做一个mybatis的一对多demo的时候，出现的错误，整了很久，整理如下
错误日志：
org.apache.ibatis.exceptions.PersistenceException: ### Error querying database. Cause: org.apache.ibatis.reflection.ReflectionException: Could not set property 'roleList' of 'class com.xiangty.bean.SysUser' with value 'SysRole [id=1, roleName=管理员, enable=1, createBy=1, createTime=Sun Oct 14 00:03:31 CST 2018]' Cause: java.lang.IllegalArgumentException: argument type mismatch ### The error may exist in com/xiangty/mapper/SysUserMapper.xml ### The error may involve com.xiangty.mapper.SysUserMapper.selectAllUserAndRole ### The error occurred while handling results ### SQL: select u.id, u.user_name, u.user_password, u.user_email, u.user_info, u.head_img, u.create_time, r.id role_id, r.role_name role_role_name, r.enabled role_enabled, r.create_by role_create_by, r.create_time role_create_time from sys_user u inner join sys_user_role ur on u.id=ur.user_id inner join sys_role r on ur.role_id=r.id ### Cause: org.apache.ibatis.reflection.ReflectionException: Could not set property 'roleList' of 'class com.xiangty.bean.SysUser' with value 'SysRole [id=1, roleName=管理员, enable=1, createBy=1, createTime=Sun Oct 14 00:03:31 CST 2018]' Cause: java.lang.IllegalArgumentException: argument type mismatch at org.apache.ibatis.exceptions.ExceptionFactory.wrapException(ExceptionFactory.java:30) at org.apache.ibatis.session.defaults.DefaultSqlSession.selectList(DefaultSqlSession.java:122) at org.apache.ibatis.session.defaults.DefaultSqlSession.selectList(DefaultSqlSession.java:113) 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.$Proxy17.selectAllUserAndRole(Unknown Source) at com.xiangty.test.SysUserMapperTest.testSelectAllUserAndRole(SysUserMapperTest.java:539) at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source) at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source) at java.lang.reflect.Method.invoke(Unknown Source) 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.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.internal.runners.statements.RunBefores.evaluate(RunBefores.java:26) 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:678) 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: Could not set property 'roleList' of 'class com.xiangty.bean.SysUser' with value 'SysRole [id=1, roleName=管理员, enable=1, createBy=1, createTime=Sun Oct 14 00:03:31 CST 2018]' Cause: java.lang.IllegalArgumentException: argument type mismatch at org.apache.ibatis.reflection.wrapper.BeanWrapper.setBeanProperty(BeanWrapper.java:185) at org.apache.ibatis.reflection.wrapper.BeanWrapper.set(BeanWrapper.java:59) at org.apache.ibatis.reflection.MetaObject.setValue(MetaObject.java:140) at org.apache.ibatis.executor.resultset.DefaultResultSetHandler.linkObjects(DefaultResultSetHandler.java:1025) at org.apache.ibatis.executor.resultset.DefaultResultSetHandler.applyNestedResultMappings(DefaultResultSetHandler.java:872) at org.apache.ibatis.executor.resultset.DefaultResultSetHandler.getRowValue(DefaultResultSetHandler.java:827) at org.apache.ibatis.executor.resultset.DefaultResultSetHandler.handleRowValuesForNestedResultMap(DefaultResultSetHandler.java:793) at org.apache.ibatis.executor.resultset.DefaultResultSetHandler.handleRowValues(DefaultResultSetHandler.java:291) 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 org.apache.ibatis.executor.CachingExecutor.query(CachingExecutor.java:82) at org.apache.ibatis.session.defaults.DefaultSqlSession.selectList(DefaultSqlSession.java:120) ... 30 more Caused by: java.lang.IllegalArgumentException: argument type mismatch at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source) at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source) at java.lang.reflect.Method.invoke(Unknown Source) at org.apache.ibatis.reflection.invoker.MethodInvoker.invoke(MethodInvoker.java:41) at org.apache.ibatis.reflection.wrapper.BeanWrapper.setBeanProperty(BeanWrapper.java:180) ... 47 more错误原因和解决：
一下是正确代码
SysUser类和SysRole类，一对多的关系
SysUser代码：
import java.util.Arrays; import java.util.Date; import java.util.List; public class SysUser { private Long id; private String userName; private String userPassword; private String userEmail; private String userInfo; private Byte[] headImg; private Date createTime; /** * 用户角色 */ private List<SysRole> roleList; public List<SysRole> getRoleList() { return roleList; } public void setRoleList(List<SysRole> roleList) { this.roleList = roleList; } public SysUser() { } public Long getId() { return id; } public void setId(Long id) { this.id = id; } public String getUserName() { return userName; } public void setUserName(String userName) { this.userName = userName; } public String getUserPassword() { return userPassword; } public void setUserPassword(String userPassword) { this.userPassword = userPassword; } public String getUserEmail() { return userEmail; } public void setUserEmail(String userEmail) { this.userEmail = userEmail; } public String getUserInfo() { return userInfo; } public void setUserInfo(String userInfo) { this.userInfo = userInfo; } public Byte[] getHeadImg() { return headImg; } public void setHeadImg(Byte[] headImg) { this.headImg = headImg; } public Date getCreateTime() { return createTime; } public void setCreateTime(Date createTime) { this.createTime = createTime; } @Override public String toString() { return "SysUser [id=" + id + ", userName=" + userName + ", userPassword=" + userPassword + ", userEmail=" + userEmail + ", userInfo=" + userInfo + ", headImg=" + Arrays.toString(headImg) + ", createTime=" + createTime + ", roleList=" + roleList + "]"; } }SysRole类：
import java.util.Date; public class SysRole { private Long id; private String roleName; private Integer enabled; private Long createBy; private Date createTime; private SysUser sysUser; public SysUser getSysUser(){ return sysUser; } public void setSysUser(SysUser sysUser){ this.sysUser = sysUser; } public SysRole() { } public Long getId() { return id; } public void setId(Long id) { this.id = id; } public String getRoleName() { return roleName; } public void setRoleName(String roleName) { this.roleName = roleName; } public Integer getEnabled() { return enabled; } public void setEnabled(Integer enabled) { this.enabled = enabled; } public Long getCreateBy() { return createBy; } public void setCreateBy(Long createBy) { this.createBy = createBy; } public Date getCreateTime() { return createTime; } public void setCreateTime(Date createTime) { this.createTime = createTime; } @Override public String toString() { return "SysRole [id=" + id + ", roleName=" + roleName + ", enable=" + enabled + ", createBy=" + createBy + ", createTime=" + createTime + ", sysUser=" + sysUser + "]"; } }
Mapper.xml
<resultMap id="userRoleListMap" type="com.xiangty.bean.SysUser"> <id property="id" column="id"/> <result property="userName" column="user_name"/> <result property="userPassword" column="user_password"/> <result property="userEmail" column="user_email"/> <result property="userInfo" column="user_info"/> <result property="headImg" column="head_img"/> <result property="createTime" column="create_time" jdbcType="TIMESTAMP"/> <!-- 注：此处的一定是ofType不是javaType --> <collection property="roleList" columnPrefix="role_" ofType="com.xiangty.bean.SysRole"> <id property="id" column="id"/> <result property="roleName" column="role_name"/> <result property="enabled" column="enabled"/> <result property="createBy" column="create_by"/> <result property="createTime" column="create_time"/> </collection> </resultMap> <select id="selectAllUserAndRole" resultMap="userRoleListMap"> select u.id, u.user_name, u.user_password, u.user_email, u.user_info, u.head_img, u.create_time, r.id role_id, r.role_name role_role_name, r.enabled role_enabled, r.create_by role_create_by, r.create_time role_create_time from sys_user u inner join sys_user_role ur on u.id=ur.user_id inner join sys_role r on ur.role_id=r.id </select>
如有错误请指正，谢谢
