java - java -cp 与 java -jar 之间的区别

Question

我使用 Spring Boot 应用程序，交付物是一个 JAR 文件。该文件需要使用命令 java -cp "parser.jar" com.ef.Parser 运行并执行一些超出本题范围的操作。在这种情况下，我有 2 个问题。

当我输入命令时 java -jar target/parser-1.5.7.RELEASE.jar com.ef.Parser ，我可以运行该应用程序。但是，当我输入命令时 java -cp target/parser-1.5.7.RELEASE.jar com.ef.Parser ，我得到错误 Error: Could not find or load main class com.ef.Parser

这里有什么问题？

我有 Parser.java包名称为 com.ef

代码如下，

@EnableJpaRepositories("com.ef.repository")
@SpringBootApplication(scanBasePackages = {"com.ef"}, exclude = JpaRepositoriesAutoConfiguration.class)
public class Parser implements CommandLineRunner {

    @Autowired
    private IpAddressService ipAddressService;

    public Parser() {

    }

    public static void main(String[] args) throws Exception {

        SpringApplication application = new SpringApplication(Parser.class);
        application.run(args);
    }



    @Override
    public void run(String... args) throws Exception {

        System.out.println("\nHello, Spring Boot!");
        exit(0);
    }
}

pom.xml提供的文件，

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">

    <modelVersion>4.0.0</modelVersion>
    <artifactId>parser</artifactId>
    <name>Log-Parser</name>
    <packaging>jar</packaging>

    <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <!-- <version>RELEASE</version> -->
        <version>1.5.7.RELEASE</version>
    </parent>

    <properties>
        <java.version>1.8</java.version>
    </properties>

    <dependencies>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>

        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-data-jpa</artifactId>
        </dependency>

        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-security</artifactId>
        </dependency>

        <!--HSQL database -->
        <dependency>
            <groupId>org.hsqldb</groupId>
            <artifactId>hsqldb</artifactId>
            <scope>runtime</scope>
        </dependency>


        <!--auto refresh using the dev tool-->
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-devtools</artifactId>
            <optional>true</optional>
        </dependency>

        <dependency>
            <groupId>javax.servlet</groupId>
            <artifactId>jstl</artifactId>
        </dependency>

        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-jdbc</artifactId>
        </dependency>

        <!--tomcat server-->
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-tomcat</artifactId>
            <scope>provided</scope>
        </dependency>

        <dependency>
            <groupId>org.apache.tomcat.embed</groupId>
            <artifactId>tomcat-embed-jasper</artifactId>
            <scope>provided</scope>
        </dependency>

        <!--live reload of the Sprign boot project-->
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-devtools</artifactId>
            <optional>true</optional>
        </dependency>

        <!--H2 database-->
        <dependency>
            <groupId>com.h2database</groupId>
            <artifactId>h2</artifactId>
            <version>1.4.196</version>
            <scope>test</scope>
        </dependency>


        <!-- https://mvnrepository.com/artifact/mysql/mysql-connector-java -->
        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
            <version>5.1.6</version>
        </dependency>

        <!--JSON -->
        <dependency>
            <groupId>com.fasterxml.jackson.core</groupId>
            <artifactId>jackson-annotations</artifactId>
            <version>2.9.1</version>
        </dependency>


        <!-- https://mvnrepository.com/artifact/commons-cli/commons-cli -->
        <!--Commons CLI-->
        <dependency>
            <groupId>commons-cli</groupId>
            <artifactId>commons-cli</artifactId>
            <version>1.4</version>
        </dependency>

        <!-- https://mvnrepository.com/artifact/commons-httpclient/commons-httpclient -->
        <dependency>
            <groupId>commons-httpclient</groupId>
            <artifactId>commons-httpclient</artifactId>
            <version>3.1</version>
        </dependency>
    </dependencies>


    <build>
        <plugins>

            <plugin>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-maven-plugin</artifactId>
            </plugin>

            <!--for the live update with the JSP file-->
            <plugin>
                <artifactId>maven-resources-plugin</artifactId>
                <version>2.6</version>
                <executions>
                    <execution>
                        <id>copy-resources</id>
                        <phase>validate</phase>
                        <goals>
                            <goal>copy-resources</goal>
                        </goals>
                        <configuration>
                            <outputDirectory>${basedir}/target/classes/static</outputDirectory>
                            <resources>
                                <resource>
                                    <directory>src/main/webapp</directory>
                                    <filtering>true</filtering>
                                </resource>
                            </resources>
                        </configuration>
                    </execution>
                </executions>
            </plugin>
        </plugins>
    </build>
</project>

第二个问题是当我运行命令 mvn clean package 时, 我得到 parser-1.5.7.RELEASE.jar在target文件夹。如何将 JAR 文件重命名为 parser.jar与 pom.xml配置？

我试图手动重命名它，但是，这行不通。

Answer 1

第二个问题的答案:

如果您假设最终的 jar 文件应命名为 parser.jar，请将其放入您的 pom:

<build>
   ...
   <finalName>parser</finalName>
   ...
</build>

来自文档:

The filename (excluding the extension, and with no path information) that the produced artifact will be called. The default value is ${artifactId}-${version}.

第一个问题的答案有点复杂。我会用一个非常蹩脚的词来解释它:“ super jar ”有点特别，不包含你期望的类。它有一个 BOOT-INF 目录，您的类位于该目录中，spring 在标准位置提供所谓的“启动器”。我建议你打开 jar 看看。您可以用类似的方式运行应用程序:

java -cp target/parser.jar -Dloader.main=com.ef.parser.Parser org.springframework.boot.loader.PropertiesLauncher

  .   ____          _            __ _ _
 /\\ / ___'_ __ _ _(_)_ __  __ _ \ \ \ \
( ( )\___ | '_ | '_| | '_ \/ _` | \ \ \ \
 \\/  ___)| |_)| | | | | || (_| |  ) ) ) )
  '  |____| .__|_| |_|_| |_\__, | / / / /
 =========|_|==============|___/=/_/_/_/
 :: Spring Boot ::        (v1.5.7.RELEASE)

详情可用here .

jar 的结构如下所示:

BOOT-INF
  |->classes
    |---com.ef.Parser
  |->lib
META-INF
org.springframework...