如何通過Java管道通過tee管道telnet

Question

爲什麼沒有輸出？我們的目標是要管的telnet通過tee用這個命令：

sh -c telnet rainmaker.wunderground.com 3000 | tee weather.txt

對於看到的telnet輸出和記錄與Java服務器響應的目的。 （雖然有遠程登錄庫我試圖使用該系統的telnet以exec，或類似的，而不是庫）。

命令被正確地迴盪在下面，但沒有輸出顯示：

thufir@mordor:~$ 
thufir@mordor:~$ java -jar NetBeansProjects/T/dist/T.jar 
Apr 05, 2016 4:36:56 AM net.bounceme.mordor.telnet.Main run 
INFO: starting.. 
Apr 05, 2016 4:36:56 AM net.bounceme.mordor.telnet.Telnet <init> 
INFO: connecting.. 
Apr 05, 2016 4:36:56 AM net.bounceme.mordor.telnet.PropertiesReader getConnection 
INFO: starting.. 
Apr 05, 2016 4:36:56 AM net.bounceme.mordor.telnet.PropertiesReader getConnection 
INFO: {weather.port=3000, weather.host=rainmaker.wunderground.com} 
Apr 05, 2016 4:36:56 AM net.bounceme.mordor.telnet.Telnet getAddress 
INFO: sh -c telnet rainmaker.wunderground.com 3000 | tee weather.txt 
a 
b 
c 
^CApr 05, 2016 4:37:01 AM net.bounceme.mordor.telnet.Telnet read 
SEVERE: exiting.. 130 
thufir@mordor:~$ 

而且，也沒有創建weather.txt：

thufir@mordor:~$ 
thufir@mordor:~$ nl weather.txt 
nl: weather.txt: No such file or directory 
thufir@mordor:~$ 

代碼：

package net.bounceme.mordor.telnet; 

import java.io.BufferedReader; 
import java.io.IOException; 
import java.io.InputStreamReader; 
import java.util.Properties; 
import java.util.logging.Level; 
import java.util.logging.Logger; 

public class Telnet { 

    private final static Logger LOG = Logger.getLogger(Telnet.class.getName()); 

    public Telnet() { 
     LOG.info("connecting.."); 
    } 

    private String getAddress() { 
     Properties props = PropertiesReader.getConnection(); 
     String host = props.getProperty("weather.host"); 
     String port = props.getProperty("weather.port"); 
     String tee = " | tee weather.txt"; 
     String address = "sh -c telnet " + host + " " + port + tee; 
     LOG.info(address); 
     return address; 
    } 

    private void read(Process process) throws IOException, InterruptedException { 
     BufferedReader input = new BufferedReader(new InputStreamReader(process.getInputStream())); 
     String line = null; 
     while ((line = input.readLine()) != null) { 
      System.out.println(line); 
     } 
     int exitVal = process.waitFor(); 
     LOG.log(Level.SEVERE, "exiting.. {0}", exitVal); 
    } 

    private void useProcessBuilder() throws IOException, InterruptedException { 
     LOG.info("using ProcessBuilder.."); 
     ProcessBuilder processBuilder = new ProcessBuilder("/bin/bash", "-c", getAddress()); 
     Process process = processBuilder.start(); 
     BufferedReader input = new BufferedReader(new InputStreamReader(process.getInputStream())); 
     String line = null; 
     while ((line = input.readLine()) != null) { 
      System.out.println(line); 
     } 
     int exitVal = process.waitFor(); 
     LOG.log(Level.SEVERE, "done {0}", exitVal); 
    } 

    public void tryProcessBuilder() { 
     try { 
      useProcessBuilder(); 
     } catch (IOException | InterruptedException ex) { 
      Logger.getLogger(Telnet.class.getName()).log(Level.SEVERE, null, ex); 
     } 
    } 

    private void connect() throws IOException, InterruptedException { 
     Runtime runtime = Runtime.getRuntime(); 
     Process process = runtime.exec(getAddress()); 
     read(process); 
    } 

    public void tryConnect() { 
     try { 
      connect(); 
     } catch (IOException | InterruptedException ex) { 
      Logger.getLogger(Telnet.class.getName()).log(Level.SEVERE, null, ex); 
     } 
    } 
} 

儘管可以通過將管道留給三通來生成輸出，但這並不能解決與telnet一起使用tee的問題。

也參見：

到陷阱的解決方案是簡單地通過 控制重定向從 所述的Runtime.exec（）方法單獨處理外部進程的標準輸出流。

http://www.javaworld.com/article/2071275/core-java/when-runtime-exec---won-t.html?page=2

Answer 1

能夠理解|的唯一事情是一個外殼。你需要執行一個shell來理解這個管道命令。