如何在Java的jtextarea上显示shell命令输出？
请帮助谢谢
您可以在代码段下方获得shell命令输出，在while循环上设置jtextarea。
try {
String cmd = "java"; // Set shell command
Process child = Runtime.getRuntime().exec(cmd);
InputStream lsOut = child.getInputStream();
InputStreamReader r = new InputStreamReader(lsOut);
BufferedReader in = new BufferedReader(r);
// read the child process' output
String line;
while ((line = in.readLine()) != null) {
System.out.println(line);
// You should set JtextArea
}
} catch (Exception e) { // exception thrown
System.err.println("Command failed!");
}
您需要将标准输出读取为流程输入流，并使用来自另一个线程的事件队列来更新JTextArea。请参见下面的示例代码：
public class OutputDisplayer implements Runnable {
protected final JTextArea textArea_;
protected Reader reader_ = null;
public OutputDisplayer(JTextArea textArea) {
textArea_ = textArea;
}
public void commence(Process proc) {
InputStream in = proc.getInputStream();
reader_ = new InputStreamReader(in);
Thread thread = new Thread(this);
thread.start();
}
public void run() {
StringBuilder buf = new StringBuilder();
try {
while( reader_ != null ) {
int c = reader_.read();
if( c==-1 ) return;
buf.append((char) c);
setText( buf.toString() );
}
} catch ( IOException ioe ) {
buf.append("\n\nERROR:\n"+ioe.toString());
setText( buf.toString() );
} finally {
try {
reader_.close();
} catch ( IOException ioe ) {
ioe.printStackTrace();
}
}
}
private void setText(final String text) {
EventQueue.invokeLater(new Runnable() {
public void run() {
textArea_.setText(text);
}
});
}
}
除了上面我的评论中的两个链接之外，我还创建并使用了TextAreaOutputStream，它有助于将输出流数据重定向到textarea：
import java.io.IOException;
import java.io.OutputStream;
import javax.swing.JTextArea;
import javax.swing.SwingUtilities;
public class TextAreaOutputStream extends OutputStream {
private final JTextArea textArea;
private final StringBuilder sb = new StringBuilder();
private String title;
public TextAreaOutputStream(final JTextArea textArea, String title) {
this.textArea = textArea;
this.title = title;
sb.append(title + "> ");
}
@Override
public void flush() {
}
@Override
public void close() {
}
@Override
public void write(int b) throws IOException {
if (b == '\r')
return;
if (b == '\n') {
final String text = sb.toString() + "\n";
SwingUtilities.invokeLater(new Runnable() {
public void run() {
textArea.append(text);
}
});
sb.setLength(0);
sb.append(title + "> ");
}
sb.append((char) b);
}
}
import java.io.OutputStream;
import javax.swing.JTextArea;
/**
* This class extends from OutputStream to redirect output to a JTextArrea
* @author www.codejava.net
*
*/
public class CustomOutputStream extends OutputStream {
private JTextArea textArea;
public CustomOutputStream(JTextArea textArea) {
this.textArea = textArea;
}
@Override
public void write(int b) throws IOException {
// redirects data to the text area
textArea.append(String.valueOf((char)b));
// scrolls the text area to the end of data
textArea.setCaretPosition(textArea.getDocument().getLength());
}
}
/*
* To change this license header, choose License Headers in Project Properties.
* To change this template file, choose Tools | Templates
* and open the template in the editor.
*/
package guiconsoleoutput;
/**
*
* @author root
*/
import java.awt.GridBagConstraints;
import java.awt.GridBagLayout;
import java.awt.Insets;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.PrintStream;
import java.util.Date;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JScrollPane;
import javax.swing.JTextArea;
import javax.swing.SwingUtilities;
import javax.swing.text.BadLocationException;
public class TextAreaLogProgram extends JFrame {
/**
* The text area which is used for displaying logging information.
*/
private JTextArea textArea;
private JButton buttonStart = new JButton("Start");
private JButton buttonClear = new JButton("Clear");
private PrintStream standardOut;
public TextAreaLogProgram() {
super(" CONSOLE ");
textArea = new JTextArea(50, 10);
textArea.setEditable(false);
PrintStream printStream = new PrintStream(new CustomOutputStream(textArea));
// keeps reference of standard output stream
standardOut = System.out;
// re-assigns standard output stream and error output stream
System.setOut(printStream);
System.setErr(printStream);
// creates the GUI
setLayout(new GridBagLayout());
GridBagConstraints constraints = new GridBagConstraints();
constraints.gridx = 0;
constraints.gridy = 0;
constraints.insets = new Insets(10, 10, 10, 10);
constraints.anchor = GridBagConstraints.WEST;
add(buttonStart, constraints);
constraints.gridx = 1;
add(buttonClear, constraints);
constraints.gridx = 0;
constraints.gridy = 1;
constraints.gridwidth = 2;
constraints.fill = GridBagConstraints.BOTH;
constraints.weightx = 1.0;
constraints.weighty = 1.0;
add(new JScrollPane(textArea), constraints);
// adds event handler for button Start
buttonStart.addActionListener(new ActionListener() {
@Override
public void actionPerformed(ActionEvent evt) {
printLog();
}
});
// adds event handler for button Clear
buttonClear.addActionListener(new ActionListener() {
@Override
public void actionPerformed(ActionEvent evt) {
// clears the text area
try {
textArea.getDocument().remove(0,
textArea.getDocument().getLength());
standardOut.println("Text area cleared");
} catch (BadLocationException ex) {
ex.printStackTrace();
}
}
});
setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
setSize(480, 320);
setLocationRelativeTo(null); // centers on screen
}
/**
* Prints log statements for testing in a thread
*/
private void printLog() {
Thread thread = new Thread(new Runnable() {
@Override
public void run() {
System.out.println("Time now is " + (new Date()));
System.out.println("lol ");
String s = null;
/*try {
// run the Unix "ps -ef" command
// using the Runtime exec method:
Process p = Runtime.getRuntime().exec("dir");
BufferedReader stdInput = new BufferedReader(new
InputStreamReader(p.getInputStream()));
BufferedReader stdError = new BufferedReader(new
InputStreamReader(p.getErrorStream()));
// read the output from the command
System.out.println("Here is the standard output of the command:\n");
while ((s = stdInput.readLine()) != null) {
System.out.println(s);
}
// read any errors from the attempted command
System.out.println("Here is the standard error of the command (if any):\n");
while ((s = stdError.readLine()) != null) {
System.out.println(s);
}
System.exit(0);
}
catch (IOException e) {
System.out.println("exception happened - here's what I know: ");
e.printStackTrace();
System.exit(-1);
}*/
try {
String cmd = "cmd /c ping 8.8.8.8"; // Set shell command
Process child = Runtime.getRuntime().exec(cmd);
InputStream lsOut = child.getInputStream();
InputStreamReader r = new InputStreamReader(lsOut);
BufferedReader in = new BufferedReader(r);
// read the child process' output
String line;
while ((line = in.readLine()) != null) {
System.out.println(line);
// You should set JtextArea
}
} catch (Exception e) { // exception thrown
System.err.println("Command failed!");
}
try {
Thread.sleep(1000);
} catch (InterruptedException ex) {
ex.printStackTrace();
}
}
});
thread.start();
}
/**
* Runs the program
*/
public static void main(String[] args) {
SwingUtilities.invokeLater(new Runnable() {
@Override
public void run() {
new TextAreaLogProgram().setVisible(true);
}
});
}
}