使用Kettle5.0.1，安装的是MySQL5.1、JDK1.6，在\data-integration\lib目录里添加mysql的JDBC包mysql-connector-java-5.0.8-bin.jar，

在新建资源库里设置好MySQL的各种信息，如下

点“测试”报如下错误

错误连接数据库 [本地MySQL的【test】数据库] : org.pentaho.di.core.exception.KettleDatabaseException:
Error occured while trying to connect to the database

Error connecting to database: (using class org.gjt.mm.mysql.Driver)
java.lang.NullPointerException

org.pentaho.di.core.exception.KettleDatabaseException:
Error occured while trying to connect to the database

Error connecting to database: (using class org.gjt.mm.mysql.Driver)
java.lang.NullPointerException

at org.pentaho.di.core.database.Database.normalConnect(Database.java:415)
at org.pentaho.di.core.database.Database.connect(Database.java:353)
at org.pentaho.di.core.database.Database.connect(Database.java:306)
at org.pentaho.di.core.database.Database.connect(Database.java:294)
at org.pentaho.di.core.database.DatabaseFactory.getConnectionTestReport(DatabaseFactory.java:84)
at org.pentaho.di.core.database.DatabaseMeta.testConnection(DatabaseMeta.java:2459)
at org.pentaho.ui.database.event.DataHandler.testDatabaseConnection(DataHandler.java:541)
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:601)
at org.pentaho.ui.xul.impl.AbstractXulDomContainer.invoke(AbstractXulDomContainer.java:329)
at org.pentaho.ui.xul.impl.AbstractXulComponent.invoke(AbstractXulComponent.java:139)
at org.pentaho.ui.xul.impl.AbstractXulComponent.invoke(AbstractXulComponent.java:123)
at org.pentaho.ui.xul.swt.tags.SwtButton.access$500(SwtButton.java:26)
at org.pentaho.ui.xul.swt.tags.SwtButton$4.widgetSelected(SwtButton.java:121)
at org.eclipse.swt.widgets.TypedListener.handleEvent(Unknown Source)
at org.eclipse.swt.widgets.EventTable.sendEvent(Unknown Source)
at org.eclipse.swt.widgets.Widget.sendEvent(Unknown Source)
at org.eclipse.swt.widgets.Display.runDeferredEvents(Unknown Source)
at org.eclipse.swt.widgets.Display.readAndDispatch(Unknown Source)
at org.eclipse.jface.window.Window.runEventLoop(Window.java:820)
at org.eclipse.jface.window.Window.open(Window.java:796)
at org.pentaho.ui.xul.swt.tags.SwtDialog.show(SwtDialog.java:375)
at org.pentaho.ui.xul.swt.tags.SwtDialog.show(SwtDialog.java:301)
at org.pentaho.di.ui.core.database.dialog.XulDatabaseDialog.open(XulDatabaseDialog.java:115)
at org.pentaho.di.ui.core.database.dialog.DatabaseDialog.open(DatabaseDialog.java:62)
at org.pentaho.di.ui.spoon.delegates.SpoonDBDelegate.newConnection(SpoonDBDelegate.java:493)
at org.pentaho.di.ui.spoon.delegates.SpoonDBDelegate.newConnection(SpoonDBDelegate.java:478)
at org.pentaho.di.ui.spoon.Spoon.doubleClickedInTree(Spoon.java:2885)
at org.pentaho.di.ui.spoon.Spoon.access$2300(Spoon.java:332)
at org.pentaho.di.ui.spoon.Spoon$27.widgetDefaultSelected(Spoon.java:5657)
at org.eclipse.swt.widgets.TypedListener.handleEvent(Unknown Source)
at org.eclipse.swt.widgets.EventTable.sendEvent(Unknown Source)
at org.eclipse.swt.widgets.Widget.sendEvent(Unknown Source)
at org.eclipse.swt.widgets.Display.runDeferredEvents(Unknown Source)
at org.eclipse.swt.widgets.Display.readAndDispatch(Unknown Source)
at org.pentaho.di.ui.spoon.Spoon.readAndDispatch(Spoon.java:1227)
at org.pentaho.di.ui.spoon.Spoon.waitForDispose(Spoon.java:7368)
at org.pentaho.di.ui.spoon.Spoon.start(Spoon.java:8673)
at org.pentaho.di.ui.spoon.Spoon.main(Spoon.java:625)
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:601)
at org.pentaho.commons.launcher.Launcher.main(Launcher.java:134)
Caused by: org.pentaho.di.core.exception.KettleDatabaseException:
Error connecting to database: (using class org.gjt.mm.mysql.Driver)
java.lang.NullPointerException

at org.pentaho.di.core.database.Database.connectUsingClass(Database.java:540)
at org.pentaho.di.core.database.Database.normalConnect(Database.java:399)
... 45 more
Caused by: java.sql.SQLException: java.lang.NullPointerException
at com.mysql.jdbc.SQLError.createSQLException(SQLError.java:910)
at com.mysql.jdbc.ServerPreparedStatement.executeInternal(ServerPreparedStatement.java:766)
at com.mysql.jdbc.PreparedStatement.execute(PreparedStatement.java:882)
at com.mysql.jdbc.Statement.createResultSetUsingServerFetch(Statement.java:525)
at com.mysql.jdbc.Statement.executeQuery(Statement.java:1158)
at com.mysql.jdbc.SQLError.convertShowWarningsToSQLWarnings(SQLError.java:710)
at com.mysql.jdbc.MysqlIO.scanForAndThrowDataTruncation(MysqlIO.java:3183)
at com.mysql.jdbc.ServerPreparedStatement.serverExecute(ServerPreparedStatement.java:1349)
at com.mysql.jdbc.ServerPreparedStatement.executeInternal(ServerPreparedStatement.java:740)
at com.mysql.jdbc.PreparedStatement.execute(PreparedStatement.java:882)
at com.mysql.jdbc.Statement.createResultSetUsingServerFetch(Statement.java:525)
at com.mysql.jdbc.Statement.executeQuery(Statement.java:1158)
at com.mysql.jdbc.Connection.loadServerVariables(Connection.java:4478)
at com.mysql.jdbc.Connection.initializePropsFromServer(Connection.java:4062)
at com.mysql.jdbc.Connection.createNewIO(Connection.java:2789)
at com.mysql.jdbc.Connection.<init>(Connection.java:1555)
at com.mysql.jdbc.NonRegisteringDriver.connect(NonRegisteringDriver.java:285)
at java.sql.DriverManager.getConnection(DriverManager.java:579)
at java.sql.DriverManager.getConnection(DriverManager.java:221)
at org.pentaho.di.core.database.Database.connectUsingClass(Database.java:524)
... 46 more

主机名 : localhost
端口 : 3306
数据库名:test

经过试验，发现出错原因是mysql的JDBC包版本选错了，改用了mysql-connector-java-5.1.30-bin.jar后就没问题了

by the way：新创建好的资源库默认【帐号：admin   密码：admin  】【帐号：guest   密码：guest】

Kettle使用MySQL作为资源库报错解决方法