如何在JTable中显示图像?
问题描述:
我想从数据库中显示blob到一个JTable列。 我的代码如下:如何在JTable中显示图像?
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;
}
当我运行这段代码JTable的dispays:[email protected]*numbers*
而不是图像本身。
答
DefaultTableModel通过调用其toString()
方法将任何对象显示为字符串。
如果您想要更改,您必须通过重写getColumnClass()
方法来告诉DefaultTableModel该列的内容。
DefaultTableModel dm = new DefaultTableModel(){
public class<?> getColumnClass(int columnIndex){
return 6==columnIndex?ImageIcon.class, String.class;
}
};
但是有一个机会,JTable
没有DefaultRenderer为ImageIcon
,仍然显示意想不到的事情。在这种情况下,您还必须自己为ImageIcon
类设置DefaultRenderer。
https://docs.oracle.com/javase/tutorial/uiswing/components/table.html
答
您可以添加显示一个图标渲染。这样的渲染器是这样的:
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;
}
}
您可以添加此渲染几个方面:
-
注册一个渲染器的ImageIcon类:
table.setDefaultRenderer(ImageIcon.class, new IconCellRenderer());
-
指定渲染一列:
int imageViewIndex = table.convertColumnIndexToView(6); // view index of ImageIcon data table.getColumnModel().getColumn(imageViewIndex).setRenderer(new IconCellRenderer());
-
子类的JTable并重写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); } };