Java 摇摆| JFileChooser
哎哎哎:# t0]https://www . geeksforgeeks . org/Java-swing-jfile chooser/
JFileChooser 是 java Swing 包的一部分。java Swing 包是 JavaTM 基础类(JFC)的一部分。JFC 包含许多有助于用 java 构建图形用户界面的特性。Java Swing 提供了按钮、面板、对话框等组件。JFileChooser 是提示用户选择文件或目录的一种简单有效的方法。 在本文中，我们将看到如何在 java swing 中使用 JFileChooser。 JFileChooser 的构造函数为:
1。JFileChooser()–指向用户默认目录 的空构造函数
Java 语言(一种计算机语言，尤用于创建网站)
// Using this process to invoke the constructor,
// JFileChooser points to user's default directory
JFileChooser j = new JFileChooser();
// Open the save dialog
j.showSaveDialog(null);
代码片段的输出:
2。JFileChooser(字符串)–使用给定的路径
Java 语言(一种计算机语言，尤用于创建网站)
// Using this process to invoke the constructor,
// JFileChooser points to the mentioned path
JFileChooser j = new JFileChooser("d:");
// Open the save dialog
j.showSaveDialog(null);
代码片段的输出:
3。JFileChooser(文件)–使用给定的文件作为路径
Java 语言(一种计算机语言，尤用于创建网站)
// Using this process to invoke the constructor,
// JFileChooser points to the mentioned path
// of the file passed
JFileChooser j = new JFileChooser(new File("C:\\Users\\pc\\Documents\\New folder\\"));
// Open the save dialog
j.showSaveDialog(null);
代码片段的输出:
4。jfilesystemview(文件系统视图)–使用给定的文件系统视图
Java 语言(一种计算机语言，尤用于创建网站)
// In this process argument passed
// is an object of File System View
JFileChooser j = new JFileChooser(FileSystemView.getFileSystemView());
// Open the save dialog
j.showSaveDialog(null);
代码片段的输出:
5。JFileChooser(字符串，文件系统视图)–使用给定的路径和文件系统视图
Java 语言(一种计算机语言，尤用于创建网站)
// In this process argument passed is an object
// of File System View, and a path
JFileChooser j = new JFileChooser("d:", FileSystemView.getFileSystemView());
// Open the save dialog
j.showSaveDialog(null);
代码片段的输出:
6。JFileChooser(文件，文件系统视图)–使用给定的当前目录和文件系统视图
Java 语言(一种计算机语言，尤用于创建网站)
// In this process argument passed is an object
// of File System View and a object of
// File class
File f = new File("C:\\Users\\pc\\Documents\\New folder\\");
JFileChooser j = new JFileChooser(f, FileSystemView.getFileSystemView());
// Open the save dialog
j.showSaveDialog(null);
代码片段的输出:
注意:上面给出的代码是代码片段，不是完整的代码，上面给出的代码片段应该根据程序员的需要和判断来调用构造函数，上面提到的路径是任意的。用户应该根据自己的需要设置路径。
JFileChooser 的实际应用
以下代码不会在联机编译器中执行。请使用离线 IDE 1。使用 JFileChooser 创建打开或保存对话框
Java 语言(一种计算机语言，尤用于创建网站)
// Java program to create open or
// save dialog using JFileChooser
import java.io.*;
import javax.swing.*;
import java.awt.event.*;
import javax.swing.filechooser.*;
class filechooser extends JFrame implements ActionListener {
// Jlabel to show the files user selects
static JLabel l;
// a default constructor
filechooser()
{
}
public static void main(String args[])
{
// frame to contains GUI elements
JFrame f = new JFrame("file chooser");
// set the size of the frame
f.setSize(400, 400);
// set the frame's visibility
f.setVisible(true);
f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
// button to open save dialog
JButton button1 = new JButton("save");
// button to open open dialog
JButton button2 = new JButton("open");
// make an object of the class filechooser
filechooser f1 = new filechooser();
// add action listener to the button to capture user
// response on buttons
button1.addActionListener(f1);
button2.addActionListener(f1);
// make a panel to add the buttons and labels
JPanel p = new JPanel();
// add buttons to the frame
p.add(button1);
p.add(button2);
// set the label to its initial value
l = new JLabel("no file selected");
// add panel to the frame
p.add(l);
f.add(p);
f.show();
}
public void actionPerformed(ActionEvent evt)
{
// if the user presses the save button show the save dialog
String com = evt.getActionCommand();
if (com.equals("save")) {
// create an object of JFileChooser class
JFileChooser j = new JFileChooser(FileSystemView.getFileSystemView().getHomeDirectory());
// invoke the showsSaveDialog function to show the save dialog
int r = j.showSaveDialog(null);
// if the user selects a file
if (r == JFileChooser.APPROVE_OPTION)
{
// set the label to the path of the selected file
l.setText(j.getSelectedFile().getAbsolutePath());
}
// if the user cancelled the operation
else
l.setText("the user cancelled the operation");
}
// if the user presses the open dialog show the open dialog
else {
// create an object of JFileChooser class
JFileChooser j = new JFileChooser(FileSystemView.getFileSystemView().getHomeDirectory());
// invoke the showsOpenDialog function to show the save dialog
int r = j.showOpenDialog(null);
// if the user selects a file
if (r == JFileChooser.APPROVE_OPTION)
{
// set the label to the path of the selected file
l.setText(j.getSelectedFile().getAbsolutePath());
}
// if the user cancelled the operation
else
l.setText("the user cancelled the operation");
}
}
}
2。使用 JFileChooser 仅选择目录
Java 语言(一种计算机语言，尤用于创建网站)
// Java program to use JFileChooser
// to select directory only
import java.io.*;
import javax.swing.*;
import java.awt.event.*;
import javax.swing.filechooser.*;
class filechooser extends JFrame implements ActionListener {
// Jlabel to show the files user selects
static JLabel l;
// a default constructor
filechooser()
{
}
public static void main(String args[])
{
// frame to contains GUI elements
JFrame f = new JFrame("file chooser to select directories");
// set the size of the frame
f.setSize(400, 400);
// set the frame's visibility
f.setVisible(true);
f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
// button to open save dialog
JButton button1 = new JButton("save");
// button to open open dialog
JButton button2 = new JButton("open");
// make an object of the class filechooser
filechooser f1 = new filechooser();
// add action listener to the button to capture user
// response on buttons
button1.addActionListener(f1);
button2.addActionListener(f1);
// make a panel to add the buttons and labels
JPanel p = new JPanel();
// add buttons to the frame
p.add(button1);
p.add(button2);
// set the label to its initial value
l = new JLabel("no file selected");
// add panel to the frame
p.add(l);
f.add(p);
f.show();
}
public void actionPerformed(ActionEvent evt)
{
// if the user presses the save button show the save dialog
String com = evt.getActionCommand();
if (com.equals("save")) {
// create an object of JFileChooser class
JFileChooser j = new JFileChooser(FileSystemView.getFileSystemView().getHomeDirectory());
// set the selection mode to directories only
j.setFileSelectionMode(JFileChooser.DIRECTORIES_ONLY);
// invoke the showsSaveDialog function to show the save dialog
int r = j.showSaveDialog(null);
if (r == JFileChooser.APPROVE_OPTION) {
// set the label to the path of the selected directory
l.setText(j.getSelectedFile().getAbsolutePath());
}
// if the user cancelled the operation
else
l.setText("the user cancelled the operation");
}
// if the user presses the open dialog show the open dialog
else {
// create an object of JFileChooser class
JFileChooser j = new JFileChooser(FileSystemView.getFileSystemView().getHomeDirectory());
// set the selection mode to directories only
j.setFileSelectionMode(JFileChooser.DIRECTORIES_ONLY);
// invoke the showsOpenDialog function to show the save dialog
int r = j.showOpenDialog(null);
if (r == JFileChooser.APPROVE_OPTION) {
// set the label to the path of the selected directory
l.setText(j.getSelectedFile().getAbsolutePath());
}
// if the user cancelled the operation
else
l.setText("the user cancelled the operation");
}
}
}
3。使用 JFileChooser 允许多重选择文件
Java 语言(一种计算机语言，尤用于创建网站)
// Java program to use JFileChooser to allow multiple selection of files
import java.io.*;
import javax.swing.*;
import java.awt.event.*;
import javax.swing.filechooser.*;
class filechooser extends JFrame implements ActionListener {
// Jlabel to show the files user selects
static JLabel l;
// a default constructor
filechooser()
{
}
public static void main(String args[])
{
// frame to contains GUI elements
JFrame f = new JFrame("file chooser to select multiple files at a time");
// set the size of the frame
f.setSize(400, 400);
// set the frame's visibility
f.setVisible(true);
f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
// button to open save dialog
JButton button1 = new JButton("save");
// button to open open dialog
JButton button2 = new JButton("open");
// make an object of the class filechooser
filechooser f1 = new filechooser();
// add action listener to the button to capture user
// response on buttons
button1.addActionListener(f1);
button2.addActionListener(f1);
// make a panel to add the buttons and labels
JPanel p = new JPanel();
// add buttons to the frame
p.add(button1);
p.add(button2);
// set the label to its initial value
l = new JLabel("no file selected");
// add panel to the frame
p.add(l);
f.add(p);
f.show();
}
public void actionPerformed(ActionEvent evt)
{
// if the user presses the save button show the save dialog
String com = evt.getActionCommand();
if (com.equals("save")) {
// create an object of JFileChooser class
JFileChooser j = new JFileChooser(FileSystemView.getFileSystemView().getHomeDirectory());
// allow multiple file selection
j.setMultiSelectionEnabled(true);
// invoke the showsSaveDialog function to show the save dialog
int r = j.showSaveDialog(null);
if (r == JFileChooser.APPROVE_OPTION) {
// get the selelcted files
File files[] = j.getSelectedFiles();
int t = 0;
// set text to blank
l.setText("");
// set the label to the path of the selected files
while (t++ < files.length)
l.setText(l.getText() + " " + files[t - 1].getName());
}
// if the user cancelled the operation
else
l.setText("the user cancelled the operation");
}
// if the user presses the open dialog show the open dialog
else {
// create an object of JFileChooser class
JFileChooser j = new JFileChooser(FileSystemView.getFileSystemView().getHomeDirectory());
// allow multiple file selection
j.setMultiSelectionEnabled(true);
// invoke the showsOpenDialog function to show the save dialog
int r = j.showOpenDialog(null);
if (r == JFileChooser.APPROVE_OPTION) {
// get the selelcted files
File files[] = j.getSelectedFiles();
// set text to blank
l.setText("");
int t = 0;
// set the label to the path of the selected files
while (t++ < files.length)
l.setText(l.getText() + " " + files[t - 1].getName());
}
// if the user cancelled the operation
else
l.setText("the user cancelled the operation");
}
}
}
4。使用 JFileChooser 限制显示给用户的文件类型
Java 语言(一种计算机语言，尤用于创建网站)
// Java program to use JFileChooser to restrict
// the type of files shown to the user
import java.io.*;
import javax.swing.*;
import java.awt.event.*;
import javax.swing.filechooser.*;
class filechooser extends JFrame implements ActionListener {
// Jlabel to show the files user selects
static JLabel l;
// a default constructor
filechooser()
{
}
public static void main(String args[])
{
// frame to contains GUI elements
JFrame f = new JFrame("file chooser");
// set the size of the frame
f.setSize(400, 400);
// set the frame's visibility
f.setVisible(true);
f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
// button to open save dialog
JButton button1 = new JButton("save");
// button to open open dialog
JButton button2 = new JButton("open");
// make an object of the class filechooser
filechooser f1 = new filechooser();
// add action listener to the button to capture user
// response on buttons
button1.addActionListener(f1);
button2.addActionListener(f1);
// make a panel to add the buttons and labels
JPanel p = new JPanel();
// add buttons to the frame
p.add(button1);
p.add(button2);
// set the label to its initial value
l = new JLabel("no file selected");
// add panel to the frame
p.add(l);
f.add(p);
f.show();
}
public void actionPerformed(ActionEvent evt)
{
// if the user presses the save button show the save dialog
String com = evt.getActionCommand();
if (com.equals("save")) {
// create an object of JFileChooser class
JFileChooser j = new JFileChooser(FileSystemView.getFileSystemView().getHomeDirectory());
// resctrict the user to select files of all types
j.setAcceptAllFileFilterUsed(false);
// set a title for the dialog
j.setDialogTitle("Select a .txt file");
// only allow files of .txt extension
FileNameExtensionFilter restrict = new FileNameExtensionFilter("Only .txt files", "txt");
j.addChoosableFileFilter(restrict);
// invoke the showsSaveDialog function to show the save dialog
int r = j.showSaveDialog(null);
// if the user selects a file
if (r == JFileChooser.APPROVE_OPTION)
{
// set the label to the path of the selected file
l.setText(j.getSelectedFile().getAbsolutePath());
}
// if the user cancelled the operation
else
l.setText("the user cancelled the operation");
}
// if the user presses the open dialog show the open dialog
else {
// create an object of JFileChooser class
JFileChooser j = new JFileChooser(FileSystemView.getFileSystemView().getHomeDirectory());
// resctrict the user to select files of all types
j.setAcceptAllFileFilterUsed(false);
// set a title for the dialog
j.setDialogTitle("Select a .txt file");
// only allow files of .txt extension
FileNameExtensionFilter restrict = new FileNameExtensionFilter("Only .txt files", "txt");
j.addChoosableFileFilter(restrict);
// invoke the showsOpenDialog function to show the save dialog
int r = j.showOpenDialog(null);
// if the user selects a file
if (r == JFileChooser.APPROVE_OPTION) {
// set the label to the path of the selected file
l.setText(j.getSelectedFile().getAbsolutePath());
}
// if the user cancelled the operation
else
l.setText("the user cancelled the operation");
}
}
}
注意: 也可以使用 setApproveButtonText(字符串)功能自定义审批按钮。这将把批准按钮 的文本设置为所需的文本。
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