一个简单的javaweb项目模板
- Controller包：表现层（视图）层。用来显示数据和接收用户数据
- Service包：业务逻辑层，用来处理页面。先写接口，后写实现类
- Dao包：持久层（数据访问层）。用来操作数据库
其中Dao包处于最底层，对于用户处于隐藏状态，对于开发者处于固定状态，其中包括Con_CloseSql类（数据库连接与关闭）、UserDao类（进行增删改查）与UserBeans（数据库数据）
Con_CloseSql类：
package dao; import java.sql.*; public class Con_CloseSql { final String JDBC_DRIVER = "com.mysql.cj.jdbc.Driver"; final String DB_URL = "jdbc:mysql://localhost:3306/表名?serverTimezone=GMT&characterEncoding=utf-8&useSSL=false"; final String USER = "root"; final String PASS = "密码"; Statement stmt = null; public Connection getConnect() { Connection conn = null; try{ Class.forName(JDBC_DRIVER); String url = DB_URL; conn = DriverManager.getConnection(url, USER, PASS); return conn; }catch(ClassNotFoundException nfe) { nfe.printStackTrace(); }catch(SQLException e) { e.printStackTrace(); } return conn; } public static void closeConnection(Connection connection) { if(connection != null) { try{ connection.close(); }catch(SQLException sqle) { sqle.printStackTrace(); } } } }
UserDao类：
package dao; import bean.UserBean; import java.sql.*; import java.util.ArrayList; import java.util.List; public class UserDao {
//保存用户数据 public void saveUser(UserBean userBean) throws SQLException { Connection connect = new Con_CloseSql().getConnect(); Statement statement = connect.createStatement(); String sql = "insert into 表名 values (?,?,?,?,?,?,?,?,?)"; try { PreparedStatement pr = connect.prepareStatement(sql); pr.setString(1, userBean.getHutype()); pr.setString(2, userBean.getHousetype()); pr.setString(3, userBean.getArea()); pr.setString(4, userBean.getNum()); pr.setString(5, userBean.getName()); pr.setString(6, userBean.getId()); pr.setString(7, userBean.getSex()); pr.setString(8, userBean.getNation()); pr.setString(9, userBean.getEducation()); pr.execute(); } catch (Exception e) { e.printStackTrace(); } finally { Con_CloseSql.closeConnection(connect); } }
//通过name删除该行 public void deleteUser(UserBean userBean) { Connection connect = new Con_CloseSql().getConnect(); String sql = "delete from 表名 where name=? "; try { PreparedStatement pr = connect.prepareStatement(sql); pr.setString(1, userBean.getName()); pr.executeUpdate(); } catch (SQLException throwables) { throwables.printStackTrace(); } }
//查询数据库中消息并从前端输出表格 public List<UserBean> query() { Connection connect = new Con_CloseSql().getConnect(); String sql = "select * from 表名"; List<UserBean> userBeans = new ArrayList<>(); try { try (PreparedStatement ps = connect.prepareStatement(sql)) { ResultSet resultSet = ps.executeQuery(sql); UserBean userBean = null; while (resultSet.next()) { String hutype = resultSet.getString("..."); String housetype = resultSet.getString("..."); String area = resultSet.getString("..."); //表头关键字 userBean = new UserBean(..., ..., ...,...);//表中元素 userBeans.add(userBean); } } } catch (SQLException e) { // TODO Auto-generated catch block e.printStackTrace(); } finally { Con_CloseSql.closeConnection(connect); } return userBeans; }
//通过名字来展示信息 public UserBean queryByName(String name) { Connection connect = new Con_CloseSql().getConnect(); String sql = "select * from census where 户主姓名 = '"+name+"' "; UserBean userBean = null; //Object[] params = {name}; try { try (PreparedStatement ps = connect.prepareStatement(sql)) { ResultSet resultSet = ps.executeQuery(sql); if (resultSet.next()) { String hutype = resultSet.getString("户别"); String housetype = resultSet.getString("住房类型"); String area = resultSet.getString("本户现住房面积"); String num = resultSet.getString("本户现住房间数"); String name1 = resultSet.getString("户主姓名"); String id = resultSet.getString("身份证号码"); String sex = resultSet.getString("性别"); String nation = resultSet.getString("民族"); String education = resultSet.getString("受教育程度"); userBean = new UserBean(hutype, housetype, area, num, name1, id, sex, nation, education); } } } catch (SQLException e) { // TODO Auto-generated catch block e.printStackTrace(); } finally { Con_CloseSql.closeConnection(connect); } return userBean; } //通过名字更新其他信息 public void upDate(UserBean user){ Connection connect = new Con_CloseSql().getConnect(); String sql="update census set 身份证号码=?,性别=?,民族=?,受教育程度=? where 户主姓名=?"; try { PreparedStatement ps = connect.prepareStatement(sql); ps.setString(1, user.getId()); ps.setString(2, user.getSex()); ps.setString(3,user.getNation()); ps.setString(4,user.getEducation()); ps.setString(5,user.getName()); int i= ps.executeUpdate(); } catch (SQLException e) { // TODO Auto-generated catch block e.printStackTrace(); }finally{ Con_CloseSql.closeConnection(connect); } }
//判断是否为该用户 public boolean isUser(String name) { Connection connect = new Con_CloseSql().getConnect(); try { String sql = "select * from census where 户主姓名 = '" + name + "'"; // 执行查询语句，并把结果集返回给ResultSet PreparedStatement pr = connect.prepareStatement(sql); ResultSet rs = pr.executeQuery(); if (rs.next()) return true; else return false; } catch (SQLException e) { // TODO Auto-generated catch block return false; } } public ArrayList<String> findDate() { Connection conn = new Con_CloseSql().getConnect(); String sql = "select * from census"; PreparedStatement pr; try { pr = (PreparedStatement)conn.prepareStatement(sql); ResultSet rs = pr.executeQuery(); int col = rs.getMetaData().getColumnCount(); ArrayList<String> m = new ArrayList<String>(); int n = 0; while (rs.next()) { for (int i = 1; i <= col; i++) { m.add(rs.getString(i) + "<br>"); System.out.print(rs.getString(i) + "\t"); if ((i == 2) && (rs.getString(i).length() < 8)) { m.add("<br>"); } } System.out.println(""); } return m; } catch (SQLException e) { e.printStackTrace(); } return null; } }
Service包主要包括各种servlet
XXXServlet类：
package service; import javax.servlet.ServletException; import javax.servlet.http.HttpServlet; import javax.servlet.http.HttpServletRequest; import javax.servlet.http.HttpServletResponse; import java.io.IOException; public class XXXServlet extends HttpServlet { @Override protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException { req.setCharacterEncoding("utf-8"); resp.setCharacterEncoding("utf-8"); resp.setContentType("text/html;utf-8"); } @Override protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException { doGet(req, resp); } }
pom.xml常用配置为：
<dependency>
<groupId>javax.servlet</groupId>
<artifactId>servlet-api</artifactId>
<version>2.5</version>
</dependency>
<dependency>
<groupId>javax.servlet.jsp</groupId>
<artifactId>javax.servlet.jsp-api</artifactId>
<version>2.3.3</version>
</dependency>
<dependency>
<groupId>mysql</groupId>
<artifactId>mysql-connector-java</artifactId>
<version>8.0.13</version>
</dependency>
<!-- https://mvnrepository.com/artifact/javax.servlet/jstl -->
<dependency>
<groupId>javax.servlet</groupId>
<artifactId>jstl</artifactId>
<version>1.2</version>
</dependency>
<!-- https://mvnrepository.com/artifact/taglibs/standard -->
<dependency>
<groupId>taglibs</groupId>
<artifactId>standard</artifactId>
<version>1.1.2</version>
</dependency>
web.xml为：
<?xml version="1.0" encoding="UTF-8"?> <web-app xmlns="http://xmlns.jcp.org/xml/ns/javaee" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://xmlns.jcp.org/xml/ns/javaee http://xmlns.jcp.org/xml/ns/javaee/web-app_4_0.xsd" version="4.0" metadata-complete="true"> <welcome-file-list> <welcome-file>index.html</welcome-file> </welcome-file-list> </web-app>
jsp基础配置为：
<%@ page contentType="text/html;charset=UTF-8" language="java" %> <%@taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core" %> <html> <head> <title>Title</title> </head> <body> </body> </html>
