真的，稳住，考上研，利用两年逆袭。一步一步来，实在不行，最后最差也不过就是就回家种地，想想也不错。
前期准备配置
建一个动态web项目
新建Dynamic Web Project
File->New->Other->Web->Dynamic Web Project新建web.xml文件并新建几个包
开始写代码
在entity在新建两个类，User（用来登录）和Hero（用来增删改查）
user表和用户表，代建。
数据库连接放util中包中
package util;import java.sql.Connection;import java.sql.DriverManager;import javax.sound.midi.Soundbank;public class DbUtil { private String dbUrl="jdbc:mysql://localhost:3306/how2java"; private String dbUserName="root"; private String dbPassword="123456"; private String jdbcName="com.mysql.jdbc.Driver"; /** * 获取数据库连接 * @return * @throws Exception */ public Connection getCon() throws Exception{ Class.forName(jdbcName); Connection con=DriverManager.getConnection(dbUrl,dbUserName,dbPassword); System.out.println("数据库连接成功！"); return con; } /** * 关闭数据库连接 * @param con * @throws Exception */ public void closeCon(Connection con) throws Exception{ if(con!=null){ con.close(); } } } hero的增删查改的方法实现放在dao包下
package dao;import java.util.ArrayList;import java.util.List;import com.mysql.jdbc.Connection;import com.mysql.jdbc.PreparedStatement;import com.mysql.jdbc.ResultSet;import com.mysql.jdbc.Statement;import entity.Hero;import util.DbUtil;public class HeroDAO { DbUtil dbutil = new DbUtil();//添加新英雄 public void add(Hero hero) { String sql = "insert into hero values(null,?,?,?)"; try { Connection c = (Connection) dbutil.getCon(); PreparedStatement ps = (PreparedStatement) c.prepareStatement(sql); ps.setString(1, hero.name); ps.setFloat(2, hero.hp); ps.setInt(3, hero.damage); ps.execute(); ResultSet rs = (ResultSet) ps.getGeneratedKeys(); if (rs.next()) { int id = rs.getInt(1); hero.id = id; } } catch (Exception e) { e.printStackTrace(); } }//更新英雄 public void update(Hero hero) { String sql = "update hero set name= ?, hp = ? , damage = ? where id = ?"; try (Connection c = (Connection) dbutil.getCon(); PreparedStatement ps = (PreparedStatement) c.prepareStatement(sql);) { ps.setString(1, hero.name); ps.setFloat(2, hero.hp); ps.setInt(3, hero.damage); ps.setInt(4, hero.id); ps.execute(); } catch (Exception e) { e.printStackTrace(); } }//删除英雄 public void delete(int id) { try (Connection c = (Connection) dbutil.getCon(); Statement s = (Statement) c.createStatement();) { String sql = "delete from hero where id = " + id; s.execute(sql); } catch (Exception e) { e.printStackTrace(); } }//根据id号获得英雄 public Hero get(int id) { Hero hero = null; try (Connection c = (Connection) dbutil.getCon(); Statement s = (Statement) c.createStatement();) { String sql = "select * from hero where id = " + id; ResultSet rs = (ResultSet) s.executeQuery(sql); if (rs.next()) { hero = new Hero(); String name = rs.getString(2); float hp = rs.getFloat("hp"); int damage = rs.getInt(4); hero.name = name; hero.hp = hp; hero.damage = damage; hero.id = id; } } catch (Exception e) { e.printStackTrace(); } return hero; } public List list() { return list(0, Short.MAX_VALUE); } public List list(int start, int count) { List heros = new ArrayList (); String sql = "select * from hero order by id asc limit ?,? "; try (Connection c = (Connection) dbutil.getCon(); PreparedStatement ps = (PreparedStatement) c.prepareStatement(sql);) { ps.setInt(1, start); ps.setInt(2, count); ResultSet rs = (ResultSet) ps.executeQuery(); while (rs.next()) { Hero hero = new Hero(); int id = rs.getInt(1); String name = rs.getString(2); float hp = rs.getFloat("hp"); int damage = rs.getInt(4); hero.id = id; hero.name = name; hero.hp = hp; hero.damage = damage; heros.add(hero); } } catch (Exception e) { e.printStackTrace(); } return heros; }}
登录模块
login.html
登录页面
从
LoginServlet servlet.LoginServlet LoginServlet /login
现在编写LoginServlet类
package servlet;import javax.servlet.http.HttpServlet;import javax.servlet.http.HttpServletRequest;import javax.servlet.http.HttpServletResponse;import com.mysql.jdbc.Connection;import com.mysql.jdbc.ResultSet;import com.mysql.jdbc.Statement;import util.DbUtil;public class LoginServlet extends HttpServlet { protected void doPost(HttpServletRequest request, HttpServletResponse response) { String name = request.getParameter("name"); String password = request.getParameter("password"); System.out.println(name + " " + password); String sql = "select * from user where name = '" + name +"' and password = '" + password+"'"; DbUtil dbConnect = new DbUtil(); try { Connection con = (Connection) dbConnect.getCon(); Statement s = (Statement) con.createStatement(); ResultSet set = (ResultSet) s.executeQuery(sql); if (set.next()) { System.out.println("账号密码正确"); request.getSession().setAttribute("userName", name); request.getRequestDispatcher("/listHero").forward(request, response);//服务器跳转 } else { response.sendRedirect("fail.html");// 客户端跳转 System.out.println("账号密码错误"); } } catch (Exception e) { e.printStackTrace(); } }} 客户端跳转我设置了登录信息错误跳转到的页面
Insert title here 密码或账号错误
回到登陆界面重新登陆
服务器跳转是在web.xml中映射一个路径，然后在相应的servlet中执行操作
HeroListServlet servlet.HeroListServlet HeroListServlet /listHero
编写HeroListServlet，以html形式展示出英雄列表
package servlet;import java.io.IOException;import java.util.List;import javax.servlet.ServletException;import javax.servlet.http.HttpServlet;import javax.servlet.http.HttpServletRequest;import javax.servlet.http.HttpServletResponse;import dao.HeroDAO;import entity.Hero;public class HeroListServlet extends HttpServlet{ protected void service(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { String userName = (String) request.getSession().getAttribute("userName"); System.out.println("欢迎"+userName); if (null == userName) { response.sendRedirect("login.html"); return; } response.setContentType("text/html; charset=UTF-8"); List heros = new HeroDAO().list(); StringBuffer sb = new StringBuffer(); sb.append(" Welcome:
"); String ps = (" %s
"); String ps1 = String.format(ps, userName); sb.append(ps1); ps1 = (" ");//增加添加新成员的连接 sb.append(ps1); sb.append(" \r\n"); sb.append(" id name hp damage delete edit \r\n"); String trFormat = " %d %s %f %d " + " delete "//添加删除连接 + " edit \r\n";//添加修改连接 for (Hero hero : heros) { //System.out.println(hero); String tr = String.format(trFormat, hero.getId(), hero.getName(), hero.getHp(), hero.getDamage(),hero.getId(),hero.getId());//设置删除和修改连接下的id就是相对应英雄的id sb.append(tr); } sb.append("
"); response.getWriter().write(sb.toString()); }} 增加新成员链接下的操作
转到添加页面addHero.html
添加英雄
package 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 dao.HeroDAO;import entity.Hero;import net.sf.json.JSONObject;public class HeroAddServlet extends HttpServlet{ protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException{ request.setCharacterEncoding("UTF-8"); String name = request.getParameter("name"); String hp = request.getParameter("hp"); String damage = request.getParameter("damage"); Hero hero = new Hero(); hero.setName(name); hero.setHp(Float.parseFloat(hp)); hero.setDamage(Integer.parseInt(damage)); new HeroDAO().add(hero); System.out.println("添加成功"+hero.toString()); request.getRequestDispatcher("/listHero").forward(request, response); }} 配置web.xml（添加编辑删除的）
HeroAddServlet /addHero HeroDeleteServlet servlet.HeroDeleteServlet HeroDeleteServlet /deleteHero HeroEditServlet servlet.HeroEditServlet HeroEditServlet /editHero
删除操作
package 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 dao.HeroDAO;public class HeroDeleteServlet extends HttpServlet { public void service(HttpServletRequest request, HttpServletResponse response) throws IOException, ServletException { int id = Integer.parseInt(request.getParameter("id"));//获得要删除的id new HeroDAO().delete(id);//调用删除英雄方法 request.getRequestDispatcher("/listHero").forward(request, response);//跳转到展示hero页面 }} 编辑操作
package servlet;import java.io.IOException;import javax.servlet.http.HttpServlet;import javax.servlet.http.HttpServletRequest;import javax.servlet.http.HttpServletResponse;import dao.HeroDAO;import entity.Hero;public class HeroEditServlet extends HttpServlet { public void service(HttpServletRequest request, HttpServletResponse response) throws IOException { int id = Integer.parseInt(request.getParameter("id")); Hero hero = new HeroDAO().get(id); StringBuffer format = new StringBuffer(); response.setContentType("text/html; charset=UTF-8"); format.append(""); format.append(" "); String html = String.format(format.toString(), hero.getName(), hero.getHp(), hero.getDamage(), hero.getId()); response.getWriter().write(html); }} package 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 dao.HeroDAO;import entity.Hero; public class HeroUpdateServlet extends HttpServlet { protected void service(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { request.setCharacterEncoding("UTF-8"); Hero hero = new Hero(); hero.setId(Integer.parseInt(request.getParameter("id"))); hero.setName(request.getParameter("name")); hero.setHp(Float.parseFloat(request.getParameter("hp"))); hero.setDamage(Integer.parseInt(request.getParameter("damage"))); new HeroDAO().update(hero); request.getRequestDispatcher("/listHero").forward(request, response); }} 小结：
- 前端的数据可以在服务端通过其name属性，利用request.getParameter("xxx");来获取
- 设置session，request.getSession().setAttribute("userName", name);这样在服务端就可以通过 request.getSession().getAttribute("userName");获取存入session的username
- 服务端跳转 request.getRequestDispatcher("success.html").forward(request, response);服务端跳转可以看到浏览器的地址依然是之前的路径路径，并不会变成success.html
- 客户端跳转 response.sendRedirect("fail.html");