java -jar 和 java -cp 区别

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Project Directory

SRC

MainTest.java

1 package org.fool.test;
2
3 public class MainTest {
4     public static void main(String[] args) {
5         System.out.println("Hello Jar");
6     }
7 }

Maven Dependency

 1 <?xml version="1.0" encoding="UTF-8"?>
 2 <project xmlns="http://maven.apache.org/POM/4.0.0"
 3          xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
 4          xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
 5     <modelVersion>4.0.0</modelVersion>
 6
 7     <groupId>org.fool.test</groupId>
 8     <artifactId>hello-jar</artifactId>
 9     <version>1.0-SNAPSHOT</version>
10
11     <build>
12         <plugins>
13             <plugin>
14                 <groupId>org.apache.maven.plugins</groupId>
15                 <artifactId>maven-compiler-plugin</artifactId>
16                 <version>3.8.1</version>
17                 <configuration>
18                     <source>1.8</source>
19                     <target>1.8</target>
20                 </configuration>
21             </plugin>
22
23             <plugin>
24                 <groupId>org.apache.maven.plugins</groupId>
25                 <artifactId>maven-assembly-plugin</artifactId>
26                 <version>3.2.0</version>
27                 <configuration>
28                     <appendAssemblyId>false</appendAssemblyId>
29                     <descriptorRefs>
30                         <descriptorRef>jar-with-dependencies</descriptorRef>
31                     </descriptorRefs>
32                     <archive>
33                         <manifest>
34                             <mainClass>org.fool.test.MainTest</mainClass>
35                         </manifest>
36                     </archive>
37                 </configuration>
38                 <executions>
39                     <execution>
40                         <id>make-assembly</id>
41                         <phase>package</phase>
42                         <goals>
43                             <goal>single</goal>
44                         </goals>
45                     </execution>
46                 </executions>
47             </plugin>
48         </plugins>
49     </build>
50
51 </project>

Note:

maven-assembly-plugin 中指定了 mainClass

clean package 后分别执行

java -jar

1 $ java -jar hello-jar-1.0-SNAPSHOT.jar
2 Hello Jar

java -cp

1 $ java -cp hello-jar-1.0-SNAPSHOT.jar org.fool.test.MainTest
2 Hello Jar

maven-assembly-plugin 中不指定 mainClass

clean package 后再次分别执行

java -jar

1 $ java -jar hello-jar-1.0-SNAPSHOT.jar
2 no main manifest attribute, in hello-jar-1.0-SNAPSHOT.jar

java -cp

1 $ java -cp hello-jar-1.0-SNAPSHOT.jar org.fool.test.MainTest
2 Hello Jar

Reference

https://www.jianshu.com/p/eabfb61e072a

https://blog.csdn.net/yulei_qq/article/details/82423683