驗證碼校驗：String.equalsIgnoreCase()
阿新 • • 發佈：2020-12-16
適用於驗證碼校驗（不區分大小寫）
public class TestString { public static void main(String[] args) { testEquals("asd", "asd"); testEquals("asD", "Asd"); } /** * @see java.lang.String#equalsIgnoreCase * usage: checking vertification code */ private static void testEquals(String a, String b) { System.out.println("\"" + a + "\".equals(\"" + b + "\") = " + a.equals(b)); System.out.println("\"" + a + "\".equalsIgnoreCase(\"" + b + "\") = " + a.equalsIgnoreCase(b)); } }
class TestString { companion object { @JvmStatic fun main(args: Array<String>) { testEquals("asd", "asd") testEquals("asD", "Asd") } private fun testEquals(a: String, b: String) { println("\"$a\".equals(\"$b\") = " + (a == b)) println("\"$a\".equalsIgnoreCase(\"$b\") = " + a.equals(b, ignoreCase = true)) } } }
執行結果
"asd".equals("asd") = true
"asd".equalsIgnoreCase("asd") = true
"asD".equals("Asd") = false
"asD".equalsIgnoreCase("Asd") = true
原始碼
public boolean equalsIgnoreCase(String anotherString) { return (this == anotherString) ? true : (anotherString != null) && (anotherString.value.length == value.length) && regionMatches(true, 0, anotherString, 0, value.length); }
1、優先判斷記憶體地址值是否一致：this == anotherString
2、不為null且長度一致的情況下： regionMatches(true, 0, anotherString, 0, value.length)
public boolean regionMatches(boolean ignoreCase, int toffset,
String other, int ooffset, int len) {
char ta[] = value;
int to = toffset;
char pa[] = other.value;
int po = ooffset;
// Note: toffset, ooffset, or len might be near -1>>>1.
//1、判斷是否陣列越界
if ((ooffset < 0) || (toffset < 0)
|| (toffset > (long)value.length - len)
|| (ooffset > (long)other.value.length - len)) {
return false;
}
//2、迴圈遍歷char是否一致
while (len-- > 0) {
char c1 = ta[to++];
char c2 = pa[po++];
if (c1 == c2) {
continue;
}
if (ignoreCase) {//是否忽略大小寫，true 則同義轉換為大寫或同義轉換為小寫進行校驗
// If characters don't match but case may be ignored,
// try converting both characters to uppercase.
// If the results match, then the comparison scan should
// continue.
char u1 = Character.toUpperCase(c1);
char u2 = Character.toUpperCase(c2);
if (u1 == u2) {
continue;
}
// Unfortunately, conversion to uppercase does not work properly
// for the Georgian alphabet, which has strange rules about case
// conversion. So we need to make one last check before
// exiting.
if (Character.toLowerCase(u1) == Character.toLowerCase(u2)) {
continue;
}
}
return false;
}
return true;
}
小寫字母轉換大寫字母
public static char toUpperCase(char ch) {
return (char)toUpperCase((int)ch);
}
public static int toUpperCase(int codePoint) {
return CharacterData.of(codePoint).toUpperCase(codePoint);
}
** testEquals(“asD”, “Asd”);
char ‘a’ = 97 ,char ‘A’=65,ch >>>8 == 0 為 true**
static final CharacterData of(int ch) {
if (ch >>> 8 == 0) { // fast-path
return CharacterDataLatin1.instance;
} else {
switch(ch >>> 16) { //plane 00-16
case(0):
return CharacterData00.instance;
case(1):
return CharacterData01.instance;
case(2):
return CharacterData02.instance;
case(14):
return CharacterData0E.instance;
case(15): // Private Use
case(16): // Private Use
return CharacterDataPrivateUse.instance;
default:
return CharacterDataUndefined.instance;
}
}
}
CharacterDataLatin1.instance
小寫字母轉大寫字母
int toUpperCase(int ch) {
int mapChar = ch;
int val = getProperties(ch);
if ((val & 0x00010000) != 0) {
if ((val & 0x07FC0000) != 0x07FC0000) {
int offset = val << 5 >> (5+18);
mapChar = ch - offset;
} else if (ch == 0x00B5) {
mapChar = 0x039C;
}
}
return mapChar;
}
大寫字母轉小寫字母
int toLowerCase(int ch) {
int mapChar = ch;
int val = getProperties(ch);
if (((val & 0x00020000) != 0) &&
((val & 0x07FC0000) != 0x07FC0000)) {
int offset = val << 5 >> (5+18);
mapChar = ch + offset;
}
return mapChar;
}
int getProperties(int ch) {
char offset = (char)ch;
int props = A[offset];
return props;
}
static {
{ // THIS CODE WAS AUTOMATICALLY CREATED BY GenerateCharacter:
char[] data = A_DATA.toCharArray();
assert (data.length == (256 * 2));
int i = 0, j = 0;
while (i < (256 * 2)) {
int entry = data[i++] << 16;
A[j++] = entry | data[i++];
}
}
}
static final int A[] = new int[256];
static final String A_DATA =
"\u4800\u100F\u4800\u100F\u4800\u100F\u4800\u100F\u4800\u100F\u4800\u100F\u4800"+
"\u100F\u4800\u100F\u4800\u100F\u5800\u400F\u5000\u400F\u5800\u400F\u6000\u400F"+
"\u5000\u400F\u4800\u100F\u4800\u100F\u4800\u100F\u4800\u100F\u4800\u100F\u4800"+
"\u100F\u4800\u100F\u4800\u100F\u4800\u100F\u4800\u100F\u4800\u100F\u4800\u100F"+
"\u4800\u100F\u4800\u100F\u5000\u400F\u5000\u400F\u5000\u400F\u5800\u400F\u6000"+
"\u400C\u6800\030\u6800\030\u2800\030\u2800\u601A\u2800\030\u6800\030\u6800"+
"\030\uE800\025\uE800\026\u6800\030\u2000\031\u3800\030\u2000\024\u3800\030"+
"\u3800\030\u1800\u3609\u1800\u3609\u1800\u3609\u1800\u3609\u1800\u3609\u1800"+
"\u3609\u1800\u3609\u1800\u3609\u1800\u3609\u1800\u3609\u3800\030\u6800\030"+
"\uE800\031\u6800\031\uE800\031\u6800\030\u6800\030\202\u7FE1\202\u7FE1\202"+
"\u7FE1\202\u7FE1\202\u7FE1\202\u7FE1\202\u7FE1\202\u7FE1\202\u7FE1\202\u7FE1"+
"\202\u7FE1\202\u7FE1\202\u7FE1\202\u7FE1\202\u7FE1\202\u7FE1\202\u7FE1\202"+
"\u7FE1\202\u7FE1\202\u7FE1\202\u7FE1\202\u7FE1\202\u7FE1\202\u7FE1\202\u7FE1"+
"\202\u7FE1\uE800\025\u6800\030\uE800\026\u6800\033\u6800\u5017\u6800\033\201"+
"\u7FE2\201\u7FE2\201\u7FE2\201\u7FE2\201\u7FE2\201\u7FE2\201\u7FE2\201\u7FE2"+
"\201\u7FE2\201\u7FE2\201\u7FE2\201\u7FE2\201\u7FE2\201\u7FE2\201\u7FE2\201"+
"\u7FE2\201\u7FE2\201\u7FE2\201\u7FE2\201\u7FE2\201\u7FE2\201\u7FE2\201\u7FE2"+
"\201\u7FE2\201\u7FE2\201\u7FE2\uE800\025\u6800\031\uE800\026\u6800\031\u4800"+
"\u100F\u4800\u100F\u4800\u100F\u4800\u100F\u4800\u100F\u4800\u100F\u5000\u100F"+
"\u4800\u100F\u4800\u100F\u4800\u100F\u4800\u100F\u4800\u100F\u4800\u100F\u4800"+
"\u100F\u4800\u100F\u4800\u100F\u4800\u100F\u4800\u100F\u4800\u100F\u4800\u100F"+
"\u4800\u100F\u4800\u100F\u4800\u100F\u4800\u100F\u4800\u100F\u4800\u100F\u4800"+
"\u100F\u4800\u100F\u4800\u100F\u4800\u100F\u4800\u100F\u4800\u100F\u4800\u100F"+
"\u3800\014\u6800\030\u2800\u601A\u2800\u601A\u2800\u601A\u2800\u601A\u6800"+
"\034\u6800\030\u6800\033\u6800\034\000\u7005\uE800\035\u6800\031\u4800\u1010"+
"\u6800\034\u6800\033\u2800\034\u2800\031\u1800\u060B\u1800\u060B\u6800\033"+
"\u07FD\u7002\u6800\030\u6800\030\u6800\033\u1800\u050B\000\u7005\uE800\036"+
"\u6800\u080B\u6800\u080B\u6800\u080B\u6800\030\202\u7001\202\u7001\202\u7001"+
"\202\u7001\202\u7001\202\u7001\202\u7001\202\u7001\202\u7001\202\u7001\202"+
"\u7001\202\u7001\202\u7001\202\u7001\202\u7001\202\u7001\202\u7001\202\u7001"+
"\202\u7001\202\u7001\202\u7001\202\u7001\202\u7001\u6800\031\202\u7001\202"+
"\u7001\202\u7001\202\u7001\202\u7001\202\u7001\202\u7001\u07FD\u7002\201\u7002"+
"\201\u7002\201\u7002\201\u7002\201\u7002\201\u7002\201\u7002\201\u7002\201"+
"\u7002\201\u7002\201\u7002\201\u7002\201\u7002\201\u7002\201\u7002\201\u7002"+
"\201\u7002\201\u7002\201\u7002\201\u7002\201\u7002\201\u7002\201\u7002\u6800"+
"\031\201\u7002\201\u7002\201\u7002\201\u7002\201\u7002\201\u7002\201\u7002"+
"\u061D\u7002";