我花了好几个小时试图理解 Android 的构建过程。

我正在使用适用于 Android 的 IntelliJ Idea(这是一个很棒的工具)。我在 IntelliJ 中打开了一个名为“Hello Android”的测试项目。该项目的文件名为 build.xml，代码如下

<?xml version="1.0" encoding="UTF-8"?>
<project name="HelloAndroid" default="help">

    <!-- The local.properties file is created and updated by the 'android' tool.
         It contains the path to the SDK. It should *NOT* be checked into
         Version Control Systems. -->
    <property file="local.properties" />

    <!-- The ant.properties file can be created by you. It is only edited by the
         'android' tool to add properties to it.
         This is the place to change some Ant specific build properties.
         Here are some properties you may want to change/update:

         source.dir
             The name of the source directory. Default is 'src'.
         out.dir
             The name of the output directory. Default is 'bin'.

         For other overridable properties, look at the beginning of the rules
         files in the SDK, at tools/ant/build.xml

         Properties related to the SDK location or the project target should
         be updated using the 'android' tool with the 'update' action.

         This file is an integral part of the build system for your
         application and should be checked into Version Control Systems.

         -->
    <property file="ant.properties" />

    <!-- if sdk.dir was not set from one of the property file, then
         get it from the ANDROID_HOME env var.
         This must be done before we load project.properties since
         the proguard config can use sdk.dir -->
    <property environment="env" />
    <condition property="sdk.dir" value="${env.ANDROID_HOME}">
        <isset property="env.ANDROID_HOME" />
    </condition>

    <!-- The project.properties file is created and updated by the 'android'
         tool, as well as ADT.

         This contains project specific properties such as project target, and library
         dependencies. Lower level build properties are stored in ant.properties
         (or in .classpath for Eclipse projects).

         This file is an integral part of the build system for your
         application and should be checked into Version Control Systems. -->
    <loadproperties srcFile="project.properties" />

    <!-- quick check on sdk.dir -->
    <fail
            message="sdk.dir is missing. Make sure to generate local.properties using 'android update project' or to inject it through the ANDROID_HOME environment variable."
            unless="sdk.dir"
    />

    <!--
        Import per project custom build rules if present at the root of the project.
        This is the place to put custom intermediary targets such as:
            -pre-build
            -pre-compile
            -post-compile (This is typically used for code obfuscation.
                           Compiled code location: ${out.classes.absolute.dir}
                           If this is not done in place, override ${out.dex.input.absolute.dir})
            -post-package
            -post-build
            -pre-clean
    -->
    <import file="custom_rules.xml" optional="true" />

    <!-- Import the actual build file.

         To customize existing targets, there are two options:
         - Customize only one target:
             - copy/paste the target into this file, *before* the
               <import> task.
             - customize it to your needs.
         - Customize the whole content of build.xml
             - copy/paste the content of the rules files (minus the top node)
               into this file, replacing the <import> task.
             - customize to your needs.

         ***********************
         ****** IMPORTANT ******
         ***********************
         In all cases you must update the value of version-tag below to read 'custom' instead of an integer,
         in order to avoid having your file be overridden by tools such as "android update project"
    -->
    <!-- version-tag: 1 -->
    <import file="${sdk.dir}/tools/ant/build.xml" />

</project>

然后我在 IntelliJ Idea Build -> Generate Ant Build 中做了以下操作并选择了以下选项

1. 生成多文件 ant build
2. 输出文件名:helloandroid
3. 启用 UI 表单编译
4. 使用项目文件中的 JSDK 定义

这导致创建了三个额外的文件

1. 你好android.properties
2. 你好android.xml
3. module_helloandroid.xml

helloandroid.properties

path.variable.maven_repository=C\:\\Users\\abc\\.m2\\repository
jdk.home.android_4.1_platform=C\:/Program Files (x86)/Android/android-sdk

helloandroid.xml

<?xml version="1.0" encoding="UTF-8"?>
<project name="HelloAndroid" default="help">

    <!-- The local.properties file is created and updated by the 'android' tool.
         It contains the path to the SDK. It should *NOT* be checked into
         Version Control Systems. -->
    <property file="local.properties" />

    <!-- The ant.properties file can be created by you. It is only edited by the
         'android' tool to add properties to it.
         This is the place to change some Ant specific build properties.
         Here are some properties you may want to change/update:

         source.dir
             The name of the source directory. Default is 'src'.
         out.dir
             The name of the output directory. Default is 'bin'.

         For other overridable properties, look at the beginning of the rules
         files in the SDK, at tools/ant/build.xml

         Properties related to the SDK location or the project target should
         be updated using the 'android' tool with the 'update' action.

         This file is an integral part of the build system for your
         application and should be checked into Version Control Systems.

         -->
    <property file="ant.properties" />

    <!-- if sdk.dir was not set from one of the property file, then
         get it from the ANDROID_HOME env var.
         This must be done before we load project.properties since
         the proguard config can use sdk.dir -->
    <property environment="env" />
    <condition property="sdk.dir" value="${env.ANDROID_HOME}">
        <isset property="env.ANDROID_HOME" />
    </condition>

    <!-- The project.properties file is created and updated by the 'android'
         tool, as well as ADT.

         This contains project specific properties such as project target, and library
         dependencies. Lower level build properties are stored in ant.properties
         (or in .classpath for Eclipse projects).

         This file is an integral part of the build system for your
         application and should be checked into Version Control Systems. -->
    <loadproperties srcFile="project.properties" />

    <!-- quick check on sdk.dir -->
    <fail
            message="sdk.dir is missing. Make sure to generate local.properties using 'android update project' or to inject it through the ANDROID_HOME environment variable."
            unless="sdk.dir"
    />

    <!--
        Import per project custom build rules if present at the root of the project.
        This is the place to put custom intermediary targets such as:
            -pre-build
            -pre-compile
            -post-compile (This is typically used for code obfuscation.
                           Compiled code location: ${out.classes.absolute.dir}
                           If this is not done in place, override ${out.dex.input.absolute.dir})
            -post-package
            -post-build
            -pre-clean
    -->
    <import file="custom_rules.xml" optional="true" />

    <!-- Import the actual build file.

         To customize existing targets, there are two options:
         - Customize only one target:
             - copy/paste the target into this file, *before* the
               <import> task.
             - customize it to your needs.
         - Customize the whole content of build.xml
             - copy/paste the content of the rules files (minus the top node)
               into this file, replacing the <import> task.
             - customize to your needs.

         ***********************
         ****** IMPORTANT ******
         ***********************
         In all cases you must update the value of version-tag below to read 'custom' instead of an integer,
         in order to avoid having your file be overridden by tools such as "android update project"
    -->
    <!-- version-tag: 1 -->
    <import file="${sdk.dir}/tools/ant/build.xml" />

</project>

module_helloandroid.xml

<copy todir="${helloandroid.output.dir}">
  <fileset dir="${module.helloandroid.basedir}/src">
    <patternset refid="compiler.resources"/>
    <type type="file"/>
    <patternset refid="excluded.from.compilation.helloandroid"/>
  </fileset>
  <fileset dir="${module.helloandroid.basedir}/gen">
    <patternset refid="compiler.resources"/>
    <type type="file"/>
    <patternset refid="excluded.from.compilation.helloandroid"/>
  </fileset>
</copy>

我的问题

1. 为什么我们有不同的build.xml 和helloandroid.xml 等两个文件？
2. 可以在构建过程中使用这些文件吗？
3. 我们能否编辑这些文件以添加更多 Ant 构建脚本？
4. 为什么 build.xml 在 env.ANDROID_HOME 显示错误？
5. 什么 helloandroid.xml 在 jdk.home.1.6 显示错误？

最佳答案

1. 构建文件可以包含其他构建文件，这是正常做法。您的项目的helloandroid.xml 与build.xml 文件完全相同，您可以随意修改其中一个并丢弃另一个。 build.xml 文件是 Ant 的首选约定。您的属性文件仅用于设置属性，模块文件看起来不会被调用，但可能存在，以便您可以包含它并按照它指定的方式进行文件复制。

2. 是的，只包括它们。可以使用 helloandroid.properties 文件代替对通用 project.properties 文件的调用，或者您可以将其保留原样。

3. 是的，请编辑它们，尽管它们应该足以让您轻松开始。

4. 您的 ANDROID_HOME 环境变量似乎尚未设置。您可以通过 IntelliJ 进行设置，但我建议您在操作系统级别进行设置。

5. 您的 JAVA_HOME 环境变量似乎尚未设置。您可以通过 IntelliJ 进行设置，但我建议您在操作系统级别进行设置。

关于android - build.xml 和 project_name.xml 的区别，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/12341386/