Two types of attribute injection methods

Attribute general injection

Write a test class ：

@Component
@PropertySource("classpath:book.properties")
public class Book {
    
    @Value("${book.name}")
    private String Name;
    @Value("${book.author}")
    private String Autor;// character string 
    @Value("${book.tags}")
    private String[] tags;// Array of strings 


    public String getName() {
    
        return Name;
    }

    public void setName(String name) {
    
        Name = name;
    }

    public String getAutor() {
    
        return Autor;
    }

    public void setAutor(String autor) {
    
        Autor = autor;
    }

    public String[] getTags() {
    
        return tags;
    }

    public void setTags(String[] tags) {
    
        this.tags = tags;
    }

    @Override
    public String toString() {
    
        return "Book{" +
                "Name='" + Name + '\'' +
                ", Autor='" + Autor + '\'' +
                ", tags=" + Arrays.toString(tags) +
                '}';
    }
}

Then , To write book.properties, because application.properties It is a system configuration class , So we create a new configuration file , adopt java Code annotation @PropertySource Put your own configuration file inside ,@Value Add the self-defined attribute variables to

book.properties The content of ：

book.name= A dream of red mansions 
book.author= Cao xueqin 
book.tags= classics , classic , Ming Dynasty 

Test code ：

@SpringBootTest
class Demo06ApplicationTests {
    
    @Autowired
    Book book;// Injection class 

    @Test
    void contextLoads() {
    
        System.out.println("book = " + book);// Print the contents of this class 
    }
}

Then we run unit tests to see the results , It is found that there will be garbled code when printed , This is because the file code is not set correctly , We should change the file encoding to UTF-8, Pictured ：

The final results ：

Type safe property Injection

We are Book Class plus @ConfigurationProperties annotation , Inside prefix The prefix is set to book, Then it will automatically scan the properties in the configuration file , Delete @Value attribute

@Component
@PropertySource("classpath:book.properties")
@ConfigurationProperties(prefix = "book")// Add new annotation 
public class Book {
    
    private String Name;
    private String Autor;
    private String[] tags;
    ....// The following code is omitted 

Finally, it runs successfully , Of course, after testing , The case of attributes does not affect automatic scanning , Case insensitive .

Maven Attribute injection

application.properties To configure ：

app.encoding=@project.build.[email protected]
aap.version=@java.[email protected]

obtain ：

app.encoding=UTF-8
aap.version=11.0.6

This configuration must be written in application.properties Configuration in progress , Other customized configuration classes will not be scanned , There is a filter

Please refer to this article for details Maven Engineering problems