStackTrace();
		}
	}
	
	/**
	 * 通用增刪改
	 * @param conn
	 * @param sql
	 * @param objs
	 * @return
	 */
	public static boolean execUpdate(Connection conn,String sql,Object ...objs){
		try {
			PreparedStatement ps = conn.prepareStatement(sql);
			for (int i = 0; i < objs.length; i++) {
				ps.setObject(i+1, objs[i]);
			}
			int i = ps.executeUpdate();
			return i>0 ? true:false;
		} catch (SQLException e) {
			e.printStackTrace();
		}
		return false;
	}
	
	/**
	 * C++鉤子函式    回撥函式
	 * 集合查詢
	 * @param sql
	 * @param call
	 * @param params
	 * @return
	 */
	public static <T> List<T> queryList(String sql,CallBack<T> call,Object...params){
		Connection conn = DBUtils.getConn();
		PreparedStatement ps = null;
		try {
			ps = conn.prepareStatement(sql);
			for(int i = 0;i<params.length;i++)
			{
				ps.setObject(i+1, params[i]);
			}
			ResultSet rs = ps.executeQuery();
			return call.getDatas(rs);
		} catch (SQLException e) {
			e.printStackTrace();
		}
		return null;
	}
	
	/**
	 * 查詢一條記錄
	 * @param sql
	 * @param call
	 * @param params
	 * @return
	 */
	public static <T> T queryOne(String sql,CallBack<T> call,Object...params)
	{
		Connection conn = DBUtils.getConn();
		PreparedStatement ps = null;
		try {
			ps = conn.prepareStatement(sql);
			for(int i = 0;i<params.length;i++)
			{
				ps.setObject(i+1, params[i]);
			}
			ResultSet rs = ps.executeQuery();
			return call.getData(rs);
		} catch (SQLException e) {
			e.printStackTrace();
		}
		return null;
	}
	
	//查詢返回介面 jdk1.8支援
//	public interface CallBack<T>{
//		default List<T> getDatas(ResultSet rs){
//			return null;
//		}
//		default T getData(ResultSet rs){
//			return null;
//		}
//	}
	
	//jdk1.8以下使用抽象類
	public static abstract class CallBack<T>{
		public List<T> getDatas(ResultSet rs){
			return null;
		}
		public T getData(ResultSet rs){
			return null;
		}
	}
	
	public static void main(String[] args) {
		System.out.println(getConn());
	}
}