java 错误集锦

• Type mismatch: cannot convert from Integer to int

原因：是因为该项目的jdk版本太低，如图所示：

右键项目-》属性》java compiler修改jdk的版本

• Exception in thread "main" java.lang.Error: Unresolved compilation problem:

at com.niuniu.practice.QRCodeEncoderHandler.main(QRCodeEncoderHandler.java:80)

原因：没有引入正确的包。

• org.apache.ibatis.exceptions.TooManyResultsException: Expected one result (or null) to be returned by selectOne(), but found: 3

• 原因：在代码中使用的是selectone()来接收，所以导致错误，原因是：查询方法中得到两个两个结果集,然而你的返回用了一个实体去接收，程序这个时候就不知道如何去分配了，所以报这个错，解决办法采用selectlist()接收。

结果集就应用用list接收，Dao接口中返回的就应该是一个List

• java.lang.NoSuchMethodError: org.springframework.dao.IncorrectResultSizeDataAccessException

解决思路：像java.lang.NoSuchMethodError: org.springframework.dao.IncorrectResultSizeDataAccessException.<init>(Ljava/lang/String;ILjava/lang/Throwable;)V这类型的错误一般是未找到方法，或者是引入多个包造成版本冲突

找到org.springframework.dao.IncorrectResultSizeDataAccessException.<init>(Ljava/lang/String;ILjava/lang/Throwable;)V所在的包，发现有两个包有这个类，一个是spring-tx，一个是另外一个包有这个类但是没这个方法，删掉这个包便正常

spring data jpa  运用，在dao类中写自己新增的方法，使用@query写hql语句，出现以下异常：

Caused by: java.lang.NoSuchMethodError: org.springframework.dao.IncorrectResultSizeDataAccessException.<init>(Ljava/lang/String;ILjava/lang/Throwable;)V

• springmvc启动tomcat报如下错误，一起的还有找不到entity下的实体类
• 原因：1，注解没加对  2，映射关系没写对 3，jar包没导入正确 4、实体类和数据库没对应上 我的问题是jar包重复了，哎，整了一天多

九月 22, 2016 3:12:17 下午 org.apache.catalina.core.ApplicationContext log SEVERE: StandardWrapper.Throwable org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'mapperscanner' defined in file [E:\myeclipse-pro-2013-offline-installer-windows\tomcat\apache-tomcat-7.0.70-windows-x64\apache-tomcat-7.0.70\webapps\notecloud\WEB-INF\classes\spring-mybatis.xml]: Cannot resolve reference to bean 'ssf' while setting bean property 'sqlSessionFactory'; nested exception is org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'ssf' defined in file [E:\myeclipse-pro-2013-offline-installer-windows\tomcat\apache-tomcat-7.0.70-windows-x64\apache-tomcat-7.0.70\webapps\notecloud\WEB-INF\classes\spring-mybatis.xml]: Invocation of init method failed; nested exception is org.springframework.core.NestedIOException: Failed to parse mapping resource: 'file [E:\myeclipse-pro-2013-offline-installer-windows\tomcat\apache-tomcat-7.0.70-windows-x64\apache-tomcat-7.0.70\webapps\notecloud\WEB-INF\classes\com\niuniu\sql\NoteMapper.xml]'; nested exception is org.apache.ibatis.builder.BuilderException: Error parsing Mapper XML. Cause: org.apache.ibatis.builder.BuilderException: Error resolving class. Cause: org.apache.ibatis.type.TypeException: Could not resolve type alias 'org.tedu.cloudnote.entity.Note'. Cause: java.lang.ClassNotFoundException: Cannot find class: org.tedu.cloudnote.entity.Note at org.springframework.beans.factory.support.BeanDefinitionValueResolver.resolveReference(BeanDefinitionValueResolver.java:326) at org.springframework.beans.factory.support.BeanDefinitionValueResolver.resolveValueIfNecessary(BeanDefinitionValueResolver.java:107) at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.applyPropertyValues(AbstractAutowireCapableBeanFactory.java:1417) at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.populateBean(AbstractAutowireCapableBeanFactory.java:1158) at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:519) at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:458) at org.springframework.beans.factory.support.AbstractBeanFactory$1.getObject(AbstractBeanFactory.java:296) at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:223) at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:293) at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:198) at org.springframework.beans.factory.support.DefaultListableBeanFactory.getBeansOfType(DefaultListableBeanFactory.java:438) at org.springframework.context.support.AbstractApplicationContext.invokeBeanFactoryPostProcessors(AbstractApplicationContext.java:624) at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:461) at org.springframework.web.servlet.FrameworkServlet.configureAndRefreshWebApplicationContext(FrameworkServlet.java:651) at org.springframework.web.servlet.FrameworkServlet.createWebApplicationContext(FrameworkServlet.java:602) at org.springframework.web.servlet.FrameworkServlet.createWebApplicationContext(FrameworkServlet.java:665) at org.springframework.web.servlet.FrameworkServlet.initWebApplicationContext(FrameworkServlet.java:521) at org.springframework.web.servlet.FrameworkServlet.initServletBean(FrameworkServlet.java:462) at org.springframework.web.servlet.HttpServletBean.init(HttpServletBean.java:136) at javax.servlet.GenericServlet.init(GenericServlet.java:158) at org.apache.catalina.core.StandardWrapper.initServlet(StandardWrapper.java:1282) at org.apache.catalina.core.StandardWrapper.loadServlet(StandardWrapper.java:1195) at org.apache.catalina.core.StandardWrapper.load(StandardWrapper.java:1085) at org.apache.catalina.core.StandardContext.loadOnStartup(StandardContext.java:5349) at org.apache.catalina.core.StandardContext.startInternal(StandardContext.java:5641) at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:147) at org.apache.catalina.core.ContainerBase.addChildInternal(ContainerBase.java:899) at org.apache.catalina.core.ContainerBase.addChild(ContainerBase.java:875) at org.apache.catalina.core.StandardHost.addChild(StandardHost.java:652) at org.apache.catalina.startup.HostConfig.deployDirectory(HostConfig.java:1260) at org.apache.catalina.startup.HostConfig$DeployDirectory.run(HostConfig.java:2002) at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:471) at java.util.concurrent.FutureTask$Sync.innerRun(FutureTask.java:334) at java.util.concurrent.FutureTask.run(FutureTask.java:166) at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1145) at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:615) at java.lang.Thread.run(Thread.java:722) Caused by: org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'ssf' defined in file [E:\myeclipse-pro-2013-offline-installer-windows\tomcat\apache-tomcat-7.0.70-windows-x64\apache-tomcat-7.0.70\webapps\notecloud\WEB-INF\classes\spring-mybatis.xml]: Invocation of init method failed; nested exception is org.springframework.core.NestedIOException: Failed to parse mapping resource: 'file [E:\myeclipse-pro-2013-offline-installer-windows\tomcat\apache-tomcat-7.0.70-windows-x64\apache-tomcat-7.0.70\webapps\notecloud\WEB-INF\classes\com\niuniu\sql\NoteMapper.xml]'; nested exception is org.apache.ibatis.builder.BuilderException: Error parsing Mapper XML. Cause: org.apache.ibatis.builder.BuilderException: Error resolving class. Cause: org.apache.ibatis.type.TypeException: Could not resolve type alias 'org.tedu.cloudnote.entity.Note'. Cause: java.lang.ClassNotFoundException: Cannot find class: org.tedu.cloudnote.entity.Note at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.initializeBean(AbstractAutowireCapableBeanFactory.java:1512) at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:521) at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:458) at org.springframework.beans.factory.support.AbstractBeanFactory$1.getObject(AbstractBeanFactory.java:296)