spring-framework

Spring Framework

Sam Brannen 03ae97b2eb Introduce Spring property for default escape character for placeholders Spring Framework 6.2 introduced support for an escape character for property placeholders (by default '\'). However, as of Spring Framework 6.2.6, there was no way to either escape the escape character or disable escape character support. For example, given a `username` property configured with the value of `Jane.Smith` and a `DOMAIN\${username}` configuration string, property placeholder replacement used to result in `DOMAIN\Jane.Smith` prior to 6.2 but now results in `DOMAIN${username}`. Similarly, an attempt to escape the escape character via `DOMAIN\\${username}` results in `DOMAIN\${username}`. In theory, one should be able to disable use of an escape character altogether, and that is currently possible by invoking setEscapeCharacter(null) on AbstractPropertyResolver and PlaceholderConfigurerSupport (the superclass of PropertySourcesPlaceholderConfigurer). However, in reality, there are two hurdles. - As of 6.2.6, an invocation of setEscapeCharacter(null) on a PropertySourcesPlaceholderConfigurer applied to its internal top-level PropertySourcesPropertyResolver but not to any nested PropertySourcesPropertyResolver, which means that the `null` escape character could not be effectively applied. - Users may not have an easy way to explicitly set the escape character to `null` for a PropertyResolver or PropertySourcesPlaceholderConfigurer. For example, Spring Boot auto-configures a PropertySourcesPlaceholderConfigurer with the default escape character enabled. This first issue above has recently been addressed by gh-34861. This commit therefore addresses the second issue as follows. - To allow developers to easily revert to the pre-6.2 behavior without changes to code or configuration strings, this commit introduces a `spring.placeholder.escapeCharacter.default` property for use with SpringProperties which globally sets the default escape character that is automatically configured in AbstractPropertyResolver and PlaceholderConfigurerSupport. - Setting the property to an empty string sets the default escape character to `null`, effectively disabling the default support for escape characters. spring.placeholder.escapeCharacter.default = - Setting the property to any other character sets the default escape character to that specific character. spring.placeholder.escapeCharacter.default = ~ - Setting the property to a string containing more than one character results in an exception. - Developers are still able to configure an explicit escape character in AbstractPropertyResolver and PlaceholderConfigurerSupport if they choose to do so. - Third-party components that wish to rely on the same feature can invoke AbstractPropertyResolver.getDefaultEscapeCharacter() to obtain the globally configured default escape character. See gh-9628 See gh-34315 See gh-34861 Closes gh-34865		11 months ago
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