Mybatis报错: org.apache.ibatis.exceptions.PersistenceException

一、问题描述

写好配置文件用JUnit进行测试，一运行就报错:

org.apache.ibatis.exceptions.PersistenceException: ### Error querying database.  Cause: org.apache.ibatis.reflection.ReflectionException: Error instantiating class com.fendo.entity.Person with invalid types () or values (). Cause: java.lang.NoSuchMethodException: com.fendo.entity.Person.<init>()### The error may exist in com/fendo/entity/Person.xml### The error may involve defaultParameterMap### The error occurred while setting parameters### SQL: select * from person### Cause: org.apache.ibatis.reflection.ReflectionException: Error instantiating class com.fendo.entity.Person with invalid types () or values (). Cause: java.lang.NoSuchMethodException: com.fendo.entity.Person.<init>()at org.apache.ibatis.exceptions.ExceptionFactory.wrapException(ExceptionFactory.java:23)at org.apache.ibatis.session.defaults.DefaultSqlSession.selectList(DefaultSqlSession.java:107)at org.apache.ibatis.session.defaults.DefaultSqlSession.selectList(DefaultSqlSession.java:98)at org.apache.ibatis.binding.MapperMethod.executeForMany(MapperMethod.java:114)at org.apache.ibatis.binding.MapperMethod.execute(MapperMethod.java:58)at org.apache.ibatis.binding.MapperProxy.invoke(MapperProxy.java:43)at com.sun.proxy.$Proxy6.getPersons(Unknown Source)at com.fendo.test.TestMybatis.test(TestMybatis.java:40)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 org.junit.runners.model.FrameworkMethod$1.runReflectiveCall(FrameworkMethod.java:50)at org.junit.internal.runners.model.ReflectiveCallable.run(ReflectiveCallable.java:12)at org.junit.runners.model.FrameworkMethod.invokeExplosively(FrameworkMethod.java:47)at org.junit.internal.runners.statements.InvokeMethod.evaluate(InvokeMethod.java:17)at org.junit.internal.runners.statements.RunBefores.evaluate(RunBefores.java:26)at org.junit.internal.runners.statements.RunAfters.evaluate(RunAfters.java:27)at org.junit.runners.ParentRunner.runLeaf(ParentRunner.java:325)at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:78)at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:57)at org.junit.runners.ParentRunner$3.run(ParentRunner.java:290)at org.junit.runners.ParentRunner$1.schedule(ParentRunner.java:71)at org.junit.runners.ParentRunner.runChildren(ParentRunner.java:288)at org.junit.runners.ParentRunner.access$000(ParentRunner.java:58)at org.junit.runners.ParentRunner$2.evaluate(ParentRunner.java:268)at org.junit.runners.ParentRunner.run(ParentRunner.java:363)at org.eclipse.jdt.internal.junit4.runner.JUnit4TestReference.run(JUnit4TestReference.java:86)at org.eclipse.jdt.internal.junit.runner.TestExecution.run(TestExecution.java:38)at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:459)at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:675)at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.run(RemoteTestRunner.java:382)at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.main(RemoteTestRunner.java:192)Caused by: org.apache.ibatis.reflection.ReflectionException: Error instantiating class com.fendo.entity.Person with invalid types () or values (). Cause: java.lang.NoSuchMethodException: com.fendo.entity.Person.<init>()at org.apache.ibatis.reflection.factory.DefaultObjectFactory.instantiateClass(DefaultObjectFactory.java:83)at org.apache.ibatis.reflection.factory.DefaultObjectFactory.create(DefaultObjectFactory.java:45)at org.apache.ibatis.reflection.factory.DefaultObjectFactory.create(DefaultObjectFactory.java:38)at org.apache.ibatis.executor.resultset.DefaultResultSetHandler.createResultObject(DefaultResultSetHandler.java:535)at org.apache.ibatis.executor.resultset.DefaultResultSetHandler.createResultObject(DefaultResultSetHandler.java:514)at org.apache.ibatis.executor.resultset.DefaultResultSetHandler.getRowValue(DefaultResultSetHandler.java:334)at org.apache.ibatis.executor.resultset.DefaultResultSetHandler.handleRowValuesForSimpleResultMap(DefaultResultSetHandler.java:294)at org.apache.ibatis.executor.resultset.DefaultResultSetHandler.handleRowValues(DefaultResultSetHandler.java:269)at org.apache.ibatis.executor.resultset.DefaultResultSetHandler.handleResultSet(DefaultResultSetHandler.java:239)at org.apache.ibatis.executor.resultset.DefaultResultSetHandler.handleResultSets(DefaultResultSetHandler.java:153)at org.apache.ibatis.executor.statement.PreparedStatementHandler.query(PreparedStatementHandler.java:57)at org.apache.ibatis.executor.statement.RoutingStatementHandler.query(RoutingStatementHandler.java:70)at org.apache.ibatis.executor.SimpleExecutor.doQuery(SimpleExecutor.java:57)at org.apache.ibatis.executor.BaseExecutor.queryFromDatabase(BaseExecutor.java:259)at org.apache.ibatis.executor.BaseExecutor.query(BaseExecutor.java:132)at org.apache.ibatis.executor.CachingExecutor.query(CachingExecutor.java:105)at org.apache.ibatis.executor.CachingExecutor.query(CachingExecutor.java:81)at org.apache.ibatis.session.defaults.DefaultSqlSession.selectList(DefaultSqlSession.java:104)... 31 moreCaused by: java.lang.NoSuchMethodException: com.fendo.entity.Person.<init>()at java.lang.Class.getConstructor0(Class.java:3082)at java.lang.Class.getDeclaredConstructor(Class.java:2178)at org.apache.ibatis.reflection.factory.DefaultObjectFactory.instantiateClass(DefaultObjectFactory.java:57)... 48 more

二、解决方法

从上面的异常可以看出: java.lang.NoSuchMethodException: com.fendo.entity.Person.<init>()

person这个实体类不能初始化，不能初始化的原因可能是没有构造方法，然后我查看了下类确实没有构造方法，为他添加个构造方法，就可以了。