Detailed description of the manifest. MF File

Open the JAR file of Java we often see that the file contains a META-INF directory, there are some files under this directory, there must be a manifest. mf: This file describes a lot of information about the JAR file. The following describes manifest in detail. for the content of the MF file, see struts first. manifest. mf file content:

Manifest-version: 1.0
Created-by: Apache ant 1.5.1
Extension-Name: Struts Framework
Specification-title: Struts Framework
Specification-vendor: Apache Software Foundation
Specification-version: 1.1
Implementation-title: Struts Framework
Implementation-vendor: Apache Software Foundation
Implementation-vendor-ID: org. Apache
Implementation-version: 1.1
Class-path: commons-beanutils.jar commons-collections.jar commons-digester.jar commons-logging.jar commons-validator.jar jakarta-oro.jar struts-legacy.jar

If we classify the configuration information in manifest, We can summarize the following categories:

I. general attributes

1. manifest-version
Used to define the version of the manifest file, for example, manifest-version: 1.0

2. Created-
The file creator. Generally, this attribute is generated by the jar command line tool, for example, created-by: Apache ant 1.5.1.

3. Signature-version
Define the signature version of the JAR File

4. Class-Path
This value is used by applications or classloaders to build an internal class search path.

2. Application-related attributes

1. Main-class
Define the entry class of the JAR file, which must be an executable class. Once this attribute is defined, you can run the JAR file through Java-jar X. jar.
 
3. Applet-related attributes

1. extendsion-list
This attribute specifies the extended information list required by the applet. Each name in the list corresponds to the following attributes:
2. <extension>-extension-name
3. <extension>-specification-version
4. <extension>-implementation-version
5. <extension>-implementation-vendor-ID
5. <extension>-implementation-URL

Iv. Extended identity attributes

1. Extension-name
This attribute defines the identity of the JAR file, such as extension-Name: Struts Framework
 
5. Package extended attributes
 
1. Implementation-title defines the title of the extension implementation
2. Implementation-version defines the version of the extension implementation
3. Implementation-vendor defines the organization of the extension implementation
4. Implementation-vendor-ID defines the identifier of the organization for the extension implementation
5. Implementation-URL: Specifies the URL of the extension package)
6. Specification-title defines the title of the extension Specification
7. Specification-version defines the version of the extension Specification
8. Specification-Vendor declares the organization that maintains the Specification
9. Sealed defines whether to seal the JAR file. The value can be true or false (which I do not quite understand)

Vi. Signature-related attributes

For signature attributes, refer to the section in mail. Jar provided by javamail.

Name: javax/mail/address. Class
Digest-algorithms: Sha MD5
Sha-Digest: ajr7rqnn // cdygouxbd06msvfi4 =
MD5-Digest: zntiq2aqatsniowxi1pqpw =

This section defines the Class Name of the class signature, the algorithm name for calculating the digest, and the corresponding digest content (encoded using base64)

VII. Custom Attributes

In addition to the attributes mentioned above, you can also add your own attributes and response values in manifest. MF. For example, the jar package of the Java program may contain the following information:

Microedition-configuration: CLDC-1.0
MIDlet-Name: j2me_mobber MIDlet suite
MIDlet-Info-URL: http://www.javayou.com/
MIDlet-icon:/icon.png
MIDlet-vendor: MIDlet suite vendor
MIDlet-1: mobber,/icon.png, mobber
MIDlet-version: 1.0.0
Microedition-profile: MIDP-1.0
MIDlet-Description: Communicator

How can we read this information? JDK provides an API for processing this information. For more information, see Java. util. in the jar package, we can pass a jar file path to jarfile, and then call the getmanifest method of jarfile to obtain manifest information.

For more information about the specifications of jar files, see
Http://java.sun.com/j2se/1.3/docs/guide/jar/jar.html

Description
Http://www-900.ibm.com/developerWorks/cn/java/j-jar/

Original article: http://www.java3z.com/cwbwebhome/article/article2/2843.html