TestDB.java

package com.company.core;

import java.sql.*;

public class TestDB {

    /**
     * @param args
     */
    public static void main(String[] args) {
        try{
            Class.forName("com.mysql.jdbc.Driver").newInstance();
            String url="jdbc:mysql://127.0.0.1:3306/test?user=root&password=1234&useUnicode=true";
           
            Connection conn=DriverManager.getConnection(url);
            Statement stmt=conn.createStatement(ResultSet.TYPE_SCROLL_SENSITIVE,ResultSet.CONCUR_UPDATABLE);
            String sql="select * from test";
            ResultSet rs=stmt.executeQuery(sql);
           
            while(rs.next()){
                System.out.println("id is:"+rs.getString(1));
                System.out.println("name is:"+rs.getString(2));
            }
           
            rs.close();
            stmt.close();
            conn.close();
        }catch(Exception ex){
            ex.printStackTrace();
        }
    }

}

下午7:18:05: 正在执行 ':StudentManagementSystem.main()'… > Task :compileJava > Task :processResources UP-TO-DATE > Task :classes > Task :StudentManagementSystem.main() java.sql.SQLException: No suitable driver found for jdbc:mysql://localhost:3306/test1?useUnicode=true&characterEncoding=gbk at java.sql/java.sql.DriverManager.getConnection(DriverManager.java:706) at java.sql/java.sql.DriverManager.getConnection(DriverManager.java:229) at StudentManagementSystem.initDatabase(StudentManagementSystem.java:39) at StudentManagementSystem.<init>(StudentManagementSystem.java:24) at StudentManagementSystem$5.run(StudentManagementSystem.java:299) at java.desktop/java.awt.event.InvocationEvent.dispatch(InvocationEvent.java:318) at java.desktop/java.awt.EventQueue.dispatchEventImpl(EventQueue.java:771) at java.desktop/java.awt.EventQueue$4.run(EventQueue.java:722) at java.desktop/java.awt.EventQueue$4.run(EventQueue.java:716) at java.base/java.security.AccessController.doPrivileged(AccessController.java:399) at java.base/java.security.ProtectionDomain$JavaSecurityAccessImpl.doIntersectionPrivilege(ProtectionDomain.java:86) at java.desktop/java.awt.EventQueue.dispatchEvent(EventQueue.java:741) at java.desktop/java.awt.EventDispatchThread.pumpOneEventForFilters(EventDispatchThread.java:203) at java.desktop/java.awt.EventDispatchThread.pumpEventsForFilter(EventDispatchThread.java:124) at java.desktop/java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:113) at java.desktop/java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:109) at java.desktop/java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:101) at java.desktop/java.awt.EventDispatchThread.run(EventDispatchThread.java:90) Exception in thread "AWT-EventQueue-0" java.lang.NullPointerException: Cannot invoke "java.sql.Connection.createStatement()" because "this.conn" is null at StudentManagementSystem.loadStudentData(StudentManagementSystem.java:267) at StudentManagementSystem.<init>(StudentManagementSystem.java:30) at StudentManagementSystem$5.run(StudentManagementSystem.java:299) at java.desktop/java.awt.event.InvocationEvent.dispatch(InvocationEvent.java:318) at java.desktop/java.awt.EventQueue.dispatchEventImpl(EventQueue.java:771) at java.desktop/java.awt.EventQueue$4.run(EventQueue.java:722) at java.desktop/java.awt.EventQueue$4.run(EventQueue.java:716) at java.base/java.security.AccessController.doPrivileged(AccessController.java:399) at java.base/java.security.ProtectionDomain$JavaSecurityAccessImpl.doIntersectionPrivilege(ProtectionDomain.java:86) at java.desktop/java.awt.EventQueue.dispatchEvent(EventQueue.java:741) at java.desktop/java.awt.EventDispatchThread.pumpOneEventForFilters(EventDispatchThread.java:203) at java.desktop/java.awt.EventDispatchThread.pumpEventsForFilter(EventDispatchThread.java:124) at java.desktop/java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:113) at java.desktop/java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:109) at java.desktop/java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:101) at java.desktop/java.awt.EventDispatchThread.run(EventDispatchThread.java:90)
最新发布
06-12
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