eclipse常见报错

（1）

报错原因为：外部tomcat已打开

（2）

报错原因为：主键必须不为空

（3）

报错原因为：连接文件要和mysql版本对上
https://www.cnblogs.com/alsf/p/9346921.htmlhttps://www.cnblogs.com/alsf/p/9346921.html

（4）
Loading class com.mysql.jdbc.Driver'. This is deprecated. The new driver class iscom.mysql.cj.jdbc.Driver’. The driver is automatically registered via the SPI and manual loading of the driver class is generally unnecessary.
解决方法：
https://blog.****.net/anaini1314/article/details/71157791

（5）
Wed May 01 16:32:37 CST 2019 WARN: Establishing SSL connection without server’s identity verification is not recommended. According to MySQL 5.5.45+, 5.6.26+ and 5.7.6+ requirements SSL connection must be established by default if explicit option isn’t set. For compliance with existing applications not using SSL the verifyServerCertificate property is set to ‘false’. You need either to explicitly disable SSL by setting useSSL=false, or set useSSL=true and provide truststore for server certificate verification.

解决方法：
https://blog.****.net/yeternity/article/details/80621758

（6）
The last packet sent successfully to the server was 0 milliseconds ago. The driver has not received
解决方法：useSSL=false
连接字符串中true改成false
https://blog.****.net/ponxbin/article/details/80608040

（7）
Illegal access: this web application instance has been stopped already. Could not load [org.quartz.StatefulJob]. The following stack trace is thrown for debugging purposes as well as to attempt to terminate the thread which caused the illegal access.
解决方法：
< Context path="/expert" docBase=“expert” debug=“0” reloadable=“false”>
https://blog.****.net/qq_30714157/article/details/81236434

（8）
ajax格式：
https://blog.****.net/maxoracle/article/details/51064756

（9）
JSONObject cannot be resolved to a type
解决方法：
https://blog.****.net/u013532827/article/details/19755907

（10）
红叉
https://blog.51cto.com/yuanhuan/1301882