02-07 23:14:34.961: W/dalvikvm(1248): VFY: unable to find class referenced in signature (Ljavax/naming/Reference;)
02-07 23:14:34.961: E/dalvikvm(1248): Could not find class 'javax.naming.StringRefAddr', referenced from method com.mysql.jdbc.ConnectionPropertiesImpl$ConnectionProperty.storeTo
02-07 23:14:34.961: W/dalvikvm(1248): VFY: unable to resolve new-instance 1332 (Ljavax/naming/StringRefAddr;) in Lcom/mysql/jdbc/ConnectionPropertiesImpl$ConnectionProperty;
02-07 23:14:34.961: D/dalvikvm(1248): VFY: replacing opcode 0x22 at 0x0006
02-07 23:15:39.101: W/System.err(1248): com.mysql.jdbc.exceptions.jdbc4.CommunicationsException: Communications link failure
02-07 23:15:39.121: W/System.err(1248): Last packet sent to the server was 0 ms ago.
02-07 23:15:39.151: W/System.err(1248): at java.lang.reflect.Constructor.constructNative(Native Method)
02-07 23:15:39.151: W/System.err(1248): at java.lang.reflect.Constructor.newInstance(Constructor.java:423)
02-07 23:15:39.151: W/System.err(1248): at com.mysql.jdbc.Util.handleNewInstance(Util.java:406)
02-07 23:15:39.151: W/System.err(1248): at com.mysql.jdbc.SQLError.createCommunicationsException(SQLError.java:1074)
02-07 23:15:39.151: W/System.err(1248): at com.mysql.jdbc.ConnectionImpl.createNewIO(ConnectionImpl.java:2120)
02-07 23:15:39.151: W/System.err(1248): at com.mysql.jdbc.ConnectionImpl.<init>(ConnectionImpl.java:723)
02-07 23:15:39.151: W/System.err(1248): at com.mysql.jdbc.JDBC4Connection.<init>(JDBC4Connection.java:46)
02-07 23:15:39.151: W/System.err(1248): at java.lang.reflect.Constructor.constructNative(Native Method)
02-07 23:15:39.151: W/System.err(1248): at java.lang.reflect.Constructor.newInstance(Constructor.java:423)
02-07 23:15:39.151: W/System.err(1248): at com.mysql.jdbc.Util.handleNewInstance(Util.java:406)
02-07 23:15:39.151: W/System.err(1248): at com.mysql.jdbc.ConnectionImpl.getInstance(ConnectionImpl.java:302)
02-07 23:15:39.151: W/System.err(1248): at com.mysql.jdbc.NonRegisteringDriver.connect(NonRegisteringDriver.java:282)
02-07 23:15:39.151: W/System.err(1248): at java.sql.DriverManager.getConnection(DriverManager.java:179)
02-07 23:15:39.171: W/System.err(1248): at java.sql.DriverManager.getConnection(DriverManager.java:213)
02-07 23:15:39.171: W/System.err(1248): at utils.MyDBUtils.getConnection(MyDBUtils.java:25)
02-07 23:15:39.171: W/System.err(1248): at DAO.StudentDao.checkLogin(StudentDao.java:101)
02-07 23:15:39.171: W/System.err(1248): at com.example.bottomtabbar.MainActivity$1$1.run(MainActivity.java:73)
02-07 23:15:39.171: W/System.err(1248): at java.lang.Thread.run(Thread.java:841)
02-07 23:15:39.171: W/System.err(1248): Caused by: com.mysql.jdbc.exceptions.jdbc4.CommunicationsException: Communications link failure
02-07 23:15:39.171: W/System.err(1248): Last packet sent to the server was 3 ms ago.
02-07 23:15:39.221: W/System.err(1248): at java.lang.reflect.Constructor.constructNative(Native Method)
02-07 23:15:39.221: W/System.err(1248): at java.lang.reflect.Constructor.newInstance(Constructor.java:423)
02-07 23:15:39.221: W/System.err(1248): at com.mysql.jdbc.Util.handleNewInstance(Util.java:406)
02-07 23:15:39.221: W/System.err(1248): at com.mysql.jdbc.SQLError.createCommunicationsException(SQLError.java:1074)
02-07 23:15:39.221: W/System.err(1248): at com.mysql.jdbc.MysqlIO.<init>(MysqlIO.java:335)
02-07 23:15:39.221: W/System.err(1248): at com.mysql.jdbc.ConnectionImpl.createNewIO(ConnectionImpl.java:2043)
02-07 23:15:39.221: W/System.err(1248): ... 13 more
02-07 23:15:39.221: W/System.err(1248): Caused by: java.net.ConnectException: failed to connect to /10.96.212.241 (port 3306): connect failed: ETIMEDOUT (Connection timed out)
02-07 23:15:39.251: W/System.err(1248): at libcore.io.IoBridge.connect(IoBridge.java:114)
02-07 23:15:39.251: W/System.err(1248): at java.net.PlainSocketImpl.connect(PlainSocketImpl.java:192)
02-07 23:15:39.261: W/System.err(1248): at java.net.PlainSocketImpl.connect(PlainSocketImpl.java:172)
02-07 23:15:39.261: W/System.err(1248): at java.net.Socket.startupSocket(Socket.java:567)
02-07 23:15:39.271: W/System.err(1248): at java.net.Socket.<init>(Socket.java:226)
02-07 23:15:39.271: W/System.err(1248): at com.mysql.jdbc.StandardSocketFactory.connect(StandardSocketFactory.java:253)
02-07 23:15:39.271: W/System.err(1248): at com.mysql.jdbc.MysqlIO.<init>(MysqlIO.java:284)
02-07 23:15:39.271: W/System.err(1248): ... 14 more
02-07 23:15:39.271: W/System.err(1248): Caused by: libcore.io.ErrnoException: connect failed: ETIMEDOUT (Connection timed out)
02-07 23:15:39.281: W/System.err(1248): at libcore.io.Posix.connect(Native Method)
02-07 23:15:39.281: W/System.err(1248): at libcore.io.BlockGuardOs.connect(BlockGuardOs.java:85)
02-07 23:15:39.281: W/System.err(1248): at libcore.io.IoBridge.connectErrno(IoBridge.java:127)
02-07 23:15:39.281: W/System.err(1248): at libcore.io.IoBridge.connect(IoBridge.java:112)
02-07 23:15:39.281: W/System.err(1248): ... 20 more
02-07 23:15:39.281: W/dalvikvm(1248): threadid=15: thread exiting with uncaught exception (group=0xb2b0fba8)
02-07 23:15:39.341: E/AndroidRuntime(1248): FATAL EXCEPTION: Thread-95
02-07 23:15:39.341: E/AndroidRuntime(1248): Process: com.example.bottomtabbar, PID: 1248
02-07 23:15:39.341: E/AndroidRuntime(1248): java.lang.NullPointerException
02-07 23:15:39.341: E/AndroidRuntime(1248): at DAO.StudentDao.checkLogin(StudentDao.java:103)
02-07 23:15:39.341: E/AndroidRuntime(1248): at com.example.bottomtabbar.MainActivity$1$1.run(MainActivity.java:73)
02-07 23:15:39.341: E/AndroidRuntime(1248): at java.lang.Thread.run(Thread.java:841)
建议看下防火墙，本地mysql客户端连接试试，成功了再试代码