Mapped Statements collection does not contain value for解決方案
阿新 • • 發佈：2018-12-12
建立簡單的mybatis的demo的時候，出現這樣的提示：
org.apache.ibatis.exceptions.PersistenceException: ### Error querying database. Cause: java.lang.IllegalArgumentException: Mapped Statements collection does not contain value for x.y.z.findUserById ### Cause: java.lang.IllegalArgumentException: Mapped Statements collection does not contain value for x.y.z.findUserById at org.apache.ibatis.exceptions.ExceptionFactory.wrapException(ExceptionFactory.java:30) at org.apache.ibatis.session.defaults.DefaultSqlSession.selectList(DefaultSqlSession.java:150) at org.apache.ibatis.session.defaults.DefaultSqlSession.selectList(DefaultSqlSession.java:141) at org.apache.ibatis.session.defaults.DefaultSqlSession.selectOne(DefaultSqlSession.java:77) at dao.userDaoImpl.findUserById(userDaoImpl.java:19) at test.TestUserClass.testFindUserById(TestUserClass.java:11) 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$2.evaluate(ParentRunner.java:268) at org.junit.runners.ParentRunner.run(ParentRunner.java:363) at org.eclipse.jdt.internal.junit4.runner.JUnit4TestReference.run(JUnit4TestReference.java:86) at org.eclipse.jdt.internal.junit.runner.TestExecution.run(TestExecution.java:38) at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:459) at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:675) at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.run(RemoteTestRunner.java:382) at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.main(RemoteTestRunner.java:192) Caused by: java.lang.IllegalArgumentException: Mapped Statements collection does not contain value for x.y.z.findUserById at org.apache.ibatis.session.Configuration$StrictMap.get(Configuration.java:888) at org.apache.ibatis.session.Configuration.getMappedStatement(Configuration.java:721) at org.apache.ibatis.session.Configuration.getMappedStatement(Configuration.java:714) at org.apache.ibatis.session.defaults.DefaultSqlSession.selectList(DefaultSqlSession.java:147) ... 27 more
網上的解決方案主要有幾種，我仔細發現，自己好像mapper裡的xml檔案沒有寫好：
before：
<mapper namespace="x.y.z.">after：
<mapper namespace="x.y.z">因為在編譯的時候namespace給我們自動新增一個點（.），驗證一下：
<mapper namespace="x.y.z.">
user=(User)session.selectOne("x.y.z..findUserById",id);結果完全正確，此坑驗證成功
如果不新增：
user=(User)session.selectOne("x.y.z.findUserById",id);
結果就是顯示最開始的錯誤