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我试图修复错误，但我无法找到如何解决这部分：

这是错误。程序运行了一下，然后抛出空指针

Properties value: DEVELOPEMENT
App is running...
Exception in thread "main" java.lang.NullPointerException
    at hu.citec.hazi.hazi.service.Service.print(Service.java:12)
    at hu.citec.hazi.hazi.Main.run(Main.java:26)
    at hu.citec.hazi.hazi.Main.main(Main.java:20)

我的代码：回购类：

package hu.citec.hazi.hazi.repo;

import java.time.LocalDateTime;

@org.springframework.stereotype.Repository
public class RepoImpl implements Repository {

    public String getPropertyMsg() {
        StringBuilder sb = new StringBuilder("Hello");
        sb.append("\n")
        .append("\t").append("HOME: ").append(System.getProperty("user.dir")).append("\n")
        .append("\t").append("USER: ").append(System.getProperty("user")).append("\n")
        .append("\t").append("TIME: ").append(LocalDateTime.now()).append("\n");

        return sb.toString();
    }

    public String runTest(String msg) {
        System.err.println(msg);
        return msg;
    }
}

仓库界面：

package hu.citec.hazi.hazi.repo;

public interface Repository {

String getPropertyMsg();

String runTest(String msg);
}

服务等级：

package hu.citec.hazi.hazi.service;

import hu.citec.hazi.hazi.repo.Repository;

@org.springframework.stereotype.Service
public class Service {

private Repository repo;


public String print() {
    return repo.getPropertyMsg();
}

public String test(String msg) {
    return  repo.runTest(msg);
}
}

MainConfig 类：

package hu.citec.hazi.hazi.config;

import org.springframework.beans.factory.annotation.Value;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.ComponentScan;
import org.springframework.context.annotation.PropertySource;

import hu.citec.hazi.hazi.entity.User;


@ComponentScan("hu.citec.hazi.hazi")
@PropertySource({ "classpath:application.properties", "classpath:application-${spring.active.profiles}.properties" })
public class MainConfig {

@Bean
public User defaultUser(@Value("${project.profile.name}") String name) {

    System.out.println("Properties value: "+ name );
    return new User(name);
}



}

主类：

package hu.citec.hazi.hazi;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.context.ApplicationContext;
import org.springframework.context.annotation.AnnotationConfigApplicationContext;
import org.springframework.stereotype.Component;

import hu.citec.hazi.hazi.config.MainConfig;
import hu.citec.hazi.hazi.service.Service;

@Component
public class Main {

    @Autowired
    private Service service;

    public static void main(String[] args) {
        ApplicationContext ctx = new AnnotationConfigApplicationContext(MainConfig.class);
        Main main = ctx.getBean(Main.class);
        main.run();
    }

    public void run() {
        System.out.println("App is running...");

        System.out.println("ÜDV! \n\t" + service.print() + "\n " +service.test("Sikeres teszt"));
    }
}

也许我犯了一些错误。对于那个很抱歉。

我还必须写更多的细节来使这个 qquestion 通过。

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0 回答 0