Bazel 构建：使用 JAXB2 从 XSD 生成 java 类

Question

我是 Bazel 的新手。我想使用 JaxB2 从 XSD 文档生成 Java 类。我找不到任何 Java_Rule 来自动生成类。查看 this google group discussion，带有显式命令的 genrule 似乎为作者生成 java 类。

我尝试使用讨论中建议的 github repository，但因 no such target '@local_jdk//:jdk-default': target 'jdk-default' not declared in package ' 错误而失败。

➜  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)

我尝试搜索java_toolchain 选项来处理上述错误，但没有成功。

有没有 Bazel 构建示例文件，我可以看看如何根据 XSD 文件生成 java 类？

Answer 1

当时 google 组讨论中的示例是正确的，但是 Java 与 Bazel 的工具链集成随着时间的推移发生了变化，并且确实目标 @local_jdk//:jdk-default 不再存在， @local_jdk//:jar 已弃用。

但更大的问题是 jaxb 和 xjc 已经 deprecated/removed 从 jdk 开始 jdk 9: http://openjdk.java.net/jeps/320

您需要单独获取 jaxb，如下所示：

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>

Bazel 构建：使用 JAXB2 从 XSD 生成 java 类

Bazel Build: Generate java classes from XSD using JAXB2

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