我正在创建一个应用程序，它显示网络中的文件和文件夹列表。如何将JScrollPane添加到从JPanel扩展的类中。 JPanel包含JButtons，表示文件和文件夹。
package fileviewer;
import java.awt.FlowLayout;
import java.awt.GridBagConstraints;
import java.awt.GridBagLayout;
import java.awt.event.MouseAdapter;
import java.awt.event.MouseEvent;
import java.awt.image.BufferedImage;
import java.io.File;
import java.io.IOException;
import java.util.ArrayList;
import javax.imageio.ImageIO;
import javax.swing.ImageIcon;
import javax.swing.JButton;
import javax.swing.JLabel;
import javax.swing.JPanel;
/*
* @author : GUNNER.
* Title : Explorer.
* Description : You can browse the folders and download the files using this.
*/
@SuppressWarnings("serial")
public class FoldersAndFiles extends JPanel {
private final static int PADDING = 20;
private ArrayList<FolderAndFilePaths> totalFoldersAndFiles;
@SuppressWarnings("unused")
private ArrayList<JButton> buttons;
private BufferedImage myImage;
public FoldersAndFiles() {
// super("Explorer");
setLayout(new FlowLayout(FlowLayout.LEFT, PADDING, PADDING));
buttons = new ArrayList<JButton>();
totalFoldersAndFiles = new ArrayList<FolderAndFilePaths>();
}
public void addToTotalFolderAndFiles(FolderAndFilePaths folderAndFile) {
if (this.totalFoldersAndFiles != null)
this.totalFoldersAndFiles.add(folderAndFile);
createFoldersAndFiles(folderAndFile);
}
private void setGBC(GridBagConstraints g, int width, int height, int gridX,
int gridY) {
g.gridheight = height;
g.gridwidth = width;
g.gridx = gridX;
g.gridy = gridY;
}
private void createFoldersAndFiles(FolderAndFilePaths folderAndFile) {
FolderClickHandler folderClickHandler = new FolderClickHandler();
FileClickHandler fileClickHandler = new FileClickHandler();
// Here is the button, Panel and layouts which we set for the explore.
JButton button = new JButton();
JPanel panel = new JPanel();
GridBagLayout layout = new GridBagLayout();
GridBagConstraints constraints = new GridBagConstraints();
// This loop adds the available folders in the given path
for (String folder : folderAndFile.getFolderNames()) {
button = new JButton();
panel = new JPanel();
panel.setLayout(layout);
// Here we set the image for the folder.
try {
myImage = ImageIO.read(new File("res/folder.png"));
button.setIcon(new ImageIcon(myImage));
new JLabel("file").setLabelFor(button);
} catch (IOException e) {
e.printStackTrace();
}
button.setName("f" + folder);
// This is to set the backgrouond of the button as transparent.
button.setOpaque(false);
button.setContentAreaFilled(false);
button.setBorderPainted(false);
// Here we set the Constraints for the buttons.
setGBC(constraints, 1, 1, 0, 0);
layout.setConstraints(button, constraints);
panel.add(button);
// This registers the Event Handler for the folder.
button.addMouseListener(folderClickHandler);
// This sets the label and Constraints for the corresponding folder.
JLabel label = new JLabel(folder);
setGBC(constraints, 1, 1, 0, 1);
layout.setConstraints(label, constraints);
panel.add(label);
add(panel);
}
// This loop adds the available files in the given path
for (String file : folderAndFile.getFileNames()) {
button = new JButton();
panel = new JPanel();
panel.setLayout(layout);
// Here we set the image for the files.
try {
myImage = ImageIO.read(new File("res/file.png"));
button.setIcon(new ImageIcon(myImage));
} catch (IOException e) {
e.printStackTrace();
}
// This is to set the backgrouond of the button as transparent.
button.setOpaque(false);
button.setContentAreaFilled(false);
button.setBorderPainted(false);
button.setName("F" + file);
setGBC(constraints, 1, 1, 0, 0);
layout.setConstraints(button, constraints);
panel.add(button);
// This register the Event Handler for the files.
button.addMouseListener(fileClickHandler);
// This sets the label and Constraints for the corresponding file.
JLabel label = new JLabel(file);
setGBC(constraints, 1, 1, 0, 1);
layout.setConstraints(label, constraints);
panel.add(label);
add(panel);
}
setVisible(true);
}
private class FolderClickHandler extends MouseAdapter {
@Override
public void mouseClicked(MouseEvent event) {
// This is used to set the background color for the selected file or
// folder.
if (event.getClickCount() == 1) {
// Here we get the button and set color.
}
// This is used to check for double clicks.
if (event.getClickCount() == 2) {
// We print the folder / file name to start with
System.out.println(((JButton) event.getSource()).getName());
}
}
}
private class FileClickHandler extends MouseAdapter {
@Override
public void mouseClicked(MouseEvent event) {
// This is used to set the background color for the selected file or
// folder.
if (event.getClickCount() == 1) {
// Here we get the button and set color.
}
// This is used to check for double clicks.
if (event.getClickCount() == 2) {
// We print the folder / file name to start with
System.out.println(((JButton) event.getSource()).getName());
}
}
}
}
答案 0 :(得分：2)
试试这个
JPanel panel=new MyPanel();
JScrollPane pane = new JScrollPane(ScrollPaneConstants.VERTICAL_SCROLLBAR_ALWAYS,
ScrollPaneConstants.HORIZONTAL_SCROLLBAR_ALWAYS);
pane.getViewport().add(panel);
这里MyPanel是一个从JPanel扩展的类。
您也可以设置水平和垂直滚动条的可见性。
- 编辑 -
请查看main方法。
public static void main(String[] a) {
JFrame fram = new JFrame();
FoldersAndFiles b = new FoldersAndFiles();
JScrollPane pane = new JScrollPane(ScrollPaneConstants.VERTICAL_SCROLLBAR_ALWAYS,
ScrollPaneConstants.HORIZONTAL_SCROLLBAR_ALWAYS);
pane.getViewport().add(b);
fram.getContentPane().add(pane);
b.addToTotalFolderAndFiles(new FolderAndFilePaths());
fram.pack();
fram.setVisible(true);
fram.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
}
答案 1 :(得分：2)
至少有两个是这样做的......
首先，通过构造函数指定视图组件......
JScrollPane scrollPane = new JScrollPane(panel);
其次，与setViewportView方法竞争......
scrollPane.setViewportView(panel);
或者，您可以直接设置JViewports视图...
scrollPane.getViewport().setView(panel);
确保将滚动窗格添加到显示中......例如......
JFrame frame = ...
JPanel panel = ...
frame.add(new JScollPsne(panel));