如何通过单击按钮从textField读取？

Question

我想通过点击检查按钮从我的textField中读取文件。如果我点击检查按钮它没有显示任何内容。它应该在textFiled_2中显示内容。但它不是从textField读取文件。 请帮忙。谢谢。

public class HLS {
    private JFrame frmHttpsLiveStreaming;
    private JTextField textField_2;
    private JTextField textField;
    /**
     * Launch the application.
     */
    public static void main(String[] args) {
        EventQueue.invokeLater(new Runnable() {
            public void run() {
                try {
                    HLS window = new HLS();
                    window.frmHttpsLiveStreaming.setVisible(true);
                } catch (Exception e) {
                    e.printStackTrace();
                }
            }
        });
    }

    /**
     * Create the application.
     */
    public HLS() {
        initialize();
    }

    /**
     * Initialize the contents of the frame.
     */
    private void initialize() {
        frmHttpsLiveStreaming = new JFrame();
        frmHttpsLiveStreaming.setTitle("HTTPS Live Streaming");
        frmHttpsLiveStreaming.setBounds(100, 100, 494, 322);
        frmHttpsLiveStreaming.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        frmHttpsLiveStreaming.getContentPane().setLayout(null);

        JButton btnBrowse = new JButton("Open File");
        btnBrowse.addActionListener(new ActionListener() {
            public void actionPerformed(ActionEvent arg0) {
                JFileChooser fs=new JFileChooser(new File("c:\\"));
                fs.setDialogTitle("Open a file");
                fs.setFileFilter(new FileTypeFilter(".m3u8",""));
                fs.setFileFilter(new FileTypeFilter(".ts",""));
                fs.setFileFilter(new FileTypeFilter(".m3u",""));
                fs.showOpenDialog(null);
                File file = fs.getSelectedFile();
                textField.setText(file.getAbsolutePath());

                }
            });
        btnBrowse.setBounds(336, 7, 89, 23);
        frmHttpsLiveStreaming.getContentPane().add(btnBrowse);

        JButton btnNewButton_1 = new JButton("Clear");
        btnNewButton_1.addActionListener(new ActionListener() {
            public void actionPerformed(ActionEvent arg0) {
                textField_2.setText("");

            }
        });
        btnNewButton_1.setBounds(237, 39, 89, 23);
        frmHttpsLiveStreaming.getContentPane().add(btnNewButton_1);

        JButton btnNewButton_2 = new JButton("Save Log File");
        btnNewButton_2.addActionListener(new ActionListener() {
            public void actionPerformed(ActionEvent arg0) {
                JFileChooser fs=new JFileChooser(new File("c:\\"));
                fs.setDialogTitle("Save Log File");
                fs.setFileFilter(new FileTypeFilter(".txt","TEXT FILE"));
                fs.setFileFilter(new FileTypeFilter(".doc","DOCUMENT FILE"));
                int result=fs.showSaveDialog(null);
                if (result==JFileChooser.APPROVE_OPTION){
                     String content=textField_2.getText();
                     File file=fs.getSelectedFile();
                     try{
                         FileWriter fw=new FileWriter(file.getPath());
                         fw.write(content);
                         fw.flush();
                         fw.close();
                     }catch (Exception e2){
                         JOptionPane.showMessageDialog(null,e2.getMessage());
                 }      
            }
        }
        });
        btnNewButton_2.setBounds(168, 239, 131, 23);
        frmHttpsLiveStreaming.getContentPane().add(btnNewButton_2);

        textField_2 = new JTextField();
        textField_2.setToolTipText("TOP");
        textField_2.setBounds(27, 73, 418, 155);
        frmHttpsLiveStreaming.getContentPane().add(textField_2);
        textField_2.setColumns(10);

        JLabel lblUrl = new JLabel("URL");
        lblUrl.setBounds(83, 11, 24, 14);
        frmHttpsLiveStreaming.getContentPane().add(lblUrl);

        textField = new JTextField();
        textField.setBounds(116, 11, 210, 19);
        frmHttpsLiveStreaming.getContentPane().add(textField);
        textField.setColumns(10);

        JButton btnNewButton = new JButton("Check");
        btnNewButton.addActionListener(new ActionListener() {
            public void actionPerformed(ActionEvent arg0) {
                ***

//这就是问题。

                 try{
                    BufferedReader br=new BufferedReader(new FileReader(file));
                     textField_2.read(br,null);
                     br.close();
                     textField_2.requestFocus();
                 }
                 catch(Exception e){


                 }
            }
        });
        btnNewButton.setBounds(126, 39, 89, 23);
        frmHttpsLiveStreaming.getContentPane().add(btnNewButton);

    }
}

请帮忙。

Answer 1

1. 您需要添加＆＃39; file＆＃39;作为从其他方法访问的字段。
2. 从文本文件中读取实现为＆＃39;而＆＃39;循环，您可能想要更改其二进制数据。
3. 您可能希望将JTextField更改为JTextArea（如果是文本数据。
）

编译并测试：

import java.awt.EventQueue;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.io.BufferedReader;
import java.io.File;
import java.io.FileReader;
import java.io.FileWriter;
import javax.swing.*;

public class HLS {

    private JFrame frmHttpsLiveStreaming;
    private JTextField textField_2;
    private JTextField textField;
    // file is accessed to the whole class
    private File file;

    /**
     * Launch the application.
     */
    public static void main(String[] args) {
        EventQueue.invokeLater(new Runnable() {
            public void run() {
                try {
                    HLS window = new HLS();
                    window.frmHttpsLiveStreaming.setVisible(true);
                } catch (Exception e) {
                    e.printStackTrace();
                }
            }
        });
    }

    /**
     * Create the application.
     */
    public HLS() {
        initialize();
    }

    /**
     * Initialize the contents of the frame.
     */
    private void initialize() {
        frmHttpsLiveStreaming = new JFrame();
        frmHttpsLiveStreaming.setTitle("HTTPS Live Streaming");
        frmHttpsLiveStreaming.setBounds(100, 100, 494, 322);
        frmHttpsLiveStreaming.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        frmHttpsLiveStreaming.getContentPane().setLayout(null);

        JButton btnBrowse = new JButton("Open File");
        btnBrowse.addActionListener(new ActionListener() {
            public void actionPerformed(ActionEvent arg0) {
                JFileChooser fs = new JFileChooser(new File("c:\\"));
                fs.setDialogTitle("Open a file");
                fs.setFileFilter(new FileTypeFilter(".m3u8", ""));
                fs.setFileFilter(new FileTypeFilter(".ts", ""));
                fs.setFileFilter(new FileTypeFilter(".m3u", ""));
                fs.showOpenDialog(null);
                file = fs.getSelectedFile();
                textField.setText(file.getAbsolutePath());

            }
        });
        btnBrowse.setBounds(336, 7, 89, 23);
        frmHttpsLiveStreaming.getContentPane().add(btnBrowse);

        JButton btnNewButton_1 = new JButton("Clear");
        btnNewButton_1.addActionListener(new ActionListener() {
            public void actionPerformed(ActionEvent arg0) {
                textField_2.setText("");

            }
        });
        btnNewButton_1.setBounds(237, 39, 89, 23);
        frmHttpsLiveStreaming.getContentPane().add(btnNewButton_1);

        JButton btnNewButton_2 = new JButton("Save Log File");
        btnNewButton_2.addActionListener(new ActionListener() {
            public void actionPerformed(ActionEvent arg0) {
                JFileChooser fs = new JFileChooser(new File("c:\\"));
                fs.setDialogTitle("Save Log File");
                fs.setFileFilter(new FileTypeFilter(".txt", "TEXT FILE"));
                fs.setFileFilter(new FileTypeFilter(".doc", "DOCUMENT FILE"));
                int result = fs.showSaveDialog(null);
                if (result == JFileChooser.APPROVE_OPTION) {
                    String content = textField_2.getText();
                    File file = fs.getSelectedFile();
                    try {
                        FileWriter fw = new FileWriter(file.getPath());
                        fw.write(content);
                        fw.flush();
                        fw.close();
                    } catch (Exception e2) {
                        JOptionPane.showMessageDialog(null, e2.getMessage());
                    }
                }
            }
        });
        btnNewButton_2.setBounds(168, 239, 131, 23);
        frmHttpsLiveStreaming.getContentPane().add(btnNewButton_2);

        textField_2 = new JTextField();
        textField_2.setToolTipText("TOP");
        textField_2.setBounds(27, 73, 418, 155);
        frmHttpsLiveStreaming.getContentPane().add(textField_2);
        textField_2.setColumns(10);

        JLabel lblUrl = new JLabel("URL");
        lblUrl.setBounds(83, 11, 24, 14);
        frmHttpsLiveStreaming.getContentPane().add(lblUrl);

        textField = new JTextField();
        textField.setBounds(116, 11, 210, 19);
        frmHttpsLiveStreaming.getContentPane().add(textField);
        textField.setColumns(10);

        JButton btnNewButton = new JButton("Check");
        btnNewButton.addActionListener(new ActionListener() {
            public void actionPerformed(ActionEvent arg0) {
                // HERE IS THE PROBLEM.

                try {
                    BufferedReader br = new BufferedReader(new FileReader(file));
                    String line;
                    // System.out.println(file.toString());

                    // read text from file until the end. add the content 
                    // to the existing data.
                    while((line = br.readLine()) != null){
                        // "\n" will be useful for JTextArea
                        textField_2.setText(textField_2.getText() + "\n" + line);
                        //System.out.println(line);
                    }
                    //textField_2.read(br, null);
                    br.close();
                    //textField_2.requestFocus();
                } catch (Exception e) {

                }
            }
        });
        btnNewButton.setBounds(126, 39, 89, 23);
        frmHttpsLiveStreaming.getContentPane().add(btnNewButton);

    }
}