我正在尝试学习 Android 和 Servlet 编程，但无法连接到本地 mySQL 数据库。我有一个简单的 Android 客户端，它向托管在 localhost 上的 servlet 发出 HTTPpost 请求。该请求似乎工作正常，但 servlet 无法找到数据库的驱动程序。我很确定mysql url是正确的，所以我猜它的驱动程序就是问题所在！
这是应该连接到数据库的实用程序类：
public class Database {
private static Connection connection = null;
/**
*
* @return
*/
public static Connection getConnection(){
if(connection!=null){
return connection;
} else {
try {
Properties db_properties = new Properties();
InputStream inStream = Database.class.getClassLoader().getResourceAsStream("/db.properties");
db_properties.load(inStream);
String dbDriver = db_properties.getProperty("dbDriver");
String url = db_properties.getProperty("url");
String dbUser = db_properties.getProperty("dbUser");
String dbPass = db_properties.getProperty("dbPassword");
connection = DriverManager.getConnection(url,dbUser,dbPass);
Class.forName(dbDriver);
} catch (IOException e) {
e.printStackTrace();
} catch (ClassNotFoundException e) {
e.printStackTrace();
} catch (SQLException e) {
e.printStackTrace();
}
}
return connection;
}
}
这是以下数据库属性文件：
driver=com.mysql.jdbc.Driver
url=jdbc:mysql://localhost:8889/gymbuddy
user=Mathan
pass=PYCCmcPDAFSj7N9B
这是 servlet 设置的样子：
这是我得到的堆栈跟踪：
java.sql.SQLException: No suitable driver found for jdbc:mysql://localhost:8889/gymbuddy?user=Mathan&password=PYCCmcPDAFSj7N9B
at java.sql.DriverManager.getConnection(DriverManager.java:602)
at java.sql.DriverManager.getConnection(DriverManager.java:207)
at com.mathanv.gb.util.Database.getConnection(Database.java:36)
at com.mathanv.gb.dao.BuddyDao.<init>(BuddyDao.java:35)
at com.mathanv.gb.controller.BuddyController.<init>(BuddyController.java:29)
at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
at sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:39)
at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:27)
at java.lang.reflect.Constructor.newInstance(Constructor.java:513)
at java.lang.Class.newInstance0(Class.java:357)
at java.lang.Class.newInstance(Class.java:310)
at org.apache.catalina.core.DefaultInstanceManager.newInstance(DefaultInstanceManager.java:138)
at org.apache.catalina.core.StandardWrapper.loadServlet(StandardWrapper.java:1137)
at org.apache.catalina.core.StandardWrapper.allocate(StandardWrapper.java:858)
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:136)
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:123)
at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:472)
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:171)
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:99)
at org.apache.catalina.valves.AccessLogValve.invoke(AccessLogValve.java:936)
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:118)
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:407)
at org.apache.coyote.http11.AbstractHttp11Processor.process(AbstractHttp11Processor.java:1004)
at org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java:589)
at org.apache.tomcat.util.net.JIoEndpoint$SocketProcessor.run(JIoEndpoint.java:310)
at java.util.concurrent.ThreadPoolExecutor$Worker.runTask(ThreadPoolExecutor.java:895)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:918)
at java.lang.Thread.run(Thread.java:680)
Mar 2, 2013 11:50:53 PM org.apache.catalina.core.StandardWrapperValve invoke
SEVERE: Servlet.service() for servlet [BuddyController] in context with path [/gbserver] threw exception
java.lang.NullPointerException
at com.mathanv.gb.dao.BuddyDao.registerBuddy(BuddyDao.java:44)
at com.mathanv.gb.controller.BuddyController.doPost(BuddyController.java:51)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:647)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:728)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:305)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:210)
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:222)
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:123)
at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:472)
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:171)
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:99)
at org.apache.catalina.valves.AccessLogValve.invoke(AccessLogValve.java:936)
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:118)
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:407)
at org.apache.coyote.http11.AbstractHttp11Processor.process(AbstractHttp11Processor.java:1004)
at org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java:589)
at org.apache.tomcat.util.net.JIoEndpoint$SocketProcessor.run(JIoEndpoint.java:310)
at java.util.concurrent.ThreadPoolExecutor$Worker.runTask(ThreadPoolExecutor.java:895)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:918)
at java.lang.Thread.run(Thread.java:680)
Help!
If you need any more information, let me know!