SqlMapClient operation; uncategorized SQLException for SQL []; SQL state [null]; error code [0];

org.springframework.jdbc.UncategorizedSQLException: SqlMapClient operation; uncategorized SQLException for SQL []; SQL state [null]; error code [0];   --- The error occurred in ibatis.xml.  --- The error occurred while applying a result map.  --- Check the User_oracle.ibatisTest.  --- The error occured while instantiating the result object  --- Cause: java.lang.RuntimeException: JavaBeansDataExchange could not instantiate result class.  Cause: java.lang.InstantiationException: com.spring.ibatis.User; nested exception is com.ibatis.common.jdbc.exception.NestedSQLException:   --- The error occurred in ibatis.xml.  --- The error occurred while applying a result map.  --- Check the User_oracle.ibatisTest.  --- The error occured while instantiating the result object  --- Cause: java.lang.RuntimeException: JavaBeansDataExchange could not instantiate result class.  Cause: java.lang.InstantiationException: com.spring.ibatis.Userat org.springframework.jdbc.support.AbstractFallbackSQLExceptionTranslator.translate(AbstractFallbackSQLExceptionTranslator.java:83)at org.springframework.jdbc.support.AbstractFallbackSQLExceptionTranslator.translate(AbstractFallbackSQLExceptionTranslator.java:80)at org.springframework.jdbc.support.AbstractFallbackSQLExceptionTranslator.translate(AbstractFallbackSQLExceptionTranslator.java:80)at org.springframework.orm.ibatis.SqlMapClientTemplate.execute(SqlMapClientTemplate.java:212)at org.springframework.orm.ibatis.SqlMapClientTemplate.executeWithListResult(SqlMapClientTemplate.java:249)at org.springframework.orm.ibatis.SqlMapClientTemplate.queryForList(SqlMapClientTemplate.java:296)at com.spring.ibatis.IDAOImpl.getList(IDAOImpl.java:16)at com.spring.batisTest.batisTest.test(batisTest.java:27)at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)at java.lang.reflect.Method.invoke(Method.java:601)at org.junit.runners.model.FrameworkMethod$1.runReflectiveCall(FrameworkMethod.java:47)at org.junit.internal.runners.model.ReflectiveCallable.run(ReflectiveCallable.java:12)at org.junit.runners.model.FrameworkMethod.invokeExplosively(FrameworkMethod.java:44)at org.junit.internal.runners.statements.InvokeMethod.evaluate(InvokeMethod.java:17)at org.junit.runners.ParentRunner.runLeaf(ParentRunner.java:271)at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:70)at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:50)at org.junit.runners.ParentRunner$3.run(ParentRunner.java:238)at org.junit.runners.ParentRunner$1.schedule(ParentRunner.java:63)at org.junit.runners.ParentRunner.runChildren(ParentRunner.java:236)at org.junit.runners.ParentRunner.access$000(ParentRunner.java:53)at org.junit.runners.ParentRunner$2.evaluate(ParentRunner.java:229)at org.junit.runners.ParentRunner.run(ParentRunner.java:309)at org.eclipse.jdt.internal.junit4.runner.JUnit4TestReference.run(JUnit4TestReference.java:50)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: com.ibatis.common.jdbc.exception.NestedSQLException:   --- The error occurred in ibatis.xml.  --- The error occurred while applying a result map.  --- Check the User_oracle.ibatisTest.  --- The error occured while instantiating the result object  --- Cause: java.lang.RuntimeException: JavaBeansDataExchange could not instantiate result class.  Cause: java.lang.InstantiationException: com.spring.ibatis.Userat com.ibatis.sqlmap.engine.mapping.statement.GeneralStatement.executeQueryWithCallback(GeneralStatement.java:188)at com.ibatis.sqlmap.engine.mapping.statement.GeneralStatement.executeQueryForList(GeneralStatement.java:123)at com.ibatis.sqlmap.engine.impl.SqlMapExecutorDelegate.queryForList(SqlMapExecutorDelegate.java:615)at com.ibatis.sqlmap.engine.impl.SqlMapExecutorDelegate.queryForList(SqlMapExecutorDelegate.java:589)at com.ibatis.sqlmap.engine.impl.SqlMapSessionImpl.queryForList(SqlMapSessionImpl.java:118)at org.springframework.orm.ibatis.SqlMapClientTemplate$3.doInSqlMapClient(SqlMapClientTemplate.java:298)at org.springframework.orm.ibatis.SqlMapClientTemplate.execute(SqlMapClientTemplate.java:209)... 27 moreCaused by: java.lang.RuntimeException: JavaBeansDataExchange could not instantiate result class.  Cause: java.lang.InstantiationException: com.spring.ibatis.Userat com.ibatis.sqlmap.engine.exchange.JavaBeanDataExchange.setData(JavaBeanDataExchange.java:108)at com.ibatis.sqlmap.engine.mapping.result.BasicResultMap.setResultObjectValues(BasicResultMap.java:373)at com.ibatis.sqlmap.engine.mapping.statement.RowHandlerCallback.handleResultObject(RowHandlerCallback.java:64)at com.ibatis.sqlmap.engine.execution.SqlExecutor.handleResults(SqlExecutor.java:382)at com.ibatis.sqlmap.engine.execution.SqlExecutor.handleMultipleResults(SqlExecutor.java:301)at com.ibatis.sqlmap.engine.execution.SqlExecutor.executeQuery(SqlExecutor.java:190)at com.ibatis.sqlmap.engine.mapping.statement.GeneralStatement.sqlExecuteQuery(GeneralStatement.java:205)at com.ibatis.sqlmap.engine.mapping.statement.GeneralStatement.executeQueryWithCallback(GeneralStatement.java:173)... 33 moreCaused by: java.lang.InstantiationException: com.spring.ibatis.Userat java.lang.Class.newInstance0(Class.java:357)at java.lang.Class.newInstance(Class.java:325)at com.ibatis.common.resources.Resources.instantiate(Resources.java:294)at com.ibatis.sqlmap.engine.mapping.result.ResultObjectFactoryUtil.createObjectInternally(ResultObjectFactoryUtil.java:127)at com.ibatis.sqlmap.engine.mapping.result.ResultObjectFactoryUtil.createObjectThroughFactory(ResultObjectFactoryUtil.java:95)at com.ibatis.sqlmap.engine.exchange.JavaBeanDataExchange.setData(JavaBeanDataExchange.java:106)... 40 more

在result class中缺少无参默认构造函数导致了抛异常

总结： 有很多开源第三方技术代码里面经常会使用到无参构造函数，特别是在使用反射来实例化对象时。所以我们在写代码过程中最好在添加带参的构造函数时，顺便把无参构造函数也声明了，这样保险点，防止发生一些意想不到的问题。

后来我在User类中加了一个午餐的构造函数，然后获取数据库中所有用户数据时，这个问题就解决了。