java - Spring Autowiring 提供 NPE。不手动创建bean

Question

我的 Spring MVC 程序中的服务类在运行应用程序时仍然为空。这两个类都是 @Service 并在 Controller 类中具有 @Autowired 但仍然为 null。我已经浏览了几天，我发现的只有两个原因，(我相信)这两个原因都不适合我的情况。

Spring boot 应用程序尝试创建一个不和谐的机器人， Autowiring 在 Controller 或 Junit 测试中不起作用(执行时出现 NPE，调试时变量显示 null)。

驱动程序类别:

package com.deth;

//imports
@SpringBootApplication
public class DethBotApplication {


    private static Logger logger = Logger.getLogger(DethBotApplication.class);

    @Autowired
    private static BotCommandListener botListener;

    public static void main(String[] args)  {
        SpringApplication.run(DethBotApplication.class, args);


        try {
            JDA jda = new JDABuilder(AccountType.BOT)
                .setToken(TOKEN)
                //.addEventListener(command controller)
                .addEventListener(botListener)
                .build(); //starts listening in discord server.

相关 Controller 代码:

package com.deth.controller;
//imports
@Component  
public class BotCommandListener extends ListenerAdapter {


        private static Logger logger = Logger.getLogger(BotCommandListener.class);

        @Autowired
        @Qualifier("raidAdminService")
        private RaidAdminService raidAdminService; 

        @Autowired
        private RaidRosterServiceImpl raidRosterService;

        @Autowired
        private RaidAttendanceService raidAttendanceService;

        @Override
        public void onMessageReceived(MessageReceivedEvent event) {
            JDA jda = event.getJDA();

            String msg = event.getMessage().getContentDisplay();
            if(msg.startsWith("!")) {
                String command = "";
                if(!msg.contains(" ")) {
                    command = msg;
                } else {
                    command = msg.subSequence(0, msg.indexOf(" ")).toString();
                    logger.trace("possible command: " + command);
                }
                try {
                    switch (command) {
                    //raid leader commands
                    case "!open":
                        raidAdminService.createRaid(event); //NPE here
                        logger.trace("!open detected");
                        break;

raidAdminService:

package com.deth.service;
//imports
@Service("raidAdminService")
public class RaidAdminServiceImpl extends CommandInfoService implements RaidAdminService {

    String intRegex = "[0-9]+";

    @Override
    public void createRaid(MessageReceivedEvent event) {
        // TODO Auto-generated method stub

包结构:

• com
  • 死亡
    • DethBot应用程序
    • Controller
      • DethBotCommandListner
    • 服务
      • RaidAdminService(接口(interface))
      • RaidAdminServiceImpl(类)....

当程序启动并运行时，在discord服务器中发送“!open”，正确命中switch语句并尝试调用createRaid方法，但RaidAdminService没有 Autowiring ，因此它在null上调用该方法。

Answer 1

我认为问题出在您的 DethBotApplication 类中。你不能在那里自动接线。主类需要先执行。之后该应用程序将查找 @Componet、@Service、@Controller... 注释。下面的代码可能会解决您的问题。

package com.deth;

//imports
import org.springframework.boot.web.servlet.support.SpringBootServletInitializer;
import org.springframework.context.ConfigurableApplicationContext;

@SpringBootApplication
public class DethBotApplication extends SpringBootServletInitializer {

    private static Logger logger = Logger.getLogger(DethBotApplication.class);

    public static void main(String[] args)  {
        ConfigurableApplicationContext context = SpringApplication.run(DethBotApplication.class, args);
        BotCommandListener botListener = context.getBean(BotCommandListener.class);
        try {
            JDA jda = new JDABuilder(AccountType.BOT)
                .setToken(TOKEN)
                //.addEventListener(command controller)
                .addEventListener(botListener)
                .build(); //starts listening in discord server.