Question

使用下面的代码，我试图模拟命令shell，我甚至创建了一个命令并调用它（Showerrlog）来帮助用户看到他在当前工作会话期间输入的无效命令，就像你一样我可以看到，我使用filehandler，这将在日志文件中保存错误的命令。但是你知道filehandler会为每个新的工作会话启动一个新文件，而新文件将命名为（file.log，file.log.1，file.log.2等），等等，问题是：如何使程序避免每次都打开一个新文件，换句话说，是不是还有其他任何方式程序只是格式化以前的工作会话并添加新的工作会话？

或者至少如何让程序打开属于当前工作会话的最后一个日志文件？

public class WithEyul implements Runnable {

    String command;

    public WithEyul(String command) {
        this.command = command;
    }

    @Override    
    public void run() {
        List<String> input = new ArrayList<String>();
        StringTokenizer tokenizer = new StringTokenizer(command);
        while (tokenizer.hasMoreTokens()) {
            input.add(tokenizer.nextToken());
        }
        ProcessBuilder pb = new ProcessBuilder(input);
        // ProcessBuilder creates a process corresponding to the input command
        // now start the process
        BufferedReader br = null;
        try {
            Process proc = pb.start();
            // obtain the input and output streams
            InputStream is = proc.getInputStream();
            InputStreamReader isr = new InputStreamReader(is);
            br = new BufferedReader(isr);
            // read what the process returned
            String line;
            while ((line = br.readLine()) != null) {
                System.out.println(line);
            }
            br.close();
        } catch (java.io.IOException ioe) {

            try {
                System.err.println("Error");

                Logger logger = Logger.getLogger("Testing");
                FileHandler fh = new FileHandler("E:/MyLogFile.log");

                logger.addHandler(fh);
                SimpleFormatter formatter = new SimpleFormatter();
                fh.setFormatter(formatter);
                logger.info(command);
            } catch (SecurityException e) {
                printStackTrace();
            } catch (IOException ex) {
                Logger.getLogger(WithEyul.class.getName()).log(Level.SEVERE, null, ex);
            }
        } finally {
            if (br != null) {
                try {
                    br.close();
                } catch (IOException ex) {
                    Logger.getLogger(WithEyul.class.getName()).log(Level.SEVERE, null, ex);
                }
            }    
        }    
    }    
}

这是主要的方法类

public class TestProcessBuilder {

    static void createProcess(String command) throws java.io.IOException {
        Thread t = new Thread(new WithEyul(command));
        t.start();    
    }

    public static void main(String[] args) throws java.io.IOException {

        String commandLine;
        File wd;
        BufferedReader console = new BufferedReader(new InputStreamReader(System.in));
        System.out.println("\n\n***** Welcome to the Java Command Shell *****");
        System.out.println("If you want to exit the shell, type END and press RETURN.\n");
        // we break out with â€˜ENDâ€™
        while (true) {
            // show the Java shell prompt and read what command they entered
            System.out.print("jsh>");
            commandLine = console.readLine();
            // if user entered a return, just loop again
            if (commandLine.equals("")) {
                continue;
            }
            if (commandLine.equalsIgnoreCase("Showerrlog")) {
                try {

                    // Runtime.getRuntime().exec("E:\\MyLogFile.log");
                    if (Desktop.isDesktopSupported()) {
                        Desktop.getDesktop().open(new File("E:\\MyLogFile.log"));
                    }

                } catch (IOException ex) {
                    Logger.getLogger(WithEyul.class.getName()).log(Level.SEVERE, null, ex);
                }
            }
            if (commandLine.toLowerCase().equals("end")) { //User wants to end shell
                System.out.println("\n***** Command Shell Terminated. See you next time. BYE for now. *****\n");
                System.exit(0);
            }

            createProcess(commandLine);

        }
    }
}

Answer 1

您可以使用FileHandler构造函数来指定旋转，限制和追加选项。

new FileHandler("E:/MyLogFile.log", 0, 1, true);

FileHandler可以出于多种原因而无法控制旋转。如果您不想处理文件轮换，可以打开FileOutputStream并用StreamHandler打包。但是，您必须处理文件锁定冲突。

每次生成错误时，您还应该避免创建和添加指向同一目标文件的处理程序。您应该在启动时安装处理程序并存储string reference to your logger。

将错误保存到文件处理程序

1 个答案: