Mybatis使用报错org.apache.ibatis.exceptions.PersistenceException:
使用Mybatis中使用Mapper动态代理方式测试报以下错误：
org.apache.ibatis.exceptions.PersistenceException:
### Error querying database. Cause: org.apache.ibatis.reflection.ReflectionException: Error instantiating class com.dcits.po.User with invalid types () or values (). Cause: java.lang.NoSuchMethodException: com.dcits.po.User.
### The error may exist in mapper\UserMapper.xml
### The error may involve com.dcits.interfacee.userMapper.selectByName-Inline
### The error occurred while setting parameters
### SQL: select * from user where username like CONCAT('%',?,'%')
### Cause: org.apache.ibatis.reflection.ReflectionException: Error instantiating class com.dcits.po.User with invalid types () or values (). Cause: java.lang.NoSuchMethodException: com.dcits.po.User.
at org.apache.ibatis.exceptions.ExceptionFactory.wrapException(ExceptionFactory.java:26)
at org.apache.ibatis.session.defaults.DefaultSqlSession.selectList(DefaultSqlSession.java:111)
at org.apache.ibatis.session.defaults.DefaultSqlSession.selectList(DefaultSqlSession.java:102)
at org.apache.ibatis.binding.MapperMethod.executeForMany(MapperMethod.java:119)
at org.apache.ibatis.binding.MapperMethod.execute(MapperMethod.java:63)
at org.apache.ibatis.binding.MapperProxy.invoke(MapperProxy.java:52)
at com.sun.proxy.$Proxy0.selectByName(Unknown Source)
at com.dcits.test.UserMapperTest.testSelectByName(UserMapperTest.java:30)
at com.dcits.test.UserMapperTest.main(UserMapperTest.java:78)
Caused by: org.apache.ibatis.reflection.ReflectionException: Error instantiating class com.dcits.po.User with invalid types () or values (). Cause: java.lang.NoSuchMethodException: com.dcits.po.User.
at org.apache.ibatis.reflection.factory.DefaultObjectFactory.instantiateClass(DefaultObjectFactory.java:86)
at org.apache.ibatis.reflection.factory.DefaultObjectFactory.create(DefaultObjectFactory.java:48)
at org.apache.ibatis.reflection.factory.DefaultObjectFactory.create(DefaultObjectFactory.java:41)
at org.apache.ibatis.executor.resultset.DefaultResultSetHandler.createResultObject(DefaultResultSetHandler.java:528)
at org.apache.ibatis.executor.resultset.DefaultResultSetHandler.createResultObject(DefaultResultSetHandler.java:507)
at org.apache.ibatis.executor.resultset.DefaultResultSetHandler.getRowValue(DefaultResultSetHandler.java:331)
at org.apache.ibatis.executor.resultset.DefaultResultSetHandler.handleRowValuesForSimpleResultMap(DefaultResultSetHandler.java:291)
at org.apache.ibatis.executor.resultset.DefaultResultSetHandler.handleRowValues(DefaultResultSetHandler.java:266)
at org.apache.ibatis.executor.resultset.DefaultResultSetHandler.handleResultSet(DefaultResultSetHandler.java:236)
at org.apache.ibatis.executor.resultset.DefaultResultSetHandler.handleResultSets(DefaultResultSetHandler.java:150)
at org.apache.ibatis.executor.statement.PreparedStatementHandler.query(PreparedStatementHandler.java:60)
at org.apache.ibatis.executor.statement.RoutingStatementHandler.query(RoutingStatementHandler.java:73)
at org.apache.ibatis.executor.SimpleExecutor.doQuery(SimpleExecutor.java:60)
at org.apache.ibatis.executor.BaseExecutor.queryFromDatabase(BaseExecutor.java:267)
at org.apache.ibatis.executor.BaseExecutor.query(BaseExecutor.java:137)
at org.apache.ibatis.executor.CachingExecutor.query(CachingExecutor.java:96)
at org.apache.ibatis.executor.CachingExecutor.query(CachingExecutor.java:77)
at org.apache.ibatis.session.defaults.DefaultSqlSession.selectList(DefaultSqlSession.java:108)
... 7 more
Caused by: java.lang.NoSuchMethodException: com.dcits.po.User.
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:60)
... 24 more
报错原因：mybatis在初始化对象时，需要无参构造进行pojo属性的加载。而我在生成pojo类时创建了有参数的构造方法。在简单的Dao中调用时是没有问题的，但是如果使用Mybatis框架根据接口定义创建接口的动态代理对象（代理对象的方法体如Dao中方法体的实现）就会报错。
解决办法：
去掉pojo类中的有参构造方法，使用无参构造方法初始化对象。
