超市订单管理系统
GitHub: github.com/hsowan/somsSOMS
Supermarket Orders Management System 超市订单管理系统Day 01
使用MyBatisMyBatis 官方文档
Refer: www.mybatis.org/mybatis-3/z…类型别名
类型别名是你的好帮手。使用它们，你就可以不用输入类的完全限定名称了。比如： 复制代码log4j2
Refer: logging.apache.org/log4j/2.x/m…Eclipse for Mac 快捷键删除一行
Command + D
Refer: www.cnblogs.com/TankXiao/p/…格式化代码
Shift + Command + FDay 02
MyBatis 核心配置mybatis-config.xml 配置configuration（配置）properties（属性）settings（设置）typeAliases（类型别名）typeHandlers（类型处理器）objectFactory（对象工厂）plugins（插件）environments（环境配置） environment（环境变量） transactionManager（事务管理器） dataSource（数据源）databaseIdProvider（数据库厂商标识）mappers（映射器）
Refer: www.mybatis.org/mybatis-3/z…mapper.xml 配置insert – 映射插入语句update – 映射更新语句delete – 映射删除语句select – 映射查询语句resultMap – 是最复杂也是最强大的元素，用来描述如何从数据库结果集中来加载对象。sql – 可被其他语句引用的可重用语句块。cache – 对给定命名空间的缓存配置。cache-ref – 对其他命名空间缓存配置的引用。
Refer: www.mybatis.org/mybatis-3/z…使用单例模式创建SqlSessionFactory/** * 主配置文件路径 */ private static String config = ＂mybatis-config.xml＂; private static SqlSessionFactory sqlSessionFactory; /** * 使用单例模式获取SqlSessionFactory * @return */ private static synchronized SqlSessionFactory getSqlSessionFactory() { if (sqlSessionFactory == null) { try { // 创建输入流读取配置文件 InputStream is = Resources.getResourceAsStream(config); // 创建SQLSession工厂 sqlSessionFactory = new SqlSessionFactoryBuilder().build(is); } catch (IOException e) { // TODO Auto-generated catch block e.printStackTrace(); } } return sqlSessionFactory; } 复制代码MavenUsing JUnit
添加下面的插件到pom.xml中: org.apache.maven.plugins maven-surefire-plugin 3.0.0-M3 复制代码
执行单元测试: mvn test
Refer: maven.apache.org/surefire/ma…Skipping Tests
mvn install -DskipTests
Refer: maven.apache.org/surefire/ma…JSP 九大内置对象+四大域对象
Refer: my.oschina.net/u/3805464/b…Java 八大基本类型byte/8 char/16 short/16 int/32 float/32 long/64 double/64 boolean/~ 复制代码Day 03
动态SQL官方文档ifchoose (when, otherwise)trim (where, set)foreachbind
www.mybatis.org/mybatis-3/z…if
改写UserMapper.xml: 复制代码
改写单元测试 testListByUsername(使用map进行传参):Map params = new HashMap(); params.put(＂username＂, ＂%user%＂); List users = session.selectList(＂com.ncucoder.mapper.UserMapper.listByUsername＂, params); 复制代码
执行结果:==> Preparing: select id, username, password from user where username like ? ==> Parameters: %user%(String) 复制代码
添加单元测试 testListByUsernameUsingLimit:Map params = new HashMap(); params.put(＂username＂, ＂%user%＂); params.put(＂start＂, 0); params.put(＂count＂, 2); List users = session.selectList(＂com.ncucoder.mapper.UserMapper.listByUsername＂, params); 复制代码
执行结果:==> Preparing: select id, username, password from user where username like ? limit ?, ? ==> Parameters: %user%(String), 0(Integer), 2(Integer) 复制代码bind 模糊查询
修改UserMapper.xml: 复制代码
修改单元测试 testListByUsername():Map params = new HashMap(); // params.put(＂username＂, ＂%user%＂); params.put(＂username＂, ＂user＂); List users = session.selectList(＂com.ncucoder.mapper.UserMapper.listByUsername＂, params); 复制代码
执行结果:==> Preparing: select id, username, password from user where username like ? ==> Parameters: %user%(String) 复制代码SQL优化 in
查询user表中id小于5的记录
使用in的查询执行计划(QEP):mysql> explain select id, username, password from user where id in (1, 2, 3, 4, 5); +----+-------------+-------+------------+------+---------------+------+---------+------+------+----------+-------------+ | id | select_type | table | partitions | type | possible_keys | key | key_len | ref | rows | filtered | Extra | +----+-------------+-------+------------+------+---------------+------+---------+------+------+----------+-------------+ | 1 | SIMPLE | user | NULL | ALL | PRIMARY | NULL | NULL | NULL | 10 | 50.00 | Using where | +----+-------------+-------+------------+------+---------------+------+---------+------+------+----------+-------------+ 1 row in set, 1 warning (0.00 sec) 复制代码
使用<的QEP:mysql> explain select id, username, password from user where id < 6; +----+-------------+-------+------------+-------+---------------+---------+---------+------+------+----------+-------------+ | id | select_type | table | partitions | type | possible_keys | key | key_len | ref | rows | filtered | Extra | +----+-------------+-------+------------+-------+---------------+---------+---------+------+------+----------+-------------+ | 1 | SIMPLE | user | NULL | range | PRIMARY | PRIMARY | 4 | NULL | 5 | 100.00 | Using where | +----+-------------+-------+------------+-------+---------------+---------+---------+------+------+----------+-------------+ 1 row in set, 1 warning (0.00 sec) 复制代码
使用between的QEP:mysql> explain select id, username, password from user where id between 1 and 5; +----+-------------+-------+------------+-------+---------------+---------+---------+------+------+----------+-------------+ | id | select_type | table | partitions | type | possible_keys | key | key_len | ref | rows | filtered | Extra | +----+-------------+-------+------------+-------+---------------+---------+---------+------+------+----------+-------------+ | 1 | SIMPLE | user | NULL | range | PRIMARY | PRIMARY | 4 | NULL | 5 | 100.00 | Using where | +----+-------------+-------+------------+-------+---------------+---------+---------+------+------+----------+-------------+ 1 row in set, 1 warning (0.00 sec) 复制代码type表示对表所使用的访问方式(最优到最差: NULL > system > const > eq_ref > ref > range > index > All)key表示MySQL Query Optimizer从possible_keys中所选择使用的索引rows表示MySQL Query Optimizer通过系统收集到的统计信息估算出来的结果集记录条数, 简单理解为查询需要扫描的记录数
分析: 使用in作为查询条件时没有使用索引而进行了全表扫描(ALL), 使用<和between作为查询条件时使用到主键索引以及索引范围扫描, 所以三者比较in的执行效率是最低的MySQL 批量插入测试数据-- 获取指定长度的随机字符串 drop function if exists `rand_string`; create function `rand_string`(n int) returns varchar(255) charset ＂utf8＂ begin DECLARE chars_str varchar(100) DEFAULT ＂abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789＂; DECLARE return_str varchar(255) DEFAULT ＂＂; DECLARE i INT DEFAULT 0; WHILE i < n DO SET return_str = concat(return_str, substring(chars_str, FLOOR(1 + RAND() * 62), 1)); SET i = i + 1; END WHILE; RETURN return_str; end; -- 插入指定数量的用户 drop procedure if exists `create_users`; create procedure `create_users`(n int) begin declare i int default 0; while (i < n) do insert into user(username, password) values (rand_string(10), rand_string(32)); set i = i + 1; end while; end; -- 调用存储过程 call create_users(1000); 复制代码Day 04MyBatis Generator官方文档
www.mybatis.org/generator/c…
问题:改用MySQL8时, 与其他数据库(mysql库)表名相同时出现错误添加依赖和插件
mybatis-generator-core: org.mybatis.generator mybatis-generator-core ${mybatis-generator.version} 复制代码
mybatis-generator-maven-plugin: org.mybatis.generator mybatis-generator-maven-plugin ${mybatis-generator.version} true true 复制代码添加配置文件generatorConfig.xml生成对应的映射文件、实体类和接口类cd ${your_project} mvn mybatis-generator:generator 复制代码
Refer:www.cnblogs.com/hhhshct/p/9…blog.csdn.net/liyonghong3…集成SpringMVC添加依赖 org.springframework spring-core ${spring.version} org.springframework spring-web ${spring.version} org.springframework spring-webmvc ${spring.version} org.springframework spring-beans ${spring.version} org.springframework spring-context ${spring.version} org.springframework spring-test ${spring.version} test org.springframework spring-jdbc ${spring.version} org.springframework spring-tx ${spring.version} org.mybatis mybatis-spring ${mybatis-spring.version} com.alibaba druid ${druid.version} 复制代码修改web.xml配置文件 soms-dispatcher org.springframework.web.servlet.DispatcherServlet contextConfigLocation classpath:spring/spring-*.xml 1 true soms-dispatcher / encodingFilter org.springframework.web.filter.CharacterEncodingFilter encoding UTF-8 forceEncoding true encodingFilter /* 复制代码添加Spring的配置文件spring-web.xmlspring-dao.xmlspring-service.xml使用MySQL8
修改依赖版本(pom.xml):8.0.16 复制代码
修改驱动路径(db.properties):driver=com.mysql.cj.jdbc.Driver 复制代码Day 05JWT + SpringSecurity
github.com/hsowan/jwt-…
作者：K8sCat
链接：https://juejin.cn/post/7056040075947147295
