一、前言

关于alibaba的dubbo源码包com.alibaba.dubbo.common.utils.NetUtils网络工具类，对主机host、网络地址InetSocketAddress及URL等相关转换处理，详情参见源码说明。

二、源码说明

package com.alibaba.dubbo.common.utils;@b@@b@import com.alibaba.dubbo.common.URL;  @b@import java.io.IOException;@b@import java.net.InetAddress;@b@import java.net.InetSocketAddress;@b@import java.net.NetworkInterface;@b@import java.net.ServerSocket;@b@import java.net.UnknownHostException;@b@import java.util.Enumeration;@b@import java.util.Map;@b@import java.util.Random;@b@import java.util.regex.Pattern;@b@@b@public class NetUtils {@b@@b@    public static final String LOCALHOST = "127.0.0.1";@b@    public static final String ANYHOST = "0.0.0.0";@b@    private static final int RND_PORT_START = 30000;@b@@b@    private static final int RND_PORT_RANGE = 10000;@b@@b@    private static final Random RANDOM = new Random(System.currentTimeMillis());@b@    private static final int MIN_PORT = 0;@b@    private static final int MAX_PORT = 65535;@b@    private static final Pattern ADDRESS_PATTERN = Pattern.compile("^\\d{1,3}(\\.\\d{1,3}){3}\\:\\d{1,5}$");@b@    private static final Pattern LOCAL_IP_PATTERN = Pattern.compile("127(\\.\\d{1,3}){3}$");@b@    private static final Pattern IP_PATTERN = Pattern.compile("\\d{1,3}(\\.\\d{1,3}){3,5}$");@b@    private static final Map<String, String> hostNameCache = new LRUCache<String, String>(1000);@b@    private static volatile InetAddress LOCAL_ADDRESS = null;@b@@b@    public static int getRandomPort() {@b@        return RND_PORT_START + RANDOM.nextInt(RND_PORT_RANGE);@b@    }@b@@b@    public static int getAvailablePort() {@b@        ServerSocket ss = null;@b@        try {@b@            ss = new ServerSocket();@b@            ss.bind(null);@b@            return ss.getLocalPort();@b@        } catch (IOException e) {@b@            return getRandomPort();@b@        } finally {@b@            if (ss != null) {@b@                try {@b@                    ss.close();@b@                } catch (IOException e) {@b@                }@b@            }@b@        }@b@    }@b@@b@    public static int getAvailablePort(int port) {@b@        if (port <= 0) {@b@            return getAvailablePort();@b@        }@b@        for (int i = port; i < MAX_PORT; i++) {@b@            ServerSocket ss = null;@b@            try {@b@                ss = new ServerSocket(i);@b@                return i;@b@            } catch (IOException e) {@b@                // continue@b@            } finally {@b@                if (ss != null) {@b@                    try {@b@                        ss.close();@b@                    } catch (IOException e) {@b@                    }@b@                }@b@            }@b@        }@b@        return port;@b@    }@b@@b@    public static boolean isInvalidPort(int port) {@b@        return port <= MIN_PORT || port > MAX_PORT;@b@    }@b@@b@    public static boolean isValidAddress(String address) {@b@        return ADDRESS_PATTERN.matcher(address).matches();@b@    }@b@@b@    public static boolean isLocalHost(String host) {@b@        return host != null@b@                && (LOCAL_IP_PATTERN.matcher(host).matches()@b@                || host.equalsIgnoreCase("localhost"));@b@    }@b@@b@    public static boolean isAnyHost(String host) {@b@        return "0.0.0.0".equals(host);@b@    }@b@@b@    public static boolean isInvalidLocalHost(String host) {@b@        return host == null@b@                || host.length() == 0@b@                || host.equalsIgnoreCase("localhost")@b@                || host.equals("0.0.0.0")@b@                || (LOCAL_IP_PATTERN.matcher(host).matches());@b@    }@b@@b@    public static boolean isValidLocalHost(String host) {@b@        return !isInvalidLocalHost(host);@b@    }@b@@b@    public static InetSocketAddress getLocalSocketAddress(String host, int port) {@b@        return isInvalidLocalHost(host) ?@b@                new InetSocketAddress(port) : new InetSocketAddress(host, port);@b@    }@b@@b@    private static boolean isValidAddress(InetAddress address) {@b@        if (address == null || address.isLoopbackAddress())@b@            return false;@b@        String name = address.getHostAddress();@b@        return (name != null@b@                && !ANYHOST.equals(name)@b@                && !LOCALHOST.equals(name)@b@                && IP_PATTERN.matcher(name).matches());@b@    }@b@@b@    public static String getLocalHost() {@b@        InetAddress address = getLocalAddress();@b@        return address == null ? LOCALHOST : address.getHostAddress();@b@    }@b@@b@    public static String filterLocalHost(String host) {@b@        if (host == null || host.length() == 0) {@b@            return host;@b@        }@b@        if (host.contains("://")) {@b@            URL u = URL.valueOf(host);@b@            if (NetUtils.isInvalidLocalHost(u.getHost())) {@b@                return u.setHost(NetUtils.getLocalHost()).toFullString();@b@            }@b@        } else if (host.contains(":")) {@b@            int i = host.lastIndexOf(':');@b@            if (NetUtils.isInvalidLocalHost(host.substring(0, i))) {@b@                return NetUtils.getLocalHost() + host.substring(i);@b@            }@b@        } else {@b@            if (NetUtils.isInvalidLocalHost(host)) {@b@                return NetUtils.getLocalHost();@b@            }@b@        }@b@        return host;@b@    }@b@@b@    /**@b@     * Find first valid IP from local network card@b@     *@b@     * @return first valid local IP@b@     */@b@    public static InetAddress getLocalAddress() {@b@        if (LOCAL_ADDRESS != null)@b@            return LOCAL_ADDRESS;@b@        InetAddress localAddress = getLocalAddress0();@b@        LOCAL_ADDRESS = localAddress;@b@        return localAddress;@b@    }@b@@b@    public static String getLogHost() {@b@        InetAddress address = getLocalAddress();@b@        return address == null ? LOCALHOST : address.getHostAddress();@b@    }@b@@b@    private static InetAddress getLocalAddress0() {@b@        InetAddress localAddress = null;@b@        try {@b@            localAddress = InetAddress.getLocalHost();@b@            if (isValidAddress(localAddress)) {@b@                return localAddress;@b@            }@b@        } catch (Throwable e) {@b@        }@b@        try {@b@            Enumeration<NetworkInterface> interfaces = NetworkInterface.getNetworkInterfaces();@b@            if (interfaces != null) {@b@                while (interfaces.hasMoreElements()) {@b@                    try {@b@                        NetworkInterface network = interfaces.nextElement();@b@                        Enumeration<InetAddress> addresses = network.getInetAddresses();@b@                        if (addresses != null) {@b@                            while (addresses.hasMoreElements()) {@b@                                try {@b@                                    InetAddress address = addresses.nextElement();@b@                                    if (isValidAddress(address)) {@b@                                        return address;@b@                                    }@b@                                } catch (Throwable e) {@b@                                }@b@                            }@b@                        }@b@                    } catch (Throwable e) {@b@                    }@b@                }@b@            }@b@        } catch (Throwable e) {@b@        }@b@        return localAddress;@b@    }@b@@b@    public static String getHostName(String address) {@b@        try {@b@            int i = address.indexOf(':');@b@            if (i > -1) {@b@                address = address.substring(0, i);@b@            }@b@            String hostname = hostNameCache.get(address);@b@            if (hostname != null && hostname.length() > 0) {@b@                return hostname;@b@            }@b@            InetAddress inetAddress = InetAddress.getByName(address);@b@            if (inetAddress != null) {@b@                hostname = inetAddress.getHostName();@b@                hostNameCache.put(address, hostname);@b@                return hostname;@b@            }@b@        } catch (Throwable e) {@b@            // ignore@b@        }@b@        return address;@b@    }@b@@b@    /**@b@     * @param hostName@b@     * @return ip address or hostName if UnknownHostException@b@     */@b@    public static String getIpByHost(String hostName) {@b@        try {@b@            return InetAddress.getByName(hostName).getHostAddress();@b@        } catch (UnknownHostException e) {@b@            return hostName;@b@        }@b@    }@b@@b@    public static String toAddressString(InetSocketAddress address) {@b@        return address.getAddress().getHostAddress() + ":" + address.getPort();@b@    }@b@@b@    public static InetSocketAddress toAddress(String address) {@b@        int i = address.indexOf(':');@b@        String host;@b@        int port;@b@        if (i > -1) {@b@            host = address.substring(0, i);@b@            port = Integer.parseInt(address.substring(i + 1));@b@        } else {@b@            host = address;@b@            port = 0;@b@        }@b@        return new InetSocketAddress(host, port);@b@    }@b@@b@    public static String toURL(String protocol, String host, int port, String path) {@b@        StringBuilder sb = new StringBuilder();@b@        sb.append(protocol).append("://");@b@        sb.append(host).append(':').append(port);@b@        if (path.charAt(0) != '/')@b@            sb.append('/');@b@        sb.append(path);@b@        return sb.toString();@b@    }@b@@b@}