【问题解决】ibatis.binding.BindingException: Type interface xxDao is not known to the MapperRegistry.

问题描述：

org.apache.ibatis.binding.BindingException: Type interface com.kuang.dao.UserDao is not known to the MapperRegistry.

MapperRegistry不知道UserDao。

原因：

XXXDaoMapper.xml写了之后，没有在mybaits-config.xml配置文件中注册mapper，

没有注册mapper，写的 XXXDaoMapper.xml就不能实现XXXDao,因为他们之间没有进行绑定，

说白了，XXXDaoMapper.xml 就是 XXXDao.java中接口的实现类，

原来写实现类，是通过 xxxDaoImpl.java类 implement dao层的接口，从而实现绑定的，现在通过namespace来实现绑定

解决办法：

mybaits-config.xml中加入：

<mappers>
    <mapper resource="com/kuang/dao/UserMapper.xml"></mapper>
</mappers>

日志:

org.apache.ibatis.binding.BindingException: Type interface com.kuang.dao.UserDao is not known to the MapperRegistry.

	at org.apache.ibatis.binding.MapperRegistry.getMapper(MapperRegistry.java:47)
	at org.apache.ibatis.session.Configuration.getMapper(Configuration.java:732)
	at org.apache.ibatis.session.defaults.DefaultSqlSession.getMapper(DefaultSqlSession.java:292)
	at com.kuang.dao.UserDaoTest.test(UserDaoTest.java:42)
	at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
	at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
	at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
	at java.lang.reflect.Method.invoke(Method.java:498)
	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$2.evaluate(ParentRunner.java:229)
	at org.junit.runners.ParentRunner.run(ParentRunner.java:309)
	at org.junit.runner.JUnitCore.run(JUnitCore.java:160)
	at com.intellij.junit4.JUnit4IdeaTestRunner.startRunnerWithArgs(JUnit4IdeaTestRunner.java:69)
	at com.intellij.rt.junit.IdeaTestRunner$Repeater.startRunnerWithArgs(IdeaTestRunner.java:33)
	at com.intellij.rt.junit.JUnitStarter.prepareStreamsAndStart(JUnitStarter.java:220)
	at com.intellij.rt.junit.JUnitStarter.main(JUnitStarter.java:53)