详解如何使用maven生成可以执行的jar

不依赖任何外界包，maven如何生成可以执行的jar?

pom中不包含任何引用的情况下，只需要在pom中添加 maven-jar-plugin即可。

解决过程

新建项目，仅包含一个main函数类：xixi.java，输出 xixi say: hello

pom中配置为

<groupid>com.paxi</groupid>
 <artifactid>xixi</artifactid>
 <version>1.0-snapshot</version>
 <packaging>jar</packaging>

 <name>xixi</name>
 <url>http://maven.apache.org</url>

 <properties>
  <project.build.sourceencoding>utf-8</project.build.sourceencoding>
 </properties>

执行 mvn clean install 生成jar包 xixi-1.0-snapshot.jar,执行jar命令,执行反馈出错

 java -jar xixi-1.0-snapshot.jar
xixi-1.0-snapshot.jar中没有主清单属性

对jar进行解压缩jar xvf xixi-1.0-snapshot.jar查看对应文件manifest.mf

 cat meta-inf/manifest.mf
manifest-version: 1.0
archiver-version: plexus archiver
built-by: paxi
created-by: apache maven 3.3.3
build-jdk: 1.8.0_121

在pom中添加插件 maven-jar-plugin

<build>
  <plugins>
   <plugin>
    <groupid>org.apache.maven.plugins</groupid>
    <artifactid>maven-jar-plugin</artifactid>
    <version>3.1.0</version>
    <configuration>
     <archive>
      <manifest>
       <mainclass>com.paxi.xixi</mainclass>
      </manifest>
     </archive>
    </configuration>
   </plugin>
  </plugins>
 </build>

执行成功输出

 java -jar xixi-1.0-snapshot.jar
xixi say: hello

再对解压缩后的manifest.mf文件查看为

 cat meta-inf/manifest.mf
manifest-version: 1.0
built-by: paxi
created-by: apache maven 3.3.3
build-jdk: 1.8.0_121
main-class: com.paxi.xixi //新增

在pom中添加依赖，maven如何生成可执行jar?

需要使用插件maven-dependency-plugin 和 maven-jar-plugin。

解决过程

在pom中仅仅增加一个apache-commons包

<groupid>com.paxi</groupid>
 <artifactid>xixi</artifactid>
 <version>1.0-snapshot</version>
 <packaging>jar</packaging>

 <name>xixi</name>
 <url>http://maven.apache.org</url>

 <properties>
  <project.build.sourceencoding>utf-8</project.build.sourceencoding>
 </properties>
 <dependencies>

   <dependency>
    <groupid>org.apache.commons</groupid>
    <artifactid>commons-lang3</artifactid>
    <version>3.7</version>
  </dependency>

 </dependencies>

在代码中运用common包中的一个类

 public static void main(string[] args) {
    string words = "xixi say: hello";
    if (stringutils.isnotblank(words))
    {
      system.out.println(words);
    }
  }

打包后直接运行出错

 java -jar xixi-1.0-snapshot.jar
exception in thread "main" java.lang.noclassdeffounderror: org/apache/commons/lang3/stringutils
    at com.paxi.xixi.main(xixi.java:11)
caused by: java.lang.classnotfoundexception: org.apache.commons.lang3.stringutils
    at java.net.urlclassloader.findclass(urlclassloader.java:381)
    at java.lang.classloader.loadclass(classloader.java:424)
    at sun.misc.launcher$appclassloader.loadclass(launcher.java:331)
    at java.lang.classloader.loadclass(classloader.java:357)
    ... 1 more

在pom中增加插件

<build>
  <plugins>
   <plugin>
    <groupid>org.apache.maven.plugins</groupid>
    <artifactid>maven-jar-plugin</artifactid>
    <version>3.1.0</version>
    <configuration>
     <archive>
      <manifest>
       <addclasspath>true</addclasspath>
       <mainclass>com.paxi.xixi</mainclass>
       <classpathprefix>libs/</classpathprefix>
      </manifest>
     </archive>
    </configuration>
   </plugin>

   <plugin>
    <groupid>org.apache.maven.plugins</groupid>
    <artifactid>maven-dependency-plugin</artifactid>
    <version>3.1.1</version>
    <executions>
     <execution>
      <id>copy-dependencies</id>
      <phase>package</phase>
      <goals>
       <goal>copy-dependencies</goal>
      </goals>
      <configuration>
       <outputdirectory>
        ${project.build.directory}/libs
       </outputdirectory>
      </configuration>
     </execution>
    </executions>
   </plugin>

  </plugins>
 </build>

再次运行

 java -jar xixi-1.0-snapshot.jar
xixi say: hello

manifest.mf文件为

 cat meta-inf/manifest.mf
manifest-version: 1.0
built-by: paxi
class-path: libs/commons-lang3-3.7.jar
created-by: apache maven 3.3.3
build-jdk: 1.8.0_121
main-class: com.paxi.xixi

不仅使用了pom中的依赖还使用了三方的jar,maven如何生成可执行jar?

编译过程需要对编译插件 maven-compiler-plugin做修改，运行的时候需要加上三方jar的目录，执行命令

 java -jar -djava.ext.dirs=lib/ target/xixi-1.0-snapshot.jar
xixi say: hello
papa say:hello

编译解决过程

测试代码为

 public static void main(string[] args) {
    string words = "xixi say: hello";
    if (stringutils.isnotblank(words))
    {
      system.out.println(words);
    }
    papa.say();
  }

使用mvn命令执行报错

[error] failed to execute goal org.apache.maven.plugins:maven-compiler-plugin:3.1:compile (default-compile) on project xixi: compilation failure
xixi/src/main/java/com/paxi/xixi.java:[15,9] 找不到符号

pom中添加编译插件

<plugin>
    <groupid>org.apache.maven.plugins</groupid>
    <artifactid>maven-compiler-plugin</artifactid>
    <version>3.1</version>
    <configuration>
     <compilerargs>
      <arg>-djava.ext.dirs=lib/</arg>
     </compilerargs>
    </configuration>
   </plugin>

打包执行

 java -jar target/xixi-1.0-snapshot.jar
xixi say: hello
exception in thread "main" java.lang.noclassdeffounderror: com/paxi/papa
  at com.paxi.xixi.main(xixi.java:15)
caused by: java.lang.classnotfoundexception: com.paxi.papa
  at java.net.urlclassloader.findclass(urlclassloader.java:381)
  at java.lang.classloader.loadclass(classloader.java:424)
  at sun.misc.launcher$appclassloader.loadclass(launcher.java:331)
  at java.lang.classloader.loadclass(classloader.java:357)
  ... 1 more

加上参数后即可得出结果

 java -jar -djava.ext.dirs=lib/ target/xixi-1.0-snapshot.jar
xixi say: hello
papa say:hello

以上就是本文的全部内容，希望对大家的学习有所帮助，也希望大家多多支持。