mybatis一些记录

1，mybatis中#{sx}会使用?进行替代，$(xx)会完整将字符串完成替代

2，mybaits，表中字段为user_id 在Address.class中没有userId属性，有对象User user。使用#{user.id}来表示。

3，当数据库中的字段信息和对象属性不一致时，需要通过resultMap来映射。

4，当数据库中的字段信息和对象的属性不一致时需要通过resultMap来映射

<resultMap type="Address" id="addressMap">
    <result column="post_code" property="postcode"/>
</resultMap>

5，NoClassDefFoundError异常

java.lang.NoClassDefFoundError: Could not initialize class tk.dongyeblog.shop.util.MyBatisUtil
at tk.dongyeblog.shop.dao.BaseDao.load(BaseDao.java:64)
at tk.dongyeblog.shop.dao.BaseDao.load(BaseDao.java:55)
at tk.dongyeblog.shop.dao.AddressDao.load(AddressDao.java:36)
at tk.dongyeblog.shop.test.TestAddressDao.testLoad(TestAddressDao.java:46)
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.junit.runners.model.FrameworkMethod$1.runReflectiveCall(FrameworkMethod.java:45)
at org.junit.internal.runners.model.ReflectiveCallable.run(ReflectiveCallable.java:15)
at org.junit.runners.model.FrameworkMethod.invokeExplosively(FrameworkMethod.java:42)
at org.junit.internal.runners.statements.InvokeMethod.evaluate(InvokeMethod.java:20)
at org.junit.internal.runners.statements.RunBefores.evaluate(RunBefores.java:28)
at org.junit.runners.ParentRunner.runLeaf(ParentRunner.java:263)
at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:68)
at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:47)
at org.junit.runners.ParentRunner$3.run(ParentRunner.java:231)
at org.junit.runners.ParentRunner$1.schedule(ParentRunner.java:60)
at org.junit.runners.ParentRunner.runChildren(ParentRunner.java:229)
at org.junit.runners.ParentRunner.access$000(ParentRunner.java:50)
at org.junit.runners.ParentRunner$2.evaluate(ParentRunner.java:222)
at org.junit.runners.ParentRunner.run(ParentRunner.java:300)
at org.eclipse.jdt.internal.junit4.runner.JUnit4TestReference.run(JUnit4TestReference.java:50)
at org.eclipse.jdt.internal.junit.runner.TestExecution.run(TestExecution.java:38)
at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:467)
at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:683)
at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.run(RemoteTestRunner.java:390)
at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.main(RemoteTestRunner.java:197)

错误找了半天，原来是Address写成Adderss了。一定要小心啊！

如果类确实存在的话，应仔细检查配置文件。一般是类名字写错了。