我有一个小的Java程序，它连接到MySQL数据库并从中读取数据。我能够成功地使用java -cp运行它，但当我尝试使用mvn exec:java运行它时，程序完成后我会收到这个异常：
[WARNING] thread Thread[MySQL Statement Cancellation Timer,5,com.mycompany.mydivision.App] was interrupted but is still alive after waiting at least 15000msecs
[WARNING] thread Thread[MySQL Statement Cancellation Timer,5,com.mycompany.mydivision.App] will linger despite being asked to die via interruption
[WARNING] NOTE: 1 thread(s) did not finish despite being asked to via interruption. This is not a problem with exec:java, it is a problem with the running code. Although not serious, it should be remedied.
[WARNING] Couldn't destroy threadgroup org.codehaus.mojo.exec.ExecJavaMojo$IsolatedThreadGroup[name=com.mycompany.mydivision.App,maxpri=10]
java.lang.IllegalThreadStateException
at java.lang.ThreadGroup.destroy(ThreadGroup.java:775)
at org.codehaus.mojo.exec.ExecJavaMojo.execute(ExecJavaMojo.java:328)
at org.apache.maven.plugin.DefaultBuildPluginManager.executeMojo(DefaultBuildPluginManager.java:134)
at org.apache.maven.lifecycle.internal.MojoExecutor.execute(MojoExecutor.java:208)
at org.apache.maven.lifecycle.internal.MojoExecutor.execute(MojoExecutor.java:153)
at org.apache.maven.lifecycle.internal.MojoExecutor.execute(MojoExecutor.java:145)
at org.apache.maven.lifecycle.internal.LifecycleModuleBuilder.buildProject(LifecycleModuleBuilder.java:116)
at org.apache.maven.lifecycle.internal.LifecycleModuleBuilder.buildProject(LifecycleModuleBuilder.java:80)
at org.apache.maven.lifecycle.internal.builder.singlethreaded.SingleThreadedBuilder.build(SingleThreadedBuilder.java:51)
at org.apache.maven.lifecycle.internal.LifecycleStarter.execute(LifecycleStarter.java:128)
at org.apache.maven.DefaultMaven.doExecute(DefaultMaven.java:307)
at org.apache.maven.DefaultMaven.doExecute(DefaultMaven.java:193)
at org.apache.maven.DefaultMaven.execute(DefaultMaven.java:106)
at org.apache.maven.cli.MavenCli.execute(MavenCli.java:862)
at org.apache.maven.cli.MavenCli.doMain(MavenCli.java:286)
at org.apache.maven.cli.MavenCli.main(MavenCli.java:197)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:606)
at org.codehaus.plexus.classworlds.launcher.Launcher.launchEnhanced(Launcher.java:289)
at org.codehaus.plexus.classworlds.launcher.Launcher.launch(Launcher.java:229)
at org.codehaus.plexus.classworlds.launcher.Launcher.mainWithExitCode(Launcher.java:415)
at org.codehaus.plexus.classworlds.launcher.Launcher.main(Launcher.java:356)
为什么会发生这种情况，我该如何修复？以下是我的代码，以防需要：
为什么会发生这种情况，我该如何修复？以下是我的代码，以防需要：
public class App
{
public static void main( String[] args )
{
try (JdbcReader reader = new JdbcReader())
{
reader.test();
}
catch (SQLException ex) {
// handle any errors
System.out.println("SQLException: " + ex.getMessage());
System.out.println("SQLState: " + ex.getSQLState());
System.out.println("VendorError: " + ex.getErrorCode());
}
catch (Exception e)
{
e.printStackTrace();
}
}
}
package com.mycompany.mydivision;
import com.vividsolutions.jts.geom.Geometry;
import java.io.Closeable;
import java.io.InputStream;
import java.sql.*;
/**
*
*/
public class JdbcReader implements Closeable{
Connection conn;
public JdbcReader() throws ClassNotFoundException, SQLException, IllegalAccessException, InstantiationException
{
// The newInstance() call is a work around for some
// broken Java implementations
Class.forName("com.mysql.jdbc.Driver").newInstance();
this.conn = DriverManager.getConnection("jdbc:mysql://localhost/mydb?user=guest");
}
/**
* https://dev.mysql.com/doc/connector-j/en/connector-j-usagenotes-statements.html
*/
public void test() throws Exception
{
Statement stmt = null;
ResultSet rs = null;
try {
stmt = this.conn.createStatement();
if (stmt.execute("SELECT * FROM mydb.my_table limit 20")) {
rs = stmt.getResultSet();
// Fetch each row from the result set
while (rs.next()) {
String name = rs.getString("name");
String description = rs.getString("Descr");
System.out.printf("%s\t%s\n", name, description);
}
}
}
finally {
// it is a good idea to release
// resources in a finally{} block
// in reverse-order of their creation
// if they are no-longer needed
if (rs != null) {
try {
System.out.println("closing ResultSet");
rs.close();
} catch (SQLException sqlEx) { } // ignore
rs = null;
}
if (stmt != null) {
try {
System.out.println("closing Statement");
stmt.close();
} catch (SQLException sqlEx) { } // ignore
stmt = null;
}
}
}
public void close()
{
if (conn != null)
{
try {
System.out.println("closing connection");
conn.close();
}
catch (SQLException ex) { } // ignore
conn = null;
}
}
}