验证身份证有效性：

package com.phonefu.android.help;


import java.util.HashMap;


/**
 * 身份证号校验 
 */
public class IdCard {


private String _codeError;


// wi =2(n-1)(mod 11)
final int[] wi = { 7, 9, 10, 5, 8, 4, 2, 1, 6, 3, 7, 9, 10, 5, 8, 4, 2, 1 };
// verify digit
final int[] vi = { 1, 0, 'X', 9, 8, 7, 6, 5, 4, 3, 2 };
private int[] ai = new int[18];
private static String[] _areaCode = { "11", "12", "13", "14", "15", "21", "22", "23", "31", "32", "33", "34", "35",
"36", "37", "41", "42", "43", "44", "45", "46", "50", "51", "52", "53", "54", "61", "62", "63", "64", "65",
"71", "81", "82", "91" };
private static HashMap<String, Integer> dateMap;
private static HashMap<String, String> areaCodeMap;
static {
dateMap = new HashMap<String, Integer>();
dateMap.put("01", 31);
dateMap.put("02", null);
dateMap.put("03", 31);
dateMap.put("04", 30);
dateMap.put("05", 31);
dateMap.put("06", 30);
dateMap.put("07", 31);
dateMap.put("08", 31);
dateMap.put("09", 30);
dateMap.put("10", 31);
dateMap.put("11", 30);
dateMap.put("12", 31);
areaCodeMap = new HashMap<String, String>();
for (String code : _areaCode) {
areaCodeMap.put(code, null);
}
}


// 验证身份证位数,15位和18位身份证
public boolean verifyLength(String code) {
int length = code.length();
if (length == 15 || length == 18) {
return true;
} else {
_codeError = "错误：输入的身份证号不是15位和18位的";
return false;
}
}


// 判断地区码
public boolean verifyAreaCode(String code) {
String areaCode = code.substring(0, 2);
// Element child= _areaCodeElement.getChild("_"+areaCode);
if (areaCodeMap.containsKey(areaCode)) {
return true;
} else {
_codeError = "错误：输入的身份证号的地区码(1-2位)[" + areaCode + "]不符合中国行政区划分代码规定(GB/T2260-1999)";
return false;
}
}


// 判断月份和日期
public boolean verifyBirthdayCode(String code) {
// 验证月份
String month = code.substring(10, 12);
boolean isEighteenCode = (18 == code.length());
if (!dateMap.containsKey(month)) {
_codeError = "错误：输入的身份证号" + (isEighteenCode ? "(11-12位)" : "(9-10位)") + "不存在[" + month
+ "]月份,不符合要求(GB/T7408)";
return false;
}
// 验证日期
String dayCode = code.substring(12, 14);
Integer day = dateMap.get(month);
String yearCode = code.substring(6, 10);
Integer year = Integer.valueOf(yearCode);


// 非2月的情况
if (day != null) {
if (Integer.valueOf(dayCode) > day || Integer.valueOf(dayCode) < 1) {
_codeError = "错误：输入的身份证号" + (isEighteenCode ? "(13-14位)" : "(11-13位)") + "[" + dayCode
+ "]号不符合小月1-30天大月1-31天的规定(GB/T7408)";
return false;
}
}
// 2月的情况
else {
// 闰月的情况
if ((year % 4 == 0 && year % 100 != 0) || (year % 400 == 0)) {
if (Integer.valueOf(dayCode) > 29 || Integer.valueOf(dayCode) < 1) {
_codeError = "错误：输入的身份证号" + (isEighteenCode ? "(13-14位)" : "(11-13位)") + "[" + dayCode + "]号在"
+ year + "闰年的情况下未符合1-29号的规定(GB/T7408)";
return false;
}
}
// 非闰月的情况
else {
if (Integer.valueOf(dayCode) > 28 || Integer.valueOf(dayCode) < 1) {
_codeError = "错误：输入的身份证号" + (isEighteenCode ? "(13-14位)" : "(11-13位)") + "[" + dayCode + "]号在"
+ year + "平年的情况下未符合1-28号的规定(GB/T7408)";
return false;
}
}
}
return true;
}


// 验证身份除了最后位其他的是否包含字母
public boolean containsAllNumber(String code) {
String str = "";
if (code.length() == 15) {
str = code.substring(0, 15);
} else if (code.length() == 18) {
str = code.substring(0, 17);
}
char[] ch = str.toCharArray();
for (int i = 0; i < ch.length; i++) {
if (!(ch[i] >= '0' && ch[i] <= '9')) {
_codeError = "错误：输入的身份证号第" + (i + 1) + "位包含字母";
return false;
}
}
return true;
}


public String getCodeError() {
return _codeError;
}


// 验证身份证
public boolean verify(String idcard) {
_codeError = "";
if (idcard == null) {
return false;
}
// 验证身份证位数,15位和18位身份证
if (!verifyLength(idcard)) {
return false;
}
// 验证身份除了最后位其他的是否包含字母
if (!containsAllNumber(idcard)) {
return false;
}


// 如果是15位的就转成18位的身份证
String eifhteencard = "";
if (idcard.length() == 15) {
eifhteencard = uptoeighteen(idcard);
} else {
eifhteencard = idcard;
}
// 验证身份证的地区码
if (!verifyAreaCode(eifhteencard)) {
return false;
}
// 判断月份和日期
if (!verifyBirthdayCode(eifhteencard)) {
return false;
}
// 验证18位校验码,校验码采用ISO 7064：1983，MOD 11-2 校验码系统
if (!verifyMOD(eifhteencard)) {
return false;
}
return true;
}


// 验证18位校验码,校验码采用ISO 7064：1983，MOD 11-2 校验码系统
public boolean verifyMOD(String code) {
String verify = code.substring(17, 18);
if ("x".equals(verify)) {
code = code.replaceAll("x", "X");
verify = "X";
}
String verifyIndex = getVerify(code);
if (verify.equals(verifyIndex)) {
return true;
}
// int x=17;
// if(code.length()==15){
// x=14;
// }
_codeError = "错误：输入的身份证号最末尾的数字验证码错误";
return false;
}


// 获得校验位
public String getVerify(String eightcardid) {
int remaining = 0;


if (eightcardid.length() == 18) {
eightcardid = eightcardid.substring(0, 17);
}


if (eightcardid.length() == 17) {
int sum = 0;
for (int i = 0; i < 17; i++) {
String k = eightcardid.substring(i, i + 1);
ai[i] = Integer.parseInt(k);
}


for (int i = 0; i < 17; i++) {
sum = sum + wi[i] * ai[i];
}
remaining = sum % 11;
}


return remaining == 2 ? "X" : String.valueOf(vi[remaining]);
}


// 15位转18位身份证
public String uptoeighteen(String fifteencardid) {
String eightcardid = fifteencardid.substring(0, 6);
eightcardid = eightcardid + "19";
eightcardid = eightcardid + fifteencardid.substring(6, 15);
eightcardid = eightcardid + getVerify(eightcardid);
return eightcardid;
}


public static void main(String[] args) {
boolean result = new IdCard().verify("421181198902185817");
System.out.println(result);
}
}