Mybatis 查询结果类型Character异常
今天开发时遇到一个问题，在执行查询方法的时候，系统提示异常String index out of range: 0；
控制台信息如下：
org.mybatis.spring.MyBatisSystemException: nested exception is org.apache.ibatis.executor.result.ResultMapException: Error attempting to get column '字段名' from result set. Cause: java.lang.StringIndexOutOfBoundsException: String index out of range: 0
at org.mybatis.spring.MyBatisExceptionTranslator.translateExceptionIfPossible(MyBatisExceptionTranslator.java:79)
at org.mybatis.spring.SqlSessionTemplate$SqlSessionInterceptor.invoke(SqlSessionTemplate.java:447)
at com.sun.proxy.$Proxy24.selectList(Unknown Source)
at org.mybatis.spring.SqlSessionTemplate.selectList(SqlSessionTemplate.java:231)
at org.apache.ibatis.binding.MapperMethod.executeForMany(MapperMethod.java:122)
at org.apache.ibatis.binding.MapperMethod.execute(MapperMethod.java:64)
at org.apache.ibatis.binding.MapperProxy.invoke(MapperProxy.java:53)
at com.sun.proxy.$Proxy67.selectOldPhoneInfo(Unknown Source)
at com.hibroad.compatibleweb.service.impl.FallDownServiceImpl.phonePup(FallDownServiceImpl.java:210)
at com.hibroad.compatibleweb.service.impl.FallDownServiceImpl$$FastClassByCGLIB$$a692b24b.invoke()
at org.springframework.cglib.proxy.MethodProxy.invoke(MethodProxy.java:204)
at org.springframework.aop.framework.CglibAopProxy$CglibMethodInvocation.invokeJoinpoint(CglibAopProxy.java:713)
at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:157)
at org.springframework.transaction.interceptor.TransactionInterceptor$1.proceedWithInvocation(TransactionInterceptor.java:98)
at org.springframework.transaction.interceptor.TransactionAspectSupport.invokeWithinTransaction(TransactionAspectSupport.java:262)
at org.springframework.transaction.interceptor.TransactionInterceptor.invoke(TransactionInterceptor.java:95)
at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:179)
at org.springframework.aop.interceptor.ExposeInvocationInterceptor.invoke(ExposeInvocationInterceptor.java:92)
at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:179)
at org.springframework.aop.framework.CglibAopProxy$DynamicAdvisedInterceptor.intercept(CglibAopProxy.java:646)
at com.hibroad.compatibleweb.service.impl.FallDownServiceImpl$$EnhancerByCGLIB$$28859386.phonePup()
at com.hibroad.compatibleweb.handler.FallDownHandler.doHandler(FallDownHandler.java:82)
at com.hibroad.compatibleweb.handler.FamilyApiHandler_Web.mappingClass(FamilyApiHandler_Web.java:238)
at com.hibroad.compatibleweb.handler.FamilyApiHandler_Web.service(FamilyApiHandler_Web.java:165)
at com.hibroad.compatibleweb.handler.FamilyApiHandler_Web.service_get(FamilyApiHandler_Web.java:57)
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:606)
at org.springframework.web.method.support.InvocableHandlerMethod.invoke(InvocableHandlerMethod.java:214)
at org.springframework.web.method.support.InvocableHandlerMethod.invokeForRequest(InvocableHandlerMethod.java:132)
at org.springframework.web.servlet.mvc.method.annotation.ServletInvocableHandlerMethod.invokeAndHandle(ServletInvocableHandlerMethod.java:104)
at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.invokeHandleMethod(RequestMappingHandlerAdapter.java:748)
at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.handleInternal(RequestMappingHandlerAdapter.java:689)
at org.springframework.web.servlet.mvc.method.AbstractHandlerMethodAdapter.handle(AbstractHandlerMethodAdapter.java:83)
at org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:945)
at org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:876)
at org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:931)
at org.springframework.web.servlet.FrameworkServlet.doGet(FrameworkServlet.java:822)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:624)
at org.springframework.web.servlet.FrameworkServlet.service(FrameworkServlet.java:807)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:731)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:303)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:208)
at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:241)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:208)
at com.hibroad.util.CorsFilter.doFilter(CorsFilter.java:24)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:241)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:208)
at org.springframework.web.filter.CharacterEncodingFilter.doFilterInternal(CharacterEncodingFilter.java:88)
at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:108)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:241)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:208)
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:219)
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:110)
at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:498)
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:169)
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:103)
at org.apache.catalina.valves.AccessLogValve.invoke(AccessLogValve.java:1025)
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:116)
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:445)
at org.apache.coyote.http11.AbstractHttp11Processor.process(AbstractHttp11Processor.java:1115)
at org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java:637)
at org.apache.tomcat.util.net.JIoEndpoint$SocketProcessor.run(JIoEndpoint.java:316)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1145)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:615)
at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61)
at java.lang.Thread.run(Thread.java:745)
Caused by: org.apache.ibatis.executor.result.ResultMapException: Error attempting to get column '字段名' from result set. Cause: java.lang.StringIndexOutOfBoundsException: String index out of range: 0
at org.apache.ibatis.type.BaseTypeHandler.getResult(BaseTypeHandler.java:68)
at org.apache.ibatis.executor.resultset.DefaultResultSetHandler.applyAutomaticMappings(DefaultResultSetHandler.java:471)
at org.apache.ibatis.executor.resultset.DefaultResultSetHandler.getRowValue(DefaultResultSetHandler.java:364)
at org.apache.ibatis.executor.resultset.DefaultResultSetHandler.handleRowValuesForSimpleResultMap(DefaultResultSetHandler.java:318)
at org.apache.ibatis.executor.resultset.DefaultResultSetHandler.handleRowValues(DefaultResultSetHandler.java:293)
at org.apache.ibatis.executor.resultset.DefaultResultSetHandler.handleResultSet(DefaultResultSetHandler.java:266)
at org.apache.ibatis.executor.resultset.DefaultResultSetHandler.handleResultSets(DefaultResultSetHandler.java:180)
at org.apache.ibatis.executor.statement.PreparedStatementHandler.query(PreparedStatementHandler.java:63)
at org.apache.ibatis.executor.statement.RoutingStatementHandler.query(RoutingStatementHandler.java:78)
at org.apache.ibatis.executor.SimpleExecutor.doQuery(SimpleExecutor.java:62)
at org.apache.ibatis.executor.BaseExecutor.queryFromDatabase(BaseExecutor.java:303)
at org.apache.ibatis.executor.BaseExecutor.query(BaseExecutor.java:154)
at org.apache.ibatis.executor.CachingExecutor.query(CachingExecutor.java:102)
at com.github.pagehelper.PageInterceptor.intercept(PageInterceptor.java:141)
at org.apache.ibatis.plugin.Plugin.invoke(Plugin.java:61)
at com.sun.proxy.$Proxy136.query(Unknown Source)
at org.apache.ibatis.session.defaults.DefaultSqlSession.selectList(DefaultSqlSession.java:120)
at org.apache.ibatis.session.defaults.DefaultSqlSession.selectList(DefaultSqlSession.java:113)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:606)
at org.mybatis.spring.SqlSessionTemplate$SqlSessionInterceptor.invoke(SqlSessionTemplate.java:434)
... 67 more
Caused by: java.lang.StringIndexOutOfBoundsException: String index out of range: 0
at java.lang.String.charAt(String.java:658)
at org.apache.ibatis.type.CharacterTypeHandler.getNullableResult(CharacterTypeHandler.java:37)
at org.apache.ibatis.type.CharacterTypeHandler.getNullableResult(CharacterTypeHandler.java:26)
at org.apache.ibatis.type.BaseTypeHandler.getResult(BaseTypeHandler.java:66) 发现控制台提到的某个字段，在Java中使用了Character类型。
然后我看了Mybatis对Character类型转换的的源码，发现Mybatis对Character内容时只进行了null的判断没有对长度进行判断，而获取值的时候直接使用charAt(0);
public class CharacterTypeHandler extends BaseTypeHandler {
@Override
public void setNonNullParameter(PreparedStatement ps, int i, Character parameter, JdbcType jdbcType) throws SQLException {
ps.setString(i, parameter.toString());
}
@Override
public Character getNullableResult(ResultSet rs, String columnName) throws SQLException {
String columnValue = rs.getString(columnName);
if (columnValue != null) {
return columnValue.charAt(0);
} else {
return null;
}
}
@Override
public Character getNullableResult(ResultSet rs, int columnIndex) throws SQLException {
String columnValue = rs.getString(columnIndex);
if (columnValue != null) {
return columnValue.charAt(0);
} else {
return null;
}
}
@Override
public Character getNullableResult(CallableStatement cs, int columnIndex) throws SQLException {
String columnValue = cs.getString(columnIndex);
if (columnValue != null) {
return columnValue.charAt(0);
} else {
return null;
}
}
} 所以只要Character类型字段的结果是空字符串的情况，就报异常。
解决方式：
1、在项目中添加Character类型的处理类；
public class MyCharacterTypeHandler extends BaseTypeHandler {
@Override
public void setNonNullParameter(PreparedStatement ps, int i, Character parameter, JdbcType jdbcType)
throws SQLException {
ps.setString(i, parameter.toString());
}
@Override
public Character getNullableResult(ResultSet rs, String columnName) throws SQLException {
String columnValue = rs.getString(columnName);
if (columnValue != null && !columnValue.isEmpty() ) {
return columnValue.charAt(0);
} else {
return null;
}
}
@Override
public Character getNullableResult(ResultSet rs, int columnIndex) throws SQLException {
String columnValue = rs.getString(columnIndex);
if (columnValue != null && !columnValue.isEmpty() ) {
return columnValue.charAt(0);
} else {
return null;
}
}
@Override
public Character getNullableResult(CallableStatement cs, int columnIndex) throws SQLException {
String columnValue = cs.getString(columnIndex);
if (columnValue != null && !columnValue.isEmpty() ) {
return columnValue.charAt(0);
} else {
return null;
}
}
} 2、在Mybatis配置文件（mybatis-config.xml）中添加处理类的配置；