对于不知道源码的项目，或者已经打包好，只需要修改少量文件的项目，可以直接操作jar包中的文件。

创建jar包

jar cvf jar-file input-file(s)

参数详解

• c ：表示创建一个jar文件
• f ：option indicates that you want the output to go to a file rather than to stdout.
• jar-file.jar：创建的jar文件名，最好指定jar后缀名
• input-file(s)：空格分割需要压缩的文件即可

可选参数

• v：打印日志
• 0：数字0，表示不压缩
• M：Indicates that the default manifest file should not be produced.
• m：Used to include manifest information from an existing manifest file：jar cmf jar-file existing-manifest input-file(s)
• -C：To change directories during execution of the command. See below for an example.

解压jar包

jar xvf jar-file [archived-file(s)]

参数详解

• x：表示解压
• f：indicates that the JAR file from which files are to be extracted is specified on the command line, rather than through stdin.
• jar-file：需要解压的文件

可选参数

• archived-file(s)：consisting of a space-separated list of the files to be extracted from the archive. If this argument is not present, the Jar tool will extract all the files in the archive.

更新文件

jar uf jar-file input-file(s)

参数详解

• u：option indicates that you want to update an existing JAR file.
• f：option indicates that the JAR file to update is specified on the command line.
• jar-file：is the existing JAR file that is to be updated.
• input-file(s)：is a space-delimited list of one or more files that you want to add to the JAR file.

删除文件

直接使用zip命令进行删除操作：

zip -d jar-file delete-file(s)

使用范例

将 cloud-sunyur-interface-prod.jar 包中的nacos-1.1.1替换为nacos-1.2.1：

# 解压jar包
jar xvf cloud-sunyur-interface-prod.jar

# 查看解压结果
$ ll
total 118272
drwxr-xr-x  4 adolphor  staff   128B Aug 25  2020 BOOT-INF
drwxr-xr-x  4 adolphor  staff   128B Aug 25  2020 META-INF
-rwxr-xr-x@ 1 adolphor  staff    57M Dec 24 09:18 cloud-sunyur-interface-prod.jar
drwxr-xr-x  3 adolphor  staff    96B Aug 25  2020 org

# 然后就可以将需要添加或更新的文件更新到jar包了，要注意：
# 1. 首先需要将更新的文件在解压出来的目录中更新掉
# 2. 然后在运行如下命令更新或新增文件：要注意如果是jar包必须使用 uvf0 而不是 uvf 参数来更新，避免把jar包压缩了，导致jvm不识别
$ jar uvf0 cloud-sunyur-interface-prod.jar BOOT-INF/lib/nacos-api-1.2.1.jar
$ jar uvf0 cloud-sunyur-interface-prod.jar BOOT-INF/lib/nacos-client-1.2.1.jar
$ jar uvf0 cloud-sunyur-interface-prod.jar BOOT-INF/lib/nacos-common-1.2.1.jar

# 使用zip命令删除
$ zip -d cloud-sunyur-interface-prod.jar BOOT-INF/lib/nacos-api-1.1.1.jar
$ zip -d cloud-sunyur-interface-prod.jar BOOT-INF/lib/nacos-client-1.1.1.jar
$ zip -d cloud-sunyur-interface-prod.jar BOOT-INF/lib/nacos-common-1.1.1.jar

# 然后验证是否能够运行即可
$ java -jar cloud-sunyur-interface-prod.jar

参考资料

• 打包或更新jar包
• Oracle - Creating a JAR File
• Oracle - Extracting the Contents of a JAR File
• Oracle - Updating a JAR File