我想将 sytem.out.println 重定向到另一个类中的 JLabel。
我有 2 个类，NextPage 和 Mctrainer。
NextPage 基本上只是一个 Jframe(我的项目的 gui)，我使用这段代码在 Nextpage 中创建了一个 Jlabel；
public class NextPage extends JFrame {
JLabel label1;
NextPage() {
label1 = new JLabel();
label1.setText("welcome");
getContentPane().add(label1);
这是 Mctrainer 的代码:
public class Mctrainer {
JLabel label1;
Mctrainer() {
HttpClient client2 = new DefaultHttpClient();
HttpPost post = new HttpPost("http://oo.hive.no/vlnch");
HttpProtocolParams.setUserAgent(client2.getParams(),"android");
try {
List <NameValuePair> nvp = new ArrayList <NameValuePair>();
nvp.add(new BasicNameValuePair("username", "test"));
nvp.add(new BasicNameValuePair("password", "test"));
nvp.add(new BasicNameValuePair("request", "login"));
nvp.add(new BasicNameValuePair("request", "mctrainer"));
post.setEntity(new UrlEncodedFormEntity(nvp));
HttpContext httpContext = new BasicHttpContext();
HttpResponse response1 = client2.execute(post, httpContext);
BufferedReader rd = new BufferedReader(new InputStreamReader(response1.getEntity().getContent()));
String line = "";
while ((line = rd.readLine()) != null) {
System.out.println(line);
}
}
catch (IOException e) {
e.printStackTrace();
}
}
Mctrainer 基本上只是使用 system.out.println 从服务器打印出 JSON 数据。 我想将其重定向以显示在我的 GUI (NextPage) 中的 JLabel 中而不是控制台中。 有关如何执行此操作的任何建议？
最佳答案
您只需更改默认输出...
public static void main(String[] args) throws UnsupportedEncodingException
{
ByteArrayOutputStream bos = new ByteArrayOutputStream();
System.setOut(new PrintStream(bos));
System.out.println("outputing an example");
JOptionPane.showMessageDialog(null, "Captured: " + bos.toString("UTF-8"));
}
此外，您的问题与 this other one 非常相似，因此我可以调整 this accepted answer 以使用 JLabel
public static void main(String[] args) throws UnsupportedEncodingException
{
CapturePane capturePane = new CapturePane();
System.setOut(new PrintStream(new StreamCapturer("STDOUT", capturePane, System.out)));
System.out.println("Output test");
JFrame frame = new JFrame();
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setLayout(new BorderLayout());
frame.add(capturePane);
frame.setSize(200, 200);
frame.setLocationRelativeTo(null);
frame.setVisible(true);
System.out.println("More output test");
}
public static class CapturePane extends JPanel implements Consumer {
private JLabel output;
public CapturePane() {
setLayout(new BorderLayout());
output = new JLabel("<html>");
add(new JScrollPane(output));
}
@Override
public void appendText(final String text) {
if (EventQueue.isDispatchThread()) {
output.setText(output.getText() + text + "<br>");
} else {
EventQueue.invokeLater(new Runnable() {
@Override
public void run() {
appendText(text);
}
});
}
}
}
public interface Consumer {
public void appendText(String text);
}
public static class StreamCapturer extends OutputStream {
private StringBuilder buffer;
private String prefix;
private Consumer consumer;
private PrintStream old;
public StreamCapturer(String prefix, Consumer consumer, PrintStream old) {
this.prefix = prefix;
buffer = new StringBuilder(128);
buffer.append("[").append(prefix).append("] ");
this.old = old;
this.consumer = consumer;
}
@Override
public void write(int b) throws IOException {
char c = (char) b;
String value = Character.toString(c);
buffer.append(value);
if (value.equals("\n")) {
consumer.appendText(buffer.toString());
buffer.delete(0, buffer.length());
buffer.append("[").append(prefix).append("] ");
}
old.print(c);
}
}
关于Java - 将 system.out.println 重定向到 JLabel，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/13893655/