java_requirement: port to Linux and refactor

Split the core requirement class into generic, Linux-specific,
and macOS-specific parts.

Additionally, the Linux version is now able to detect Java versions
(the previous Linuxbrew implementation was only able to detect
if Java was present at all.)

1 files changed, 40 insertions, 0 deletions

diff --git a/Library/Homebrew/extend/os/mac/requirements/java_requirement.rb b/Library/Homebrew/extend/os/mac/requirements/java_requirement.rb
new file mode 100644
index 000000000..9c60aff95
--- /dev/null
+++ b/Library/Homebrew/extend/os/mac/requirements/java_requirement.rb
@@ -0,0 +1,40 @@
+class JavaRequirement
+  cask "java"
+
+  env do
+    env_java_common
+    java_home = Pathname.new(@java_home)
+    if (java_home/"include").exist? # Oracle JVM
+      env_oracle_jdk
+    else # Apple JVM
+      env_apple
+    end
+  end
+
+  private
+
+  def possible_javas
+    javas = []
+    javas << Pathname.new(ENV["JAVA_HOME"])/"bin/java" if ENV["JAVA_HOME"]
+    javas << java_home_cmd
+    javas << which("java")
+    javas
+  end
+
+  def java_home_cmd
+    return nil unless File.executable?("/usr/libexec/java_home")
+    args = %w[--failfast]
+    args << "--version" << @version.to_s if @version
+    java_home = Utils.popen_read("/usr/libexec/java_home", *args).chomp
+    return nil unless $?.success?
+    Pathname.new(java_home)/"bin/java"
+  end
+
+  def env_apple
+    ENV.append_to_cflags "-I/System/Library/Frameworks/JavaVM.framework/Versions/Current/Headers/"
+  end
+
+  def oracle_java_os
+    :darwin
+  end
+end