java jar包后台运行的两种方式详解

nohup java -jar demo.jar > nohup.log 2>&1 &

[Unit]
Description=Your Java Application as a Service
After=network.target
 
[Service]
User=<username>
Type=simple
ExecStart=/usr/bin/java -jar /path/to/your-application.jar
Restart=on-failure
 
[Install]
WantedBy=multi-user.target

sudo systemctl daemon-reload

sudo systemctl start your-service.service

sudo systemctl enable your-service.service

@echo off
start javaw -jar demo.jar
exit

CreateObject("Wscript.Shell").Run "cmd /c start javaw -jar your-application.jar", 0, True

 java -jar demo.jar start

package com.demo;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;

import java.io.File;
import java.util.*;

@SpringBootApplication
public class DemoApplication {
    public static final String START = "start";
    private static String osName = System.getProperty("os.name").toLowerCase();

    private static String id = UUID.randomUUID().toString();

    public static void main(String[] args) {
        HashSet<String> argSet = new HashSet<>(Arrays.asList(args));
        if (argSet.contains("-Dapplication.id")||!argSet.contains(START)) {
            SpringApplication.run(DemoApplication.class, args);
        } else{
            start();
        }
    }

    /**
     * 参考io.vertx.core.impl.launcher.commands.StartCommand
     */
    public static void start() {
        System.out.println("Starting application background...");
        List<String> cmd = new ArrayList<>();
        ProcessBuilder builder = new ProcessBuilder();
        addJavaCommand(cmd);
        // Add the classpath to env.
        builder.environment().put("CLASSPATH", System.getProperty("java.class.path"));
        //jar包运行
        if (getJar() != null) {
            cmd.add("-jar");
            cmd.add(getJar());
        } else {
            //开发工具运行
            cmd.add(getFirstSegmentOfCommand());
            cmd.add("run");
        }
        cmd.add("-Dapplication.id=" + id);
        try {
            builder.command(cmd);
            builder.start();
            System.out.println(id);
        } catch (Exception e) {
            System.out.println("Cannot create application process");
            System.exit(12);
        }

    }

    private static void addJavaCommand(List<String> cmd) {
        if (osName.contains("windows")) {
            cmd.add("cmd.exe");
            cmd.add("/C");
            cmd.add("start");
            cmd.add("application-id - " + id);
            cmd.add("/B");
        }
        cmd.add(getJava().getAbsolutePath());
        String opts = System.getenv("JAVA_OPTS");
        if (opts != null) {
            cmd.addAll(Arrays.asList(opts.split(" ")));
        }
    }

    private static File getJava() {
        File java;
        File home = new File(System.getProperty("java.home"));
        if (osName.contains("windows")) {
            java = new File(home, "bin/java.exe");
        } else {
            java = new File(home, "bin/java");
        }

        if (!java.isFile()) {
            System.out.println("Cannot find java executable - " + java.getAbsolutePath() + " does not exist");
            System.exit(14);
        }
        return java;
    }

    public static String getJar() {
        // Check whether or not the "sun.java.command" system property is defined,
        // if it is, check whether the first segment of the command ends with ".jar".
        String segment = getFirstSegmentOfCommand();
        if (segment != null && segment.endsWith(".jar")) {
            return segment;
        } else {
            // Second attend is to check the classpath. If the classpath contains only one element,
            // it's the fat jar
            String classpath = System.getProperty("java.class.path");
            if (!classpath.isEmpty() && !classpath.contains(File.pathSeparator) && classpath.endsWith(".jar")) {
                return classpath;
            }
        }

        return null;

    }

    /**
     * @return the first segment of the command line.
     */
    public static String getFirstSegmentOfCommand() {
        String cmd = System.getProperty("sun.java.command");
        if (cmd != null) {
            String[] segments = cmd.split(" ");
            if (segments.length >= 1) {
                return segments[0];
            }
        }
        return null;
    }

}