ConsoleAppender: support JLine's org.jline.jansi.AnsiConsole for <withJansi> - #1050
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ceki merged 1 commit intoJul 24, 2026
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…ansi>
Jansi was migrated from FuseSource (org.fusesource.jansi) to JLine
(org.jline.jansi), which changed the package of AnsiConsole. Because
ConsoleAppender loaded the FuseSource class name by reflection, <withJansi>
silently fell back to the plain stream ("Failed to create AnsiPrintStream",
ClassNotFoundException: org.fusesource.jansi.AnsiConsole) for users who now
have only the JLine Jansi artifact on the classpath.
Probe the JLine coordinates first and fall back to the legacy FuseSource
ones, so <withJansi> keeps working with either artifact.
Fixes qos-ch#1043
Signed-off-by: seonwoo_jung <79202163+seonwooj0810@users.noreply.github.com>
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@seonwooj0810 Thank you for this PR. Its conciseness was a plus. |
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Fixes #1043
Root cause
Jansi was migrated from FuseSource (
org.fusesource.jansi) to JLine (org.jline.jansi), which changed the package ofAnsiConsole.ConsoleAppender.wrapWithJansi(...)loaded the FuseSource class name by reflection (org.fusesource.jansi.AnsiConsole), so for users who now have only the JLine Jansi artifact on the classpath,<withJansi>silently degrades to the plain stream:Change
ConsoleAppendernow probes an ordered list of candidate class names — JLineorg.jline.jansi.AnsiConsolefirst, then the legacy FuseSourceorg.fusesource.jansi.AnsiConsole— via a smallloadAnsiConsoleClass(ClassLoader)helper. JLine repackages the same Jansi 2 API (out()/err()/systemInstall()), so the existing reflective method lookup is unchanged.This matches the approach suggested in the issue thread ("try the new class name and fall back to the old one").
Tests
ConsoleAppenderJansiClassResolutionTest(dependency-free, uses a customClassLoaderto simulate each environment): verifies JLine is preferred when both are present, falls back to FuseSource when JLine is absent, and throwsClassNotFoundExceptionwhen neither is available. These fail against the old hard-coded lookup in a JLine-only environment and pass after the change.JansiConsoleAppenderTest(FuseSource on the classpath) still passes, confirming the legacy path is preserved.Verification done: built and ran
mvn -pl logback-core test -Dtest=ConsoleAppenderJansiClassResolutionTest(3 passed) andmvn -pl logback-core-blackbox test -Dtest=JansiConsoleAppenderTest(2 passed) on JDK 25 with--release 17.Note: the JPMS
module-info/ OSGiImport-Packagedescriptors still referenceorg.fusesource.jansionly; I kept this PR to the runtime reflective lookup to stay minimal, but happy to add JLine to those optional requirements as a follow-up if desired.