Question

我想将数据库中的blob显示为JTable列。我的代码如下：

public JTable getTable(String table,String query)throws Exception{

    JTable t1 = new JTable();

    DefaultTableModel dm = new DefaultTableModel();
    Statement st = con.createStatement();
    ResultSet rs = st.executeQuery(query);
    ResultSetMetaData rsmd = rs.getMetaData();
    int cols = rsmd.getColumnCount();
    String c[] = new String[cols];
    for(int i=0;i<cols;i++){
        c[i]=rsmd.getColumnName(i+1);
        dm.addColumn(c[i]);
    }


    //get data from rows

    Object row[]=new Object[cols];
    while(rs.next()){
        row[0] = rs.getString(1);
        row[1] = rs.getString(2);
        row[2] = rs.getString(3);
        row[3] = rs.getString(4);
        row[4] = rs.getString(5);
        row[5] = rs.getString(6);
        java.sql.Blob blob = rs.getBlob(7);
        int blobLength = (int) blob.length();
        byte[] blobAsBytes = blob.getBytes(1, blobLength);
        ImageIcon picture = new ImageIcon(blobAsBytes);

        row[6] = picture;
        row[7] = rs.getString(8);
        row[8] = rs.getString(9);

        dm.addRow(row);
    }

    t1.setModel(dm);
    con.close();
    return t1;
}

当我运行此代码时，JTable会发送：javax.swing.ImageIcon@*numbers*而不是图像本身。

Answer 1

DefaultTableModel通过调用toString()方法将任何对象显示为String。

如果你想改变它，你必须通过覆盖getColumnClass()方法告诉DefaultTableModel列的内容是什么。

   DefaultTableModel dm = new DefaultTableModel(){
     public class<?> getColumnClass(int columnIndex){
         return 6==columnIndex?ImageIcon.class, String.class;
     }
   };

但是JTable可能没有ImageIcon的DefaultRenderer，但仍会显示意外情况。在这种情况下，您还必须自己为类ImageIcon设置DefaultRenderer。

https://docs.oracle.com/javase/tutorial/uiswing/components/table.html

JTable Cell Renderer

Answer 2

您可以添加显示图标的渲染器。这样的渲染器看起来像这样：

public class IconCellRenderer extends DefaultTableCellRenderer {
    @Override
    public Component getTableCellRendererComponent( JTable table, Object value, boolean isSelected, boolean hasFocus, int row, int column ) {
        Component c = super.getTableCellRendererComponent( table, value, isSelected, hasFocus, row, column );
        ((JLabel) c).setIcon( (ImageIcon) value );
        ((JLabel) c).setText( "" );
        return c;
    }
}

您可以通过以下几种方式添加此渲染器：

为ImageIcon类注册渲染器：

table.setDefaultRenderer( ImageIcon.class, new IconCellRenderer( ) );

指定列的渲染器：

int imageViewIndex = table.convertColumnIndexToView( 6 ); // view index of ImageIcon data
table.getColumnModel( ).getColumn( imageViewIndex ).setRenderer( new IconCellRenderer( ) );

子类JTable并覆盖getCellRenderer：

final int imageModelIndex = 6; // model index of ImageIcon data
JTable table = new JTable( ) {
    TableCellRenderer imageIconRenderer = new IconCellRenderer( );
    @Override
    public TableCellRenderer getCellRenderer( int row, int column ) {
        if( convertColumnIndexToModel( column ) == imageModelIndex )
            return imageIconRenderer;
        else
            return super.getCellRenderer( row, column );
    }
};

如何在JTable中显示图像？

2 个答案: