Mybatis的CRUD小Demo
为方便查看每次的增删改结果,封装了查询,用来显示数据库的记录;
public static void showInfo(){ SqlSession session = getSqlSesion(); String sql = "me.gacl.mapping.userMapper.getUsers"; List<Map<String,String>> users = session.selectList(sql); for(Map<String,String> u : users){ System.out.println("id:" + u.get("id").toString() + "--NAME:" + u.get("NAME")); } session.close(); }
id字段数据库数据类型是int,返回Map接收查询结果,接收时使用了List<Map<String,String>>接收结果集;
<select id="getUsers" resultType="Map"> select * from users </select>
然后一直报错:
java.lang.ClassCastException: java.lang.Integer cannot be cast to java.lang.String at me.gacl.util.MyBatisUtil.showInfo(MyBatisUtil.java:46) at me.gacl.test.TestDBUtil.upUser(TestDBUtil.java:71) 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: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)
最终改了接收结果集才解决问题:
public static void showInfo(){ SqlSession session = getSqlSesion(); String sql = "me.gacl.mapping.userMapper.getUsers"; List<Map<String,Object>> users = session.selectList(sql); for(Map<String,Object> u : users){ System.out.println("id:" + u.get("id").toString() + "--NAME:" + u.get("NAME")); } session.close(); }
做一个随笔记录,纪念自己的坑。