Bazel Build: Generate java classes from XSD using JAXB2 - xsd

Question

I am new to Bazel. I want to generate Java classes from an XSD document using JaxB2.
I could not find any Java_Rule to auto-generate the classes.
Looking at this google group discussion, a genrule with explicit command seems to generate java classes for the author.
I tried using the github repository suggested in the discussion but failed with no such target '#local_jdk//:jdk-default': target 'jdk-default' not declared in package ' error.
➜ bazel-xjc-master bazel build //...
ERROR: /Users/<user>/bazel-xjc-master/BUILD.bazel:1:8: no such target '#local_jdk//:jdk-default': target 'jdk-default' not declared in package '' (did you mean 'jre-default'?) defined by /private/var/tmp/.../local_jdk/BUILD.bazel and referenced by '//:sample-messages'
ERROR: Analysis of target '//:sample-messages' failed; build aborted: Analysis failed
INFO: Elapsed time: 0.152s
INFO: 0 processes.
FAILED: Build did NOT complete successfully (1 packages loaded, 6 targets configured)
I tried searchingjava_toolchain options to handle the above error but without any success.
Is there a Bazel build example file somewhere I can look at on how to generate java classes based on an XSD file?

Answer 1

The examples in the google group discussion were correct at the time, but Java toolchain integration with Bazel has changed over time, and indeed the target #local_jdk//:jdk-default no longer exists, and #local_jdk//:jar is deprecated.
But the bigger issue is that jaxb and xjc have been deprecated/removed from the jdk starting with jdk 9: http://openjdk.java.net/jeps/320
You'll need to get jaxb separately, something like this:
BUILD.bazel:
load("#rules_jvm_external//:defs.bzl", "artifact")
genrule(
name = "sample-messages",
srcs = [
"src/main/xsd/sample.xsd",
"src/main/xjb/sample.xjb",
],
outs = ["sample-messages.srcjar"],
cmd = """
mkdir sample-messages
$(location :xjc) -quiet -d sample-messages -b $(location src/main/xjb/sample.xjb) -verbose $(location src/main/xsd/sample.xsd)
jar cf $# sample-messages
""",
exec_tools = [
":xjc",
],
)
java_binary(
name = "xjc",
# See bin/xjc.sh in
# https://repo1.maven.org/maven2/com/sun/xml/bind/jaxb-ri/3.0.2/jaxb-ri-3.0.2.zip
main_class = "com.sun.tools.xjc.XJCFacade",
runtime_deps = [
artifact("com.sun.xml.bind:jaxb-ri:3.0.2"),
],
)
java_library(
name = "sample-lib",
srcs = [":sample-messages"],
deps = [
artifact("jakarta.xml.bind:jakarta.xml.bind-api:3.0.1"),
]
)
WORKSPACE:
load("#bazel_tools//tools/build_defs/repo:http.bzl", "http_archive")
RULES_JVM_EXTERNAL_TAG = "4.2"
RULES_JVM_EXTERNAL_SHA = "cd1a77b7b02e8e008439ca76fd34f5b07aecb8c752961f9640dea15e9e5ba1ca"
http_archive(
name = "rules_jvm_external",
strip_prefix = "rules_jvm_external-%s" % RULES_JVM_EXTERNAL_TAG,
sha256 = RULES_JVM_EXTERNAL_SHA,
url = "https://github.com/bazelbuild/rules_jvm_external/archive/%s.zip" % RULES_JVM_EXTERNAL_TAG,
)
load("#rules_jvm_external//:repositories.bzl", "rules_jvm_external_deps")
rules_jvm_external_deps()
load("#rules_jvm_external//:setup.bzl", "rules_jvm_external_setup")
rules_jvm_external_setup()
load("#rules_jvm_external//:defs.bzl", "maven_install")
maven_install(
artifacts = [
"com.sun.xml.bind:jaxb-ri:3.0.2",
"jakarta.xml.bind:jakarta.xml.bind-api:3.0.1",
],
# rules_jvm_external doesn't handle zip dependencies correctly, see
# https://github.com/bazelbuild/rules_jvm_external/issues/671
excluded_artifacts = [
"com.sun.xml.bind:jaxb-samples",
"com.sun.xml.bind:jaxb-release-documentation",
],
repositories = [
"https://repo1.maven.org/maven2",
],
)
src/main/xjb/sample.xjb:
<?xml version='1.0' encoding='UTF-8'?>
<jxb:bindings version="3.0"
xmlns:jxb="https://jakarta.ee/xml/ns/jaxb"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xmlns:xs="http://www.w3.org/2001/XMLSchema"
xsi:schemaLocation="http://java.sun.com/xml/ns/jaxb http://java.sun.com/xml/ns/jaxb/bindingschema_2_0.xsd">
<jxb:bindings schemaLocation="../xsd/sample.xsd" node="/xs:schema">
<jxb:schemaBindings>
<jxb:package name="org.acme.sample"/>
</jxb:schemaBindings>
</jxb:bindings>
</jxb:bindings>
src/main/xsd/sample.xsd:
<?xml version="1.0" encoding="UTF-8" ?>
<xs:schema xmlns:xs="http://www.w3.org/2001/XMLSchema">
<xs:element name="Sample">
<xs:complexType>
<xs:sequence>
<xs:element name="Date" type="xs:date"/>
<xs:element name="Content">
<xs:complexType>
<xs:sequence>
<xs:element name="Title" type="xs:string"/>
<xs:element name="Note" type="xs:string" minOccurs="0"/>
</xs:sequence>
</xs:complexType>
</xs:element>
</xs:sequence>
<xs:attribute name="color" type="xs:string" use="required"/>
</xs:complexType>
</xs:element>
</xs:schema>