Netty代码写法总结4Java

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# 总结4

# Final类并在构造函数里验证空参


public final class ProxyConnectionEvent {

    private final String protocol;
    private final String authScheme;
    private final SocketAddress proxyAddress;
    private final SocketAddress destinationAddress;
    private String strVal;

    /**
     * Creates a new event that indicates a successful connection attempt to the destination address.
     */
    public ProxyConnectionEvent(
            String protocol, String authScheme, SocketAddress proxyAddress, SocketAddress destinationAddress) {
        if (protocol == null) {
            throw new NullPointerException("protocol");
        }
        if (authScheme == null) {
            throw new NullPointerException("authScheme");
        }
        if (proxyAddress == null) {
            throw new NullPointerException("proxyAddress");
        }
        if (destinationAddress == null) {
            throw new NullPointerException("destinationAddress");
        }

        this.protocol = protocol;
        this.authScheme = authScheme;
        this.proxyAddress = proxyAddress;
        this.destinationAddress = destinationAddress;
    }

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# Epoll调用原生方法

/**
 * Tells if <a href="http://netty.io/wiki/native-transports.html">{@code netty-transport-native-epoll}</a> is supported.
 */
public final class Epoll {

    private static final Throwable UNAVAILABILITY_CAUSE;

    static  {
        Throwable cause = null;
        int epollFd = -1;
        int eventFd = -1;
        try {
            epollFd = Native.epollCreate();
            eventFd = Native.eventFd();
        } catch (Throwable t) {
            cause = t;
        } finally {
            if (epollFd != -1) {
                try {
                    Native.close(epollFd);
                } catch (Exception ignore) {
                    // ignore
                }
            }
            if (eventFd != -1) {
                try {
                    Native.close(eventFd);
                } catch (Exception ignore) {
                    // ignore
                }
            }
        }

        if (cause != null) {
            UNAVAILABILITY_CAUSE = cause;
        } else {
            UNAVAILABILITY_CAUSE = null;
        }
    }

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原生方法：


final class Native {

    static {
        String name = SystemPropertyUtil.get("os.name").toLowerCase(Locale.UK).trim();
        if (!name.startsWith("linux")) {
            throw new IllegalStateException("Only supported on Linux");
        }
        NativeLibraryLoader.load("netty-transport-native-epoll", PlatformDependent.getClassLoader(Native.class));
    }
    

    public static native int eventFd();
    public static native void eventFdWrite(int fd, long value);
    public static native void eventFdRead(int fd);
    public static native int epollCreate();

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# 自定义实现集合，并可以比较


public interface ChannelGroup extends Set<Channel>, Comparable<ChannelGroup> {

    /**
     * Returns the name of this group.  A group name is purely for helping
     * you to distinguish one group from others.
     */
    String name();

    /**
     * Returns the {@link Channel} which has the specified {@link ChannelId}.
     *
     * @return the matching {@link Channel} if found. {@code null} otherwise.
     */
    Channel find(ChannelId id);

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# 自定义迭代器


/**
 * {@link ChannelException} which holds {@link ChannelFuture}s that failed because of an error.
 */
public class ChannelGroupException extends ChannelException implements Iterable<Map.Entry<Channel, Throwable>> {
    private static final long serialVersionUID = -4093064295562629453L;
    private final Collection<Map.Entry<Channel, Throwable>> failed;

    public ChannelGroupException(Collection<Map.Entry<Channel, Throwable>> causes) {
        if (causes == null) {
            throw new NullPointerException("causes");
        }
        if (causes.isEmpty()) {
            throw new IllegalArgumentException("causes must be non empty");
        }
        failed = Collections.unmodifiableCollection(causes);
    }

    /**
     * Returns a {@link Iterator} which contains all the {@link Throwable} that was a cause of the failure and the
     * related id of the {@link Channel}.
     */
    @Override
    public Iterator<Map.Entry<Channel, Throwable>> iterator() {
        return failed.iterator();
    }
}

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#Java