"Java Spring - 写入资源文件夹中的现有文件"

Question

I have a simple in-memory db in which I load users from XML file at app startup. Now whenever someone registers I want to save that new user in this xml file. My approach is to everytime get all the users, append new one and save to xml. However, seems like nothing is written in file at time the new user registers. I am aware that this approach is not save but this is for educational reason only.

This is my save to xml class

public class SaveXml {
    @Autowired
    private UserRepository userRepository;

    public void saveUserToXml (User newUser) {
        try {
            ClassLoader classLoader = getClass().getClassLoader();
            File file = new File(classLoader.getResource("Users.xml").getFile());
            FileWriter fileWriter = new FileWriter(file);

            List<User> usersList = new ArrayList<>();
            //populate arraylist with all users;
            userRepository.findAll().forEach(usersList::add);
            usersList.add(newUser);

            XmlMapper xmlMapper = new XmlMapper();
            String xmlContent = xmlMapper.writeValueAsString(usersList);
            fileWriter.close();
        }
        catch (Exception e){}
    }
}

Xml file that is placed in resource folder:

<?xml version="1.0" encoding="UTF-8"?>
<users>
    <user>
        <username>Tom</username>
        <password>123</password>
    </user>
    <user>
        <username>Moc</username>
        <password>1234</password>
    </user>
</users>

Users class

@JacksonXmlRootElement(localName = "users")
@Data
@NoArgsConstructor
public class Users {
    @JacksonXmlElementWrapper(useWrapping = false)
    private List<User> user;

    public Users(List<User> newUser) {
        this.user = newUser;
    }

    public List<User> getUser() {
        return user;
    }

    public void setUser(List<User> user) {
        this.user = user;
    }
}

User class

@Data
public class User
{
    @Id @GeneratedValue(strategy= GenerationType.IDENTITY)
    //defining id as column name
    @Column
    private int id;
    //defining name as column name
    @Column
    private String username;
    //defining password column
    @Column
    private String password;
}

Answer 1

You could use FileUtils<\/code> from Apache.

    <dependency>
        <groupId>commons-io</groupId>
        <artifactId>commons-io</artifactId>
    </dependency>