清單 1. 把 ActionListener 定義為 GUI 中的一個按鈕
findWidgetButton.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent e) {
try {
String value = widgetValue.getText();
if (value == null || value.equals("")) {
dLabel.setText("Please enter a valid widgetID");
} else {
dLabel.setText(getOrderStatus(value));
}
} catch (Exception ex) {
dLabel.setText("Widget doesn't exist in system");
}
}
//more code
}); |
單擊 GUI 的按鈕組件后，直接從數據庫中檢索某個特定命令的狀態，如清單 2 所示：
清單 2. GUI 通過 getOrderStatus 方法直接與數據庫通信
private String getOrderStatus(String value) {
String retValue = "Widget doesn't exist in system";
Connection con = null;
Statement stmt = null;
ResultSet rs = null;
try {
con = DriverManager.getConnection("jdbc:hsqldb:hsql://127.0.0.1", "sa", "");
stmt = con.createStatement();
rs = stmt.executeQuery("select order.status "
+ "from order, widget where widget.name = "
+ "'" + value + "' "
+ "and widget.id = order.widget_id;");
StringBuffer buff = new StringBuffer(); |
