Reason: the meta-inf/manifest.mf file in the jar package is missing the key value pair of “main class”
terms of settlement:
<build>
<pluginManagement>
<plugins>
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-jar-plugin</artifactId>
<configuration>
<archive>
<manifest>
<mainClass>com.u1w2.sla.App</mainClass>
</manifest>
</archive>
</configuration>
</plugin>
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When executing Java – jar xxx.jar com.helloworld under Linux system, you will often be prompted: no main manifest attribute, in xxx.jar
The reasons are as follows:
Normally, when Java is packaged as a jar package, you need to specify the main class item in manifest.mf to find the corresponding main class when running Java – jar xxx.jar. Because – jar means that the following jar package has a main class to run independently, you need to specify this class when you package it into a jar package
If you want to specify the class you want to run at runtime, you should use – CP/– classpath to specify it. The command is as follows:
for example: Java – CP xxx.jar com.helloworld
Packaging can also be specified in the following way to directly run the jar file Java – jar XXX. Jar
<plugins>
<!-- When packaging the jar file, configure the manifest file and add the jar dependencies of the lib package -->
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-jar-plugin</artifactId>
<version>2.6</version>
<configuration>
<classesDirectory>target/classes/</classesDirectory>
<archive>
<manifest>
<mainClass>com.alibaba.dubbo.container.Main</mainClass>
<!-- Timestamped version not recorded in MANIFEST.MF file when packing -->
<useUniqueVersions>false</useUniqueVersions>
<addClasspath>true</addClasspath>
<classpathPrefix>crm-lib/</classpathPrefix>
</manifest>
<manifestEntries>
<Class-Path>.</Class-Path>
</manifestEntries>
</archive>
</configuration>
</plugin>
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-dependency-plugin</artifactId>
<executions>
<execution>
<id>copy-dependencies</id>
<phase>package</phase>
<goals>
<goal>copy-dependencies</goal>
</goals>
<configuration>
<type>jar</type>
<includeTypes>jar</includeTypes>
<outputDirectory>
${project.build.directory}/crm-lib
</outputDirectory>
</configuration>
</execution>
</executions>
</plugin>
</plugins>Recently, the springboot version was upgraded to 2.1.6. Release , and the springcloud version was upgraded to Greenwich. Sr2 when pushing the remote image to Ranger, it has been unable to start. The log shows no main manifest attribute, in/APP. Jar
Packaging tools have not changed, no problem before, and then click the mouse packaging plug-in found no version number
<plugin>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-maven-plugin</artifactId>
<!--Be sure to match the springboot version number, because the new version of springboot no longer sets the dependencies of this plugin-->
<version>${spring-boot.version}</version>
<executions>
<execution>
<goals>
<goal>repackage</goal>
</goals>
</execution>
</executions>
</plugin>
Add in the version number and it’s done
The reason for the error is that the build. Gradle file is missing the package plug-in for gradle
buildscript {
dependencies {
classpath("org.springframework.boot:spring-boot-gradle-plugin:2.2.6.RELEASE")
}
}
plugins {
id 'java'
}
apply plugin: 'java'
apply plugin: 'org.springframework.boot'
group 'com.guanguan.docker'
version '1.0-SNAPSHOT'
sourceCompatibility = 1.8
repositories {
mavenCentral()
}
dependencies {
compile('org.springframework.boot:spring-boot-starter-web:2.2.6.RELEASE')
testCompile group: 'junit', name: 'junit', version: '4.12'
}
Just patch spring-boot-gradle-plugin.
Verification.
./gradlew build
$ java -jar ./build/libs/scaffold-1.0-SNAPSHOT.jar
Then you can see the program get up.