文章目录- 前言
- UUID 处理的更改
- 正则表达式的更改
- 结束
前言
Android 14 已经出来好久好久了…
今天其他的暂且不论，单纯的讲一下 OpenJDK 17 更新的两点变更（扒源代码）~
- 对正则表达式的更改
- UUID 处理
首先，正则表达式的更改：现在，为了更严格地遵循 OpenJDK 的语义，不允许无效的组引用。您可能会看到 java.util.regex.Matcher 类抛出 IllegalArgumentException 的新情况，因此请务必测试应用中使用正则表达式的情形。如需在测试期间启用或停用此变更，请使用兼容性框架工具切换 DISALLOW_INVALID_GROUP_REFERENCE 标志。
其次，UUID 处理：现在，验证输入参数时，java.util.UUID.fromString() 方法会执行更严格的检查，因此您可能会在反序列化期间看到 IllegalArgumentException。如需在测试期间启用或停用此变更，请使用兼容性框架工具切换 ENABLE_STRICT_VALIDATION 标志。
巴拉巴拉，以上是官网的言论，诸君可以看官方的描述地址
UUID 处理的更改
原有代码逻辑~
代码语言：javascript复制 /**
* Creates a {@code UUID} from the string standard representation as
* described in the {@link #toString} method.
*
* @param name
* A string that specifies a {@code UUID}
*
* @return A {@code UUID} with the specified value
*
* @throws IllegalArgumentException
* If name does not conform to the string representation as
* described in {@link #toString}
*
*/
public static UUID fromString(String name) {
String[] components = name.split("-");
if (components.length != 5)
//仅会判断以-分割的数组长度是否等于5来抛出异常
throw new IllegalArgumentException("Invalid UUID string: " name);
for (int i=0; i<5; i )
components[i] = "0x" components[i];
long mostSigBits = Long.decode(components[0]).longValue();
mostSigBits <<= 16;
mostSigBits |= Long.decode(components[1]).longValue();
mostSigBits <<= 16;
mostSigBits |= Long.decode(components[2]).longValue();
long leastSigBits = Long.decode(components[3]).longValue();
leastSigBits <<= 48;
leastSigBits |= Long.decode(components[4]).longValue();
return new UUID(mostSigBits, leastSigBits);
}新代码逻辑~
代码语言：javascript复制/**
* Creates a {@code UUID} from the string standard representation as
* described in the {@link #toString} method.
*
* @param name
* A string that specifies a {@code UUID}
*
* @return A {@code UUID} with the specified value
*
* @throws IllegalArgumentException
* If name does not conform to the string representation as
* described in {@link #toString}
*
*/
public static UUID fromString(String name) {
// BEGIN Android-changed: Java 8 behaviour is more lenient and the new implementation
// might break apps (b/254278943).
// Using old implementation for apps targeting Android older than U.
// 取反！ 如果设备的sdk版本，大于等于 UPSIDE_DOWN_CAKE（34）的话，且启用严格验证
if (!(VMRuntime.getSdkVersion() >= VersionCodes.UPSIDE_DOWN_CAKE
&& Compatibility.isChangeEnabled(ENABLE_STRICT_VALIDATION))) {
return fromStringJava8(name);
}
//如果小于或者没开启严格验证，则执行其他的验证
return fromStringCurrentJava(name);
// END Android-changed: Java 8 behaviour is more lenient and the new implementation
// might break apps (b/254278943).
}如下是java8 的判断方式（跟原来一致）
代码语言：javascript复制 /**
* Extracted for testing purposes only.
* @hide
*/
public static UUID fromStringJava8(String name) {
String[] components = name.split("-");
if (components.length != 5)
throw new IllegalArgumentException("Invalid UUID string: " name);
for (int i=0; i<5; i )
components[i] = "0x" components[i];
long mostSigBits = Long.decode(components[0]).longValue();
mostSigBits <<= 16;
mostSigBits |= Long.decode(components[1]).longValue();
mostSigBits <<= 16;
mostSigBits |= Long.decode(components[2]).longValue();
long leastSigBits = Long.decode(components[3]).longValue();
leastSigBits <<= 48;
leastSigBits |= Long.decode(components[4]).longValue();
return new UUID(mostSigBits, leastSigBits);
}如下是执行34或者开启严格验证的方法：
代码语言：javascript复制/**
* Extracted for testing purposes only.
* @hide
*/
public static UUID fromStringCurrentJava(String name) {
if (name.length() == 36) {
char ch1 = name.charAt(8);
char ch2 = name.charAt(13);
char ch3 = name.charAt(18);
char ch4 = name.charAt(23);
if (ch1 == '-' && ch2 == '-' && ch3 == '-' && ch4 == '-') {
long msb1 = parse4Nibbles(name, 0);
long msb2 = parse4Nibbles(name, 4);
long msb3 = parse4Nibbles(name, 9);
long msb4 = parse4Nibbles(name, 14);
long lsb1 = parse4Nibbles(name, 19);
long lsb2 = parse4Nibbles(name, 24);
long lsb3 = parse4Nibbles(name, 28);
long lsb4 = parse4Nibbles(name, 32);
if ((msb1 | msb2 | msb3 | msb4 | lsb1 | lsb2 | lsb3 | lsb4) >= 0) {
return new UUID(
msb1 << 48 | msb2 << 32 | msb3 << 16 | msb4,
lsb1 << 48 | lsb2 << 32 | lsb3 << 16 | lsb4);
}
}
}
return fromString1(name);
}
private static UUID fromString1(String name) {
int len = name.length();
if (len > 36) {
throw new IllegalArgumentException("UUID string too large");
}
int dash1 = name.indexOf('-', 0);
int dash2 = name.indexOf('-', dash1 1);
int dash3 = name.indexOf('-', dash2 1);
int dash4 = name.indexOf('-', dash3 1);
int dash5 = name.indexOf('-', dash4 1);
// For any valid input, dash1 through dash4 will be positive and dash5
// negative, but it's enough to check dash4 and dash5:
// - if dash1 is -1, dash4 will be -1
// - if dash1 is positive but dash2 is -1, dash4 will be -1
// - if dash1 and dash2 is positive, dash3 will be -1, dash4 will be
// positive, but so will dash5
if (dash4 < 0 || dash5 >= 0) {
throw new IllegalArgumentException("Invalid UUID string: " name);
}
long mostSigBits = Long.parseLong(name, 0, dash1, 16) & 0xffffffffL;
mostSigBits <<= 16;
mostSigBits |= Long.parseLong(name, dash1 1, dash2, 16) & 0xffffL;
mostSigBits <<= 16;
mostSigBits |= Long.parseLong(name, dash2 1, dash3, 16) & 0xffffL;
long leastSigBits = Long.parseLong(name, dash3 1, dash4, 16) & 0xffffL;
leastSigBits <<= 48;
leastSigBits |= Long.parseLong(name, dash4 1, len, 16) & 0xffffffffffffL;
return new UUID(mostSigBits, leastSigBits);
}解析： 从代码的角度看起来是多了好多验证，梳理一下：
代码语言：javascript复制1. 判断是否34（sdk版本），且未开启严格验证的情况下，还是按照原有代码执行，仅仅判断 以-分割的数组长度是否等于5，若不等于5，则主动抛出异常；
2. 如果sdk版本大于等于34，且开启了严格验证，则会执行fromStringCurrentJava（）& fromString1（）方法，
fromStringCurrentJava方法中没有主动抛出异常的代码，判断长度是否=36，不等于则执行 fromString1，若等于则继续执行，获取字符串下标8、13、18、23的值，若这四个值不等于 - ，则执行 fromString1；
在fromString1； 方法中，传递的字符串长度不得大于36，若超出则主动抛异常；
继续判断；对于任何有效输入，dash1 到 dash4 将为正数，dash5 将为正数，负数，但检查 dash4 和 dash5 就足够了：
若是dash4小于0，dash5大于等于0，则主动抛出异常；正则表达式的更改
原有代码逻辑~
代码语言：javascript复制/**
* Attempts to match the entire region against the pattern.
*
* <p> If the match succeeds then more information can be obtained via the
* <tt>start</tt>, <tt>end</tt>, and <tt>group</tt> methods. </p>
*
* @return <tt>true</tt> if, and only if, the entire region sequence
* matches this matcher's pattern
*/
public boolean matches() {
synchronized (this) {
matchFound = nativeMatcher.matches(groups);
}
return matchFound;新代码逻辑~
代码语言：javascript复制 /**
* Attempts to match the entire region against the pattern.
*
* <p> If the match succeeds then more information can be obtained via the
* {@code start}, {@code end}, and {@code group} methods. </p>
*
* @return {@code true} if, and only if, the entire region sequence
* matches this matcher's pattern
*/
public boolean matches() {
synchronized (this) {
matchFound = nativeMatcher.matches(groups);
}
//主要增加一个这个
modCount ;
return matchFound;
}modCount的描述 ：记录该匹配器状态被修改的次数
代码语言：javascript复制 /**
* Number of times this matcher's state has been modified
*/
int modCount;结束
不是我说哈，你都是系统代码了，还起个 fromString1 这样的方法名称，丢人不~ 就这，有问题私聊我~ 再会~
