Alert弹窗

• 创建Alert弹窗类型决定弹窗内的按钮类型和图标，如果该alert中没有对应的按钮却给该类型的按钮设置了监听，则会报错NullPointerException

  Alert alert = new Alert(Alert.AlertType.INFORMATION);
  

• 添加指定类型的按钮alert.getDialogPane().getButtonTypes().add(ButtonType.CLOSE);

• 获取指定类型的按钮

  Button ok = (Button) alert.getDialogPane().lookupButton(ButtonType.OK);  
  Button cancel = (Button) alert.getDialogPane().lookupButton(ButtonType.CANCEL);  
  Button close = (Button) alert.getDialogPane().lookupButton(ButtonType.CLOSE);
  

• 删除按钮，删除的按钮由弹窗中设置的按钮顺序决定alert.getDialogPane().getButtonTypes().remove(0);

• 设置文本、标题、图标

  alert.setTitle("alert");  
  alert.setHeaderText("HeaderText");  
  alert.setContentText("ContentText");  
  ImageView imageView = new ImageView("images/logo.png");  
  imageView.setPreserveRatio(true);  
  imageView.setFitWidth(25);  
  alert.setGraphic(imageView);
  

• 设置模态alert.initModality(Modality.APPLICATION_MODAL);

• 展示alert.show();