java.io.StreamCorruptedException：无效的流头：626F6775使用mysql blob，java对象和自定义对象

Question

我正在开发一个需要将自定义类的对象存储到数据库中并能够检索该对象并在以后使用它的应用程序。

自定义类称为Quiz ，数据库为mySQL，我正在使用Blob存储对象。

我能够存储对象，但是当我尝试检索对象以供使用时，出现以下错误。 是的，我已经用谷歌搜索了。 我发现了一些类似的问题，并尝试了无济于事的解决方案。 请查看下面的代码摘录，如果您需要更多信息，请告诉我。

谢谢！

//Storing the Quiz object

public static void setQuizObject(String classId, Object quiz, int quizEnabled) {
    try {
        if (connect.isValid(0)) {
            statement = connect.createStatement();
            statement.executeUpdate("insert into " + 
                    DBHelper.MJLADB_QUIZTABLE + "(" + 
                    DBHelper.MJLADB_QUIZTABLE_CLASSID + ", " + 
                    DBHelper.MJLADB_QUIZTABLE_QUIZOBJECT + ", " + 
                    DBHelper.MJLADB_QUIZTABLE_QUIZENABLED + ") values ('" + 
                    classId + "', '" + 
                    quiz + "', '" + 
                    quizEnabled + "')");
        }
    } catch (SQLException e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
    }
}

---

//Getting the quiz object (handling the conversion from resultset to an arraylist)

    public static ArrayList<Object[]> resultSetToTableModel(ResultSet row) throws SQLException {

        ArrayList<Object[]> classList = new ArrayList<Object[]>();
        ResultSetMetaData meta = row.getMetaData();

        Object cols[] = new Object[meta.getColumnCount()];
        for (int i = 0; i < cols.length; i++) {
            cols[i] = meta.getColumnLabel(i + 1);
        }
        classList.add(cols);

        while (row.next()) {
            Object data[] = new Object[cols.length];
            int quizColumn = -1;
            try {
                quizColumn = row.findColumn(DBHelper.MJLADB_QUIZTABLE_QUIZOBJECT_A);
            }
            catch (SQLException e) {
                quizColumn = -1;
            }

            for (int i = 0; i < data.length; i++) {
//              if (row.getInt(DBHelper.MJLADB_QUIZTABLE_QUIZOBJECT_A) == (i + 1)) {
                Object x;
                Quiz quiz;
                if (quizColumn == (i + 1)) {
                    InputStream is = row.getBlob(i + 1).getBinaryStream();
                    try {
                        ObjectInputStream ois = new ObjectInputStream(is);
                        x = ois.readObject();
                        quiz = (Quiz)x;
                        data[i] = quiz;
                    } catch (IOException e) {
                        // TODO Auto-generated catch block
                        e.printStackTrace();
                    } catch (ClassNotFoundException e) {
                        // TODO Auto-generated catch block
                        e.printStackTrace();
                    }

                }
                else {
                    data[i] = row.getObject(i + 1); 
                }
            }
//original stuff
//          Object data[] = new Object[cols.length];
//          for (int i = 0; i < data.length; i++) {
//              data[i] = row.getObject(i + 1);
//          }
            classList.add(data);
        }

        return classList;
    }

---

//The problem:

java.io.StreamCorruptedException: invalid stream header: 626F6775
    at java.io.ObjectInputStream.readStreamHeader(Unknown Source)
    at java.io.ObjectInputStream.<init>(Unknown Source)
    at school.cs321.mjla.util.DBHelper.resultSetToTableModel(DBHelper.java:533)
    at school.cs321.mjla.util.DBHelper.getTQuizList(DBHelper.java:445)
    at school.cs321.mjla.controlpanel.ControlPanelModel.<init>(ControlPanelModel.java:46)
    at school.cs321.mjla.mediator.Mediator.startControlPanel(Mediator.java:97)
    at school.cs321.mjla.mainview.MainViewController.controlPanelbutton(MainViewController.java:55)
    at school.cs321.mjla.mainview.MainView$6.actionPerformed(MainView.java:169)
    at javax.swing.AbstractButton.fireActionPerformed(Unknown Source)
    at javax.swing.AbstractButton$Handler.actionPerformed(Unknown Source)
    at javax.swing.DefaultButtonModel.fireActionPerformed(Unknown Source)
    at javax.swing.DefaultButtonModel.setPressed(Unknown Source)
    at javax.swing.plaf.basic.BasicButtonListener.mouseReleased(Unknown Source)
    at java.awt.Component.processMouseEvent(Unknown Source)
    at javax.swing.JComponent.processMouseEvent(Unknown Source)
    at java.awt.Component.processEvent(Unknown Source)
    at java.awt.Container.processEvent(Unknown Source)
    at java.awt.Component.dispatchEventImpl(Unknown Source)
    at java.awt.Container.dispatchEventImpl(Unknown Source)
    at java.awt.Component.dispatchEvent(Unknown Source)
    at java.awt.LightweightDispatcher.retargetMouseEvent(Unknown Source)
    at java.awt.LightweightDispatcher.processMouseEvent(Unknown Source)
    at java.awt.LightweightDispatcher.dispatchEvent(Unknown Source)
    at java.awt.Container.dispatchEventImpl(Unknown Source)
    at java.awt.Window.dispatchEventImpl(Unknown Source)
    at java.awt.Component.dispatchEvent(Unknown Source)
    at java.awt.EventQueue.dispatchEventImpl(Unknown Source)
    at java.awt.EventQueue.access$000(Unknown Source)
    at java.awt.EventQueue$1.run(Unknown Source)
    at java.awt.EventQueue$1.run(Unknown Source)
    at java.security.AccessController.doPrivileged(Native Method)
    at java.security.AccessControlContext$1.doIntersectionPrivilege(Unknown Source)
    at java.security.AccessControlContext$1.doIntersectionPrivilege(Unknown Source)
    at java.awt.EventQueue$2.run(Unknown Source)
    at java.awt.EventQueue$2.run(Unknown Source)
    at java.security.AccessController.doPrivileged(Native Method)
    at java.security.AccessControlContext$1.doIntersectionPrivilege(Unknown Source)
    at java.awt.EventQueue.dispatchEvent(Unknown Source)
    at java.awt.EventDispatchThread.pumpOneEventForFilters(Unknown Source)
    at java.awt.EventDispatchThread.pumpEventsForFilter(Unknown Source)
    at java.awt.EventDispatchThread.pumpEventsForHierarchy(Unknown Source)
    at java.awt.EventDispatchThread.pumpEvents(Unknown Source)
    at java.awt.EventDispatchThread.pumpEvents(Unknown Source)
    at java.awt.EventDispatchThread.run(Unknown Source)

Answer 1

我想到了。 我忘了序列化我的对象了！

这是工作后的最终代码：

public static ArrayList<Object[]> resultSetToTableModel(ResultSet row) throws SQLException {

        ArrayList<Object[]> classList = new ArrayList<Object[]>();
        ResultSetMetaData meta = row.getMetaData();

        Object cols[] = new Object[meta.getColumnCount()];
        for (int i = 0; i < cols.length; i++) {
            cols[i] = meta.getColumnLabel(i + 1);
        }
        classList.add(cols);

        while (row.next()) {
            Object data[] = new Object[cols.length];
            int quizColumn = -1;
            try {
                quizColumn = row.findColumn(DBHelper.MJLADB_QUIZTABLE_QUIZOBJECT_A);
                if (quizColumn > 0) {
                    System.out.println("greater than 0");
                }
            }
            catch (SQLException e) {
                quizColumn = -1;
            }

            for (int i = 0; i < data.length; i++) {
                if (quizColumn == (i + 1)) {
                    byte[] buf = row.getBytes(i + 1);
                    ObjectInputStream objectIn = null;
                    if (buf != null) {
                        try {
                            objectIn = new ObjectInputStream(new ByteArrayInputStream(buf));
                            data[i] = objectIn.readObject();
                        } catch (IOException e) {
                            // TODO Auto-generated catch block
                            e.printStackTrace();
                        } catch (ClassNotFoundException e) {
                            // TODO Auto-generated catch block
                            e.printStackTrace();
                        }

                    }

                }
                else {
                    data[i] = row.getObject(i + 1); 
                }
            }
            classList.add(data);
        }

        return classList;
    }