请老师帮忙看一下，报下面的错误
java.lang.ClassNotFoundException: com.mysql.cj.jdbc.Driver
at java.net.URLClassLoader.findClass(Unknown Source)
at java.lang.ClassLoader.loadClass(Unknown Source)
at sun.misc.Launcher$AppClassLoader.loadClass(Unknown Source)
at java.lang.ClassLoader.loadClass(Unknown Source)
at java.lang.Class.forName0(Native Method)
at java.lang.Class.forName(Unknown Source)
at com.imooc.jdbc.JDBCDemo1.demo1(JDBCDemo1.java:20)
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: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.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:86)
at org.eclipse.jdt.internal.junit.runner.TestExecution.run(TestExecution.java:38)
at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:538)
at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:760)
at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.run(RemoteTestRunner.java:460)
at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.main(RemoteTestRunner.java:206)
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 | package com.imooc.jdbc;import java.sql.Connection;import java.sql.DriverManager;import java.sql.ResultSet;import java.sql.SQLException;import java.sql.Statement;import org.junit.Test;/** * * JDBC的入门程序 */public class JDBCDemo1 { @Test public void demo1() { try { // 1.加载驱动 Class.forName("com.mysql.cj.jdbc.Driver"); // 2.获得连接 Connection conn = DriverManager.getConnection( "jdbc:mysql://localhost:3306/JDBC_test" + "?useSSL=false&serverTimezone=Hongkong&useUnicode=true&characterEncoding=utf-8", "root", "115224"); //3.创建执行SQL语句的对象，并且执行SQL //3.1创建执行sql的对象 String sql = "select * from user"; Statement stmt = conn.createStatement(); //3.2执行sql ResultSet resultSet = stmt.executeQuery(sql); while(resultSet.next()) { int uid = resultSet.getInt("uid"); String username = resultSet.getString("username"); String password = resultSet.getString("password"); String name = resultSet.getString("name"); System.out.println(uid+" "+username+" "+password+" "+name); } //4.释放资源 resultSet.close(); stmt.close(); conn.close(); } catch (ClassNotFoundException e) { // TODO Auto-generated catch block e.printStackTrace(); } catch (SQLException e) { // TODO Auto-generated catch block e.printStackTrace(); } }} |
正在回答
报错提示是这个工程中有报错，同学看的是这个JDBCDemo这个项目么？
该报错只是询问你，不影响这个代码执行，只是你的JDBCDemo这个项目中有错误，问你要不要继续。
祝学习愉快
还有一个问题，虽然现在可以运行，但每次Run AS的时候会出现以下提示
解决了，换了一个mysql-connector-java-8.0 jar包就可以了
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