put process handling in separate class

.gitignore

@@ -0,0 +1,4 @@
+target/
+*~
+.*~
+

src/main/java/de/hottis/mbusMaster/MbusMaster.java

@@ -1,10 +1,5 @@
 package de.hottis.mbusMaster;
 
-import java.io.FileInputStream;
-import java.io.InputStream;
-import java.io.OutputStream;
-import java.io.InputStreamReader;
-import java.io.BufferedReader;
 import java.util.Properties;
 
 import org.apache.logging.log4j.LogManager;
@@ -27,40 +22,20 @@ public class MbusMaster {
 		logger.debug("Configuration loaded");
 		*/
 
-		ProcessBuilder pb = new ProcessBuilder("/usr/local/bin/mbusgw", "-l", "-v");
+		MbusgwChild mbusgw = new MbusgwChild(true);
-		pb.redirectError(ProcessBuilder.Redirect.INHERIT);
+		mbusgw.start();
-		Process p = pb.start();
-		System.out.println("Process started");
 
 
+		mbusgw.sendRequest((byte)0x5b, (byte)80);
 
-		InputStream i = p.getInputStream();
+		byte[] frame = mbusgw.collectResponse();
-		OutputStream o = p.getOutputStream();
-		System.out.println("Streams collected");
-
-		byte[] b = { 0x5b, 80 };
-
-		o.write(b);
-		System.out.println("Data written");
-
-		o.flush();
-		System.out.println("Data flushed");
-
-
-		byte[] header = new byte[2];
-		int n = i.read(header, 0, 2);
-		int responseCode = Byte.toUnsignedInt(header[0]);
-		int responseLen = Byte.toUnsignedInt(header[1]);
-		System.out.println("n: " + n + ", h: " + responseCode + ", l: " + responseLen);
-
-		byte[] frame = new byte[responseLen];
-		n = i.read(frame, 0, responseLen);
 		for (byte x : frame) {
 			System.out.print(Integer.toHexString(Byte.toUnsignedInt(x)) + " ");
 		}
 		System.out.println();
 
-
+		System.out.println("Stopping mbusgw process");
+		mbusgw.stop();
 
 	}		
 }

src/main/java/de/hottis/mbusMaster/MbusgwChild.java

@@ -0,0 +1,100 @@
+package de.hottis.mbusMaster;
+
+import java.io.FileInputStream;
+import java.io.InputStream;
+import java.io.OutputStream;
+import java.io.InputStreamReader;
+import java.io.BufferedReader;
+import java.io.IOException;
+
+import java.util.Properties;
+
+import org.apache.logging.log4j.LogManager;
+import org.apache.logging.log4j.Logger;
+
+
+public class MbusgwChild {
+	static final Logger logger = LogManager.getRootLogger();
+
+
+  private Process mbusgwProcess;
+  private InputStream processInput;
+  private OutputStream processOutput;
+  private boolean verbose;
+  private Thread stderrToLog;
+
+
+  public MbusgwChild(boolean verbose) {
+    this.verbose = verbose;
+  }
+	
+	public void start() throws IOException {
+		logger.info("InterfaceChild starting");
+
+		ProcessBuilder pb = new ProcessBuilder("/usr/local/bin/mbusgw", "-l", "-v");
+		this.mbusgwProcess = pb.start();
+		logger.debug("Process started");
+
+		this.processInput = this.mbusgwProcess.getInputStream();
+		InputStream processError = this.mbusgwProcess.getErrorStream();
+		this.processOutput = this.mbusgwProcess.getOutputStream();
+		logger.debug("Streams collected");
+
+		BufferedReader br = new BufferedReader(new InputStreamReader(processError));
+
+		this.stderrToLog = new Thread(() -> {
+			String line;
+			try {
+				while ((line = br.readLine()) != null) {
+					logger.debug(line);
+				}
+			} catch (IOException ex) {
+				logger.debug("exception caught: " + ex.getMessage());
+			}
+		}, "stderrToLog");
+		stderrToLog.start();
+    logger.debug("stderrToLog thread started");
+  }
+
+  public void stop() throws InterruptedException {
+    logger.info("About to stop mbusgw child process");
+    this.mbusgwProcess.destroy();
+    this.mbusgwProcess.waitFor();
+    logger.info("Process stopped");
+
+    logger.info("About to stop stderrToLog thread");
+    this.stderrToLog.interrupt();
+    this.stderrToLog.join();
+    logger.info("Thread joined");
+  }
+
+  public InputStream getProcessInputStream() {
+    return this.processInput;
+  }
+
+  public OutputStream getProcessOutputStream() {
+    return this.processOutput;
+  }
+
+  public void sendRequest(byte cmd, byte addr) throws IOException {
+		byte[] b = { cmd, addr };
+
+		this.processOutput.write(b);
+		logger.debug("Request written");
+
+		this.processOutput.flush();
+		logger.debug("Request flushed");
+  }
+
+  public byte[] collectResponse() throws IOException {
+		byte[] header = new byte[2];
+		int n = this.processInput.read(header, 0, 2);
+		int responseCode = Byte.toUnsignedInt(header[0]);
+    int responseLen = Byte.toUnsignedInt(header[1]);
+    logger.debug("n: " + n + ", h: " + responseCode + ", l: " + responseLen);
+		byte[] frame = new byte[responseLen];
+    n = this.processInput.read(frame, 0, responseLen);
+    logger.debug("frame completely read");
+    return frame;
+  }
+}

src/main/resources/log4j2.xml

@@ -1,5 +1,5 @@
 <?xml version="1.0" encoding="UTF-8"?>
-<Configuration debug="false">
+<Configuration debug="true">
   <Appenders>
     <Console name="ConsoleAppender" target="SYSTEM_OUT">
       <PatternLayout pattern="%d [%t, %F, %L] %-5level - %msg%n%throwable"/>