我知道有很多主题，有类似的问题，但是没有一个建议的解决方案适合我。
我正在使用MAMP，并尝试使用以下代码连接到已有的现有数据库：
String url = "jdbc:mysql://localhost:3306/db_name";
String user = "root";
String pass = "root";
try {
Class.forName("com.mysql.jdbc.Driver").newInstance();
} catch (ClassNotFoundException ex) {
System.err.println("Class not found");
ex.printStackTrace();
} catch (InstantiationException ex) {
System.out.println("Instantiation exception");
ex.printStackTrace();
} catch (IllegalAccessException ex) {
System.out.println("Illegal access exception");
ex.printStackTrace();
} // catch
try {
System.out.println("Connecting to the database..");
Connection conn = DriverManager.getConnection(url, user, pass);
System.out.println("Successfully connected to the database");
} catch (SQLException ex) {
System.err.println("Unable to connect to the database");
ex.printStackTrace();
} // catch
执行代码时，我得到以下异常：
Unable to connect to the database
java.sql.SQLException: Access denied for user 'root'@'localhost' (using password: YES)
at com.mysql.jdbc.SQLError.createSQLException(SQLError.java:1073)
at com.mysql.jdbc.MysqlIO.checkErrorPacket(MysqlIO.java:3609)
at com.mysql.jdbc.MysqlIO.checkErrorPacket(MysqlIO.java:3541)
at com.mysql.jdbc.MysqlIO.checkErrorPacket(MysqlIO.java:943)
at com.mysql.jdbc.MysqlIO.secureAuth411(MysqlIO.java:4113)
at com.mysql.jdbc.MysqlIO.doHandshake(MysqlIO.java:1308)
at com.mysql.jdbc.ConnectionImpl.coreConnect(ConnectionImpl.java:2336)
at com.mysql.jdbc.ConnectionImpl.connectOneTryOnly(ConnectionImpl.java:2369)
at com.mysql.jdbc.ConnectionImpl.createNewIO(ConnectionImpl.java:2153)
at com.mysql.jdbc.ConnectionImpl.<init>(ConnectionImpl.java:792)
at com.mysql.jdbc.JDBC4Connection.<init>(JDBC4Connection.java:47)
at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
at sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:62)
at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45)
at java.lang.reflect.Constructor.newInstance(Constructor.java:422)
at com.mysql.jdbc.Util.handleNewInstance(Util.java:411)
at com.mysql.jdbc.ConnectionImpl.getInstance(ConnectionImpl.java:381)
at com.mysql.jdbc.NonRegisteringDriver.connect(NonRegisteringDriver.java:305)
at java.sql.DriverManager.getConnection(DriverManager.java:664)
at java.sql.DriverManager.getConnection(DriverManager.java:247)
at registrationsystem.SignUpForm.submitJButtonActionPerformed(SignUpForm.java:293)
at registrationsystem.SignUpForm.access$000(SignUpForm.java:19)
at registrationsystem.SignUpForm$1.actionPerformed(SignUpForm.java:94)
at javax.swing.AbstractButton.fireActionPerformed(AbstractButton.java:2022)
at javax.swing.AbstractButton$Handler.actionPerformed(AbstractButton.java:2348)
at javax.swing.DefaultButtonModel.fireActionPerformed(DefaultButtonModel.java:402)
at javax.swing.DefaultButtonModel.setPressed(DefaultButtonModel.java:259)
at javax.swing.plaf.basic.BasicButtonListener.mouseReleased(BasicButtonListener.java:252)
at java.awt.Component.processMouseEvent(Component.java:6535)
at javax.swing.JComponent.processMouseEvent(JComponent.java:3324)
at java.awt.Component.processEvent(Component.java:6300)
at java.awt.Container.processEvent(Container.java:2236)
at java.awt.Component.dispatchEventImpl(Component.java:4891)
at java.awt.Container.dispatchEventImpl(Container.java:2294)
at java.awt.Component.dispatchEvent(Component.java:4713)
at java.awt.LightweightDispatcher.retargetMouseEvent(Container.java:4888)
at java.awt.LightweightDispatcher.processMouseEvent(Container.java:4525)
at java.awt.LightweightDispatcher.dispatchEvent(Container.java:4466)
at java.awt.Container.dispatchEventImpl(Container.java:2280)
at java.awt.Window.dispatchEventImpl(Window.java:2750)
at java.awt.Component.dispatchEvent(Component.java:4713)
at java.awt.EventQueue.dispatchEventImpl(EventQueue.java:758)
at java.awt.EventQueue.access$500(EventQueue.java:97)
at java.awt.EventQueue$3.run(EventQueue.java:709)
at java.awt.EventQueue$3.run(EventQueue.java:703)
at java.security.AccessController.doPrivileged(Native Method)
at java.security.ProtectionDomain$JavaSecurityAccessImpl.doIntersectionPrivilege(ProtectionDomain.java:76)
at java.security.ProtectionDomain$JavaSecurityAccessImpl.doIntersectionPrivilege(ProtectionDomain.java:86)
at java.awt.EventQueue$4.run(EventQueue.java:731)
at java.awt.EventQueue$4.run(EventQueue.java:729)
at java.security.AccessController.doPrivileged(Native Method)
at java.security.ProtectionDomain$JavaSecurityAccessImpl.doIntersectionPrivilege(ProtectionDomain.java:76)
at java.awt.EventQueue.dispatchEvent(EventQueue.java:728)
at java.awt.EventDispatchThread.pumpOneEventForFilters(EventDispatchThread.java:201)
at java.awt.EventDispatchThread.pumpEventsForFilter(EventDispatchThread.java:116)
at java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:105)
at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:101)
at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:93)
at java.awt.EventDispatchThread.run(EventDispatchThread.java:82)
到目前为止我为解决问题所做的尝试：
1）执行GRANT ALL PRIVILEGES ON *.* TO 'root'@'localhost' IDENTIFIED BY 'root' WITH GRANT OPTION;
2）尝试创建另一个用户（而不是使用root），但没有任何运气
3）当我运行MAMP时，指定端口3306，用户root和密码root，因此我认为我没有使用错误的密码或端口。
4）我尝试使用
进行连接conn = DriverManager.getConnection("jdbc:mysql://localhost:3306/db_name?user=root&password=root");