MyBatis编写hello world代码的方法

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目录

准备 SQL 脚本下载需要的依赖 jar 包准备日志配置文件 & jdbc 配置编写 hello world

准备 SQL 脚本

这里我使用的数据库是 MySQL 7 版本 。表设计了 student （学生表） ， course （课程表），score（分数表）脚本如下：

SET NAMES utf8mb4;SET FOREIGN_KEY_CHECKS = 0;-- ------------------------------ Table structure for course-- ----------------------------DROP TABLE IF EXISTS `course`;CREATE TABLE `course`  (  `course_id` int(10) UNSIGNED NOT NULL AUTO_INCREMENT,  `name` varchar(255) CHARACTER SET utf8mb4 COLLATE utf8mb4_general_ci NOT NULL DEFAULT '',  PRIMARY KEY (`course_id`) USING BTREE) ENGINE = InnoDB CHARACTER SET = utf8mb4 COLLATE = utf8mb4_general_ci ROW_FORMAT = Dynamic;-- ------------------------------ Records of course-- ----------------------------INSERT INTO `course` VALUES (1, '仁德');INSERT INTO `course` VALUES (2, '霸道');INSERT INTO `course` VALUES (3, '兵法');INSERT INTO `course` VALUES (4, '骑马');INSERT INTO `course` VALUES (5, '射箭');INSERT INTO `course` VALUES (6, '防御');INSERT INTO `course` VALUES (7, '青龙偃月刀');INSERT INTO `course` VALUES (8, '丈八蛇矛');INSERT INTO `course` VALUES (9, '长枪');INSERT INTO `course` VALUES (10, '制衡');INSERT INTO `course` VALUES (11, '医术');INSERT INTO `course` VALUES (12, '观星');INSERT INTO `course` VALUES (13, '天文');INSERT INTO `course` VALUES (14, '地理');INSERT INTO `course` VALUES (15, '兵器');INSERT INTO `course` VALUES (16, '双股剑');INSERT INTO `course` VALUES (17, '龙胆');INSERT INTO `course` VALUES (18, '铁骑');-- ------------------------------ Table structure for score-- ----------------------------DROP TABLE IF EXISTS `score`;CREATE TABLE `score`  (  `score_id` int(11) UNSIGNED NOT NULL AUTO_INCREMENT,  `student_id` int(10) UNSIGNED NOT NULL,  `course_id` int(10) UNSIGNED NOT NULL,  `score` decimal(65, 0) UNSIGNED NOT NULL,  PRIMARY KEY (`score_id`) USING BTREE) ENGINE = InnoDB CHARACTER SET = utf8mb4 COLLATE = utf8mb4_general_ci ROW_FORMAT = Dynamic;-- ------------------------------ Records of score-- ----------------------------INSERT INTO `score` VALUES (1, 1, 7, 99);INSERT INTO `score` VALUES (2, 2, 8, 95);INSERT INTO `score` VALUES (3, 3, 17, 99);INSERT INTO `score` VALUES (4, 4, 5, 90);INSERT INTO `score` VALUES (5, 5, 18, 96);INSERT INTO `score` VALUES (6, 5, 9, 90);INSERT INTO `score` VALUES (7, 4, 9, 96);INSERT INTO `score` VALUES (8, 6, 1, 99);INSERT INTO `score` VALUES (9, 6, 3, 60);INSERT INTO `score` VALUES (10, 6, 16, 80);INSERT INTO `score` VALUES (11, 7, 12, 96);INSERT INTO `score` VALUES (12, 7, 13, 93);INSERT INTO `score` VALUES (13, 7, 14, 98);INSERT INTO `score` VALUES (14, 8, 12, 96);INSERT INTO `score` VALUES (15, 9, 10, 91);INSERT INTO `score` VALUES (16, 10, 2, 99);INSERT INTO `score` VALUES (17, 10, 3, 95);INSERT INTO `score` VALUES (18, 11, 11, 100);INSERT INTO `score` VALUES (19, 12, 15, 93);-- ------------------------------ Table structure for student-- ----------------------------DROP TABLE IF EXISTS `student`;CREATE TABLE `student`  (  `student_id` int(11) UNSIGNED NOT NULL AUTO_INCREMENT,  `name` varchar(255) CHARACTER SET utf8mb4 COLLATE utf8mb4_general_ci NOT NULL,  `sex` varchar(255) CHARACTER SET utf8mb4 COLLATE utf8mb4_general_ci NOT NULL,  `age` tinyint(4) UNSIGNED NOT NULL,  `create_time` datetime(0) NOT NULL ON UPDATE CURRENT_TIMESTAMP(0),  `modify_time` datetime(0) NOT NULL ON UPDATE CURRENT_TIMESTAMP(0),  PRIMARY KEY (`student_id`) USING BTREE) ENGINE = InnoDB CHARACTER SET = utf8mb4 COLLATE = utf8mb4_general_ci ROW_FORMAT = Dynamic;-- ------------------------------ Records of student-- ----------------------------INSERT INTO `student` VALUES (1, '关羽', '男', 55, '2019-10-31 10:23:50', '2019-10-31 10:23:52');INSERT INTO `student` VALUES (2, '张飞', '男', 52, '2019-10-31 10:25:50', '2019-10-31 10:25:50');INSERT INTO `student` VALUES (3, '赵云', '男', 50, '2019-10-31 10:24:37', '2019-10-31 10:24:39');INSERT INTO `student` VALUES (4, '黄忠', '男', 60, '2019-10-31 10:25:06', '2019-10-31 10:25:08');INSERT INTO `student` VALUES (5, '马超', '男', 40, '2019-10-31 10:25:23', '2019-10-31 10:25:27');INSERT INTO `student` VALUES (6, '刘备', '男', 55, '2019-10-31 10:25:43', '2019-10-31 10:25:46');INSERT INTO `student` VALUES (7, '诸葛亮', '男', 30, '2019-10-31 10:26:05', '2019-10-31 10:26:07');INSERT INTO `student` VALUES (8, '郭嘉', '男', 25, '2019-10-31 10:26:32', '2019-10-31 10:26:35');INSERT INTO `student` VALUES (9, '孙权', '男', 27, '2019-10-31 10:26:51', '2019-10-31 10:26:53');INSERT INTO `student` VALUES (10, '曹操', '男', 60, '2019-10-31 10:27:08', '2019-10-31 10:27:10');INSERT INTO `student` VALUES (11, '华佗', '男', 70, '2019-10-31 10:27:23', '2019-10-31 10:27:25');INSERT INTO `student` VALUES (12, '孙尚香', '女', 25, '2019-10-31 10:27:42', '2019-10-31 10:27:45');SET FOREIGN_KEY_CHECKS = 1;

下载需要的依赖 jar 包

这里我使用的项目构建工具是 maven ， 以下代码只选取 dependencies 标签部分 ：

                    org.mybatis            mybatis            3.5.3                            junit            junit            4.12            test                            org.projectlombok            lombok            1.18.10            provided                            mysql            mysql-connector-java            6.0.6                            log4j            log4j            1.2.17                            org.slf4j            slf4j-api            1.7.28            

准备日志配置文件 & jdbc 配置

LOG 使用 log4j （mybatis log 支持中包含对 log4j 的支持）

lo4j.properties

log4j.rootLogger=TRACE, stdoutlog4j.appender.stdout=org.apache.log4j.ConsoleAppenderlog4j.appender.stdout.layout=org.apache.log4j.PatternLayoutlog4j.appender.stdout.layout.ConversionPattern=%-d{yyyy-MM-dd HH:mm:ss.SSS} [%t] -[%c] -[%p]%m%nlog4j.logger.org.apache.ibatis=TRACE

jdbc.properties 配置

jdbc.driver=com.mysql.cj.jdbc.Driverjdbc.url=jdbc:mysql://localhost:3306/mybatis-demo?characterEncoding=utf8&allowMultiQueries=true&useSSL=false&serverTimezone=Asia/Shanghaijdbc.user=xxxjdbc.password=xxx

注意使用 mysql-connector-java 6 以上版本的时候需要指定serverTimezone 参数，否则启动时会报错。

编写 hello world 代码

1. 编写和数据库表对应的实体类

Student class

package org.hepeng.demo.mybatis.entity;import lombok.Data;import java.util.Date;/** * @author he peng */@Datapublic class Student {    private Integer studentId;    private String name;    private String sex;    private Byte age;    private Date createTime;    private Date modifyTime;}

Course class

package org.hepeng.demo.mybatis.entity;import lombok.Data;/** * @author he peng */@Datapublic class Course {    private Integer courseId;    private String name;}

Score class

package org.hepeng.demo.mybatis.entity;import lombok.Data;/** * @author he peng */@Datapublic class Score {    private Integer scoreId;    private Integer studentId;    private Integer courseId;    private Double score;}

2. 编写 mybatis 配置文件

mybatis-config.xml

3. 编写 mapper 配置文件

在 resources 目录下新建 mapper 目录 ，mapper 目录下新建 StudentMapper.xml （ mapper/StudentMapper.xml ）

            select * from student    

4. 编写测试代码

package org.hepeng.demo.mybatis;import lombok.extern.slf4j.Slf4j;import org.apache.ibatis.io.Resources;import org.apache.ibatis.session.SqlSessionFactory;import org.apache.ibatis.session.SqlSessionFactoryBuilder;import org.junit.Assert;import org.junit.Before;import java.io.InputStream;import java.util.List;/** * @author he peng */@Slf4jpublic class Test {    SqlSessionFactory sqlSessionFactory;    @Before    public void sqlSessionFactory() throws Exception {        InputStream inputStream = Resources.getResourceAsStream("mybatis-config.xml");        sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream);    }    @org.junit.Test    public void helloWorld() {        // sqlId = mapper.xml 中的 namespace.id        String sqlId = "Student.selectAll";        List