问题描述
我的目标是能够编辑JTable单元，该单元一旦被编辑并保存，就将值保存到数据库中并将该值加载到JTable上。当前，一旦我尝试编辑JTable单元并按Enter，就不会保存数据。我意识到没有调用TableModelListener； ActualizeTable模型中的system.out代码不起作用。
以下代码用于框架；我已经删除了一些代码（即JButton ActionListeners），因为它们对于本主题来说是不必要的。
public class InventoryFrame extends JFrame{
DatabaseManager dbman;
private JPanel p = new JPanel();
private final JButton getAll = new JButton("Get All");
private final JButton add = new JButton("Add");
private final JButton delete = new JButton("Delete");
private final JButton edit = new JButton("Edit");
private ResultSet rs;
private JTable jt;
public InventoryFrame() throws Exception {
// Todo Auto-generated constructor stub
super();
setTitle("Inventory");
setSize(800,600);
p.setLayout(new BorderLayout());
setDefaultCloSEOperation(EXIT_ON_CLOSE);
setLocationRelativeto(null);
isResizable();
getContentPane().add(p);
p.add(getAll,BorderLayout.norTH);
dbman = new DatabaseManager();
if(null == rs) {
rs = dbman.getAllQuery();
}
InventoryTableModel itm = new InventoryTableModel(rs);
getAll.addActionListener(new ActionListener() {
@Override
public void actionPerformed(ActionEvent arg0) {
jt = new JTable(itm);
jt.setColumnSelectionAllowed(true);
jt.setRowSelectionAllowed(true);
/*if (jt.getCellEditor() != null) {
jt.getCellEditor().stopCellEditing();
}*/
JScrollPane sp = new JScrollPane(jt);
p.add(sp,BorderLayout.CENTER);
pack();
setSize(800,600);
doLayout();
}
});
itm.addTableModelListener(new TableModelListener() {
@Override
public void tableChanged(TableModelEvent e) {
// Todo Auto-generated method stub
actualizeTable(e);
}
});
public void actualizeTable(TableModelEvent e) {
System.out.println("entering editing..."+e.getType()+","+TableModelEvent.UPDATE);
if ((int) e.getType() == TableModelEvent.UPDATE) {
System.out.println("editing...");
InventoryTableModel model = (InventoryTableModel) ((TableModel) e.getSource());
int row = e.getFirstRow();
int column = e.getColumn();
String input = String.valueOf(model.getValueAt(jt.getSelectedRow(),jt.getSelectedColumn()));
dbman.update(column,input);
model.setValueAt(input,row,column);
pack();
setSize(800,600);
doLayout();
}
}
}
这是我的InventoryTableModel类：
public class InventoryTableModel extends AbstractTableModel {
private ResultSet rset;
private int rowCount = 0;
private int columnCnt=0;
private String columnName = "";
public InventoryTableModel(ResultSet rs){
// Todo Auto-generated constructor stub
rset = rs;
try {
if(rset.last()) {
rowCount = rset.getRow();
}
columnCnt = rset.getMetaData().getColumnCount();
} catch (sqlException e) {
// Todo Auto-generated catch block
e.printstacktrace();
}
}
@Override
public int getColumnCount() {
return columnCnt;
}
@Override
public int getRowCount() {
return rowCount;
}
@Override
public Object getValueAt(int row,int col) {
// Todo Auto-generated method stub
try {
if(!rset.absolute(row+1)) {
return null;
}
Object value = rset.getobject(col +1);
//System.out.println("value is: "+value);
return value;
} catch (sqlException e) {
// Todo Auto-generated catch block
e.printstacktrace();
}
return null;
}
public boolean isCellEditable(int row,int col) {
return true;
}
public String getColumnName(int col) {
try {
String colName = rset.getMetaData().getColumnName(col+1);
if (colName.equals("ProductID")) {
return "Product ID";
} else if (colName.equals("ProductName")){
return "Product Name";
} else if (colName.equals("DateAdded")) {
return "Date Added";
}
return colName;
} catch (sqlException e) {
// Todo Auto-generated catch block
e.printstacktrace();
}
return "";
}
}
这是被调用的update（）方法，它是DatabaseManager类的一部分：
public DatabaseManager() throws Exception {
try {
Class.forName("com.MysqL.jdbc.Driver");
// Setup the connection with the DB
connection = DriverManager
.getConnection("jdbc:MysqL://localhost:3306/inventory",username,password);
statement = connection.createStatement();
System.out.println("Successfully Connected");
} catch (Exception e) {
throw e;
}
}
public ResultSet getAllQuery() {
try {
resultSet = statement.executeQuery("select * from inventory");
} catch (Exception e){
e.printstacktrace();
}
return resultSet;
}
public void update(int col,String input) {
String colName = "";
if (col == 1) {
colName = "ProductID";
} else if (col == 2) {
colName = "ProductName";
} else if (col == 3) {
colName = "Price";
} else if (col == 4) {
colName = "Quantity";
} else if (col == 5) {
colName = "Description";
} else if (col == 6) {
colName = "Category";
} else if (col == 7) {
colName = "DateAdded";
}
try {
String query = "UPDATE INVENTORY "
+ "SET "+colName+ "= ?"
+ " WHERE PRODUCTID = ?";
pstatement = connection.prepareStatement(query);
pstatement.setString(1,input);
pstatement.setInt(2,col);
pstatement.execute();
} catch (Exception e) {
e.printstacktrace();
}
}
任何帮助将不胜感激！
解决方法
我的目标是能够编辑一个JTable单元，该单元一旦被编辑并保存，就将值保存到数据库中并将其加载到JTable中。
您对JTable和/或TableModelListener的理解是错误的。
在JTable中编辑单元格时，数据将通过TableModel方法存储在setValueAt(...)中。然后，setValueAt()方法将调用TableModelListener，以指示对TableModel进行了更改。
您没有得到TableModelEvent，因为您的TableModel没有实现setValueAt(...)方法。
我建议您无需创建自定义TableModel。而是将数据从ResultSet复制到DefaultTableModel，然后在DefaultTableModel中使用JTable。
DefaultTableModel确实实现了setValueAt(...)。因此，当您编辑JTable时，数据将保存到TableModel并生成TableModelEvent。然后，您可以在TableModelListener中更新数据库。
签出：How to get a DefaultTableModel object's data into a subclass of DefaultTableModel的示例显示了如何将数据从ResultSet普遍加载到DefaultTableModel。