老师好，原来运行时成功的，后来不知道怎么了就出现这样的错误

package com.study.mybatis;

import com.study.mybatis.entity.Goods;
import com.study.mybatis.entity.Students;
import com.study.mybatis.utils.MyBatisUtils;
import org.apache.ibatis.io.Resources;
import org.apache.ibatis.session.SqlSession;
import org.apache.ibatis.session.SqlSessionFactory;
import org.apache.ibatis.session.SqlSessionFactoryBuilder;
import org.junit.Test;

import java.io.IOException;
import java.io.Reader;
import java.sql.Connection;
import java.util.List;


public class MybatisTesttor {
   @Test
   public void testSqlSessionFactory() throws IOException {
       Reader reader=Resources.getResourceAsReader("mybatis-config.xml");
       SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(reader);
       System.out.println("_sqlSessionFactory加载成功_");
       SqlSession sqlSession = null;
       try {
           sqlSession = sqlSessionFactory.openSession();
           Connection connection = sqlSession.getConnection();
           System.out.println(connection);
       }catch (Exception e){
           e.printStackTrace();
       }finally {
           if (sqlSession!=null){
               sqlSession.close();
           }

       }

   }

   @Test
   public  void testMyBatisUtils() throws Exception {
       SqlSession sqlSession= null;
       try{
           sqlSession=MyBatisUtils.openSession();
           Connection connection = sqlSession.getConnection();
           System.out.println(connection);
       }catch (Exception e){
           throw e;
       }finally {
           MyBatisUtils.closeSession(sqlSession);
       }
   }

   @Test
   public void testSelectAll() throws Exception {
       SqlSession session=null;
       try {
           session=MyBatisUtils.openSession();
           List<Goods> list=session.selectList("goods.selectAll");
           for (Goods g:list){
               System.out.println(g.getTitle());
           }
       }catch (Exception e){
           throw e;
       }finally {
           MyBatisUtils.closeSession(session);
       }
   }

"C:\Program Files\Java\jdk1.8.0_131\bin\java.exe" -ea -Didea.test.cyclic.buffer.size=1048576 "-javaagent:D:\JetBrains\IntelliJ IDEA 2020.1.3\lib\idea_rt.jar=65519:D:\JetBrains\IntelliJ IDEA 2020.1.3\bin" -Dfile.encoding=UTF-8 -classpath "D:\JetBrains\IntelliJ IDEA 2020.1.3\lib\idea_rt.jar;D:\JetBrains\IntelliJ IDEA 2020.1.3\plugins\junit\lib\junit5-rt.jar;D:\JetBrains\IntelliJ IDEA 2020.1.3\plugins\junit\lib\junit-rt.jar;C:\Program Files\Java\jdk1.8.0_131\jre\lib\charsets.jar;C:\Program Files\Java\jdk1.8.0_131\jre\lib\deploy.jar;C:\Program Files\Java\jdk1.8.0_131\jre\lib\ext\access-bridge-64.jar;C:\Program Files\Java\jdk1.8.0_131\jre\lib\ext\cldrdata.jar;C:\Program Files\Java\jdk1.8.0_131\jre\lib\ext\dnsns.jar;C:\Program Files\Java\jdk1.8.0_131\jre\lib\ext\jaccess.jar;C:\Program Files\Java\jdk1.8.0_131\jre\lib\ext\jfxrt.jar;C:\Program Files\Java\jdk1.8.0_131\jre\lib\ext\localedata.jar;C:\Program Files\Java\jdk1.8.0_131\jre\lib\ext\nashorn.jar;C:\Program Files\Java\jdk1.8.0_131\jre\lib\ext\sunec.jar;C:\Program Files\Java\jdk1.8.0_131\jre\lib\ext\sunjce_provider.jar;C:\Program Files\Java\jdk1.8.0_131\jre\lib\ext\sunmscapi.jar;C:\Program Files\Java\jdk1.8.0_131\jre\lib\ext\sunpkcs11.jar;C:\Program Files\Java\jdk1.8.0_131\jre\lib\ext\zipfs.jar;C:\Program Files\Java\jdk1.8.0_131\jre\lib\javaws.jar;C:\Program Files\Java\jdk1.8.0_131\jre\lib\jce.jar;C:\Program Files\Java\jdk1.8.0_131\jre\lib\jfr.jar;C:\Program Files\Java\jdk1.8.0_131\jre\lib\jfxswt.jar;C:\Program Files\Java\jdk1.8.0_131\jre\lib\jsse.jar;C:\Program Files\Java\jdk1.8.0_131\jre\lib\management-agent.jar;C:\Program Files\Java\jdk1.8.0_131\jre\lib\plugin.jar;C:\Program Files\Java\jdk1.8.0_131\jre\lib\resources.jar;C:\Program Files\Java\jdk1.8.0_131\jre\lib\rt.jar;D:\IdeaProjects\mybatis\target\test-classes;D:\IdeaProjects\mybatis\target\classes;C:\Users\10160\.m2\repository\org\mybatis\mybatis\3.5.5\mybatis-3.5.5.jar;C:\Users\10160\.m2\repository\mysql\mysql-connector-java\5.1.38\mysql-connector-java-5.1.38.jar;C:\Users\10160\.m2\repository\junit\junit\4.8.2\junit-4.8.2.jar" com.intellij.rt.junit.JUnitStarter -ideVersion5 -junit4 com.study.mybatis.MybatisTesttor,testSelectAll

java.lang.NoClassDefFoundError: Could not initialize class com.study.mybatis.utils.MyBatisUtils

at com.study.mybatis.MybatisTesttor.testSelectAll(MybatisTesttor.java:66)

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:44)

at org.junit.internal.runners.model.ReflectiveCallable.run(ReflectiveCallable.java:15)

at org.junit.runners.model.FrameworkMethod.invokeExplosively(FrameworkMethod.java:41)

at org.junit.internal.runners.statements.InvokeMethod.evaluate(InvokeMethod.java:20)

at org.junit.runners.BlockJUnit4ClassRunner.runNotIgnored(BlockJUnit4ClassRunner.java:79)

at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:71)

at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:49)

at org.junit.runners.ParentRunner$3.run(ParentRunner.java:193)

at org.junit.runners.ParentRunner$1.schedule(ParentRunner.java:52)

at org.junit.runners.ParentRunner.runChildren(ParentRunner.java:191)

at org.junit.runners.ParentRunner.access$000(ParentRunner.java:42)

at org.junit.runners.ParentRunner$2.evaluate(ParentRunner.java:184)

at org.junit.runners.ParentRunner.run(ParentRunner.java:236)

at org.junit.runner.JUnitCore.run(JUnitCore.java:157)

at com.intellij.junit4.JUnit4IdeaTestRunner.startRunnerWithArgs(JUnit4IdeaTestRunner.java:68)

at com.intellij.rt.junit.IdeaTestRunner$Repeater.startRunnerWithArgs(IdeaTestRunner.java:33)

at com.intellij.rt.junit.JUnitStarter.prepareStreamsAndStart(JUnitStarter.java:230)

at com.intellij.rt.junit.JUnitStarter.main(JUnitStarter.java:58)

Process finished with exit code -1