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歡迎跳轉到本文的原文鏈接：https://honeypps.com/network/java-udp-comm/

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經過TCP和串口通訊編程的了解，相信大家應該掌握CommBuff的套路了，這里首先展示的是通過UDP編程的方式實現CommBuff接口，之后通過簡單工廠模式的應用說明如何屏蔽底層通訊差異。

UdpImpl類如下：

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package com.zzh.comm;import java.io.IOException; import java.net.DatagramPacket; import java.net.DatagramSocket; import java.net.InetAddress; import java.net.SocketException; import java.net.UnknownHostException; import java.util.Map;import org.apache.log4j.Logger;public class UdpImpl implements CommBuff {private Logger logger = Logger.getLogger(Object.class.getName());private int local_port;private int dest_port;private String ip;private int time_out;DatagramSocket client = null;private String fileName = "/udp.properties";public UdpImpl(){Map<String,String> map = new ReadProperties().getPropertiesMap(fileName);try{local_port = Integer.parseInt(map.get("udp_local_port"));dest_port = Integer.parseInt(map.get("udp_dest_port"));time_out = Integer.parseInt(map.get("udp_timeout"));ip = map.get("udp_dest_ip");}catch (Exception e){logger.error(e.getMessage());}}@Overridepublic byte[] readBuff(){if(client == null){throw new RuntimeException("clinet is null!");}byte[] recvBuf = new byte[1024];DatagramPacket recvPacket = new DatagramPacket(recvBuf , recvBuf.length);try{client.receive(recvPacket);}catch (IOException e){logger.info(e.getMessage());return new byte[0];}byte[] ans = new byte[recvPacket.getLength()];System.arraycopy(recvPacket.getData(), 0, ans, 0, recvPacket.getLength());logger.info("網口接收："+CommUtil.bytesToHex(ans));return ans;}@Overridepublic void writeBuff(byte[] message){if(client == null){throw new RuntimeException("clinet is null!");}try{InetAddress addr = InetAddress.getByName(ip);DatagramPacket sendPacket = new DatagramPacket(message,message.length,addr,dest_port);client.send(sendPacket);logger.info("發送成功: "+CommUtil.bytesToHex(message));}catch (UnknownHostException e){logger.error(e.getMessage());}catch (IOException e){logger.error(e.getMessage());}}@Overridepublic void open() {try{client = new DatagramSocket(local_port);client.setSoTimeout(time_out);if(client != null){logger.info("client open succeed!");}}catch (SocketException e){logger.error(e.getMessage());}}@Overridepublic void close() {if(client != null){client.close();}}@Overridepublic Object getInfo(){return null;}}

UdpImpl實現了CommBuff接口的各個方法。UDP Socket采用的數據包的方式進行通訊的，這個可以與TCP的方式區分開。

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下面通過一個簡單工廠模式，可以實現底層通訊的便利性。

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package com.zzh.comm;public class CommFactory {public CommBuff getCommBuff(String properties) throws Exception{if(properties.equals("comm_serial")){return new SerialImpl();}else if(properties.equals("comm_tcpServer")){return new TcpServerImpl();}else if(properties.equals("comm_tcpClient")){return new TcpClientImpl();}else if(properties.equals("comm_udp")){return new UdpImpl();}else{throw new Exception("Communication para error: no found avaliable communication Object instance.");}} }

上面的getCommBuff方法通過參數properties可以初始化不同的通訊接口實現類，這樣上次應用只需調用Commbuff接口的方法，而無需與底層通訊的細節相融合，極大的降低了程序間的耦合性。

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本篇就簡單的闡述到這里。但是下面會附加一個程序，這個程序通過調用CommFactory的方法生成底層通訊的實例，程序的主要內容是電力行業的某個通訊規約（Modbus）的實現，如果非電力行業的通訊，可以不必了解程序中的細節，可以大概看一下怎么使用.

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package com.zzh.protocol;import java.util.Calendar; import java.util.Map; import java.util.concurrent.ConcurrentLinkedDeque; import java.util.concurrent.ExecutorService; import java.util.concurrent.Executors; import java.util.concurrent.TimeUnit;import com.zzh.comm.CommBuff; import com.zzh.comm.CommFactory; import com.zzh.comm.CommUtil; import com.zzh.comm.ReadProperties; import com.zzh.dao.ModbusDao; import com.zzh.dao.ModbusDaoImpl; import com.zzh.dao.pojo.ModbusPojo;public class Modbus {private CommBuff comm;private int comm_timeout;private byte devAddr;private static int RECV_SIZE = 35;private static int RECV_INNER_SIZE = 30;private static int MINUTE=60000;private volatile boolean refreshFlag = false;private ModbusPojo modbusPojo; private ConcurrentLinkedDeque<Byte> deque = new ConcurrentLinkedDeque<Byte>();private String fileName = "/modbus.properties";public Modbus(){Map<String,String> map = new ReadProperties().getPropertiesMap(fileName);String comm_way = map.get("modbus_comm_way");String comm_timeouts = map.get("comm_timeout");comm_timeout = Integer.parseInt(comm_timeouts);String devAddrs = map.get("devAddr");devAddr = Byte.parseByte(devAddrs);if(comm_way!=null){modbusPojo = new ModbusPojo(); try{comm = new CommFactory().getCommBuff(comm_way);}catch (Exception e){e.printStackTrace();}comm.open();ExecutorService pool = Executors.newFixedThreadPool(2);Thread thread1 = new Thread(new readThread());thread1.setDaemon(true);Thread thread2 = new Thread(new dbThread());thread2.setDaemon(true);pool.execute(thread1);pool.execute(thread2);}else{throw new RuntimeException("沒有配置好合適的串口參數");}}private class readThread implements Runnable{@Overridepublic void run(){while(true){byte[] recvBuff = comm.readBuff();if(recvBuff.length>0){for(int i=0;i<recvBuff.length;i++){deque.add(recvBuff[i]);}}try{TimeUnit.MILLISECONDS.sleep(1000);}catch (InterruptedException e){e.printStackTrace();}}}}private class dbThread implements Runnable{@Overridepublic void run(){while(true){if(refreshFlag == true){Calendar now = Calendar.getInstance();if(now.get(Calendar.MINUTE)%5==0) // if(true){synchronized (modbusPojo){filterModbusPojo();modbusPojo.setNow(TimeUtil.getDateOfMM(now)); // modbusPojo.setNow(new java.sql.Timestamp(new Date().getTime()));ModbusDao md = new ModbusDaoImpl();md.addModbus(modbusPojo);}}}try{TimeUnit.MILLISECONDS.sleep(MINUTE); // TimeUnit.MILLISECONDS.sleep(1000);}catch (InterruptedException e){e.printStackTrace();}}}}public void filterModbusPojo(){modbusPojo.setQua(0);if(modbusPojo.getEnvTemperature()>ModbusUtil.TEMPERATURE_UP){modbusPojo.setEnvTemperature(ModbusUtil.TEMPERATURE_UP);System.out.println("getEnvTemperature = "+modbusPojo.getEnvTemperature());modbusPojo.setQua(1);}if(modbusPojo.getEnvTemperature()<ModbusUtil.TEMPERATURE_LOW){modbusPojo.setEnvTemperature(ModbusUtil.TEMPERATURE_LOW);System.out.println("getEnvTemperature = "+modbusPojo.getEnvTemperature());modbusPojo.setQua(1);}if(modbusPojo.getTemperature()>ModbusUtil.TEMPERATURE_UP){modbusPojo.setTemperature(ModbusUtil.TEMPERATURE_UP);System.out.println("getTemperature = "+modbusPojo.getTemperature());modbusPojo.setQua(1);}if(modbusPojo.getTemperature()<ModbusUtil.TEMPERATURE_LOW){modbusPojo.setTemperature(ModbusUtil.TEMPERATURE_LOW);System.out.println("getTemperature = "+modbusPojo.getTemperature());modbusPojo.setQua(1);}if(modbusPojo.getHumidity()>ModbusUtil.HUMIDITY_UP){modbusPojo.setHumidity(ModbusUtil.HUMIDITY_UP);System.out.println("getHumidity = "+modbusPojo.getHumidity());modbusPojo.setQua(1);}if(modbusPojo.getHumidity()<ModbusUtil.HUMIDITY_LOW){modbusPojo.setHumidity(ModbusUtil.HUMIDITY_LOW);System.out.println("getHumidity = "+modbusPojo.getHumidity());modbusPojo.setQua(1);}if(modbusPojo.getPressure()>ModbusUtil.PRESSURE_UP){modbusPojo.setPressure(ModbusUtil.PRESSURE_UP);System.out.println("getPressure = "+modbusPojo.getPressure());modbusPojo.setQua(1);}if(modbusPojo.getPressure()<ModbusUtil.PRESSURE_LOW){modbusPojo.setPressure(ModbusUtil.PRESSURE_LOW);System.out.println("getPressure = "+modbusPojo.getPressure());modbusPojo.setQua(1);}if(modbusPojo.getIrradiance()>ModbusUtil.IRRADIANCE_UP){modbusPojo.setIrradiance(ModbusUtil.IRRADIANCE_UP);System.out.println("getIrradiance = "+modbusPojo.getIrradiance());modbusPojo.setQua(1);}if(modbusPojo.getIrradiance()<ModbusUtil.IRRADIANCE_LOW){modbusPojo.setIrradiance(ModbusUtil.IRRADIANCE_LOW);System.out.println("getIrradiance = "+modbusPojo.getIrradiance());modbusPojo.setQua(1);}if(modbusPojo.getScaIrradiance()>ModbusUtil.IRRADIANCE_UP){modbusPojo.setScaIrradiance(ModbusUtil.IRRADIANCE_UP);System.out.println("getScaIrradiance = "+modbusPojo.getScaIrradiance());modbusPojo.setQua(1);}if(modbusPojo.getScaIrradiance()<ModbusUtil.IRRADIANCE_LOW){modbusPojo.setScaIrradiance(ModbusUtil.IRRADIANCE_LOW);System.out.println("getScaIrradiance = "+modbusPojo.getScaIrradiance());modbusPojo.setQua(1);}if(modbusPojo.getDirIrradiance()>ModbusUtil.IRRADIANCE_UP){modbusPojo.setDirIrradiance(ModbusUtil.IRRADIANCE_UP);System.out.println("getDirIrradiance = "+modbusPojo.getDirIrradiance());modbusPojo.setQua(1);}if(modbusPojo.getDirIrradiance()<ModbusUtil.IRRADIANCE_LOW){modbusPojo.setDirIrradiance(ModbusUtil.IRRADIANCE_LOW);System.out.println("getDirIrradiance = "+modbusPojo.getDirIrradiance());modbusPojo.setQua(1);}if(modbusPojo.getWindSpeed()>ModbusUtil.UAVG_UP){modbusPojo.setWindSpeed(ModbusUtil.UAVG_UP);System.out.println("getWindSpeed = "+modbusPojo.getWindSpeed());modbusPojo.setQua(1);}if(modbusPojo.getWindSpeed()<ModbusUtil.UAVG_LOW){modbusPojo.setWindSpeed(ModbusUtil.UAVG_LOW);System.out.println("getWindSpeed = "+modbusPojo.getWindSpeed());modbusPojo.setQua(1);}if(modbusPojo.getWindDir()>ModbusUtil.VAVG_UP){modbusPojo.setWindDir(ModbusUtil.VAVG_UP);System.out.println("getWindDir = "+modbusPojo.getWindDir());modbusPojo.setQua(1);}if(modbusPojo.getWindDir()<ModbusUtil.VAVG_LOW){modbusPojo.setWindDir(ModbusUtil.VAVG_LOW);System.out.println("getWindDir = "+modbusPojo.getWindDir());modbusPojo.setQua(1);}}public void process(){try{TimeUnit.MILLISECONDS.sleep(comm_timeout);}catch (InterruptedException e){e.printStackTrace();}recvProcess();sendProcess();}public void recvProcess(){refreshFlag = false;byte[] recvBuff = new byte[RECV_INNER_SIZE];while(deque.size()>=RECV_SIZE){Byte first = deque.pollFirst();if(first == devAddr){Byte second = deque.pollFirst();if(second == 0x03){Byte third = deque.pollFirst();if(third == RECV_INNER_SIZE){for(int i=0;i<RECV_INNER_SIZE;i++){recvBuff[i] = deque.pollFirst();}deque.pollFirst();deque.pollFirst();dealRecvBuff(recvBuff);}}}}}public void dealRecvBuff(byte[] recvBuff){System.out.println(CommUtil.bytesToHex(recvBuff));refreshFlag = true;getModbusPojo(recvBuff); // modbusPojo.print();}public void getModbusPojo(byte[] recvBuff){int temp;synchronized (modbusPojo){for(int i=0;i<recvBuff.length;){switch(i){case 0:temp = ModbusUtil.getSignedAns(recvBuff, 0, 1);double envTemperature = temp*0.1;modbusPojo.setEnvTemperature(envTemperature);break;case 2:temp = ModbusUtil.getSignedAns(recvBuff, 2, 3);double temperature = temp*0.1;modbusPojo.setTemperature(temperature);break;case 4:temp = ModbusUtil.getUnsignedAns(recvBuff, 4, 5);double humidity = temp*0.1;modbusPojo.setHumidity(humidity);break;case 6:temp = ModbusUtil.getUnsignedAns(recvBuff, 6, 7);double pressure = temp*0.1;modbusPojo.setPressure(pressure);break;case 8:temp = ModbusUtil.getUnsignedAns(recvBuff, 8, 9);modbusPojo.setIrradiance(temp);break;case 10:temp = ModbusUtil.getUnsignedAns(recvBuff, 10, 11);modbusPojo.setScaIrradiance(temp);break;case 12:temp = ModbusUtil.getUnsignedAns(recvBuff, 12, 13);modbusPojo.setDirIrradiance(temp);break;case 14:temp = ModbusUtil.getUnsignedAns(recvBuff, 14, 15);modbusPojo.setWindDir(temp);break;case 16:temp = ModbusUtil.getUnsignedAns(recvBuff, 16, 17);double windSpeed = temp*0.1;modbusPojo.setWindSpeed(windSpeed);break;case 18:temp = ModbusUtil.getUnsignedAns(recvBuff, 18, 19);double windSpeedTwo = temp*0.1;modbusPojo.setWindSpeedTwo(windSpeedTwo);break;case 20:temp = ModbusUtil.getUnsignedAns(recvBuff, 20, 21);double windSpeedTen = temp*0.1;modbusPojo.setWindSpeedTen(windSpeedTen);break;case 22:temp = ModbusUtil.getUnsignedAns(recvBuff, 22, 23);modbusPojo.setDailyExposure(temp);break;case 24:temp = ModbusUtil.getUnsignedAns(recvBuff, 24, 25);double totalExposure = temp*0.001;modbusPojo.setTotalExposure(totalExposure);break;case 26:temp = ModbusUtil.getUnsignedAns(recvBuff, 26, 27);double scaExposure = temp*0.001;modbusPojo.setScaExposure(scaExposure);break;case 28:temp = ModbusUtil.getUnsignedAns(recvBuff, 28, 29);double dirExposure = temp*0.001;modbusPojo.setDirExposure(dirExposure);break;}i=i+2;}}}public void sendProcess(){byte[] message = new byte[8];int sendLen = 0;message[sendLen++] = devAddr;message[sendLen++] = 0x03;message[sendLen++] = 0x00;message[sendLen++] = 0x00;message[sendLen++] = 0x00;message[sendLen++] = 0x0F;byte[] crc = CommUtil.CRC16(message,6);message[sendLen++] = crc[0];message[sendLen++] = crc[1];comm.writeBuff(message);}}

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歡迎跳轉到本文的原文鏈接：https://honeypps.com/network/java-udp-comm/

歡迎支持筆者新作：《深入理解Kafka:核心設計與實踐原理》和《RabbitMQ實戰指南》，同時歡迎關注筆者的微信公眾號：朱小廝的博客。

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