Java学习Day37：HTML 第六章：黄金国（项目思路梳理）

第一天：后端思路梳理及代码实现

1.数据库设计

数据库设计使用一张表（course）设计

sql 复制代码

CREATE TABLE course(
     id INT  PRIMARY KEY AUTO_INCREMENT  COMMENT '课程ID',
     cname VARCHAR(255) NOT NULL COMMENT '课程名称',
     price DOUBLE  NOT NULL COMMENT '售卖价格',
     num_sort INT NOT    NULL DEFAULT 0 COMMENT '排序',
     cstatus  TINYINT NOT NULL DEFAULT 1 COMMENT '状态',
     course_bri VARCHAR(255)   NOT NULL COMMENT '课程简介',
     teacher_name    VARCHAR(255)   NOT NULL COMMENT '讲师姓名',   
     teacher_bri   VARCHAR(255)   COMMENT '讲师简介',
     course_ol TEXT   NOT NULL COMMENT '课程概述',
     price_sale DOUBLE  COMMENT  '原价',
     activ_flag VARCHAR(255) COMMENT  '活动标签',
     img_url VARCHAR(255) COMMENT  '图片路径',
     share_title VARCHAR(255) NOT NULL COMMENT  '分享标题',
     share_bri VARCHAR(255) NOT NULL COMMENT  '分享简介',
     course_other TEXT COMMENT  'markdown',
    createTime   DATETIME DEFAULT CURRENT_TIMESTAMP NULL COMMENT '创建时间',
    updateTime   DATETIME DEFAULT CURRENT_TIMESTAMP NULL ON UPDATE CURRENT_TIMESTAMP COMMENT '修改时间');

2.环境搭建，依赖导入

使用三层架构，搭项目；

3.接口分析以及接口文档的书写

一共需要五个接口，接下来开始接口分析及书写；

1.测试类测试数据库连接

2.集成Tomcat

3.优化sevleat

发现书写接口时，不同接口对应不同的sevlet对象的话，会产生大量sevlet对象！

思路：使用反射机制来动态调用方法，使用继承机制来讲sevlet和具体执行方法分开！

java 复制代码

package com.gzd.controller;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;
import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;
public class BaseController extends HttpServlet {
    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        String method=req.getParameter("method");
        if (method!=null){
            Class  clazz = this.getClass();
            try {
                Method method1 = clazz.getMethod(method, HttpServletRequest.class, HttpServletResponse.class);
                method1.invoke(this,req,resp);
            } catch (NoSuchMethodException e) {
                throw new RuntimeException(e);
            } catch (InvocationTargetException e) {
                throw new RuntimeException(e);
            } catch (IllegalAccessException e) {
                throw new RuntimeException(e);
            }
        }
    }
}

复制代码

=======================================================================================

java 复制代码

package com.gzd.controller;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

@WebServlet("/course")
public class CourseManagerController extends BaseController{
    public void findAll(HttpServletRequest req, HttpServletResponse resp){
        System.out.println("我是findAll方法");
    }
    public void findByName(HttpServletRequest req, HttpServletResponse resp){
        System.out.println("我是findByName方法");
    }
    public void findByStatus(HttpServletRequest req, HttpServletResponse resp){
        System.out.println("我是findByStatus方法");
    }
}

4.测试数据和实体类

java 复制代码

package com.gzd.javaBean;
import lombok.AllArgsConstructor;
import lombok.Data;
import lombok.NoArgsConstructor;
import java.util.Date;
@Data
@AllArgsConstructor//有参构造
@NoArgsConstructor//无参构造
public class Course {
    private Integer id;
    private String cname;
    private Double price;
    private Integer numSort;
    private Integer cstatus;
    private String courseBri;
    private String teacherName;
    private String teacherBri;
    private String courseOl;
    private Double priceSale;
    private String activFlag;
    private String imgUrl;
    private String shareTitle;
    private String shareBri;
    private String courseOther;
    private Date createTime;
    private Date updateTime;
}

sql 复制代码

INSERT INTO course (cname, price, num_sort, cstatus, course_bri, teacher_name, teacher_bri, course_ol, price_sale, activ_flag, img_url, share_title, share_bri, course_other, createTime, updateTime)  
VALUES   
('数据库基础', 99.99, 1, 1, '介绍数据库的基本概念和操作', '张老师', '资深数据库专家，多年教学经验', '本课程将详细介绍数据库的基础知识和常用操作。', 199.99, '限时优惠', 'https://example.com/database.jpg', '学习数据库，从基础开始', '掌握数据库知识，提升编程技能。', '## 数据库简介\n### 什么是数据库\n...\n### 数据库的作用\n...', NOW(), NOW()),  
  
('Java编程入门', 149.99, 2, 1, 'Java编程语言入门课程，适合零基础学员', '李老师', 'Java开发专家，擅长Java Web开发', '本课程将引导学员从零开始学习Java编程语言。', 299.99, '早鸟优惠', 'https://example.com/java.jpg', 'Java编程，轻松入门', '零基础学Java，成为编程高手。', '## Java简介\n### Java的历史\n...\n### Java的特点\n...', NOW(), NOW()),  
  
('Python数据分析', 299.99, 3, 1, '利用Python进行数据分析的实战课程', '王老师', '数据分析专家，擅长Python和机器学习', '本课程将教授学员如何使用Python进行数据分析。', 399.99, '新用户专享', 'https://example.com/python.jpg', 'Python数据分析，提升职场竞争力', '掌握Python数据分析，解锁职场新技能。', '## Python数据分析简介\n### 为什么选择Python\n...\n### Python数据分析工具\n...', NOW(), NOW());

5.接口编写：

java 复制代码

public interface CourseDao {
    
    public List<Course> findAll();
    public Course findByname(String cname);
    //查询状态
    public List<Course> findBystatus(String status);

    public int insert(Course course);
}

java 复制代码

public class CourseDaoImp implements CourseDao {
    //注入依赖
    private JdbcTemplate jdbcTemplate = new JdbcTemplate(JDBCUtils.getDataSource());
    @Override
    public List<Course> findAll() {
        return jdbcTemplate.query("SELECT id,cname,price,num_sort,cstatus FROM course",
                new BeanPropertyRowMapper<Course>(Course.class));
    }

    @Override
    public Course findByname(String cname) {
        return jdbcTemplate.query("SELECT id,cname,price,num_sort,cstatus FROM course where cname=?",
                new BeanPropertyRowMapper<Course>(Course.class),cname).get(0);
    }

    @Override
    public List<Course> findBystatus(String cstatus) {
        return jdbcTemplate.query("SELECT id,cname,price,num_sort,cstatus FROM course where cstatus=?",
                new BeanPropertyRowMapper<Course>(Course.class),cstatus);

    }

    @Override
    public int insert(Course course) {
        Object[] arr = {
                course.getCname(),
                course.getPrice(),
                course.getNumSort(),
                course.getCstatus(),
                course.getCourseBri(),
                course.getTeacherName(),
                course.getTeacherBri(),
                course.getCourseOl(),
                course.getPriceSale(),
                course.getActivFlag(),
                course.getImgUrl(),
                course.getShareTitle(),
                course.getShareBri(),
                course.getCourseOther(),
                course.getCreateTime(),
                course.getUpdateTime()};
        return   jdbcTemplate.update("insert into course values (null,?,?,?,?,?,?,?,?,?,?,?,?,?,?,?,?)", arr);
    }
}

java 复制代码

public interface CourseService {

    //查询所有
    public String findAll();
    public String findByname(String cname);
    public String findBystatus(String status);

    //保存
    public String saveCourse(Course course);
}

java 复制代码

public class CourseServiceImp implements CourseService {
    //注入依赖Dao层
    private CourseDao courseDao = new CourseDaoImp();
    @Override
    public String findAll() {

        return  JSON.toJSONString(courseDao.findAll());
    }

    @Override
    public String findByname(String cname) {
        return JSON.toJSONString(courseDao.findByname(cname));
    }

    @Override
    public String findBystatus(String status) {
        return JSON.toJSONString(courseDao.findBystatus(status));
    }

    @Override
    public String saveCourse(Course course) {

        int insert = courseDao.insert(course);
         if (insert ==0){
             return "error!";
         }
        return  "success";
    }
}

java 复制代码

@WebServlet("/course")
public class CourseManagerController extends BaseController {
    //注入依赖
    private CourseService courseService = new CourseServiceImp();
    //1：查询所有
    public void findAll(HttpServletRequest req, HttpServletResponse resp)throws Exception{
         resp.setCharacterEncoding("UTF-8");
        System.out.println(courseService.findAll());
         resp.getWriter().write(courseService.findAll());

    }
    //2:根据课程名称查询
    public void findByName(HttpServletRequest req, HttpServletResponse resp)throws Exception{
        //乱码问题
        req.setCharacterEncoding("UTF-8");
        String cname = req.getParameter("cname");
        resp.setCharacterEncoding("UTF-8");
        resp.getWriter().write(courseService.findByname(cname));
    }
    public void findByStatus(HttpServletRequest req, HttpServletResponse resp)throws Exception{
         resp.setCharacterEncoding("UTF-8");
         resp.getWriter().write(courseService.findBystatus(req.getParameter("cstatus")));
    }
    //新建接口
    public void saveCourse(HttpServletRequest req, HttpServletResponse resp) throws Exception{
        //接受前端数据
        DiskFileItemFactory factory = new DiskFileItemFactory();
        //核心类
        ServletFileUpload upload = new ServletFileUpload(factory);
        //开始解析
        //判断req有没有二进制的表单
        boolean flag = ServletFileUpload.isMultipartContent(req);
        //实体类
        Course course = new Course();
        //map集合
        Map<String,Object> map = new HashMap<>();
        if (flag){
            //转换
            List<FileItem> list= upload.parseRequest(req);
            if (list!=null){
                for (FileItem fileItem :  list){
                    //实体类
                    //普通数据 文件数据
                    boolean flag_ = fileItem.isFormField();
                    if (flag_){
                        //获取key
                        String key = fileItem.getFieldName();
                        //获取value,指定字符集
                        String value = fileItem.getString("UTF-8");
                        //实体类封装
                       map.put(key,value);
                    }else {
                        InputStream inputStream = fileItem.getInputStream();
                        String imgurl  = "http://localhost:8080/uploda"+System.currentTimeMillis()+fileItem.getName();
                        FileOutputStream outputStream = new FileOutputStream(imgurl);
                        //读写操作
                        IOUtils.copy(inputStream,outputStream);
                        //添加到map中
                        map.put("imgurl",imgurl);
                    }
                }
            }
        }
        //完成封装，调用service
        BeanUtils.populate(course,map);
        resp.getWriter().write(courseService.saveCourse(course));
    }
    //修改接口
}

java 复制代码

public class BaseController extends HttpServlet {
    @Override
    protected void service(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        //所有的请求都能接 method+接口名
        String method = req.getParameter("method");
        if (method!=null){
            try {
                //获取运行当前类时对象
                Class  class_ = this.getClass();//Class对象<>  CourseManagerController
                //Object o = class_.getConstructor().newInstance();
                //获取当前运行时类的方法
                Method class_method = class_.getMethod(method, HttpServletRequest.class,
                        HttpServletResponse.class);
                //调用方啊
                class_method.invoke(this,req,resp);
            } catch (Exception e) {
                System.out.println("没有该请求");
                e.printStackTrace();
            }
        }

    }
}