Question

我想：

执行Bash脚本
阅读日志文件

我使用processBuilder执行以下代码，该代码具有读取日志文件的readLog函数和执行命令的executeBash，然后销毁processbuilder的readlog进程。但是当readLog文件正在读取实时日志文件时，executeBash永远不会被调用。

如何实时读取日志文件并与executeBash同时显示？

public void performAction(OssSystem system) {
        readLog(system);
        executeBash(system);
    }

public void executeBash(OssSystem system) {
    try {
        Process process = new ProcessBuilder().command("/bin/sh", system.getCommand_path(), system.getParam()).start();

        BufferedReader reader
                = new BufferedReader(new InputStreamReader(process.getInputStream()));
        StringBuilder builder = new StringBuilder();
        String line = null;
        while ((line = reader.readLine()) != null) {
            builder.append(line);
            builder.append(System.getProperty("line.separator"));
        }
        int status = process.waitFor();
        cmdResult = builder.toString() + " command status " + status;
        int exitValue = process.exitValue();            
        readProcess.destroy();
    } catch (IOException ex) {
        LOG.log(Level.SEVERE, null, ex);
    } catch (InterruptedException ex) {
        LOG.log(Level.SEVERE, null, ex);
    }

}

String logOutput;

Process readProcess;

public void readLog(OssSystem system) {

    String user = system.getUsername() + "@" + system.getIp();
    String cmd = "tail -f " + system.getLog_dir() + " | less";      
    try {
        readProcess = new ProcessBuilder().command("/usr/bin/ssh", user, cmd).start();
        int status = readProcess.waitFor();
        BufferedReader reader
                = new BufferedReader(new InputStreamReader(readProcess.getInputStream()));
        StringBuilder builder = new StringBuilder();
        String line = null;
        while ((line = reader.readLine()) != null) {
            builder.append(line);
            builder.append(System.getProperty("line.separator"));
        }
        logOutput = builder.toString() + " command status " + status;
    } catch (IOException ex) {
        Logger.getLogger(Shell.class.getName()).log(Level.SEVERE, null, ex);
    } catch (InterruptedException ex) {
        Logger.getLogger(Shell.class.getName()).log(Level.SEVERE, null, ex);
    }
}

Answer 1

根据javadoc，

如果需要，导致当前线程等待，直到进程由此Process对象表示已终止。此方法返回如果子进程已经终止，则立即执行。如果子进程尚未终止，调用线程将被阻塞直到子进程退出。

因此readProcess.waitFor();将阻塞主线程，并且在readProcess终止之前你永远不会期望调用executeBash(system);。

您可以启动一个帖子来启动readProcess。

public void performAction(OssSystem system) {
    readLog(system);
    ExecuteBashThread thread = new ExecuteBashThread(system);
    thread.start();
}

class ExecuteBashThread extends Thread{
    private OssSystem system;
    public ExecuteBashThread(OssSystem system){
        this.system = system;
    }
    @Override
    public void run(){
        executeBash(system);
    }
}

processbuilder监视远程服务器

1 个答案: