在应用MyBatis时，使用对象关系映射，将对象和Aliase映射起来。
在Mybatis的文档明确写出，如果你没有明确定义实体类的Aliase，框架会自动将Class Name自动作为别名。
那么问题来了，当使用java -jar xxx.jar&启动的时候，会报出以下错误，
Error resolving class. Cause: org.apache.ibatis.type.TypeException: Could not resolve type alias "XXXXX".Cause: java.lang.ClassNotFoundException: Cannot find class: XXXXX
从异常信息来看，明显就是无法从本地检索到alise对应的类，并最终导致sqlSessionFactory等初始化失败。而且吊轨的是，直接在Idea中启动是没有问题的，启动jar包才会出现这个问题
参考博主A_Beaver的文章，原来mybatis的facroty需要加载SpringBoot独特的虚拟文件系统，才能识别类路径
public SpringBootVFS() {
this.resourceResolver = new PathMatchingResourcePatternResolver(getClass().getClassLoader());
}从以上代码看，其实是通过PathMatchingResourcePatternResolver实现资源的加载
修复该问题只需要在mybatis的配置类中，设置一下factory即可，
@Bean(name = "masterSqlSessionFactory")
@Primary
public SqlSessionFactory sqlSessionFactory(@Qualifier("masterDataSource") DataSource dataSource) throws Exception {
SqlSessionFactoryBean bean = new SqlSessionFactoryBean();
bean.setDataSource(dataSource);
bean.setVfs(SpringBootVFS.class);//设置SpringBootVFS
bean.setTypeAliasesPackage("com.fulan.domain.red");
...
}1.1 创建项目
1.2 修改POM文件，添加相关依赖
修改pom.xml文件，在其中添加下面依赖。
<!--Thymeleaf启动器--> <dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-thymeleaf</artifactId> </dependency> <dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-web</artifactId> </dependency> <!--mybatis启动器--> <dependency> <groupId>org.mybatis.spring.boot</groupId> <artifactId>mybatis-spring-boot-starter</artifactId> <version>2.1.3</version> </dependency> <!--jdbc启动器--> <dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-jdbc</artifactId> </dependency> <!--数据库驱动坐标--> <dependency> <groupId>mysql</groupId> <artifactId>mysql-connector-java</artifactId> <version>8.0.12</version> </dependency> <!--Druid数据源依赖--> <dependency> <groupId>com.alibaba</groupId> <artifactId>druid</artifactId> <version>1.1.10</version> </dependency>
1.3 配置数据源
在application.yml文件中配置如下代码。
spring: datasource: driver-class-name: com.mysql.cj.jdbc.Driver url: jdbc:mysql://localhost:3306/test?useUnicode=true&characterEnconding=utf-8&useSSL=false&serverTimezone=GMT%2B8 username: root password: root type: com.alibaba.druid.pool.DruidDataSource
2.1 添加generator插件坐标
<!--配置generator插件-->
<plugin>
<groupId>org.mybatis.generator</groupId>
<artifactId>mybatis-generator-maven-plugin</artifactId>
<version>1.4.0</version>
<dependencies>
<dependency>
<groupId>mysql</groupId>
<artifactId>mysql-connector-java</artifactId>
<version>8.0.12</version>
</dependency>
</dependencies>
<!--指定配置文件的路径-->
<configuration>
<configurationFile>${project.basedir}/src/main/resources/generator.xml</configurationFile>
<verbose>true</verbose>
<overwrite>true</overwrite>
</configuration>
</plugin>2.2 添加generator配置文件
将文件命名为generator.xml，在src/main/resources中添加。
<?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> <context id="testTables" targetRuntime="MyBatis3"> <commentGenerator> <!-- 是否去除自动生成的注释 true：是 ： false:否 --> <property name="suppressAllComments" value="true" /> </commentGenerator> <!-- 数据库连接信息：驱动类、连接地址、用户名、密码--> <jdbcConnection driverClass="com.mysql.cj.jdbc.Driver" connectionURL="jdbc:mysql://localhost:3306/test?useUnicode=true&characterEnconding=utf-8&useSSL=false&serverTimezone=UTC" userId="root" password="root"> </jdbcConnection> <!-- 默认false，把JDBC DECIMAL 和 NUMERIC 类型解析为 Integer true，把JDBC DECIMAL 和 NUMERIC 类型解析为java.math.BigDecimal --> <javaTypeResolver> <property name="forceBigDecimals" value="false" /> </javaTypeResolver> <!--targetProject:生成PO类的位置--> <javaModelGenerator targetPackage="com.example.springbootmybatis.pojo" targetProject=".srcmainjava"> <!--enableSubPackages:是否让schema作为包的后缀--> <property name="enableSubPackages" value="false" /> <!-- 从数据库返回的值被清理前后的空格 --> <property name="trimStrings" value="true" /> </javaModelGenerator> <!--对应的mapper.xml文件 --> <sqlMapGenerator targetPackage="com.example.springbootmybatis.mapper" targetProject=".srcmainjava"> <!--enableSubPackages:是否让schema作为包的后缀--> <property name="enableSubPackages" value="false" /> </sqlMapGenerator> <!-- 对应的Mapper接口类文件 --> <javaClientGenerator type="XMLMAPPER" targetPackage="com.example.springbootmybatis.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="users"></table> <!-- 列出要生成代码的所有表，这里配置的是不生成Example文件 --> <!-- <table tableName="userinfo" domainObjectName="UserInfoPO" --> <!-- enableCountByExample="false" enableUpdateByExample="false" --> <!-- enableDeleteByExample="false" enableSelectByExample="false" --> <!-- selectByExampleQueryId="false"> --> <!-- <property name="useActualColumnNames" value="false" /> --> <!-- </table> --> </context> </generatorConfiguration>
2.3 添加generator配置文件的DTD文件
可以在工具栏中的File->Settings中添加，也可以直接在文件中按alt+shift自动添加。
2.4 运行generator插件生成代码
3.1 添加资源拷贝插件坐标
<!--配置资源拷贝插件--> <resources> <resource> <directory>src/main/java</directory> <includes> <include>**/*.xml</include> </includes> </resource> <resource> <directory>src/main/resources</directory> <includes> <include>**/*.yml</include> </includes> </resource> </resources>
3.2 修改启动类添加@MapperScan注解
package com.example.springbootmybatis;
import org.mybatis.spring.annotation.MapperScan;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
@SpringBootApplication
@MapperScan("com.example.springbootmybatis.mapper")//指定扫描接口与映射配置文件的包名
public class DemoApplication {
public static void main(String[] args) {
SpringApplication.run(DemoApplication.class, args);
}
}mybatis: # 扫描classpath中mapper目录下的映射配置文件，针对于映射文件放到了resources目录下 mapper-locations: classpath:/mapper/*.xml # 定义包别名，使用pojo时可以直接使用pojo的类型名称不用加包名 type-aliases-package: com.example.springbootmybatis.pojo
5.1 创建页面
<!DOCTYPE html>
<html xmlns:th="http://www.thymeleaf.org">
<link rel="shortcut icon" href="../resources/favicon.ico" th:href="@{/static/favion.ico}">
<head>
<meta charset="UTF-8">
<title>测试SpringBoot连接PostgreSQL数据库</title>
</head>
<body>
<form th:action="@{/user/addUser}" method="post">
<input type="text" name="userid"><br>
<input type="text" name="username"><br>
<input type="text" name="usersex"><br>
<input type="submit" value="添加"><br>
</form>
</body>
</html>5.2 创建Controller
5.2.1 PageController
package com.example.springbootmybatis.controller;
import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.PathVariable;
import org.springframework.web.bind.annotation.RequestMapping;
/**
* 页面跳转Controller
*/
@Controller
public class PageController {
/**
* 页面跳转方法
*/
@RequestMapping("/{page}")
public String showPage(@PathVariable String page){
return page;
}
}5.2.2 UsersController
package com.example.springbootmybatis.controller;
import com.example.springbootmybatis.pojo.Users;
import com.example.springbootmybatis.service.UsersService;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.PostMapping;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;
/**
* 用户管理Controller
*/
@RestController
@RequestMapping("/user")
public class UsersController {
@Autowired
private UsersService usersService;
/**
* 添加用户
*/
@PostMapping("/addUser")
public String addUsers(Users users){
try {
this.usersService.addUsers(users);
} catch (Exception e){
e.printStackTrace();
return "error";
}
return "redirect:/ok";
}
}5.3 创建Service 接口实现类Impl
/**
* 用户管理业务层
*/
@Service
public class UsersServiceImpl implements UsersService {
@Autowired
private UsersMapper usersMapper;
@Override
@Transactional
public void addUsers(Users users) {
this.usersMapper.insert(users);
}
}接口
public interface UsersService {
void addUsers(Users users);
}1. Mybatis Generator自动生成，数据库的同名表也会生产的问题
[WARNING] Table Configuration users matched more than one table (test..users,performance_schema..users)
[WARNING] Cannot obtain primary key information from the database, generated objects may be incomplete
在 MyBatis Generator官网 中对这一问题做出了解答。
翻译如下：Mysql 无法正常支持 SQL catalogs 和 schema。因此，最好不要在 generator 配置文件中指定 catalog 以及schema，仅需指定数据表的名字并在 JDBC URL 中指定数据库即可。如果使用 mysql-connector-java 8.x 版本，generator 会为MySql中信息数据库(sys, information_schema, performance_schema)的表生成代码，若要避免这种操作，请在 JDBC URL 中加入属性“nullCatalogMeansCurrent=true”。
修改配置文件generator.xml
<jdbcConnection driverClass="com.mysql.cj.jdbc.Driver" connectionURL="jdbc:mysql://localhost:3306/test?useUnicode=true&characterEnconding=utf-8&useSSL=false&serverTimezone=UTC" userId="username" password="password"> <property name="nullCatalogMeansCurrent" value="true"/> </jdbcConnection>
2. 页面出现500错误
2020-06-27 14:23:42.459 ERROR 19676 --- [nio-8080-exec-1] o.a.c.c.C.[.[.[/].[dispatcherServlet] : Servlet.service() for servlet [dispatcherServlet] in context with path [] threw exception [Circular view path [addUsers]: would dispatch back to the current handler URL [/addUsers] again. Check your ViewResolver setup! (Hint: This may be the result of an unspecified view, due to default view name generation.)] with root cause
javax.servlet.ServletException: Circular view path [addUsers]: would dispatch back to the current handler URL [/addUsers] again. Check your ViewResolver setup! (Hint: This may be the result of an unspecified view, due to default view name generation.)
at org.springframework.web.servlet.view.InternalResourceView.prepareForRendering(InternalResourceView.java:210) ~[spring-webmvc-5.2.7.RELEASE.jar:5.2.7.RELEASE]
at
查了很多博客，但是都不是自己的问题，自己的问题是在pom.xml配置文件中的资源路径中，没有写所有，而是单独的xml和yml配置文件。要加载所有的静态资源。
<!--原本的--> <!--资源文件的路径--> <resource> <directory>src/main/resources</directory> <includes> <include>**/*.yml</include> <include>**/*.xml</include> </includes> <!-- <filtering>false</filtering>--> </resource> <!--修改后的--> <!--资源文件的路径--> <resource> <directory>src/main/resources</directory> <includes> <include>**/*.*</include> </includes> <!-- <filtering>false</filtering>--> </resource>
