最近在项目中应用到springboot与mybatis，在进行整合过程中遇到一些坑，在此将其整理出来，便于以后查阅与复习。
项目运行环境为：eclispe+jdk1.8+maven
搭建Spring Boot环境
首先建立maven project,在生成的pom文件中加入依赖，代码如下：
<parent>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-parent</artifactId>
<version>1.5.2.RELEASE</version>
<relativePath/> <!-- lookup parent from repository --></parent><properties>
<project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
<project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding>
<java.version>1.8</java.version></properties><dependencies>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-web</artifactId>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-test</artifactId>
</dependency>
<dependency>
<groupId>org.mybatis.spring.boot</groupId>
<artifactId>mybatis-spring-boot-starter</artifactId>
<version>1.3.0</version>
</dependency>
<dependency>
<groupId>mysql</groupId>
<artifactId>mysql-connector-java</artifactId>
<scope>runtime</scope>
</dependency>
<!--分页插件-->
<dependency>
<groupId>com.github.pagehelper</groupId>
<artifactId>pagehelper-spring-boot-starter</artifactId>
<version>1.2.1</version>
</dependency>
<!-- alibaba的druid数据库连接池 -->
<dependency>
<groupId>com.alibaba</groupId>
<artifactId>druid</artifactId>
<version>1.0.29</version>
</dependency></dependencies><build>
<plugins>
<plugin>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-maven-plugin</artifactId>
</plugin>
<!-- mybatis generator 自动生成代码插件 -->
<plugin>
<groupId>org.mybatis.generator</groupId>
<artifactId>mybatis-generator-maven-plugin</artifactId>
<version>1.3.2</version>
<configuration>
<configurationFile>${basedir}/src/main/resources/generator/generatorConfig.xml</configurationFile>
<overwrite>true</overwrite>
<verbose>true</verbose>
</configuration>
</plugin>
</plugins></build>配置好依赖后进行maven install,此时注意的坑：
坑一：启动maven install报错：
[ERROR] Failed to execute goal org.springframework.boot:spring-boot-maven-plugin:1.5.2.RELEASE:repackage (default) on project springboot-mybatis: Execution default of goal org.springframework.boot:spring-boot-maven-plugin:1.5.2.RELEASE:repackage failed: Unable to find main class -> [Help 1] [ERROR] [ERROR] To see the full stack trace of the errors, re-run Maven with the -e switch. [ERROR] Re-run Maven using the -X switch to enable full debug logging. [ERROR] [ERROR] For more information about the errors and possible solutions, please read the following articles: [ERROR] [Help 1] http://cwiki.apache.org/confluence/display/MAVEN/PluginExecutionException
报错原因是没有启动类
解决方法:编写启动类Main.java正常运行！
@SpringBootApplicationpublic class Main {
public static void main(String[] args) {
SpringApplication.run(Main.class, args);
}
}坑二：启动maven install报错：
[ERROR] Failed to execute goal org.apache.maven.plugins:maven-compiler-plugin:3.1:compile (default-compile) on project springboot-mybatis: Compilation failure[ERROR] No compiler is provided in this environment. Perhaps you are running on a JRE rather than a JDK? [ERROR] -> [Help 1] [ERROR] [ERROR] To see the full stack trace of the errors, re-run Maven with the -e switch. [ERROR] Re-run Maven using the -X switch to enable full debug logging. [ERROR] [ERROR] For more information about the errors and possible solutions, please read the following articles: [ERROR] [Help 1] http://cwiki.apache.org/confluence/display/MAVEN/MojoFailureException
报错原因：项目的java环境与电脑环境不符合，例如我的新建项目运行环境为J2SE-1.5,报错是在我将其改为jre1.8之后
解决方案：
右键项目——build path——Configure build path——Libraries——双击Jre System Libraries如下图所示：
选择Alternate JRE 如2处的下拉框只有jre，点击3处的Install JREs，依次经过add——Standard VM——next——Directory,选择本机的jdk位置点击finish
在install JREs位置将默认勾选更改jdk,如下图所示，并保存。
再次maven install项目正常。如下所示：
[INFO] BUILD SUCCESS[INFO] ------------------------------------------------------------------------ [INFO] Total time: 3.351 s [INFO] Finished at: 2018-09-05T21:20:48+08:00[INFO] Final Memory: 23M/181M[INFO] ------------------------------------------------------------------------
在src/main/resources新建文件：application.yml，内容如下所示：
server: port: 8080spring: datasource: name: test url: jdbc:mysql://localhost:3306/test username: root password: 123456 driver-class-name: com.mysql.jdbc.Driver## 该配置节点为独立的节点mybatis: mapper-locations: classpath:mapper/*.xml #pagehelper分页插件pagehelper: helperDialect: mysql reasonable: true supportMethodsArguments: true params: count=countSql
至此springboot环境搭建完毕！
逆向工程应用
首先应该注意到在pom文件中有配置逆向工程xml文件的位置：src/main/resources/generator/generatorConfig.xml
因而在src/main/resources下新建generator文件夹，并建立generatorConfig.xml文件，代码如下：
<?xml version="1.0" encoding="UTF-8"?><!DOCTYPE generatorConfiguration PUBLIC "-//mybatis.org//DTD MyBatis Generator Configuration 1.0//EN" "http://mybatis.org/dtd/mybatis-generator-config_1_0.dtd"><generatorConfiguration> <!-- 数据库驱动:选择你的本地硬盘上面的数据库驱动包--> <classPathEntry location="E:\plugins\maven\repo\mysql\mysql-connector-java\5.1.41\mysql-connector-java-5.1.41.jar"/> <context id="DB2Tables" targetRuntime="MyBatis3"> <commentGenerator> <property name="suppressDate" value="true"/> <!-- 是否去除自动生成的注释 true：是 ： false:否 --> <property name="suppressAllComments" value="true"/> </commentGenerator> <!--数据库链接URL，用户名、密码 --> <jdbcConnection driverClass="com.mysql.jdbc.Driver" connectionURL="jdbc:mysql://localhost/test" userId="root" password="123456"> </jdbcConnection> <javaTypeResolver> <property name="forceBigDecimals" value="false"/> </javaTypeResolver> <!-- 生成pojo类的位置--> <javaModelGenerator targetPackage="com.luis.entity" targetProject="src/main/java"> <property name="enableSubPackages" value="true"/> <property name="trimStrings" value="true"/> </javaModelGenerator> <!-- 生成映射文件的包名和位置--> <sqlMapGenerator targetPackage="mapper" targetProject="src/main/resources"> <!-- enableSubPackages 是否让schema作为包的后缀--> <property name="enableSubPackages" value="false"/> </sqlMapGenerator> <!-- 生成mapper接口的位置--> <javaClientGenerator type="XMLMAPPER" targetPackage="com.luis.mapper" targetProject="src/main/java"> <!-- enableSubPackages 是否让schema作为包的后缀--> <property name="enableSubPackages" value="false"/> </javaClientGenerator> <!-- 指定数据库表 --> <table schema="" tableName="user"></table> </context></generatorConfiguration>
根据个人环境将配置文件中的配置进行更改，如数据库密码，包名，对应数据库表
所用的数据库表如下：
DROP TABLE IF EXISTS `user`;CREATE TABLE `user` ( `id` bigint(20) NOT NULL, `name` varchar(255) NOT NULL, `age` int(4) NOT NULL,
PRIMARY KEY (`id`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8;INSERT INTO `user` VALUES ('1', 'wanger', '22');INSERT INTO `user` VALUES ('2', 'zhangsan', '18');INSERT INTO `user` VALUES ('3', 'lisi', '23');INSERT INTO `user` VALUES ('4', 'wangwu', '21');配置完成后，右键项目，选择run as——Maven build——在下面两处分别填入：
Goals: mybatis-generator:generate -e
Profiles: generatorConfig.xml
如下图所示：
出现如下所示，代码生成成功，刷新项目即可。
[INFO] Generating Example class for table user[INFO] Generating Record class for table user[INFO] Generating Mapper Interface for table user[INFO] Generating SQL Map for table user[INFO] Saving file UserMapper.xml[INFO] Saving file UserExample.java[INFO] Saving file User.java[INFO] Saving file UserMapper.java[INFO] ------------------------------------------------------------------------[INFO] BUILD SUCCESS[INFO] ------------------------------------------------------------------------
需要注意的是：逆向工程生成的代码不会覆盖，因而不能重复多次生成。
此处也有个小坑，逆向工程的代码生成后，启动项目会报如下错误：
*************************** APPLICATION FAILED TO START *************************** Description: Field userMapper in com.luis.service.impl.UserServiceImpl required a bean of type 'com.luis.mapper.UserMapper' that could not be found. Action: Consider defining a bean of type 'com.luis.mapper.UserMapper' in your configuration.
解决方案：
1、给生成的mapper接口文件前加注解：@Mapper 即可解决。但需要给每一个mapper文件前加，繁琐，因而有第二种类解决办法
2、在启动类前加@MapperScan({"com.luis.mapper"})，其中com.luis.mapper为mapper文件的所在位置。
参考自：http://412887952-qq-com.iteye.com/blog/2392672
分页应用
逆向工程已经生成了entity类，及dao层的mapper接口与*mapper.xml文件，因而/只用编写service层与web层。
首先在UserService中编写接口，代码如下：
public interface UserService { User selectByName(String name); List<User> findAllUser(int pageNum, int pageSize);
}在UserServiceImpl文件进行实现，代码如下所示：
@Servicepublic class UserServiceImpl implements UserService { @Autowired
private UserMapper userMapper;
@Override
public User selectByName(String name) {
UserExample example = new UserExample();
Criteria criteria = example.createCriteria();
criteria.andNameEqualTo(name);
List<User> users = userMapper.selectByExample(example); if (users != null && users.size() > 0) { return users.get(0);
} return null;
}
/**
* pageNum 开始页数
* pageSize 每页显示的数据条数
*/
@Override
public List<User> findAllUser(int pageNum, int pageSize) { //将参数传给方法实现分页
PageHelper.startPage(pageNum, pageSize);
UserExample example = new UserExample();
List<User> list = userMapper.selectByExample(example); return list;
}
}最后在controller层对查询结果进行接收，UserController代码如下：
@Controller@RestControllerpublic class UserController {
@Autowired
private UserService userService;
@RequestMapping("/test") public User querUserByName() {
User user = userService.selectByName("luis");
System.out.println(user.toString()); return user;
}
@RequestMapping("/list") public List<User> querUser() {
List<User> list = userService.findAllUser(1, 2); //获取分页信息
PageInfo<User> pageInfo = new PageInfo<>(list);
System.out.println("total:" + pageInfo.getTotal());
System.out.println("pages:" + pageInfo.getPages());
System.out.println("pageSize:" + pageInfo.getPageSize()); return list;
}
}测试
此前在项目编写过程中已经对可能出现的错误进行了总结，最后，对项目的功能进行测试，通过加@RestController注解将数据传输到浏览器中。
测试mybatis与springboot，浏览器输入http://localhost:8080/test，浏览器输出：
{"id":1,"name":"wanger","age":22}分页测试，浏览器输入http://localhost:8080/list，浏览器输出：
[{"id":1,"name":"wanger","age":22},{"id":2,"name":"zhangsan","age":18}]eclipse输出：
total:4pages:2pageSize:2
项目搭建完毕，具体代码参见github
本文参考了：
http://412887952-qq-com.iteye.com/blog/2392672
https://blog.csdn.net/rico_rico/article/details/79408474
https://blog.csdn.net/winter_chen001/article/details/77249029
作者：luis
出处：http://www.cnblogs.com/liuyi6/
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