java - Java 中的 awk 命令

Question

我想在 Java 中使用 awk 命令行。为此，我有这段代码(我在教程中看到了这段代码):

Map map = new HashMap();
map.put("file", new File(fileDirectory)); 

CommandLine cmdLine = new CommandLine("awk"); 
cmdLine.addArgument("{print $1}", false); 
cmdLine.addArgument("${file}"); 
cmdLine.setSubstitutionMap(map);
System.out.println(cmdLine.toString()); 

DefaultExecuteResultHandler resultHandler = new   DefaultExecuteResultHandler();  
ExecuteWatchdog watchdog = new ExecuteWatchdog(10000); 
DefaultExecutor executor = new DefaultExecutor(); 
executor.setWatchdog(watchdog); 
executor.execute(cmdLine, resultHandler); 

resultHandler.waitFor(); 

在此示例中，我的代码打印文件的第一列。

10
10
10
10
10
10
10
10
10
10
10
10
10
10
10

我想将输出打印到文件中，但我无法弄清楚。

Answer 1

通常，要在 Java 中以编程方式运行 awk 命令，您可以使用 Jawk 。我被要求自己 build 它，但没什么大不了的。我已经使用 1.03 版本进行了测试，以编程方式调用 awk 命令，如下所示，适合我的用例。

            String[] awkArgs= { "-f", awkProgramPath };
            // Create a stream to hold the output
            ByteArrayOutputStream baos = new ByteArrayOutputStream();
            PrintStream ps = new PrintStream(baos);
            // Tell Java to use your byte arrya output stream temporarily
            System.setOut(ps);

            AwkParameters parameters = new AwkParameters(Main.class, null);
            AwkSettings settings = parameters.parseCommandLineArguments(awkArgs);

            //Instead of passing file as argument setting the file content as input. 
            //This is done to adapt the line delimiters in file content to the specific OS. Otherwise Jawk fails in splitting the lines.
            //If it is not required, this step cab be skipped and the input file path can be passed as additional argument
            String inputFileContent = new String(Files.readAllBytes(inputFile.toPath())); 
            //Adapting line delimiter.
            inputFileContent = inputFileContent.replaceAll("[\r]?\n", System.getProperty("line.separator"));
            settings.setInput(new ByteArrayInputStream(inputFileContent.getBytes()));

            //Invoking the awk command
            Awk awk = new Awk();
            awk.invoke(settings);
            //Set the old print stream back. May be you can do it in try..finally block to be failsafe.
            System.setOut(sysout);
            //Get the output from byte array output stream
            String output = baos.toString();

您可能需要在类路径中添加 slf4j.jar，这是 jamk.jar 内部所需的。