我在互联网上有一个 MySQL 数据库。我可以通过浏览器和 MySQL Workbench 成功访问它。我向 Netbeans 添加了数据库。当我尝试从 Netbeans 连接数据库时,出现此错误:
com.mysql.jdbc.exceptions.jdbc4.CommunicationsException
Error code 0, SQL state 08S01: Communications link failure
The last packet successfully received from the server was 14.047 milliseconds ago. The last packet sent successfully to the server was 1 milliseconds ago.
我还尝试使用 Restful Web 服务连接数据库。我收到此错误:
GET RequestFailed RequestFailed --> Status: (500)
Response: {
HTTP Status 500 -
type Exception report
message
descriptionThe server encountered an internal error () that prevented it from fulfilling this request.
exception
javax.servlet.ServletException: Exception [EclipseLink-4002] (Eclipse Persistence Services - 2.3.2.v20111125-r10461): org.eclipse.persistence.exceptions.DatabaseException
Internal Exception: com.mysql.jdbc.exceptions.jdbc4.MySQLNonTransientConnectionException: No operations allowed after connection closed.
Error Code: 0
Call: SELECT o_id, isim, not, yas FROM ogrenci
Query: ReadAllQuery(referenceClass=Ogrenci sql="SELECT o_id, isim, not, yas FROM ogrenci")
root cause
Exception [EclipseLink-4002] (Eclipse Persistence Services - 2.3.2.v20111125-r10461): org.eclipse.persistence.exceptions.DatabaseException
Internal Exception: com.mysql.jdbc.exceptions.jdbc4.MySQLNonTransientConnectionException: No operations allowed after connection closed.
Error Code: 0
Call: SELECT o_id, isim, not, yas FROM ogrenci
Query: ReadAllQuery(referenceClass=Ogrenci sql="SELECT o_id, isim, not, yas FROM ogrenci")
root cause
com.mysql.jdbc.exceptions.jdbc4.MySQLNonTransientConnectionException: No operations allowed after connection closed.
root cause
com.mysql.jdbc.exceptions.jdbc4.CommunicationsException: Communications link failure
The last packet successfully received from the server was 228.471 milliseconds ago. The last packet sent successfully to the server was 11 milliseconds ago.
root cause
java.io.EOFException: Can not read response from server. Expected to read 4 bytes, read 0 bytes before connection was unexpectedly lost.
note The full stack traces of the exception and its root causes are available in the GlassFish Server Open Source Edition 3.1.2.2 logs.
最佳答案
尝试增加 wait_timeout
mysql 变量:
设置 wait_timeout=300;
关于java - 我无法从 Netbeans 连接数据库,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/16857729/