Mybatis：逆向工程配合生成报Cannot instantiate object of type tk.mybatis.mapper.generator.

野性酷女 2022-01-29 05:59 301阅读 0赞

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使用 tk.mybatis 准备生成继承通用Mapper的Dao、Entity和Mapper文件时，

运行mybatis-generator报了如下错误：

[ERROR] Failed to execute goal org.mybatis.generator:mybatis-generator-maven-plugin:1.3.5:generate (default-cli) on project base: Execution default-cli of goal org.mybatis.generator:mybatis-generator-maven-plugin:1.3.5:generate failed: Cannot instantiate object of type tk.mybatis.mapper.generator.MapperPlugin -> [Help 1]
    org.apache.maven.lifecycle.LifecycleExecutionException: Failed to execute goal org.mybatis.generator:mybatis-generator-maven-plugin:1.3.5:generate (default-cli) on project base: Execution default-cli of goal org.mybatis.generator:mybatis-generator-maven-plugin:1.3.5:generate failed: Cannot instantiate object of type tk.mybatis.mapper.generator.MapperPlugin
        at org.apache.maven.lifecycle.internal.MojoExecutor.execute(MojoExecutor.java:212)
        at org.apache.maven.lifecycle.internal.MojoExecutor.execute(MojoExecutor.java:153)
        at org.apache.maven.lifecycle.internal.MojoExecutor.execute(MojoExecutor.java:145)
        at org.apache.maven.lifecycle.internal.LifecycleModuleBuilder.buildProject(LifecycleModuleBuilder.java:116)
        at org.apache.maven.lifecycle.internal.LifecycleModuleBuilder.buildProject(LifecycleModuleBuilder.java:80)
        at org.apache.maven.lifecycle.internal.builder.singlethreaded.SingleThreadedBuilder.build(SingleThreadedBuilder.java:51)
        at org.apache.maven.lifecycle.internal.LifecycleStarter.execute(LifecycleStarter.java:128)
        at org.apache.maven.DefaultMaven.doExecute(DefaultMaven.java:307)
        at org.apache.maven.DefaultMaven.doExecute(DefaultMaven.java:193)
        at org.apache.maven.DefaultMaven.execute(DefaultMaven.java:106)
        at org.apache.maven.cli.MavenCli.execute(MavenCli.java:863)
        at org.apache.maven.cli.MavenCli.doMain(MavenCli.java:288)
        at org.apache.maven.cli.MavenCli.main(MavenCli.java:199)
        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:497)
        at org.codehaus.plexus.classworlds.launcher.Launcher.launchEnhanced(Launcher.java:289)
        at org.codehaus.plexus.classworlds.launcher.Launcher.launch(Launcher.java:229)
        at org.codehaus.plexus.classworlds.launcher.Launcher.mainWithExitCode(Launcher.java:415)
        at org.codehaus.plexus.classworlds.launcher.Launcher.main(Launcher.java:356)
        at org.codehaus.classworlds.Launcher.main(Launcher.java:47)
    Caused by: org.apache.maven.plugin.PluginExecutionException: Execution default-cli of goal org.mybatis.generator:mybatis-generator-maven-plugin:1.3.5:generate failed: Cannot instantiate object of type tk.mybatis.mapper.generator.MapperPlugin
        at org.apache.maven.plugin.DefaultBuildPluginManager.executeMojo(DefaultBuildPluginManager.java:145)
        at org.apache.maven.lifecycle.internal.MojoExecutor.execute(MojoExecutor.java:207)
        ... 21 more
    Caused by: java.lang.RuntimeException: Cannot instantiate object of type tk.mybatis.mapper.generator.MapperPlugin
        at org.mybatis.generator.internal.ObjectFactory.createInternalObject(ObjectFactory.java:229)
        at org.mybatis.generator.internal.ObjectFactory.createPlugin(ObjectFactory.java:284)
        at org.mybatis.generator.config.Context.generateFiles(Context.java:704)
        at org.mybatis.generator.api.MyBatisGenerator.generate(MyBatisGenerator.java:269)
        at org.mybatis.generator.api.MyBatisGenerator.generate(MyBatisGenerator.java:189)
        at org.mybatis.generator.maven.MyBatisGeneratorMojo.execute(MyBatisGeneratorMojo.java:199)
        at org.apache.maven.plugin.DefaultBuildPluginManager.executeMojo(DefaultBuildPluginManager.java:134)
        ... 22 more
    Caused by: java.lang.ClassNotFoundException: tk.mybatis.mapper.generator.MapperPlugin
        at org.codehaus.plexus.classworlds.strategy.SelfFirstStrategy.loadClass(SelfFirstStrategy.java:50)
        at org.codehaus.plexus.classworlds.realm.ClassRealm.unsynchronizedLoadClass(ClassRealm.java:271)
        at org.codehaus.plexus.classworlds.realm.ClassRealm.loadClass(ClassRealm.java:247)
        at org.codehaus.plexus.classworlds.realm.ClassRealm.loadClass(ClassRealm.java:239)
        at java.lang.Class.forName0(Native Method)
        at java.lang.Class.forName(Class.java:348)
        at org.mybatis.generator.internal.ObjectFactory.internalClassForName(ObjectFactory.java:181)
        at org.mybatis.generator.internal.ObjectFactory.createInternalObject(ObjectFactory.java:225)
        ... 28 more
    [ERROR] 
    [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

可以看到主要报错信息如下：

> 1、org.apache.maven.lifecycle.LifecycleExecutionException: Failed to execute goal org.mybatis.generator:mybatis-generator-maven-plugin:1.3.5:generate (default-cli) on project base: Execution default-cli of goal org.mybatis.generator:mybatis-generator-maven-plugin:1.3.5:generate failed: Cannot instantiate object of type tk.mybatis.mapper.generator.MapperPlugin；  
> 2、org.apache.maven.plugin.PluginExecutionException: Execution default-cli of goal org.mybatis.generator:mybatis-generator-maven-plugin:1.3.5:generate failed: Cannot instantiate object of type tk.mybatis.mapper.generator.MapperPlugin；  
> 3、java.lang.RuntimeException: Cannot instantiate object of type tk.mybatis.mapper.generator.MapperPlugin；  
> 4、java.lang.ClassNotFoundException: tk.mybatis.mapper.generator.MapperPlugin。

经度娘一波，发现网上提供的解决办法有以下几种：

1、把mybatis-generator.xml配置文件中的 javaClientGenerator标签里的type赋值"XMLMAPPER"或"ANNOTATEDMAPPER"，仔细检查后这条排除；

2、更新org.mybatis.mapper.generator.MapperPlugin这个插件的版本，但把 tk.mybatis:mapper从v3.3.6升级到v3.4.6后问题依旧存在，这条排除；

后来发现报错信息里出现"ClassNotFoundException"，在思考会不会是maven导入的包mybatis-generator没有找到，所以尝试调换依赖的位置：

调换前-->

调换后-->

<plugin>
              <groupId>org.mybatis.generator</groupId>
              <artifactId>mybatis-generator-maven-plugin</artifactId>
              <version>1.3.5</version>
              <configuration>
                <verbose>true</verbose>
                <overwrite>true</overwrite>
                <configurationFile>src/main/resources/mybatis/generator-config.xml</configurationFile>
              </configuration>
              <dependencies>
                
                <dependency>
                  <groupId>org.mybatis.generator</groupId>
                  <artifactId>mybatis-generator-core</artifactId>
                  <version>1.3.5</version>
                </dependency>
                <dependency>
                  <groupId>tk.mybatis</groupId>
                  <artifactId>mapper</artifactId>
                  <version>3.4.6</version>
                </dependency>
              </dependencies>
    </plugin>

结果再次运行mybatis-generator成功生成文件，就是插件在之前引入的位置运行时找不到，把依赖位置改到插件中

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