java输出文本文件中的变量

Question

我有一些Java代码，如下所示：

public synchronized void printLinkStatistics(Logger log)
{
    log.info("\tInput Port = " + inputPort);
    Set <Long> ts = statData.keySet();
    for(Long t: ts)
    {   double utilization = statData.get(t);
        if (utilization!=0.0) 
        {
            utilization *= 8.0;
            utilization /= 1e6;
            if (!Double.isNaN(utilization))
            {
            log.info("\t\tTimestamp = " + t + ", Utilization = " + utilization + "Mbps");

           }
        }
    }
}

这段代码将在控制台中写入利用率，但我还需要在一个文件中写入利用率+时间戳，以便将来绘制试点。 如何使用此变量创建文件？ 我在Ubuntu 12.04中使用Eclipse

伊迪丝 我正在执行此操作，但文件为空：

public synchronized void printLinkStatistics(Logger log)
{ 
    try
    {
    PrintWriter pw = new PrintWriter(new File("output.txt"));
    log.info("\tInput Port = " + inputPort);
    Set <Long> ts = statData.keySet();
    for(Long t: ts)
    {   double utilization = statData.get(t);
        if (utilization!=0.0) 
        {
            utilization *= 8.0;
            utilization /= 1e6;
            if (!Double.isNaN(utilization))
            {
            log.info("\t\tTimestamp = " + t + ", Utilization = " + utilization + "Mbps");
            pw.println("\t\tTimestamp = " + t + ", Utilization = " + utilization + "Mbps");
            }
        }
    }
    }
    catch (FileNotFoundException e) {
        e.printStackTrace(); //handle exception as you want
                                        }
}

Answer 1

您可以使用PrintWriter并将输出重定向到文件。PrintWriter有许多有用的方法，使编写输出变得更容易（有关更多信息，请阅读java文档）。例如

PrintWriter pw = new PrintWriter(new File("output.txt"));
pw.println("hello");
pw.flush();

更新后的代码如下所示

public synchronized void printLinkStatistics(Logger log, PrintWriter writer)
{
    log.info("\tInput Port = " + inputPort);
    Set <Long> ts = statData.keySet();
    for(Long t: ts)
    {   double utilization = statData.get(t);
        if (utilization!=0.0) 
        {
            utilization *= 8.0;
            utilization /= 1e6;
            if (!Double.isNaN(utilization))
            {
            log.info("\t\tTimestamp = " + t + ", Utilization = " + utilization + "Mbps");
      writer.println("\t\tTimestamp = " + t + ", Utilization = " + utilization + "Mbps");

           }
        }
    }
    writer.flush();
}

为了调用您的方法，您需要像这样将代码包装在try/catch块中

try {
    PrintWriter pw = new PrintWriter(new File("output.txt"));
    printLinkStatistics(logger, pw);
} catch (FileNotFoundException e) {
    e.printStackTrace(); //handle exception as you want
}