问题场景
今天小编在MyBatis 整合Spring 的时候,使用到了@MapperScan,在启动期出现了一个错误:
Invalid default: public abstract java.lang.Class org.mybatis.spring.annotation.MapperScan.factoryBean()
对于这个错误,小编也是倍感无奈,怎么会出现这个错误呢,看一下我的依赖有没有错误:
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compile(project( ":spring-context" )) // compile(project(":spring-instrument")) // https://mvnrepository.com/artifact/cglib/cglib compile group: 'cglib' , name: 'cglib' , version: '2.2.2' // https://mvnrepository.com/artifact/mysql/mysql-connector-java compile group: 'mysql' , name: 'mysql-connector-java' , version: '8.0.21' // https://mvnrepository.com/artifact/org.mybatis/mybatis compile group: 'org.mybatis' , name: 'mybatis' , version: '3.5.2' // https://mvnrepository.com/artifact/org.mybatis/mybatis-spring compile group: 'org.mybatis' , name: 'mybatis-spring' , version: '2.0.2' |
完全没得毛病呀,他妈的,究竟是哪里出现了问题呢,小编这时将SpringFramework 源码从github 上clone 下来了,导入idea 开始寻找问题所在。。。
问题根源
经过不懈的努力,小编终于找到了问题根源,在AnnotationsScanner 类中的这个方法:
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static Annotation[] getDeclaredAnnotations(AnnotatedElement source, boolean defensive) { boolean cached = false ; Annotation[] annotations = declaredAnnotationCache.get(source); if (annotations != null ) { cached = true ; } else { // 使用@MapperScan 的时候会报错,引入spring-jdbc 即可 // 具体原因暂时还不清楚 // Invalid default: public abstract java.lang.Class org.mybatis.spring.annotation.MapperScan.factoryBean() annotations = source.getDeclaredAnnotations(); if (annotations.length != 0 ) { boolean allIgnored = true ; for ( int i = 0 ; i < annotations.length; i++) { Annotation annotation = annotations[i]; if (isIgnorable(annotation.annotationType()) || !AttributeMethods.forAnnotationType(annotation.annotationType()).isValid(annotation)) { annotations[i] = null ; } else { allIgnored = false ; } } annotations = (allIgnored ? NO_ANNOTATIONS : annotations); if (source instanceof Class || source instanceof Member) { declaredAnnotationCache.put(source, annotations); cached = true ; } } } if (!defensive || annotations.length == 0 || !cached) { return annotations; } return annotations.clone(); } |
AnnotatedElement 对于这个类,小编也是不太清楚,这时也倍感无奈,这个方法主要做的事情就是将Appconfig 配置类中的注解扫描下来,那会不会是注解的问题呢,在@MapperScan 注解的注释中发现小编的代码与MyBatis-Spring 开发团队提供的实例代码一致,这就让人想不明白了:
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* <pre class = "code" > * &# 064 ;Configuration * &# 064 ;MapperScan( "org.mybatis.spring.sample.mapper" ) * public class AppConfig { * * &# 064 ;Bean * public DataSource dataSource() { * return new EmbeddedDatabaseBuilder().addScript( "schema.sql" ).build(); * } * * &# 064 ;Bean * public DataSourceTransactionManager transactionManager() { * return new DataSourceTransactionManager(dataSource()); * } * * &# 064 ;Bean * public SqlSessionFactory sqlSessionFactory() throws Exception { * SqlSessionFactoryBean sessionFactory = new SqlSessionFactoryBean(); * sessionFactory.setDataSource(dataSource()); * return sessionFactory.getObject(); * } * } * </pre> |
问题追溯
我这个时候被起疯了都,从GitHub 上由把mybatis-spring 的源码clone 了下来,导入idea,首先看一下mybatis-spring 的依赖:
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< dependencies > <!-- Compile dependencies --> < dependency > < groupId >org.mybatis</ groupId > < artifactId >mybatis</ artifactId > < version >${mybatis.version}</ version > < scope >provided</ scope > </ dependency > < dependency > < groupId >org.springframework</ groupId > < artifactId >spring-context</ artifactId > < version >${spring.version}</ version > < scope >provided</ scope > </ dependency > < dependency > < groupId >org.springframework</ groupId > < artifactId >spring-jdbc</ artifactId > < version >${spring.version}</ version > < scope >provided</ scope > </ dependency > < dependency > < groupId >org.springframework.batch</ groupId > < artifactId >spring-batch-infrastructure</ artifactId > < version >${spring-batch.version}</ version > < scope >provided</ scope > </ dependency > |
从依赖中看到了什么,tmd,<scope>provided</scope>,这个怎么讲,太无语了,其中它引入了spring-jdbc 的依赖。想象一下,@MapperScan 注解中是不是也使用到了spring-jdbc 的类,然后在使用@MapperScan 的时候没有加入spring-jdbc 的依赖,导致注解在扫描期间的错误,没毛病解释的通,找一下@MapperScan 中是否使用到了spring-jdbc 的依赖。
问题解决
果不其然,下面用一张图来看吧。
所以呢,在项目中加入spring-jdbc 完美解决。
SpringBoot @MapperScan的注意事项
错误代码如下:
[dispatcherServlet] : Servlet.service() for servlet [dispatcherServlet] in context with path [] threw exception [Request processing failed; nested exception is org.mybatis.spring.MyBatisSystemException: nested exception is org.apache.ibatis.builder.BuilderException: Error invoking SqlProvider method (tk.mybatis.mapper.provider.base.BaseSelectProvider.dynamicSQL). Cause: java.lang.InstantiationException: tk.mybatis.mapper.provider.base.BaseSelectProvider] with root cause
检查@MapperScan导入的包是否为
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import tk.mybatis.spring.annotation.MapperScan; |
切记不要导成
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import org.mybatis.spring.annotation.MapperScan |
以上为个人经验,希望能给大家一个参考,也希望大家多多支持服务器之家。
原文链接:https://blog.csdn.net/zhagnchong480/article/details/111562366