为什么ant Manifest任务拆分长主类名？

Question

以下是我的Ant构建文件内容：

<?xml version="1.0"?>
<project name="testant"
         basedir=".">
  <property file="build.properties" />
  <target name="manifest">
    <tstamp />
    <manifest mode="update"
              file="manifest.mf">
      <attribute name="Built-By"
                 value="${user.name}" />
      <section name="common">
        <attribute name="Specification-Title"
                   value="${ant.project.name}" />
        <attribute name="Specification-Version"
                   value="1.0.0" />
        <attribute name="Specification-Vendor"
                   value="" />
        <attribute name="Implementation-Title"
                   value="" />
        <attribute name="Implementation-Version"
                   value="${TODAY}" />
        <attribute name="Implementation-Vendor"
                   value="" />
      </section>
      <attribute name="Main-Class"
                 value="${main.class}" />
    </manifest>
  </target>
</project>

以下是我的build.properties。

packages=com.javacodegeeks.patterns.strategypattern.*
main.class=com.javacodegeeks.patterns.strategypattern.TestStrategyPattern

以下是我的输出manifest.mf。

Manifest-Version: 1.0
Ant-Version: Apache Ant 1.10.6
Created-By: 10.0.2+13 (Oracle Corporation)
Built-By: root
Main-Class: com.javacodegeeks.patterns.strategypattern.TestStrategyPat
 tern

Name: common
Specification-Title: testant
Specification-Version: 1.0.0
Specification-Vendor: 
Implementation-Title: 
Implementation-Version: July 7 2019
Implementation-Vendor: 

为什么在主类名称中会生成空格？

它不会影响使用ant任务或jar命令生成jar文件。

可执行jar也可以按预期工作。

Answer 1

According to the JAR specification，

• 线路长度：

- No line may be longer than 72 bytes (not characters), in its UTF8-encoded form. If a value would make the initial line longer than this, it should be continued on extra lines (each starting with a single SPACE).

一些工具似乎忽略了这一要求，但Ant对此很严格。您的代码行换行长度为70个字符，可能加上\r\n。