DriverManager.getConnection() 失败

Question

在我的异步类 DBcon 中，我连接到数据库

Class.forName("com.mysql.jdbc.Driver");
Connection con = DriverManager.getConnection(url, user, pass);

在doInBackground()方法中工作得很好但是，当我在另一种方法中尝试它时它不起作用

public void login() throws SQLException {
        try {
            Class.forName("com.mysql.jdbc.Driver");
            Connection con = DriverManager.getConnection(url, user, pass);
        
        } catch(Exception e) {
            Log.d(TAG, "login: failed");
        }
}

它在Connection con = DriverManager.getConnection(url, user, pass);失败

错误：

at com.mysql.jdbc.Connection.createNewIO(Connection.java:1830)
W/System.err:     at com.mysql.jdbc.Connection.<init>(Connection.java:430)
W/System.err:     at com.mysql.jdbc.NonRegisteringDriver.connect(NonRegisteringDriver.java:268)
W/System.err:     at java.sql.DriverManager.getConnection(DriverManager.java:580)
W/System.err:     at java.sql.DriverManager.getConnection(DriverManager.java:218)
W/System.err:     at de.egeplast.logistikscanner.DBcon.login(DBcon.java:212)
W/System.err:     at de.egeplast.logistikscanner.Honeywell$3.onClick(Honeywell.java:138)
W/System.err:     at android.view.View.performClick(View.java:7448)
W/System.err:     at com.google.android.material.button.MaterialButton.performClick(MaterialButton.java:1194)
W/System.err:     at android.view.View.performClickInternal(View.java:7425)
W/System.err:     at android.view.View.access$3600(View.java:810)
W/System.err:     at android.view.View$PerformClick.run(View.java:28309)
W/System.err:     at android.os.Handler.handleCallback(Handler.java:938)
W/System.err:     at android.os.Handler.dispatchMessage(Handler.java:99)
W/System.err:     at android.os.Looper.loop(Looper.java:223)
W/System.err:     at android.app.ActivityThread.main(ActivityThread.java:7697)
W/System.err:     at java.lang.reflect.Method.invoke(Native Method)
W/System.err:     at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:592)
W/System.err:     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:952)

url、user、pass都对

Answer 1

如果您有类似的问题，只需将其放入另一个线程...

public void login() throws SQLException {
    Thread t = new Thread() {
        @Override 
        public void run() {
        try {
            Class.forName("com.mysql.jdbc.Driver");
            Connection con = DriverManager.getConnection(url, user, pass);
        
        } catch(Exception e) {
            Log.d(TAG, "login: failed");
        }
}
};
}