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目录
数据库表是应⽤程序开发中的⼀个重要环节, 数据库表的设计往往会决定我们的应⽤需求是否能顺利实现, 甚至决定我们的实现方式. 如何设计表以及这些表有哪些字段、关系也是非常重要的.
数据库表设计是依据业务需求来设计的,数据库表通常分两种: 实体表和关系表.
创建数据库 book_test
- -- 创建数据库
- DROP DATABASE IF EXISTS book_test;
- CREATE DATABASE book_test DEFAULT CHARACTER SET utf8mb4;
- USE book_test;
- -- ⽤户表
- DROP TABLE IF EXISTS user_info;
- CREATE TABLE user_info (
- `id` INT NOT NULL AUTO_INCREMENT,
- `user_name` VARCHAR ( 128 ) NOT NULL,
- `password` VARCHAR ( 128 ) NOT NULL,
- `delete_flag` TINYINT ( 4 ) NULL DEFAULT 0,
- `create_time` DATETIME DEFAULT now(),
- `update_time` DATETIME DEFAULT now() ON UPDATE now(),
- PRIMARY KEY ( `id` ),
- UNIQUE INDEX `user_name_UNIQUE` ( `user_name` ASC )) ENGINE = INNODB DEFAULT CHARSET = utf8mb4 COMMENT = '⽤户表 ';
- -- 图书表
- DROP TABLE IF EXISTS book_info;
- CREATE TABLE `book_info` (
- `id` INT ( 11 ) NOT NULL AUTO_INCREMENT,
- `book_name` VARCHAR ( 127 ) NOT NULL,
- `author` VARCHAR ( 127 ) NOT NULL,
- `count` INT ( 11 ) NOT NULL,
- `price` DECIMAL (7,2 ) NOT NULL,
- `publish` VARCHAR ( 256 ) NOT NULL,
- `status` TINYINT ( 4 ) DEFAULT 1 COMMENT '0-⽆效 , 1-正常 , 2-不允许借阅 ',
- `create_time` DATETIME DEFAULT now(),
- `update_time` DATETIME DEFAULT now() ON UPDATE now(),
- PRIMARY KEY ( `id` )
- ) ENGINE = INNODB DEFAULT CHARSET = utf8mb4;
-
- -- 初始化数据
- INSERT INTO user_info ( user_name, PASSWORD ) VALUES ( "admin", "admin" );
- INSERT INTO user_info ( user_name, PASSWORD ) VALUES ( "zhangsan", "123456" );
- -- 初始化图书数据
- INSERT INTO `book_info` (book_name,author,count, price, publish) VALUES ('活着 ','Romised',100,12.2,'出版社');
- INSERT INTO `book_info` (book_name,author,count, price, publish) VALUES ('不活着', 'Romised', 100, 22.2, '出版社');
- INSERT INTO `book_info` (book_name,author,count, price, publish) VALUES ('想活着 ','Romised',100,32.2,'出版社');
- INSERT INTO `book_info` (book_name,author,count, price, publish) VALUES ('要活着 ','Romised',100,42.2,'出版社');

修改pom.xml文件:
- <dependency>
- <groupId>org.mybatis.spring.boot</groupId>
- <artifactId>mybatis-spring-boot-starter</artifactId>
- <version>2.3.1</version>
- </dependency>
- <dependency>
- <groupId>com.mysql</groupId>
- <artifactId>mysql-connector-j</artifactId>
- <scope>runtime</scope>
- </dependency>
修改application.yml配置文件:
# 数据库连接配置 spring: datasource: url: jdbc:mysql://127.0.0.1:3306/book_test?characterEncoding=utf8&useSSL=false username: root password: 123456 driver-class-name: com.mysql.cj.jdbc.Driver mybatis: configuration: map-underscore-to-camel-case: true #配置驼峰自动转换 # log-impl: org.apache.ibatis.logging.stdout.StdOutImpl #打印sql语句 mapper-locations: classpath:mapper/**Mapper.xml # 设置日志文件的文件名 logging: file: name: logger/spring-book.log
创建UserInfo类:
- @Data
- public class UserInfo {
- private Integer id;
- private String userName;
- private String password;
- private Integer deleteFlag;
- private Date createTime;
- private Date updateTime;
- }
创建BookInfo类:
- @Data
- public class BookInfo {
- private Integer id;
- private String bookName;
- private String author;
- private Integer count;
- //前端展示精度
- @JsonFormat(shape = JsonFormat.Shape.STRING)
- private BigDecimal price;
- private String publish;
- private Integer status; //0-删除 1-可借阅,2-不可借阅
- private String statusCN;
- }
约定前后端交互接口:
- [请求]
- /user/login
- Content-Type: application/x-www-form-urlencoded; charset=UTF-8
-
- [参数]
- name=zhangsan&password=123456 8
- [响应]
- true //账号密码验证正确 , 否则返回false
浏览器给服务器发送/user/login这样的HTTP请求,服务器给浏览器返回Boolean类型的数据
实现服务器代码
控制层:从数据库中, 根据名称查询用户, 如果可以查到, 并且密码⼀致, 就认为登录成功
创建UserController:
- @RequestMapping("/user")
- @RestController
- public class UserController {
- @Autowired
- private UserService userService;
-
- @RequestMapping("/login")
- public Boolean login(String userName, String password, HttpSession session){
- //校验参数是否为空
- if (!StringUtils.hasLength(userName) || !StringUtils.hasLength(password)){
- return false;
- }
-
- //验证账号密码是否正确
- //1. 根据用户名去查找用户信息
- UserInfo userInfo = userService.getUserInfoByName(userName);
- //2. 比对密码是否正确
- if (userInfo==null || userInfo.getId()<=0){
- return false;
- }
- if (password.equals(userInfo.getPassword())){
- //账号密码正确
- //存Session
- userInfo.setPassword("");
- session.setAttribute(Constants.SESSION_USER_KEY,userInfo);
- return true;
- }
-
- return false;
-
- }
- }

业务层:
创建UserService:
- @Service
- public class UserService {
- @Autowired
- private UserInfoMapper userInfoMapper;
-
- public UserInfo getUserInfoByName(String name){
- return userInfoMapper.selectUserByName(name);
- }
- }
数据层:
创建UserInfoMapper:
- @Mapper
- public interface UserInfoMapper {
- /**
- * 根据用户名称查询用户信息
- * @param name
- * @return
- */
- @Select("select * from user_info where user_name=#{name}")
- UserInfo selectUserByName(String name);
-
- }
这边使用*是为了方便观察,开发中需要挨个写出数据库字段名
测试:
部署程序,验证服务器是否能够正确返回数据,可以在Postman中输入URL进行测试,最好联动前端一起进行测试:
输⼊错误的⽤户名和密码, 页面弹窗警告
输入正确的用户名和密码, 页面正常跳转到booklist.html页面
约定前后端交互接口:
- [请求]
- /book/addBook
- Content-Type: application/x-www-form-urlencoded; charset=UTF-8
- [参数]
- bookName=图书1&author=作者1&count=23&price=36&publish=出版社1&status=1
- [响应]
- "" //失败信息 , 成功时返回空字符串
我们约定,浏览器给服务器发送book/addBook这样的HTTP请求,以from表单的形式提交数据
服务器返回处理结果, 返回""表示添加图书成功, 否则, 返回失败信息.
实现服务器代码
控制层:
创建BookController:
- @Slf4j
- @RequestMapping("/book")
- @RestController
- public class BookController {
-
- @Autowired
- private BookService bookService;
-
- @RequestMapping("/getBookListByPage")
- public Result getBookListByPage(PageRequest pageRequest, HttpSession session){
- log.info("查询翻页信息, pageRequest:{}",pageRequest);
- //用户登录校验
- UserInfo userInfo = (UserInfo) session.getAttribute(Constants.SESSION_USER_KEY);
- if (userInfo==null|| userInfo.getId()<=0 || "".equals(userInfo.getUserName())){
- //用户未登录
- return Result.unlogin();
- }
- //校验成功
- if (pageRequest.getPageSize()<0 || pageRequest.getCurrentPage()<1){
- return Result.fail("参数校验失败");
- }
- PageResult<BookInfo> bookInfoPageResult = null;
- try {
- bookInfoPageResult = bookService.selectBookInfoByPage(pageRequest);
- return Result.success(bookInfoPageResult);
- }catch (Exception e){
- log.error("查询翻页信息错误,e:{}",e);
- return Result.fail(e.getMessage());
- }
- }
-
- @RequestMapping(value = "/addBook", produces = "application/json")
- public String addBook(BookInfo bookInfo){
- log.info("接收到添加图书请求, bookInfo:{}",bookInfo);
- //参数校验
- if (!StringUtils.hasLength(bookInfo.getBookName())
- || !StringUtils.hasLength(bookInfo.getAuthor())
- || bookInfo.getCount()<0
- || bookInfo.getPrice()==null
- || !StringUtils.hasLength(bookInfo.getPublish())){
- return "参数校验失败, 请检查入参";
- }
- Integer result = bookService.addBook(bookInfo);
- if (result<=0){
- log.error("添加图书出错:bookInfo:{}",bookInfo);
- return "添加图书出错, 请联系管理人";
- }
- return "";
- }
- }

业务层:
创建BookService:
- @Slf4j
- @Service
- public class BookService {
-
- @Autowired
- private BookInfoMapper bookInfoMapper;
- /**
- * 添加图书
- *
- * @param bookInfo
- * @return
- */
- public Integer addBook(BookInfo bookInfo) {
- Integer result = 0;
- try {
- result = bookInfoMapper.insertBook(bookInfo);
- } catch (Exception e) {
- log.error("添加图书出错, e:{}", e);
- }
- return result;
- }
- }

数据层:
创建BookInfoMapper文件:
- @Mapper
- public interface BookInfoMapper {
- /**
- * 获取当前页的信息
- * @param offset
- * @param pageSize
- * @return
- */
- @Select("select * from book_info where status !=0 " +
- "order by id asc limit #{offset},#{pageSize}")
- List<BookInfo> selectBookInfoByPage(Integer offset, Integer pageSize);
-
- @Insert("insert into book_info (book_name,author, count, price, publish, status) " +
- "values(#{bookName}, #{author}, #{count}, #{price},#{publish}, #{status})")
- Integer insertBook(BookInfo bookInfo);
- }

前端代码中补全add():
- function add() {
- $.ajax({
- type:"post",
- url: "/book/addBook",
- data:$("#addBook").serialize(),//提交整个form表单
- success:function(result){
-
- if (result != null && result.code == "SUCCESS" && result.data=="") {
- //图书添加成功
- location.href = "book_list.html";
- }else{
- console.log(result.code);
- alert(result);
- }
- },
- error: function (error) {
- console.log(error);
- //用户未登录
- if (error != null && error.status == 401) {
- location.href = "login.html";
- }
-
- }
- });
-
- }

假设数据库中的数据有很多,一下子全部展示出来肯定不现实,我们可以使用分页来解决这个问题
分页时, 数据是如何展示的呢 第1页: 显⽰1-10 条的数据、第2页: 显⽰11-20 条的数据 第3页: 显⽰21-30 条的数据 以此类推...
要想实现这个功能, 从数据库中进行分页查询 ,我们要使用LIMIT关键字
查询第一页的SQL语句:
SELECT * FROM book_info LIMIT 0,10
查询第二页的SQL语句:
SELECT * FROM book_info LIMIT 10,10
查询第三页的SQL语句:
SELECT * FROM book_info LIMIT 20,10
观察以上SQL语句 ,发现: 开始索引⼀直在改变, 每页显⽰条数是固定的 开始索引的计算公式: 开始索引 = (当前页码 - 1) * 每页显示条数
前端在发起查询请求时 ,需要向服务端传递的参数 。
currentPage 当前页码,默认值为1
pageSize 每页显示条数,默认值为10
为了项⽬更好的扩展性, 通常不设置固定值,而是以参数的形式来进行传递 扩展性: 软件系统具备面对未来需求变化而进行扩展的能⼒
比如当前需求⼀页显示10条, 后期需求改为⼀页显示20条, 后端代码不需要任何修改
后端响应时, 需要响应给前端的数据
records 所查询到的数据列表(存储到List 集合中)
total 总记录数 (用于告诉前端显示多少页, 显示页数为:(total+pageSize-1)/pageSize
显示页数totalPage 计算公式为 : total % pagesize == 0 ? total / pagesize : (total / pagesize)+1 ;
pagesize - 1 是 total / pageSize 的最⼤的余数 ,所以(total + pagesize -1) / pagesize就得到总页数
翻页请求和响应部分, 我们通常封装在两个对象中
翻页请求对象:
- @Data
- public class PageRequest {
- private int currentPage = 1; // 当前页
- private int pageSize = 10; // 每页中的记录数
- private int offset;
- public int getOffset() {
- return (currentPage-1) * pageSize;
- }
- }
翻页列表结果类:
- import lombok.Data;
- import java.util.List;
- @Data
- public class PageResult<T> {
- private int total;//所有记录数
- private List<T> records; // 当前页数据
- public PageResult(Integer total, List<T> records) {
- this.total = total;
- this.records = records;
- }
- }
返回结果中, 使⽤泛型来定义记录的类型
约定前后端交互接口
[请求] /book/getListByPage?currentPage=1 Content-Type: application/x-www-form-urlencoded; charset=UTF-8 [参数] [响应] Content-Type: application/json 10 { "total": 25, "records": [{ "id": 25, "bookName": "图书21", "author": "作者2", "count": 29, "price": 22.00, "publish": "出版社1", "status": 1, "statusCN": "可借阅 " }, { ...... } ] }
我们约定,浏览器给服务器发送book/getListByPage这样的HTTP请求,通过currentPage参数告诉服务器当前请求为第几页的数据, 后端根据请求参数, 返回对应页的数据
实现服务器代码
控制层:
完善 BookController:
- @Slf4j
- @RequestMapping("/book")
- @RestController
- public class BookController {
-
- @Autowired
- private BookService bookService;
-
- @RequestMapping("/getBookListByPage")
- public Result getBookListByPage(PageRequest pageRequest, HttpSession session){
- log.info("查询翻页信息, pageRequest:{}",pageRequest);
- // //用户登录校验
- // UserInfo userInfo = (UserInfo) session.getAttribute(Constants.SESSION_USER_KEY);
- // if (userInfo==null|| userInfo.getId()<=0 || "".equals(userInfo.getUserName())){
- // //用户未登录
- // return Result.unlogin();
- // }
- //校验成功
- if (pageRequest.getPageSize()<0 || pageRequest.getCurrentPage()<1){
- return Result.fail("参数校验失败");
- }
- PageResult<BookInfo> bookInfoPageResult = null;
- try {
- bookInfoPageResult = bookService.selectBookInfoByPage(pageRequest);
- return Result.success(bookInfoPageResult);
- }catch (Exception e){
- log.error("查询翻页信息错误,e:{}",e);
- return Result.fail(e.getMessage());
- }
- }
-
- @RequestMapping(value = "/addBook", produces = "application/json")
- public String addBook(BookInfo bookInfo){
- log.info("接收到添加图书请求, bookInfo:{}",bookInfo);
- //参数校验
- if (!StringUtils.hasLength(bookInfo.getBookName())
- || !StringUtils.hasLength(bookInfo.getAuthor())
- || bookInfo.getCount()<0
- || bookInfo.getPrice()==null
- || !StringUtils.hasLength(bookInfo.getPublish())){
- return "参数校验失败, 请检查入参";
- }
- Integer result = bookService.addBook(bookInfo);
- if (result<=0){
- log.error("添加图书出错:bookInfo:{}",bookInfo);
- return "添加图书出错, 请联系管理人";
- }
- return "";
-
- }
-
- @RequestMapping("/queryBookInfoById")
- public BookInfo queryBookInfoById(Integer bookId){
- // long start = System.currentTimeMillis();
- log.info("根据ID查询图书, bookId:"+bookId);
- BookInfo bookInfo = null;
- try {
- bookInfo = bookService.queryBookInfoById(bookId);
- }catch (Exception e){
- log.error("查询图书失败, e:{}",e);
- }
- // long end = System.currentTimeMillis();
- // log.info("queryBookInfoById 执行耗时: "+ (end-start) + "ms");
- return bookInfo;
- }
-
- @RequestMapping(value = "/updateBook", produces = "application/json")
- public String updateBook(BookInfo bookInfo){
- log.info("接收到更新图书的请求, bookInfo:{}",bookInfo);
- Integer result = bookService.updateBook(bookInfo);
- if (result == 0){
- log.error("更新图书失败, 请联系管理员");
- return "更新图书失败, 请联系管理员";
- }
- return "";
- }
-
- @RequestMapping(value = "/batchDelete", produces = "application/json")
- public String batchDelete(@RequestParam List<Integer> ids){
- log.info("接收请求, 批量删除图书, 图书ID:{}",ids);
- Integer result = bookService.batchDelete(ids);
- if (result<=0){
- log.error("批量删除失败, ids:{}",ids);
- return "批量删除失败, 请联系管理员";
- }
- return "";
- }
- }
-

业务层:
BookService
- @Slf4j
- @Service
- public class BookService {
-
- @Autowired
- private BookInfoMapper bookInfoMapper;
-
- public PageResult<BookInfo> selectBookInfoByPage(PageRequest pageRequest) {
- if (pageRequest == null) {
- return null;
- }
- //获取总记录数
- Integer count = bookInfoMapper.count();
- //获取当前记录
- List<BookInfo> bookInfos = bookInfoMapper.selectBookInfoByPage(pageRequest.getOffset(), pageRequest.getPageSize());
- if (bookInfos != null && bookInfos.size() > 0) {
- for (BookInfo bookInfo : bookInfos) {
- //根据status 获取状态的定义
- bookInfo.setStatusCN(BookStatusEnum.getNameByCode(bookInfo.getStatus()).getName());
- }
- }
-
- return new PageResult<>(bookInfos, count, pageRequest);
-
- }
-
- /**
- * 添加图书
- *
- * @param bookInfo
- * @return
- */
- public Integer addBook(BookInfo bookInfo) {
- Integer result = 0;
- try {
- result = bookInfoMapper.insertBook(bookInfo);
- } catch (Exception e) {
- log.error("添加图书出错, e:{}", e);
- }
- return result;
- }
-
- public BookInfo queryBookInfoById(Integer id) {
- return bookInfoMapper.queryBookInfoById(id);
- }
-
- /**
- * 更新图书
- * @param bookInfo
- * @return
- */
- public Integer updateBook(BookInfo bookInfo) {
- Integer result = 0;
- try {
- result = bookInfoMapper.updateBook(bookInfo);
- } catch (Exception e) {
- log.error("更新图书失败, e:{}", e);
- }
- return result;
- }
- public Integer batchDelete(List<Integer> ids){
- Integer result =0;
- try {
- result = bookInfoMapper.batchDelete(ids);
- }catch (Exception e){
- log.error("批量删除图书失败, ids:{}",ids);
- }
- return result;
- }
- }

翻页信息需要返回数据的总数和列表信息, 需要查两次SQL
图书状态: 图书状态和数据库存储的status有⼀定的对应关系
如果后续状态码有变动, 我们需要修改项目中所有涉及的代码, 这种情况, 通常采用枚举类来处理映射关系
数据层:
翻页查询SQL
- @Mapper
- public interface BookInfoMapper {
- /**
- * 获取当前页的信息
- * @param offset
- * @param pageSize
- * @return
- */
- @Select("select * from book_info where status !=0 " +
- "order by id asc limit #{offset},#{pageSize}")
- List<BookInfo> selectBookInfoByPage(Integer offset, Integer pageSize);
-
- /**
- * 获取总记录数
- * @return
- */
- @Select("select count(1) from book_info where status !=0")
- Integer count();
- }

实现客户端代码:
- function getBookList() {
- $.ajax({
- type: "get",
- url: "/book/getBookListByPage" + location.search,
- success: function (result) {
- //真实的前端处理逻辑, 要比咱们代码复杂
- if (result.code == "UNLOGIN") {
- location.href = "login.html";
- return;
- }
-
- var finalHtml = "";
- //加载列表
- var pageResult = result.data;
- for (var book of pageResult.records) {
- //根据每一条记录去拼接html, 也就是一个tr
- finalHtml += '<tr>';
- finalHtml += '<td><input type="checkbox" name="selectBook" value="' + book.id + '" id="selectBook" class="book-select"></td>';
- finalHtml += '<td>' + book.id + '</td>';
- finalHtml += '<td>' + book.bookName + '</td>';
- finalHtml += '<td>' + book.author + '</td>';
- finalHtml += '<td>' + book.count + '</td>';
- finalHtml += '<td>' + book.price + '</td>';
- finalHtml += '<td>' + book.publish + '</td>';
- finalHtml += '<td>' + book.statusCN + '</td>';
- finalHtml += '<td><div class="op">';
- finalHtml += '<a href="book_update.html?bookId=' + book.id + '">修改</a>';
- finalHtml += '<a href="javascript:void(0)" onclick="deleteBook(' + book.id + ')">删除</a>';
- finalHtml += '</div></td></tr>';
- }
-
- $("tbody").html(finalHtml);
-
- //翻页信息
- $("#pageContainer").jqPaginator({
- totalCounts: pageResult.total, //总记录数
- pageSize: 10, //每页的个数
- visiblePages: 5, //可视页数
- currentPage: pageResult.pageRequest.currentPage, //当前页码
- first: '<li class="page-item"><a class="page-link">首页</a></li>',
- prev: '<li class="page-item"><a class="page-link" href="javascript:void(0);">上一页<\/a><\/li>',
- next: '<li class="page-item"><a class="page-link" href="javascript:void(0);">下一页<\/a><\/li>',
- last: '<li class="page-item"><a class="page-link" href="javascript:void(0);">最后一页<\/a><\/li>',
- page: '<li class="page-item"><a class="page-link" href="javascript:void(0);">{{page}}<\/a><\/li>',
- //页面初始化和页码点击时都会执行
- onPageChange: function (page, type) {
- console.log("第" + page + "页, 类型:" + type);
- if (type == "change") {
- location.href = "book_list.html?currentPage=" + page;
- }
-
- }
- });
-
- },
- error: function (error) {
- console.log(error);
- if (error.status == 401) {
- console.log("401");
- location.href = "login.html";
- }
- }
- });
- }

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