Java 文本到数字格式IPv4
文本到数字格式IPv4
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源代码：
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//来自 N o w J a v a . c o m - 时 代 Java2
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/*4
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* Copyright (c) 2004, 2015, Oracle and/or its affiliates. All rights reserved.6
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* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.8
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*10
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* This code is free software; you can redistribute it and/or modify it12
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* under the terms of the GNU General Public License version 2 only, as14
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* published by the Free Software Foundation. Oracle designates this16
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* particular file as subject to the "Classpath" exception as provided18
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* by Oracle in the LICENSE file that accompanied this code.20
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*22
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* This code is distributed in the hope that it will be useful, but WITHOUT24
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* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or26
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* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License28
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* version 2 for more details (a copy is included in the LICENSE file that30
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* accompanied this code).32
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*34
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* You should have received a copy of the GNU General Public License version36
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* 2 along with this work; if not, write to the Free Software Foundation,38
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* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.40
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*42
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* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA44
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* or visit www.oracle.com if you need additional information or have any46
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* questions.48
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*/50
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//package com.nowjava;52
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public class Main {55
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public static void main(String[] argv) throws Exception {57
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String src = "nowjava.com";59
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System.out.println(java.util.Arrays61
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.toString(textToNumericFormatV4(src)));63
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}65
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private static final int INADDR4SZ = 4;68
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@SuppressWarnings("fallthrough")71
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public static byte[] textToNumericFormatV4(String src) {73
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byte[] res = new byte[INADDR4SZ];75
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long tmpValue = 0;78
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int currByte = 0;80
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boolean newOctet = true;/* 来 自 nowjava.com - 时 代 Java*/82
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int len = src.length();85
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if (len == 0 || len > 15) {87
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return null;89
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}91
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/*93
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* When only one part is given, the value is stored directly in95
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* the network address without any byte rearrangement.97
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*99
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* When a two part address is supplied, the last part is101
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* interpreted as a 24-bit quantity and placed in the right103
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* most three bytes of the network address. This makes the105
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* two part address format convenient for specifying Class A107
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* network addresses as net.host.109
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*111
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* When a three part address is specified, the last part is113
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* interpreted as a 16-bit quantity and placed in the right115
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* most two bytes of the network address. This makes the117
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* three part address format convenient for specifying119
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* Class B net- work addresses as 128.net.host.121
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*123
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* When four parts are specified, each is interpreted as a125
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* byte of data and assigned, from left to right, to the127
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* four bytes of an IPv4 address.129
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*131
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* We determine and parse the leading parts, if any, as single133
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* byte values in one pass directly into the resulting byte[],135
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* then the remainder is treated as a 8-to-32-bit entity and137
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* translated into the remaining bytes in the array.139
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*/141
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for (int i = 0; i < len; i++) {143
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char c = src.charAt(i);145
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if (c == '.') {147
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if (newOctet || tmpValue < 0 || tmpValue > 0xff149
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|| currByte == 3) {151
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return null;153
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}155
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res[currByte++] = (byte) (tmpValue & 0xff);157
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tmpValue = 0;159
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newOctet = true;161
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} else {163
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int digit = Character.digit(c, 10);165
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if (digit < 0) {167
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