Prior to this commit, utility methods in
org.springframework.util.Assert accepted String arguments for custom
error messages. Such Strings are evaluated (e.g., concatenated)
eagerly, and for performance reasons, it was therefore not always
possible to make use of these utility methods. Consequently, there are
several places in the code base that "inline" identical functionality
in order to lazily evaluate error message concatenation and avoid an
unnecessary performance penalty. This leads to verbose code like the
following.
if (!contextPath.startsWith("/")) {
throw new IllegalArgumentException("contextPath '" + contextPath +
"' must start with '/'.");
}
if (contextPath.endsWith("/")) {
throw new IllegalArgumentException("contextPath '" + contextPath +
"' must not end with '/'.");
}
This commit addresses this shortcoming by introducing Supplier<String>
variants of all utility methods in org.springframework.util.Assert that
allow custom error messages to be evaluated lazily via a lambda
expression that is only evaluated if the assertion fails. This results
in a simplification of the previous examples as follows.
Assert.isTrue(contextPath.startsWith("/"), () -> "contextPath '" +
contextPath + "' must start with '/'.");
Assert.isTrue(!contextPath.endsWith("/"), () -> "contextPath '" +
contextPath + "' must not end with '/'.");
Issue: SPR-14450
17dd5dd22d