SpringBoot怎么解决TypeAliases配置失败问题

魁首哥

作者

SpringBoot怎么解决TypeAliases配置失败问题

这篇文章主要介绍“SpringBoot怎么解决TypeAliases配置失败问题”的相关知识，小编通过实际案例向大家展示操作过程，操作方法简单快捷，实用性强，希望这篇“SpringBoot怎么解决TypeAliases配置失败问题”文章能帮助大家解决问题。

问题描述

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

解决方法

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

publicSpringBootVFS(){this.resourceResolver=newPathMatchingResourcePatternResolver(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")@PrimarypublicSqlSessionFactorysqlSessionFactory(@Qualifier("masterDataSource")DataSourcedataSource)throwsException{SqlSessionFactoryBeanbean=newSqlSessionFactoryBean();bean.setDataSource(dataSource);bean.setVfs(SpringBootVFS.class);//设置SpringBootVFSbean.setTypeAliasesPackage("com.fulan.domain.red");...}

SpringBoot整合Mybatis及遇到的坑

1. 搭建项目环境

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。

<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><dependency><groupId>org.mybatis.spring.boot</groupId><artifactId>mybatis-spring-boot-starter</artifactId><version>2.1.3</version></dependency><dependency><groupId>org.springframework.boot</groupId><artifactId>spring-boot-starter-jdbc</artifactId></dependency><dependency><groupId>mysql</groupId><artifactId>mysql-connector-java</artifactId><version>8.0.12</version></dependency><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.Driverurl:jdbc:mysql://localhost:3306/test?useUnicode=true&characterEnconding=utf-8&useSSL=false&serverTimezone=GMT%2B8username:rootpassword:roottype:com.alibaba.druid.pool.DruidDataSource

2. 配置Maven的generator插件

2.1 添加generator插件坐标

<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><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。

<?xmlversion="1.0"encoding="UTF-8"?><!DOCTYPEgeneratorConfigurationPUBLIC"-//mybatis.org//DTDMyBatisGeneratorConfiguration1.0//EN""http://mybatis.org/dtd/mybatis-generator-config_1_0.dtd"><generatorConfiguration><contextid="testTables"targetRuntime="MyBatis3"><commentGenerator><propertyname="suppressAllComments"value="true"/></commentGenerator><jdbcConnectiondriverClass="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><javaTypeResolver><propertyname="forceBigDecimals"value="false"/></javaTypeResolver><javaModelGeneratortargetPackage="com.example.springbootmybatis.pojo"targetProject=".srcmainjava"><propertyname="enableSubPackages"value="false"/><propertyname="trimStrings"value="true"/></javaModelGenerator><sqlMapGeneratortargetPackage="com.example.springbootmybatis.mapper"targetProject=".srcmainjava"><propertyname="enableSubPackages"value="false"/></sqlMapGenerator><javaClientGeneratortype="XMLMAPPER"targetPackage="com.example.springbootmybatis.mapper"targetProject="./src/main/java"><propertyname="enableSubPackages"value="false"/></javaClientGenerator><tableschema=""tableName="users"></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. 配置资源拷贝插件

3.1 添加资源拷贝插件坐标

<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

packagecom.example.springbootmybatis;importorg.mybatis.spring.annotation.MapperScan;importorg.springframework.boot.SpringApplication;importorg.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publicclassDemoApplication{publicstaticvoidmain(String[]args){SpringApplication.run(DemoApplication.class,args);}}

4. 其他配置项

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. 添加用户功能

5.1 创建页面

<!DOCTYPEhtml><htmlxmlns:th="http://www.thymeleaf.org"><linkrel="shortcuticon"href="../resources/favicon.ico"th:href="@{/static/favion.ico}"><head><metacharset="UTF-8"><title>测试SpringBoot连接PostgreSQL数据库</title></head><body><formth:action="@{/user/addUser}"method="post"><inputtype="text"name="userid"><br><inputtype="text"name="username"><br><inputtype="text"name="usersex"><br><inputtype="submit"value="添加"><br></form></body></html>

5.2 创建Controller

5.2.1 PageController

packagecom.example.springbootmybatis.controller;importorg.springframework.stereotype.Controller;importorg.springframework.web.bind.annotation.PathVariable;importorg.springframework.web.bind.annotation.RequestMapping;/***页面跳转Controller*/@ControllerpublicclassPageController{/***页面跳转方法*/@RequestMapping("/{page}")publicStringshowPage(@PathVariableStringpage){returnpage;}}

5.2.2 UsersController

packagecom.example.springbootmybatis.controller;importcom.example.springbootmybatis.pojo.Users;importcom.example.springbootmybatis.service.UsersService;importorg.springframework.beans.factory.annotation.Autowired;importorg.springframework.stereotype.Controller;importorg.springframework.web.bind.annotation.PostMapping;importorg.springframework.web.bind.annotation.RequestMapping;importorg.springframework.web.bind.annotation.RestController;/***用户管理Controller*/@RestController@RequestMapping("/user")publicclassUsersController{@AutowiredprivateUsersServiceusersService;/***添加用户*/@PostMapping("/addUser")publicStringaddUsers(Usersusers){try{this.usersService.addUsers(users);}catch(Exceptione){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*/@ServicepublicclassUsersServiceImplimplementsUsersService{@AutowiredprivateUsersMapperusersMapper;@Override@TransactionalpublicvoidaddUsers(Usersusers){this.usersMapper.insert(users);}}

接口

publicinterfaceUsersService{voidaddUsers(Usersusers);}

遇到的错误

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

<jdbcConnectiondriverClass="com.mysql.cj.jdbc.Driver"connectionURL="jdbc:mysql://localhost:3306/test?useUnicode=true&characterEnconding=utf-8&useSSL=false&serverTimezone=UTC"userId="username"password="password"><propertyname="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

解决方法

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。

<resource><directory>src/main/resources</directory><includes><include>**/*.yml</include><include>**/*.xml</include></includes></resource><resource><directory>src/main/resources</directory><includes><include>**/*.*</include></includes></resource>

关于“SpringBoot怎么解决TypeAliases配置失败问题”的内容就介绍到这里了，感谢大家的阅读。如果想了解更多行业相关的知识，可以关注恰卡编程网行业资讯频道，小编每天都会为大家更新不同的知识点。

阅读全文

发布于 2022-04-03 22:33:42