java代码实现snmap每秒接收报文数，每秒发送报文数，接受丢弃报文数，发送丢弃报文数

实现该功能需要使用Java的Socket API，通过监听网络接口获取每秒的报文统计信息。以下是一个基本的示例代码：

import java.net.*;
import java.util.concurrent.*;

public class SnmpStats {
    private static final int PORT = 161;
    private static final int NUM_THREADS = 1;
    private static final int NUM_SECONDS = 10;
    
    public static void main(String[] args) throws Exception {
        InetAddress address = InetAddress.getLocalHost();
        DatagramSocket socket = new DatagramSocket(PORT, address);
        
        ExecutorService executor = Executors.newFixedThreadPool(NUM_THREADS);
        Callable<Mib> task = new SnmpCallable(socket);
        
        for (int i = 0; i < NUM_SECONDS; i++) {
            Future<Mib> future = executor.submit(task);
            Mib mib = future.get();
            
            System.out.printf("Received %d packets, sent %d packets, %d packets dropped on receive, %d packets dropped on send\n",
                mib.getIfInUcastPkts(), mib.getIfOutUcastPkts(), mib.getIfInErrors(), mib.getIfOutErrors());
            
            Thread.sleep(1000);
        }
        
        executor.shutdown();
        socket.close();
    }
}

class SnmpCallable implements Callable<Mib> {
    private DatagramSocket socket;
    
    public SnmpCallable(DatagramSocket socket) {
        this.socket = socket;
    }
    
    public Mib call() throws Exception {
        byte[] buffer = new byte[4096];
        DatagramPacket packet = new DatagramPacket(buffer, buffer.length);
        
        Mib mib = new Mib();
        
        socket.setSoTimeout(1000);
        
        while (true) {
            try {
                socket.receive(packet);
                mib.incIfInUcastPkts();
            } catch (SocketTimeoutException e) {
                break;
            }
        }
        
        return mib;
    }
}

class Mib {
    private int ifInUcastPkts;
    private int ifOutUcastPkts;
    private int ifInErrors;
    private int ifOutErrors;
    
    public synchronized void incIfInUcastPkts() {
        ifInUcastPkts++;
    }
    
    public synchronized void incIfOutUcastPkts() {
        ifOutUcastPkts++;
    }
    
    public synchronized void incIfInErrors() {
        ifInErrors++;
    }
    
    public synchronized void incIfOutErrors() {
        ifOutErrors++;
    }
    
    public synchronized int getIfInUcastPkts() {
        return ifInUcastPkts;
    }
    
    public synchronized int getIfOutUcastPkts() {
        return ifOutUcastPkts;
    }
    
    public synchronized int getIfInErrors() {
        return ifInErrors;
    }
    
    public synchronized int getIfOutErrors() {
        return ifOutErrors;
    }
}

该示例代码使用了一个线程池和一个可调用对象，可调用对象是一个循环，每秒钟收集统计信息，然后将其存储在MIB（管理信息库）对象中。该示例代码只能收集接收方面的统计信息，如果要收集发送方面的统计信息，需要将代码稍作修改，在循环中调用`socket.send()`来发送报文，并相应地更新MIB对象。