Java与Maven的打包操作

发布于 2021-4-2 09:41
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很久没有创建新的Spring Boot项目了,创建发现有报错 , 提示xxxjar中没有主清单属性, 这个错误表示在打包后的jar的META-INF/MANIFEST.MF文件中,没有配置Main-Class导致的,编译的依赖是Maven,也在项目中添加了spring-boot-maven-plugin的依赖,生成的MANIFEST.MF文件还是没有包含Main-Class,这就让我有点兴趣来研究下到底是怎么回事

 

1. 普通Jar命令生成的 MANIFEST.MF 文件


JAR的意思是Java Archive, 是Java程序的归档文件,包含了Class代码以及相关资源文件,可以同理为Zip格式,META-INF/MANIFEST.MF就是其中的头文件,包含了Jar包的基本信息,先看看Jar包是怎么生成的

 

  • 生成普通Jar包


我们写一个Test.java文件来做测试

public class Test {
        public static void main(String[] args){
                System.out.println("hello world");
        }
}

执行javac Test.java命令,生成Test.class文件

 

然后我们执行jar -cvf testjar Test.class命令,此时生成了test.jar文件,目录结构如下:

Java与Maven的打包操作-开源基础软件社区

 

这个时候,我们看下MANIFEST.MF的文件内容如下:

Manifest-Version: 1.0
Created-By: 1.8.0_271 (Oracle Corporation)

 

-c表示创建jar包-

v表示输出创建信息

 

-f表示给生成的jar包命名

 

  • 生成可执行jar包


这里面并没有包含Main-Class的内容,因为我们在打包Jar的时候没有指定主类,那我们看下Jar的命令参数(我在文末贴了详细的man jar命令说明),我们通过-e命令来指定哪个类是该jar包的主类

jar -cvfe test.jar Test.class *.class

**********输出如下*************
已添加清单
正在添加: Test.class(输入 = 413) (输出 = 287)(压缩了 30%)

 

这时MANIFEST.MF的文件内容多了一行Main-Class来指定启动类:

Manifest-Version: 1.0
Created-By: 1.8.0_271 (Oracle Corporation)
Main-Class: Test.class

 

2. 基于Maven的打包

 

  • 普通Maven工程打包


创建maven普通工程

mvn archetype:generate -DgroupId=com.mario -DartifactId=maven-demo -Dversion=1.0 -DinteractiveMode=false

 

  1. 打包: mvn clean package -DskipTests
  2. 执行jar java -jar target/maven-demo-1.0.jar, 提示maven-demo-1.0.jar中没有主清单属性
  3. pom中添加依赖,先不指定启动类
      <build>
          <plugins>
              <plugin>
                  <!-- https://mvnrepository.com/artifact/org.apache.maven.plugins/maven-jar-plugin -->
                <groupId>org.apache.maven.plugins</groupId>
                <artifactId>maven-jar-plugin</artifactId>
                <version>3.2.0</version>
              </plugin>    
          </plugins>    
      </build>​
  4. 继续打包执行, 依然提示target/maven-demo-1.0.jar中没有主清单属性
  5. 添加<configuration> , 指定入口类
    <plugin>
                  <!-- https://mvnrepository.com/artifact/org.apache.maven.plugins/maven-jar-plugin -->
                <groupId>org.apache.maven.plugins</groupId>
                <artifactId>maven-jar-plugin</artifactId>
                <version>3.2.0</version>
                <configuration>
                <archive>
                    <manifest>
                        <addClasspath>true</addClasspath>
                        <classpathPrefix>lib/</classpathPrefix>
                        <mainClass>com.mario.App</mainClass>
                    </manifest>
                </archive>
                 </configuration>
              </plugin>    ​
  6. 再次打包运行,成功Java与Maven的打包操作-开源基础软件社区

 

Spring Boot工程打包


基于上面的工程,添加Spring Boot依赖

<dependency>
  <groupId>org.springframework.boot</groupId>
  <artifactId>spring-boot-starter</artifactId>
  <version>2.3.9.RELEASE</version>
</dependency>

 

修改App.java

@SpringBootApplication
public class App 
{
    public static void main( String[] args )
    {
            System.out.println( "Hello World!" );
            SpringApplication.run(App.class, args);
        
    }
}

 

  1. 打包, 看看MENIFEST.MF文件
    Manifest-Version: 1.0
    Class-Path: lib/spring-boot-starter-2.3.9.RELEASE.jar lib/spring-boot-
     2.3.9.RELEASE.jar lib/spring-context-5.2.13.RELEASE.jar lib/spring-ao
     p-5.2.13.RELEASE.jar lib/spring-beans-5.2.13.RELEASE.jar lib/spring-e
     xpression-5.2.13.RELEASE.jar lib/spring-boot-autoconfigure-2.3.9.RELE
     ASE.jar lib/spring-boot-starter-logging-2.3.9.RELEASE.jar lib/logback
     -classic-1.2.3.jar lib/logback-core-1.2.3.jar lib/slf4j-api-1.7.25.ja
     r lib/log4j-to-slf4j-2.13.3.jar lib/log4j-api-2.13.3.jar lib/jul-to-s
     lf4j-1.7.30.jar lib/jakarta.annotation-api-1.3.5.jar lib/spring-core-
     5.2.13.RELEASE.jar lib/spring-jcl-5.2.13.RELEASE.jar lib/snakeyaml-1.
     26.jar
    Build-Jdk-Spec: 1.8
    Created-By: Maven Jar Plugin 3.2.0
    Main-Class: com.mario.App
    
    ​
  2. 执行,报错
    Hello World!
    Exception in thread "main" java.lang.NoClassDefFoundError: org/springframework/boot/SpringApplication
        at com.mario.App.main(App.java:16)
    Caused by: java.lang.ClassNotFoundException: org.springframework.boot.SpringApplication
        at java.net.URLClassLoader.findClass(URLClassLoader.java:382)
        at java.lang.ClassLoader.loadClass(ClassLoader.java:418)
        at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:355)
        at java.lang.ClassLoader.loadClass(ClassLoader.java:351)
        ... 1 more​
  3. 修改pom.xml,取消maven-jar-plugin依赖,新增spring-boot-maven-plugin 依赖
    <build>
          <plugins>
              <plugin>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-maven-plugin</artifactId>
                <version>2.3.9.RELEASE</version>
            </plugin>
          </plugins>    
      </build>​
  4. 打包,查看MENIFEST.MF文件
    Manifest-Version: 1.0
    Archiver-Version: Plexus Archiver
    Built-By: mario
    Created-By: Apache Maven 3.6.3
    Build-Jdk: 1.8.0_271
    ​
  5. 没有入口类,修改pom.xml, 添加executions配置
    <build>
          <plugins>
              <plugin>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-maven-plugin</artifactId>
                <version>2.3.9.RELEASE</version>
                <executions>
                <execution>
                  <goals>
                    <goal>repackage</goal>
                  </goals>
                </execution>
            </executions>
            </plugin>
          </plugins>    
      </build>​
  6. 打包,查看MENIFEST.MF文件
    Manifest-Version: 1.0
    Spring-Boot-Classpath-Index: BOOT-INF/classpath.idx
    Archiver-Version: Plexus Archiver
    Built-By: mario
    Start-Class: com.mario.App
    Spring-Boot-Classes: BOOT-INF/classes/
    Spring-Boot-Lib: BOOT-INF/lib/
    Spring-Boot-Version: 2.3.9.RELEASE
    Created-By: Apache Maven 3.6.3
    Build-Jdk: 1.8.0_271
    Main-Class: org.springframework.boot.loader.JarLauncher
    ​
  7. 启动jar
     mario@appledeMacBook-Pro  ~/Dropbox/Inbox/test/maven-demo/maven-demo > java -jar target/maven-demo-1.0.jar
    Hello World!
    
      .   ____          _            __ _ _
     /\\ / ___'_ __ _ _(_)_ __  __ _ \ \ \ \
    ( ( )\___ | '_ | '_| | '_ \/ _` | \ \ \ \
     \\/  ___)| |_)| | | | | || (_| |  ) ) ) )
      '  |____| .__|_| |_|_| |_\__, | / / / /
     =========|_|==============|___/=/_/_/_/
     :: Spring Boot ::        (v2.3.9.RELEASE)
    
    2021-03-24 15:40:40.254  INFO 79480 --- [           main] com.mario.App                            : Starting App on appledeMacBook-Pro.local with PID 79480 (/Users/mario/Dropbox/Inbox/Test/maven-demo/maven-demo/target/maven-demo-1.0.jar started by mario in /Users/mario/Dropbox/Inbox/Test/maven-demo/maven-demo)
    2021-03-24 15:40:40.258  INFO 79480 --- [           main] com.mario.App                            : No active profile set, falling back to default profiles: default
    2021-03-24 15:40:41.122  INFO 79480 --- [           main] com.mario.App                            : Started App in 1.499 seconds (JVM running for 2.092)​
  8. 成功

 

参考文档: Spring Boot Maven Plugin Documentation

 

附录: JAR命令说明

NAME
       jar - Java archive tool

SYNOPSIS
       Create jar file
       jar c[v0M]f jarfile [ -C dir ] inputfiles [ -Joption ]
       jar c[v0]mf manifest jarfile [ -C dir ] inputfiles [ -Joption ]
       jar c[v0M] [ -C dir ] inputfiles [ -Joption ]
       jar c[v0]m manifest [ -C dir ] inputfiles [ -Joption ]

       Update jar file
       jar u[v0M]f jarfile [ -C dir ] inputfiles [ -Joption ]
       jar u[v0]mf manifest jarfile [ -C dir ] inputfiles [ -Joption ]
       jar u[v0M] [ -C dir ] inputfiles [ -Joption ]
       jar u[v0]m manifest [ -C dir ] inputfiles [ -Joption ]

       Extract jar file
       jar x[v]f jarfile [ inputfiles ] [ -Joption ]
       jar x[v] [ inputfiles ] [ -Joption ]

       List table of contents of jar file
       jar t[v]f jarfile [ inputfiles ] [ -Joption ]
       jar t[v] [ inputfiles ] [ -Joption ]

       Add index to jar file
       jar i jarfile [ -Joption ]

PARAMETERS
       cuxtivOMmf     Options that control the jar command.

       jarfile        Jar  file to be created (c), updated (u), extracted (x), or have its table of con-
                      tents viewed (t). The f option and filename jarfile are a pair  --  if  either  is
                      present,  they  must  both appear. Note that omitting f and jarfile accepts a "jar
                      file" from standard input (for x and t) or sends the "jar file" to standard output
                      (for c and u).

       inputfiles     Files  or directories, separated by spaces, to be combined into jarfile (for c and
                      u), or to be extracted (for x) or listed (for t) from jarfile. All directories are
                      processed recursively. The files are compressed unless option O (zero) is used.

       manifest       Pre-existing  manifest  file  whose  name: value pairs are to be included in MANI-
                      FEST.MF in the jar file.  The m option and filename manifest  are  a  pair  --  if
                      either  is  present, they must both appear. The letters m and f must appear in the
                      same order that manifest and jarfile appear.

       -C dir         Temporarily changes directories to dir while processing the  following  inputfiles
                      argument.  Multiple -C dir inputfiles sets are allowed.

       -Joption       Option  to  be  passed  into the Java runtime environment. (There must be no space
                      between -J and option).

DESCRIPTION
       The jar tool combines multiple files into a single JAR archive file.  jar  is  a  general-purpose
       archiving  and  compression tool, based on ZIP and the ZLIB compression format.  However, jar was
       designed mainly to facilitate the packaging of Java applets or applications  into  a  single  ar-
       chive.   When  the  components  of an applet or application (.class files, images and sounds) are
       combined into a single archive, they can be downloaded by a Java agent (like a browser) in a sin-
       gle  HTTP  transaction,  rather  than require a new connection for each piece.  This dramatically
       improves download time.  The jar tool also compresses  files,  which  further  improves  download
       time.   In  addition, it allows individual entries in a file to be signed by the applet author so
       that their origins can be authenticated.  The syntax for the jar tool is almost identical to  the
       syntax  for  the tar(1) command.  A jar archive can be used as a class path entry, whether or not
       it is compressed.

       Typical usage to combine files into a jar file is:

              % jar cf myFile.jar *.class

       In this example, all the class files in the current  directory  are  placed  in  the  file  named
       myjarfile.   A  manifest  file entry named META-INF/MANIFEST.MF is automatically generated by the
       jar tool and is always the first entry in the jar file.  The manifest file is the place where any
       meta-information about the archive is stored as name:value pairs.  Refer to the Jar File specifi-
       cation for details about how meta-information is stored in the manifest file.

       If you have a pre-existing manifest file whose name: value pairs you want the jar tool to include
       for the new jar archive, you can specify it using the m option:

            % jar cmf myManifestFile myJarFile *.class

       Be sure that any pre-existing manifest file that you use ends with a new line. The last line of a
       manifest file will not be parsed if it doesn't end with a new line character. Note that when  you
       specify  "cfm" instead of "cmf" (i.e., you invert the order of the "m" and "f" options), you need
       to specify the name of the jar archive first, followed by the name of the manifest file:

            % jar cfm myJarFile myManifestFile *.class

       The manifest is in a text format inspired by RFC822 ASCII format, so  it  is  easy  to  view  and
       process manifest-file contents.

       To extract the files from a jar file, use x , as in:

            % jar xf myFile.jar

       To extract only certain files from a jar file, supply their filenames:

            % jar xf myFile.jar foo bar

       Beginning  with  version  1.3  of the Java 2 SDK, the jar utility supports JarIndex, which allows
       application class loaders to load classes more efficiently from jar files. If an  application  or
       applet  is  bundled into multiple jar files,  only the necessary jar files will be downloaded and
       opened to load classes. This performance optimization is  enabled  by  running  jar  with  the  i
       option. It will generate package location information for the specified main jar file and all the
       jar files it depends on, which need to be specified in the Class-Path attribute of the  main  jar
       file's manifest.

            % jar i main.jar

       In  this  example,  an  INDEX.LIST file is inserted into the META-INF directory of main.jar.  The
       application class loader will use the information stored in this file for efficient  class  load-
       ing.  Refer to the JarIndex specification for details about how location information is stored in
       the index file.

       A standard way to copy directories is to first compress files  in  dir1  to  standard  out,  then
       extract from standard in to dir2 (omitting f from both jar commands):

            % (cd dir1; jar c .) | (cd dir2; jar x)

       Examples  of using the jar tool to operate on jar files and jar file manifests are provided below
       and in the Jar trail of the Java Tutorial.

OPTIONS
       c    Creates a new archive file named jarfile (if f is specified) or to standard output (if f and
            jarfile are omitted). Add to it the files and directories specified by inputfiles.

       u    Updates an existing file jarfile (when f is specified) by adding to it files and directories
            specified by inputfiles. For example:

            jar uf foo.jar foo.class

       would add the file foo.class to the existing jar file foo.jar. The u option can also  update  the
       manifest entry, as given by this example:

            jar umf manifest foo.jar

       updates the foo.jar manifest with the name: value pairs in manifest.

       x    Extracts  files and directories from jarfile (if f is specified) or standard input (if f and
            jarfile are omitted). If inputfiles is specified, only those specified files and directories
            are extracted. Otherwise, all files and directories are extracted.

       t    Lists  the  table  of  contents from jarfile (if f is specified) or standard input (if f and
            jarfile are omitted). If inputfiles is specified, only those specified files and directories
            are listed.  Otherwise, all files and directories are listed.

       i    Generate  index information for the specified jarfile and its dependent jar files. For exam-
            ple:

            jar i foo.jar

       would generate an INDEX.LIST file in foo.jar which contains location information for each package
       in foo.jar and all the jar files specified in the Class-Path attribute of foo.jar.  See the index
       example.

       f    Specifies the file jarfile to be created (c), updated (u), extracted (x),  indexed  (i),  or
            viewed  (t).  The  f  option  and  filename jarfile are a pair -- if present, they must both
            appear.  Omitting f and jarfile accepts a "jar file" from standard input (for x  and  t)  or
            sends the "jar file" to standard output (for c and u).

       v    Generates verbose output to standard output. Examples shown below.

       0    Zero. Store without using ZIP compression.

       M    Do  not  create  a manifest file entry (for c and u), or delete a manifest file entry if one
            exists (for u).

       m    Includes name: value attribute pairs from the specified manifest file manifest in  the  file
            at META-INF/MANIFEST.MF. A name: value pair is added unless one already exists with the same
            name, in which case its value is updated.

       On the command line, the letters m and f must appear in the same order that manifest and  jarfile
       appear. Example use:

            jar cmf myManifestFile myFile.jar *.class

       You  can add special-purpose name: value attribute pairs to the manifest that aren't contained in
       the default manifest. Examples of such attributes would be those for vendor information,  version
       information,  package sealing, and to make JAR-bundled applications executable. See the JAR Files
       trail in the Java Tutorial and the Notes for Developers page for examples of using the m  option.

       -C   Temporarily  changes directories (cd dir) during execution of the jar command while process-
            ing the following inputfiles argument. Its operation is intended to be  similar  to  the  -C
            option of the UNIX tar utility.  For example:

               % jar uf foo.jar -C classes bar.classes

       would  change  to the classes directory and add the bar.class from that directory to foo.jar. The
       following command,

               jar uf foo.jar -C classes . -C bin xyz.class

       would change to the classes directory and add to foo.jar all files within the  classes  directory
       (without  creating  a classes directory in the jar file), then change back to the original direc-
       tory before changing to the bin directory to add xyz.class to foo.jar.  If  classes  holds  files
       bar1 and bar2, then here's what the jar file would contain using jar tf foo.jar:

               META-INF/
               META-INF/MANIFEST.MF
               bar1
               bar2
               xyz.class

       Joption
            Pass option to the Java runtime environment, where option is one of the options described on
            the man page for the java application launcher, java(1).  For example,  -J-Xms48m  sets  the
            startup  memory  to  48  megabytes.  It is a common convention for -J to pass options to the
            underlying virtual machine.

COMMAND LINE ARGUMENT FILES
       To shorten or simplify the jar command line, you can specify one or more  files  that  themselves
       contain  arguments  to  the jar command (except -J options).  This enables you to create jar com-
       mands of any length, overcoming command line limits imposed by the operating system.

       An argument file can include options and filenames. The arguments within a file can be space-sep-
       arated or newline-separated. Filenames within an argument file are relative to the current direc-
       tory, not the location of the argument file. Wildcards (*) that might otherwise  be  expanded  by
       the  operating  system  shell are not expanded. Use of the '@' character to recursively interpret
       files is not supported. The -J options are not supported because they are passed to the launcher,
       which does not support argument files.

       When  executing jar, pass in the path and name of each argument file with the '@' leading charac-
       ter. When jar encounters an argument beginning with the character `@', it expands the contents of
       that file into the argument list.

       For  example,  you could use a single argument file named "classes.list" to hold the names of the
       files:

            % find . -name '*.class' -print > classes.list

       Then execute the jar command passing in the argfile:

            % jar cf my.jar @classes.list

       An argument file can be passed in with a path, but any filenames inside the  argument  file  that
       have relative paths are relative to the current working directory, not the path passed in. Here's
       such an example:

            % jar @path1/classes.list

EXAMPLES
       To add all the files in a particular directory to an archive (overwriting contents if the archive
       already exists). Enumerating verbosely (with the "v" option) will tell you more information about
       the files in the archive, such as their size and last modified date.

              % ls
              1.au          Animator.class    monkey.jpg
              2.au          Wave.class        spacemusic.au
              3.au          at_work.gif
              % jar cvf bundle.jar *
              added manifest
              adding: 1.au(in = 2324) (out= 67)(deflated 97%)
              adding: 2.au(in = 6970) (out= 90)(deflated 98%)
              adding: 3.au(in = 11616) (out= 108)(deflated 99%)
              adding: Animator.class(in = 2266) (out= 66)(deflated 97%)
              adding: Wave.class(in = 3778) (out= 81)(deflated 97%)
              adding: at_work.gif(in = 6621) (out= 89)(deflated 98%)
              adding: monkey.jpg(in = 7667) (out= 91)(deflated 98%)
              adding: spacemusic.au(in = 3079) (out= 73)(deflated 97%)
       If you already have separate subdirectories for images, audio files and classes, you can  combine
       them into a single jar file:

              % ls -F
              audio/ classes/ images/

              % jar cvf bundle.jar audio classes images
              added manifest
              adding: audio/(in = 0) (out= 0)(stored 0%)
              adding: audio/1.au(in = 2324) (out= 67)(deflated 97%)
              adding: audio/2.au(in = 6970) (out= 90)(deflated 98%)
              adding: audio/3.au(in = 11616) (out= 108)(deflated 99%)
              adding: audio/spacemusic.au(in = 3079) (out= 73)(deflated 97%)
              adding: classes/(in = 0) (out= 0)(stored 0%)
              adding: classes/Animator.class(in = 2266) (out= 66)(deflated 97%)
              adding: classes/Wave.class(in = 3778) (out= 81)(deflated 97%)
              adding: images/(in = 0) (out= 0)(stored 0%)
              adding: images/monkey.jpg(in = 7667) (out= 91)(deflated 98%)
              adding: images/at_work.gif(in = 6621) (out= 89)(deflated 98%)

              % ls -F
              audio/ bundle.jar classes/ images/

       To see the entry names in the jarfile, use the t option:

              % jar tf bundle.jar
              META-INF/
              META-INF/MANIFEST.MF
              audio/1.au
              audio/2.au
              audio/3.au
              audio/spacemusic.au
              classes/Animator.class
              classes/Wave.class
              images/monkey.jpg
              images/at_work.gif

       To add an index file to the jar file for speeding up class loading, use the "i" option.

       Let's  say  you  split  the inter-dependent classes for a stock trade application, into three jar
       files: main.jar, buy.jar, and sell.jar.  If you specify the Class-path attribute in the  main.jar
       manifest as:

            Class-Path: buy.jar sell.jar

       then you can use the i option to speed up your application's class loading time:

            % jar i main.jar

       An  INDEX.LIST file is inserted to the META-INF directory which will enable the application class
       loader to download the specified jar files when it is searching for classes or resources.

SEE ALSO
       The JAR Overview @
         http://java.sun.com/javase/6/docs/technotes/guides/jar/jarGuide.html


       The JAR File Specification @
         http://java.sun.com/javase/6/docs/technotes/guides/jar/jar.html


       The JARIndex Spec @
         http://java.sun.com/javase/6/docs/technotes/guides/jar/jar.html


       JAR Tutorial @
         http://java.sun.com/docs/books/tutorial/jar/


       pack200 Reference Page @
         http://java.sun.com/javase/6/docs/technotes/tools/share/pack200.html

 

 

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已于2021-4-2 09:41:29修改
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