大家好，又见面了，我是你们的朋友全栈君。
对以下demo进行了扩展，增了消息循环和等待。
Java中的DatagramPacket与DatagramSocket的初步
扩展的代码如下：
1.接收端工程代码：
由于接收端的控制台log会被发送端的log冲掉，所以把log写到文件中。
package com.ameyume.receiver;
import java.io.File;
import java.io.FileNotFoundException;
import java.io.FileWriter;
import java.io.IOException;
import java.net.DatagramPacket;
import java.net.DatagramSocket;
import java.net.InetAddress;
import java.net.SocketAddress;
import java.text.SimpleDateFormat;
import java.util.Date;
public class Receiver {
private static final String LOG_FILE_NAME = "receiver.txt";
public static void main(String[] args) {
// TODO Auto-generated method stub
// 先删除旧的log文件
File f = new File(LOG_FILE_NAME);
if (f.exists()) {
f.delete();
}
System.out.println(getDateString() + " Receiver main BEGIN >>>>>>\n");
LogToFile("Receiver main BEGIN >>>>>>\n");
try {
// 确定接受方的IP和端口号，IP地址为本地机器地址
InetAddress ip = InetAddress.getLocalHost();
int port = 12365;
for(int i = 0; i < 5; i++) {
// 创建接收方的套接字,并指定端口号和IP地址
DatagramSocket getSocket = new DatagramSocket(port, ip);
// 确定数据报接受的数据的数组大小
byte[] buf = new byte[1024];
// 创建接受类型的数据报，数据将存储在buf中
DatagramPacket getPacket = new DatagramPacket(buf, buf.length);
// 通过套接字接收数据, 此方法是阻塞的，会一直等待消息
System.out.println(getDateString() + " Receiver begin receive message ...");
LogToFile("Receiver begin receive message ...");
getSocket.receive(getPacket);
System.out.println(getDateString() + " Receiver end receive message ...");
LogToFile("Receiver end receive message ...");
// 解析发送方传递的消息，并打印
String getMes = new String(buf, 0, getPacket.getLength());
System.out.println(getDateString() + " Receiver 对方发送的消息：" + getMes);
LogToFile("Receiver 对方发送的消息：" + getMes);
// 通过数据报得到发送方的IP和端口号，并打印
InetAddress sendIP = getPacket.getAddress();
int sendPort = getPacket.getPort();
System.out.println(getDateString() + " Receiver 对方的IP地址是：" + sendIP.getHostAddress());
LogToFile("Receiver 对方的IP地址是：" + sendIP.getHostAddress());
System.out.println(getDateString() + " Receiver 对方的端口号是：" + sendPort);
LogToFile("Receiver 对方的端口号是：" + sendPort + '\n');
// 通过数据报得到发送方的套接字地址
SocketAddress sendAddress = getPacket.getSocketAddress();
// 确定要反馈发送方的消息内容，并转换为字节数组
String feedback = "接收方说：我收到了消息【" + getMes + "】";
byte[] backBuf = feedback.getBytes();
// 创建发送类型的数据报
DatagramPacket sendPacket = new DatagramPacket(backBuf, backBuf.length, sendAddress);
// 通过套接字发送数据
getSocket.send(sendPacket);
// 关闭套接字
getSocket.close();
}
} catch (Exception e) {
e.printStackTrace();
}
System.out.println(getDateString() + " Receiver main END <<<<<<");
LogToFile("Receiver main END <<<<<<");
}
public static String getDateString() {
SimpleDateFormat df = new SimpleDateFormat("MM-dd HH:mm:ss.SSS"); // 设置日期格式
return df.format(new Date()); // new Date()为获取当前系统时间
}
public static void LogToFile(String log) {
File sdFile = new File(LOG_FILE_NAME);
try {
FileWriter fw = new FileWriter(sdFile, true);
fw.write(getDateString() + " " + log + '\n');
fw.close();
} catch (FileNotFoundException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
}
}
}
package com.ameyume.receiver;
import java.io.File;
import java.io.FileNotFoundException;
import java.io.FileWriter;
import java.io.IOException;
import java.net.DatagramPacket;
import java.net.DatagramSocket;
import java.net.InetAddress;
import java.net.SocketAddress;
import java.text.SimpleDateFormat;
import java.util.Date;
public class Receiver {
private static final String LOG_FILE_NAME = "receiver.txt";
public static void main(String[] args) {
// TODO Auto-generated method stub
// 先删除旧的log文件
File f = new File(LOG_FILE_NAME);
if (f.exists()) {
f.delete();
}
System.out.println(getDateString() + " Receiver main BEGIN >>>>>>\n");
LogToFile("Receiver main BEGIN >>>>>>\n");
try {
// 确定接受方的IP和端口号，IP地址为本地机器地址
InetAddress ip = InetAddress.getLocalHost();
int port = 12365;
for(int i = 0; i < 5; i++) {
// 创建接收方的套接字,并指定端口号和IP地址
DatagramSocket getSocket = new DatagramSocket(port, ip);
// 确定数据报接受的数据的数组大小
byte[] buf = new byte[1024];
// 创建接受类型的数据报，数据将存储在buf中
DatagramPacket getPacket = new DatagramPacket(buf, buf.length);
// 通过套接字接收数据, 此方法是阻塞的，会一直等待消息
System.out.println(getDateString() + " Receiver begin receive message ...");
LogToFile("Receiver begin receive message ...");
getSocket.receive(getPacket);
System.out.println(getDateString() + " Receiver end receive message ...");
LogToFile("Receiver end receive message ...");
// 解析发送方传递的消息，并打印
String getMes = new String(buf, 0, getPacket.getLength());
System.out.println(getDateString() + " Receiver 对方发送的消息：" + getMes);
LogToFile("Receiver 对方发送的消息：" + getMes);
// 通过数据报得到发送方的IP和端口号，并打印
InetAddress sendIP = getPacket.getAddress();
int sendPort = getPacket.getPort();
System.out.println(getDateString() + " Receiver 对方的IP地址是：" + sendIP.getHostAddress());
LogToFile("Receiver 对方的IP地址是：" + sendIP.getHostAddress());
System.out.println(getDateString() + " Receiver 对方的端口号是：" + sendPort);
LogToFile("Receiver 对方的端口号是：" + sendPort + '\n');
// 通过数据报得到发送方的套接字地址
SocketAddress sendAddress = getPacket.getSocketAddress();
// 确定要反馈发送方的消息内容，并转换为字节数组
String feedback = "接收方说：我收到了消息【" + getMes + "】";
byte[] backBuf = feedback.getBytes();
// 创建发送类型的数据报
DatagramPacket sendPacket = new DatagramPacket(backBuf, backBuf.length, sendAddress);
// 通过套接字发送数据
getSocket.send(sendPacket);
// 关闭套接字
getSocket.close();
}
} catch (Exception e) {
e.printStackTrace();
}
System.out.println(getDateString() + " Receiver main END <<<<<<");
LogToFile("Receiver main END <<<<<<");
}
public static String getDateString() {
SimpleDateFormat df = new SimpleDateFormat("MM-dd HH:mm:ss.SSS"); // 设置日期格式
return df.format(new Date()); // new Date()为获取当前系统时间
}
public static void LogToFile(String log) {
File sdFile = new File(LOG_FILE_NAME);
try {
FileWriter fw = new FileWriter(sdFile, true);
fw.write(getDateString() + " " + log + '\n');
fw.close();
} catch (FileNotFoundException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
}
}
}
2.发送端工程代码：
package com.ameyume.sender;
import java.io.File;
import java.io.FileNotFoundException;
import java.io.FileWriter;
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.text.SimpleDateFormat;
import java.util.Date;
public class Sender {
private static final String LOG_FILE_NAME = "sender.txt";
public static void main(String[] args) {
// TODO Auto-generated method stub
// 先删除旧的log文件
File f = new File(LOG_FILE_NAME);
if (f.exists()) {
f.delete();
}
System.out.println(getDateString() + " Sender main BEGIN >>>>>>\n");
LogToFile("Sender main BEGIN >>>>>>\n");
try {
// 创建发送方的套接字，IP默认为本地，不指定端口号则系统随机设置一个可用的端口号
DatagramSocket sendSocket = new DatagramSocket(/*12341*/);
for (int i = 0; i < 5; i++) {
// 确定要发送的内容
String msg = "你好，接收方：" + i;
// 由于数据报的数据是以字节数组的形式存储的，所以转为转换数据
byte[] buffer = msg.getBytes();
// 确定发送方的IP地址及端口号，地址为本地机器地址
int port = 12365;
InetAddress ip = InetAddress.getLocalHost();
// 创建发送类型的数据库
// 构造数据报包，用来将长度为 length 的包发送到指定主机上的指定端口号
DatagramPacket sendPacket = new DatagramPacket(buffer, buffer.length, ip, port);
// 通过套接字发送数据
System.out.println(getDateString() + " Sender send packet ..");
LogToFile("Sender send packet ..");
sendSocket.send(sendPacket);
// 确定接收反馈数据的缓冲存储器，即存储数据的字节数组
byte[] getBuffer = new byte[1024];
// 确定接收类型的数据报
DatagramPacket getPacket = new DatagramPacket(getBuffer, getBuffer.length);
// 通过套接字接收数据
System.out.println(getDateString() + " Sender receive packet ...");
LogToFile("Sender receive packet ...");
sendSocket.receive(getPacket);
// 解析反馈的消息，并输出
String backMsg = new String(getBuffer, 0, getPacket.getLength());
System.out.println(getDateString() + " Sender 接收方返回的消息：" + backMsg);
LogToFile("Sender 接收方返回的消息：" + backMsg);
System.out.println(getDateString() + " Sender waiting 5s ...\n");
LogToFile("Sender waiting 5s ...\n");
Thread.sleep(5000);
}
// 关闭套接字
sendSocket.close();
} catch (SocketException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} catch (UnknownHostException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} catch (InterruptedException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
System.out.println(getDateString() + " Sender main END <<<<<<");
LogToFile("Sender main END <<<<<<");
}
public static String getDateString() {
SimpleDateFormat df = new SimpleDateFormat("MM-dd HH:mm:ss.SSS"); // 设置日期格式
return df.format(new Date()); // new Date()为获取当前系统时间
}
public static void LogToFile(String log) {
File file = new File(LOG_FILE_NAME);
try {
FileWriter fw = new FileWriter(file, true);
fw.write(getDateString() + " " + log + '\n');
fw.close();
} catch (FileNotFoundException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
}
}
}
package com.ameyume.sender;
import java.io.File;
import java.io.FileNotFoundException;
import java.io.FileWriter;
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.text.SimpleDateFormat;
import java.util.Date;
public class Sender {
private static final String LOG_FILE_NAME = "sender.txt";
public static void main(String[] args) {
// TODO Auto-generated method stub
// 先删除旧的log文件
File f = new File(LOG_FILE_NAME);
if (f.exists()) {
f.delete();
}
System.out.println(getDateString() + " Sender main BEGIN >>>>>>\n");
LogToFile("Sender main BEGIN >>>>>>\n");
try {
// 创建发送方的套接字，IP默认为本地，不指定端口号则系统随机设置一个可用的端口号
DatagramSocket sendSocket = new DatagramSocket(/*12341*/);
for (int i = 0; i < 5; i++) {
// 确定要发送的内容
String msg = "你好，接收方：" + i;
// 由于数据报的数据是以字节数组的形式存储的，所以转为转换数据
byte[] buffer = msg.getBytes();
// 确定发送方的IP地址及端口号，地址为本地机器地址
int port = 12365;
InetAddress ip = InetAddress.getLocalHost();
// 创建发送类型的数据库
// 构造数据报包，用来将长度为 length 的包发送到指定主机上的指定端口号
DatagramPacket sendPacket = new DatagramPacket(buffer, buffer.length, ip, port);
// 通过套接字发送数据
System.out.println(getDateString() + " Sender send packet ..");
LogToFile("Sender send packet ..");
sendSocket.send(sendPacket);
// 确定接收反馈数据的缓冲存储器，即存储数据的字节数组
byte[] getBuffer = new byte[1024];
// 确定接收类型的数据报
DatagramPacket getPacket = new DatagramPacket(getBuffer, getBuffer.length);
// 通过套接字接收数据
System.out.println(getDateString() + " Sender receive packet ...");
LogToFile("Sender receive packet ...");
sendSocket.receive(getPacket);
// 解析反馈的消息，并输出
String backMsg = new String(getBuffer, 0, getPacket.getLength());
System.out.println(getDateString() + " Sender 接收方返回的消息：" + backMsg);
LogToFile("Sender 接收方返回的消息：" + backMsg);
System.out.println(getDateString() + " Sender waiting 5s ...\n");
LogToFile("Sender waiting 5s ...\n");
Thread.sleep(5000);
}
// 关闭套接字
sendSocket.close();
} catch (SocketException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} catch (UnknownHostException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} catch (InterruptedException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
System.out.println(getDateString() + " Sender main END <<<<<<");
LogToFile("Sender main END <<<<<<");
}
public static String getDateString() {
SimpleDateFormat df = new SimpleDateFormat("MM-dd HH:mm:ss.SSS"); // 设置日期格式
return df.format(new Date()); // new Date()为获取当前系统时间
}
public static void LogToFile(String log) {
File file = new File(LOG_FILE_NAME);
try {
FileWriter fw = new FileWriter(file, true);
fw.write(getDateString() + " " + log + '\n');
fw.close();
} catch (FileNotFoundException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
}
}
}
3.
先运行Receiver工程，正在阻塞等待接收发送方发送的消息，总共接收到了5个消息，每个消息间隔5秒钟
log输出如下：
05-19 12:10:13.115 Receiver main BEGIN >>>>>>
05-19 12:10:13.119 Receiver begin receive message …
05-19 12:10:18.886 Receiver end receive message …
05-19 12:10:18.886 Receiver 对方发送的消息：你好，接收方：0
05-19 12:10:18.887 Receiver 对方的IP地址是：127.0.0.1
05-19 12:10:18.887 Receiver 对方的端口号是：50312
05-19 12:10:18.887 Receiver begin receive message …
05-19 12:10:23.890 Receiver end receive message …
05-19 12:10:23.891 Receiver 对方发送的消息：你好，接收方：1
05-19 12:10:23.891 Receiver 对方的IP地址是：127.0.0.1
05-19 12:10:23.892 Receiver 对方的端口号是：50312
05-19 12:10:23.893 Receiver begin receive message …
05-19 12:10:28.896 Receiver end receive message …
05-19 12:10:28.897 Receiver 对方发送的消息：你好，接收方：2
05-19 12:10:28.898 Receiver 对方的IP地址是：127.0.0.1
05-19 12:10:28.902 Receiver 对方的端口号是：50312
05-19 12:10:28.903 Receiver begin receive message …
05-19 12:10:33.906 Receiver end receive message …
05-19 12:10:33.907 Receiver 对方发送的消息：你好，接收方：3
05-19 12:10:33.907 Receiver 对方的IP地址是：127.0.0.1
05-19 12:10:33.908 Receiver 对方的端口号是：50312
05-19 12:10:33.909 Receiver begin receive message …
05-19 12:10:38.923 Receiver end receive message …
05-19 12:10:38.924 Receiver 对方发送的消息：你好，接收方：4
05-19 12:10:38.925 Receiver 对方的IP地址是：127.0.0.1
05-19 12:10:38.925 Receiver 对方的端口号是：50312
05-19 12:10:38.926 Receiver main END <<<<<<
4. 再运行Sender工程，每间隔5秒钟发送一个消息给发送方，共发送了5个消息
接收方都收到了，并有返回消息给发送方
log输出如下：
05-19 12:10:18.881 Sender main BEGIN >>>>>>
05-19 12:10:18.885 Sender send packet ..
05-19 12:10:18.886 Sender receive packet …
05-19 12:10:18.887 Sender 接收方返回的消息：接收方说：我收到了消息【你好，接收方：0】
05-19 12:10:18.888 Sender waiting 5s …
05-19 12:10:23.889 Sender send packet ..
05-19 12:10:23.890 Sender receive packet …
05-19 12:10:23.893 Sender 接收方返回的消息：接收方说：我收到了消息【你好，接收方：1】
05-19 12:10:23.894 Sender waiting 5s …
05-19 12:10:28.895 Sender send packet ..
05-19 12:10:28.896 Sender receive packet …
05-19 12:10:28.903 Sender 接收方返回的消息：接收方说：我收到了消息【你好，接收方：2】
05-19 12:10:28.904 Sender waiting 5s …
05-19 12:10:33.905 Sender send packet ..
05-19 12:10:33.906 Sender receive packet …
05-19 12:10:33.921 Sender 接收方返回的消息：接收方说：我收到了消息【你好，接收方：3】
05-19 12:10:33.921 Sender waiting 5s …
05-19 12:10:38.922 Sender send packet ..
05-19 12:10:38.923 Sender receive packet …
05-19 12:10:38.926 Sender 接收方返回的消息：接收方说：我收到了消息【你好，接收方：4】
05-19 12:10:38.927 Sender waiting 5s …
05-19 12:10:43.928 Sender main END <<<<<<
05-19 12:10:18.886 Receiver end receive message …
05-19 12:10:18.886 Receiver 对方发送的消息：你好，接收方：0
05-19 12:10:18.887 Receiver 对方的IP地址是：127.0.0.1
05-19 12:10:18.887 Receiver 对方的端口号是：50312
05-19 12:10:23.890 Receiver end receive message …
05-19 12:10:23.891 Receiver 对方发送的消息：你好，接收方：1
05-19 12:10:23.891 Receiver 对方的IP地址是：127.0.0.1
05-19 12:10:23.892 Receiver 对方的端口号是：50312
05-19 12:10:28.896 Receiver end receive message …
05-19 12:10:28.897 Receiver 对方发送的消息：你好，接收方：2
05-19 12:10:28.898 Receiver 对方的IP地址是：127.0.0.1
05-19 12:10:28.902 Receiver 对方的端口号是：50312
05-19 12:10:33.906 Receiver end receive message …
05-19 12:10:33.907 Receiver 对方发送的消息：你好，接收方：3
05-19 12:10:33.907 Receiver 对方的IP地址是：127.0.0.1
05-19 12:10:33.908 Receiver 对方的端口号是：50312
05-19 12:10:38.923 Receiver end receive message …
05-19 12:10:38.924 Receiver 对方发送的消息：你好，接收方：4
05-19 12:10:38.925 Receiver 对方的IP地址是：127.0.0.1
05-19 12:10:38.925 Receiver 对方的端口号是：50312
接收方都收到了，并有返回消息给发送方
log输出如下：
05-19 12:10:18.881 Sender main BEGIN >>>>>>
05-19 12:10:18.886 Sender receive packet …
05-19 12:10:18.887 Sender 接收方返回的消息：接收方说：我收到了消息【你好，接收方：0】
05-19 12:10:18.888 Sender waiting 5s …
05-19 12:10:23.890 Sender receive packet …
05-19 12:10:23.893 Sender 接收方返回的消息：接收方说：我收到了消息【你好，接收方：1】
05-19 12:10:23.894 Sender waiting 5s …
05-19 12:10:28.896 Sender receive packet …
05-19 12:10:28.903 Sender 接收方返回的消息：接收方说：我收到了消息【你好，接收方：2】
05-19 12:10:28.904 Sender waiting 5s …
05-19 12:10:33.906 Sender receive packet …
05-19 12:10:33.921 Sender 接收方返回的消息：接收方说：我收到了消息【你好，接收方：3】
05-19 12:10:33.921 Sender waiting 5s …
05-19 12:10:38.923 Sender receive packet …
05-19 12:10:38.926 Sender 接收方返回的消息：接收方说：我收到了消息【你好，接收方：4】
05-19 12:10:38.927 Sender waiting 5s …
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