    <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>2.1.4.RELEASE</version>
    </parent>
 
    <properties>
        <java.version>1.8</java.version>
        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
        <project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding>
        <tk.mybatis.version>1.1.5</tk.mybatis.version>
        <pagehelper.version>1.2.3</pagehelper.version>
    </properties>
 
    <dependencies>
 
        <dependency>
            <groupId>tk.mybatis</groupId>
            <artifactId>mapper-spring-boot-starter</artifactId>
            <version>${tk.mybatis.version}</version>
        </dependency>
 
        <!-- pageHelper -->
        <dependency>
            <groupId>com.github.pagehelper</groupId>
            <artifactId>pagehelper-spring-boot-starter</artifactId>
            <version>${pagehelper.version}</version>
        </dependency>
    </dependencies>

啟動報(bào)異常如下：

Caused by: java.lang.StringIndexOutOfBoundsException: String index out of range: -1 ?

Caused by: java.lang.StringIndexOutOfBoundsException: String index out of range: -1
?at java.lang.AbstractStringBuilder.substring(AbstractStringBuilder.java:908)
?at java.lang.StringBuilder.substring(StringBuilder.java:76)
?at tk.mybatis.mapper.mapperhelper.SqlHelper.getAllColumns(SqlHelper.java:247)
?at tk.mybatis.mapper.mapperhelper.SqlHelper.exampleSelectColumns(SqlHelper.java:534)
?at tk.mybatis.mapper.provider.ExampleProvider.selectByExample(ExampleProvider.java:96)
?at tk.mybatis.mapper.provider.ExampleProvider.selectByExampleAndRowBounds(ExampleProvider.java:111)
?at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
?at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
?at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
?at java.lang.reflect.Method.invoke(Method.java:498)
?at tk.mybatis.mapper.mapperhelper.MapperTemplate.setSqlSource(MapperTemplate.java:246)
?... 29 common frames omitted

有說是版本不兼容的問題，有說什么MapperScan注解換成tk的，都不行，找了半天，原來是因?yàn)槎x的數(shù)據(jù)實(shí)體類中沒有定義任何屬性造成的： ?

導(dǎo)致mapper掃描xml的時(shí)候，會去找對應(yīng)的實(shí)體類，結(jié)果發(fā)現(xiàn)一個(gè)字段（列）都沒有，于是就拋了異常

博主為什么會出現(xiàn)這種情況呢？

我搭框架的時(shí)候，會依據(jù)產(chǎn)品設(shè)計(jì)好Controller、Service和Dao層，Dao層的entity我只定義，里面的內(nèi)容由具體的開發(fā)者填充，于是乎就出現(xiàn)了，架子搭好了卻跑不起來的尷尬局面，解決的辦法就是，entity實(shí)體類不要空，隨便意思下，給個(gè)id即可：