Question

以下java代码在运行时抛出此错误：ResultSet关闭后不允许操作。令人好奇的是，代码的预期功能正在完成。密码确实发生了变化，表明该语句确实已执行。最后的“失败”输出似乎表明代码在某处有异常。有什么想法吗？

private void ChangeSQLPassword(String userName,char[] pass) {
        Connection conn = null;
        String hashed = "";
        String salt = "";
        String concat = "";
        try {
            String url = "jdbc:mysql://localhost:3306/PM";
            Class.forName("com.mysql.jdbc.Driver").newInstance();
            conn = DriverManager.getConnection(url, "Tempuser", "temppass");
            System.out.println("Database connection established");
        } catch (Exception e) {
            e.printStackTrace();
            System.err.println("Cannot connect to database server");
        } finally {
            if (conn != null) {
                try {
                    System.err.println("Connection not null...");
                    salt = getSalt();
                    hashed = sha256(pass,salt);
                    Statement sta3 = conn.createStatement();
                    ResultSet rs = sta3.executeQuery("SELECT * FROM pmusers"); //Select users
                    System.out.println(userName + " " + new String(pass));
                    while (rs.next() == true) { //Loop through results
                        if (rs.getString("username").equals(userName)) {
                            concat = concat.concat("UPDATE pmusers SET Hashed = '" + hashed + "', Salt = '" + salt + "' WHERE Username = '" + userName +"';");
                            sta3.executeUpdate(concat);
                        }
                    }
                } catch (Exception e) { /* ignore close errors */
                    e.printStackTrace();
                    System.err.println("Failed.");
                }
            }
        }
    }

static String sha256(char[] input, String Salt) throws NoSuchAlgorithmException {
    MessageDigest mDigest = MessageDigest.getInstance("SHA-256");
    byte[] result;
    StringBuffer sb = new StringBuffer();
    try {
        mDigest.update(Salt.getBytes("UTF-8"));
        result = mDigest.digest(String.valueOf(input).getBytes("UTF-8"));
        for (int i = 0; i < result.length; i++) {
            sb.append(Integer.toString((result[i] & 0xff) + 0x100, 16).substring(1));
        }
    } catch (UnsupportedEncodingException e) {
        System.out.println("Encoding failed.");
    }

    String hashed = org.apache.commons.codec.binary.Base64.encodeBase64URLSafeString(String.valueOf(sb).getBytes());

    return hashed;
}

private static String getSalt() throws NoSuchAlgorithmException, NoSuchProviderException {
    //Always use a SecureRandom generator
    SecureRandom sr = SecureRandom.getInstance("SHA1PRNG", "SUN");
    //Create array for salt
    byte[] salt = new byte[16];
    //Get a random salt
    sr.nextBytes(salt);
    //return salt
    return salt.toString();
}

堆栈跟踪： java.sql.SQLException：ResultSet关闭后不允许操作在com.mysql.jdbc.SQLError.createSQLException（SQLError.java:996）在com.mysql.jdbc.SQLError.createSQLException（SQLError.java:935）在com.mysql.jdbc.SQLError.createSQLException（SQLError.java:924）在com.mysql.jdbc.SQLError.createSQLException（SQLError.java:870）在com.mysql.jdbc.ResultSetImpl.checkClosed（ResultSetImpl.java:734）在com.mysql.jdbc.ResultSetImpl.next（ResultSetImpl.java:6313）在ServerInterface.ChangeSQLPassword（ServerInterface.java:585）在ServerInterface.access $ 300（ServerInterface.java:68）在ServerInterface $ 2.actionPerformed（ServerInterface.java:277）在javax.swing.AbstractButton.fireActionPerformed（AbstractButton.java:2018）在javax.swing.AbstractButton $ Handler.actionPerformed（AbstractButton.java:2341）在javax.swing.DefaultButtonModel.fireActionPerformed（DefaultButtonModel.java:402）在javax.swing.DefaultButtonModel.setPressed（DefaultButtonModel.java:259）在javax.swing.plaf.basic.BasicButtonListener.mouseReleased（BasicButtonListener.java:252）在java.awt.Component.processMouseEvent（Component.java:6505）在javax.swing.JComponent.processMouseEvent（JComponent.java:3320） at java.awt.Component.processEvent（Component.java:6270） at java.awt.Container.processEvent（Container.java:2229） at java.awt.Component.dispatchEventImpl（Component.java:4861） at java.awt.Container.dispatchEventImpl（Container.java:2287） at java.awt.Component.dispatchEvent（Component.java:4687） at java.awt.LightweightDispatcher.retargetMouseEvent（Container.java:4832） at java.awt.LightweightDispatcher.processMouseEvent（Container.java:4492） at java.awt.LightweightDispatcher.dispatchEvent（Container.java:4422） at java.awt.Container.dispatchEventImpl（Container.java:2273） at java.awt.Window.dispatchEventImpl（Window.java:2719） at java.awt.Component.dispatchEvent（Component.java:4687） at java.awt.EventQueue.dispatchEventImpl（EventQueue.java:735） at java.awt.EventQueue.access $ 200（EventQueue.java:103） at java.awt.EventQueue $ 3.run（EventQueue.java:694） at java.awt.EventQueue $ 3.run（EventQueue.java:692） at java.security.AccessController.doPrivileged（Native Method） at java.security.ProtectionDomain $ 1.doIntersectionPrivilege（ProtectionDomain.java:76） at java.security.ProtectionDomain $ 1.doIntersectionPrivilege（ProtectionDomain.java:87） at java.awt.EventQueue $ 4.run（EventQueue.java:708） at java.awt.EventQueue $ 4.run（EventQueue.java:706） at java.security.AccessController.doPrivileged（Native Method） at java.security.ProtectionDomain $ 1.doIntersectionPrivilege（ProtectionDomain.java:76） at java.awt.EventQueue.dispatchEvent（EventQueue.java:705） at java.awt.EventDispatchThread.pumpOneEventForFilters（EventDispatchThread.java:242） at java.awt.EventDispatchThread.pumpEventsForFilter（EventDispatchThread.java:161） at java.awt.EventDispatchThread.pumpEventsForHierarchy（EventDispatchThread.java:150） at java.awt.EventDispatchThread.pumpEvents（EventDispatchThread.java:146） at java.awt.EventDispatchThread.pumpEvents（EventDispatchThread.java:138） at java.awt.EventDispatchThread.run（EventDispatchThread.java:91）

失败。

非常感谢！

Answer 1

您正在重复使用sta3：尝试

concat = concat.concat(...
Statement sta4 = conn.createStatement();
sta4.executeUpdate(concat);

Mysql更新似乎正在工作，但抛出语句关闭错误

1 个答案: