Mybatis 查询结果类型为char时候：Cause: java.lang.StringIndexOutOfBoundsException: String index out of range: 0…「建议收藏」

使用mybatis处理某个类型为char的字段时候爆出了这么个错误：

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(<generated>)
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(<generated>)
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)

这个字段是char类型的，别的都好，就这个报错，问题定位到mybatis处理char上，我们看看mybatis是怎么处理char的，附上mybatis处理的源代码：

/**
*    Copyright 2009-2015 the original author or authors.
*
*    Licensed under the Apache License, Version 2.0 (the "License");
*    you may not use this file except in compliance with the License.
*    You may obtain a copy of the License at
*
*       http://www.apache.org/licenses/LICENSE-2.0
*
*    Unless required by applicable law or agreed to in writing, software
*    distributed under the License is distributed on an "AS IS" BASIS,
*    WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
*    See the License for the specific language governing permissions and
*    limitations under the License.
*/
package org.apache.ibatis.type;
import java.sql.CallableStatement;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
/**
* @author Clinton Begin
*/
public class CharacterTypeHandler extends BaseTypeHandler<Character> {
@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;
}
}
}

只判断了是否为null，就直接charAt(0)了，如果columnValue为空，直接就异常了。怎么处理呢重写一个typeHandle<Character>

package com.lpc.config;
import org.apache.ibatis.type.BaseTypeHandler;
import org.apache.ibatis.type.JdbcType;
import java.sql.CallableStatement;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
public class MyCharacterTypeHandler extends BaseTypeHandler<Character> {
@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;
}
}
}

然后在mybatis-config.xml中写上：

<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE configuration PUBLIC "-//mybatis.org//DTD Config 3.0//EN"
"http://mybatis.org/dtd/mybatis-3-config.dtd">
<configuration>
<typeHandlers>
<typeHandler javaType="java.lang.Character" jdbcType="CHAR" handler="com.lpc.config.MyCharacterTypeHandler" />
</typeHandlers>
</configuration>

在application.properties中加上mybatis-config配置：

mybatis.config-location=classpath:mybatis-config.xml

在mapper.xml文件中的这一字段需要修改，如下：

<result column="orderNum" property="orderNum" jdbcType="CHAR" typeHandler="com.lpc.config.MyCharacterTypeHandler"/>

好了，重启搞定！！