打印BufferedReader返回的多行

Question

我正在编写一个程序,它基本上通过java发送linux命令,然后打印输出.如果输出只有一行但是多行输出我无法弄清楚我做错了什么,它工作正常.例如,要检查内存使用情况,我使用"free"命令,但它只返回第1行和第3行.这是我的代码:

if (clinetChoice.equals("3"))
    {
        String command = "free";

        Process process = Runtime.getRuntime().exec(command);

        BufferedReader reader = new BufferedReader(new InputStreamReader(process.getInputStream()));

        System.out.println("You Chose Option Three");

        String line;            

        while ((line = reader.readLine()) != null)
        {
            output += line;
            System.out.println(line);
            line = reader.readLine();
        }

    }

当我运行它时它只返回:

total  used  free  share  buffers  cached
-/+ buffers/cache:  6546546  65464645

客户代码:

while ((fromServer = input.readLine()) != null)
    {
        System.out.println("Server: " + fromServer);            
        if (fromServer.equals("Bye"))
            break;          

        System.out.print("Enter your choice: ");
        fromClient = stdIn.readLine().trim();

        if(fromClient.equals("1"))
        {
            System.out.println("Client: " + fromClient);
            output.println(fromClient);

        }
        if(fromClient.equals("2"))
        {
            System.out.println("Client: " + fromClient);
            output.println(fromClient);

        }
        if(fromClient.equals("3"))
        {
            System.out.println("Client: " + fromClient);
            output.println(fromClient);

        }
        if(fromClient.equals("4"))
        {
            System.out.println("Client: " + fromClient);
            output.println(fromClient);
            break;

        }


    }

Answer 1

你正在调用readLine循环测试和循环体.因此,对于循环的每次迭代,readLine都会调用两次,并且其中一个结果将被丢弃:它不会被打印或添加到output.这与您描述的结果相匹配.

这个循环应该足够了:

while ((line = reader.readLine()) != null)
{
    output += line + System.getProperty("line.separator");
    System.out.println(line);
}

如果您只是尝试打印整个输出一次,并且因为您在output变量中收集输出,则可以移出println循环:

while ((line = reader.readLine()) != null)
{
    output += line + System.getProperty("line.separator");
}

System.out.println(output);