@The difference between configurationproperties and @value

Catalog

1 Preface

2 @ConfigurationProperties and @value The difference between

3 usage

3.1 @ConfigurationProperties

3.2 @Value

 4 Specify profile

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1 Preface

In normal development , We will configure a large number of parameters in application.properties perhaps application.yml In file , adopt @ConfigurationProperties Note or @value Annotation can easily get these values .

2 @ConfigurationProperties and @value The difference between

The two annotation buckets can read the properties in the configuration file and bind to javaBean in , But the two have the following differences

1） Use different positions

@ConfigurationProperties： Marked on JavaBean On the class name of ;

@Value: Marked on JavaBean On the properties of .

2） function

@ConfigurationProperties： Used for configuration in batch binding configuration file ;

@Value： You can only specify the binding location one by one , The binding granularity is smaller

3） Loose binding supports different

@ConfigurationProperties： Support for loose binding , For example, entity class Person One of the attributes in is username, Then the attribute name in the configuration file supports the following writing ：person.username、person_name、person.user_name、PERSON_USER_NAME

@Value： Loose binding is not supported

4) Complex type encapsulation

@ConfigurationProperties： Supports all types of encapsulation , for example Map、List、Set And objects

@Value： Only encapsulation of basic data types is supported , for example ： character string 、 Boolean value 、 Integer and other types

5） Different application scenarios , There is no obvious difference between the two , They are only suitable for different scenarios . If you just get a value in the configuration file , It is recommended to use @Value annotation ; If you specially write a JavaBean To map with the configuration file , It is recommended to use @ConfigurationProperties annotation .

3 usage

3.1 @ConfigurationProperties

Entity class ：

package com.liubujun.springdataelasticsearch.entity;

import org.springframework.boot.context.properties.ConfigurationProperties;
import org.springframework.stereotype.Component;

/**
 * @Author: liubujun
 * @Date: 2022/6/30 13:57
 */

@Component
@ConfigurationProperties(prefix = "person")
public class Person {

    private String username;

    private Integer age;

    private String address;

    public String getUsername() {
        return username;
    }

    public void setUsername(String username) {
        this.username = username;
    }

    public Integer getAge() {
        return age;
    }

    public void setAge(Integer age) {
        this.age = age;
    }

    public String getAddress() {
        return address;
    }

    public void setAddress(String address) {
        this.address = address;
    }

    @Override
    public String toString() {
        return "Person{" +
                "username='" + username + '\'' +
                ", age=" + age +
                ", address='" + address + '\'' +
                '}';
    }

}

The configuration file ：

person.username=Tony teacher 
person.age=21
person.address= The global village 

Test class ：

 @Autowired
    private Person person;

    @Test
    public void test(){
        System.out.println(" full name :"+person.getUsername()+"、 Age :"+person.getAge()+"、 Address :"+person.getAddress());
    }

Running results ：

  From the running results, we can find that we can successfully obtain relevant values from the configuration file .

Be careful ：@ConfigurationProperties Support for loose binding

Change the configuration file to ：

person.user_name=Tony teacher 
person.age=21
person.address= The global village 

The test found that the value is still obtained normally ：

Be careful ： @ConfigurationProperties Support complex type encapsulation

Change the configuration file to ：

person.user_name=Tony teacher 
person.age=21
person.address= The global village 
person.email[0][email protected]
person.email[1][email protected]
person.email[2][email protected]

Add a field to the entity class to modify it ：

@Component
@ConfigurationProperties(value = "person")
public class Person {


    private String username;


    private Integer age;


    private String address;

    private List<String> email;

    public String getUsername() {
        return username;
    }

    public void setUsername(String username) {
        this.username = username;
    }

    public Integer getAge() {
        return age;
    }

    public void setAge(Integer age) {
        this.age = age;
    }

    public String getAddress() {
        return address;
    }

    public void setAddress(String address) {
        this.address = address;
    }

    public List<String> getEmail() {
        return email;
    }

    public void setEmail(List<String> email) {
        this.email = email;
    }

    @Override
    public String toString() {
        return "Person{" +
                "username='" + username + '\'' +
                ", age=" + age +
                ", address='" + address + '\'' +
                ", email=" + email +
                '}';
    }
}

Test class ：

@Autowired
    private Person person;


    @Test
    public void test(){
        System.out.println(" full name :"+person.getUsername()+"、 Age :"+person.getAge()+"、 Address :"+person.getAddress()+"、email:"+person.getEmail());
    }

result ：

3.2 @Value

The entity classes are as follows ： Other configurations remain unchanged

@Component
public class Person {

    @Value("${person_username}")
    private String username;

    @Value("${person.age}")
    private Integer age;

    @Value("${person.address}")
    private String address;

    public String getUsername() {
        return username;
    }

    public void setUsername(String username) {
        this.username = username;
    }

    public Integer getAge() {
        return age;
    }

    public void setAge(Integer age) {
        this.age = age;
    }

    public String getAddress() {
        return address;
    }

    public void setAddress(String address) {
        this.address = address;
    }

    @Override
    public String toString() {
        return "Person{" +
                "username='" + username + '\'' +
                ", age=" + age +
                ", address='" + address + '\'' +
                '}';
    }

}

Test the normal output ：

Be careful ：@Value Loose binding is not supported , If you change the configuration file to the following ：

person.user_name=Tony teacher 
person.age=21
person.address= The global village 

The test found that “username” Value , The error information is as follows ：

Error creating bean with name 'person': Injection of autowired dependencies failed; nested exception is java.lang.IllegalArgumentException: Could not resolve placeholder 'person_username' in value "${person_username}"

Be careful ：@Value Complex type encapsulation is not supported , Add an entity class List Type field

@Component
public class Person {

    @Value("${person.username}")
    private String username;

    @Value("${person.age}")
    private Integer age;

    @Value("${person.address}")
    private String address;

    @Value("${person.email}")
    private List<String> email;

    public String getUsername() {
        return username;
    }

    public void setUsername(String username) {
        this.username = username;
    }

    public Integer getAge() {
        return age;
    }

    public void setAge(Integer age) {
        this.age = age;
    }

    public String getAddress() {
        return address;
    }

    public void setAddress(String address) {
        this.address = address;
    }

    public List<String> getEmail() {
        return email;
    }

    public void setEmail(List<String> email) {
        this.email = email;
    }

    @Override
    public String toString() {
        return "Person{" +
                "username='" + username + '\'' +
                ", age=" + age +
                ", address='" + address + '\'' +
                ", email=" + email +
                '}';
    }
}

The configuration file is modified as follows ：

person.user_name=Tony teacher 
person.age=21
person.address= The global village 
person.email[0][email protected]
person.email[1][email protected]
person.email[2][email protected]

Test class ：

@Autowired
    private Person person;

    @Test
    public void test(){
        System.out.println(" full name :"+person.getUsername()+"、 Age :"+person.getAge()+"、 Address :"+person.getAddress()+"、email:"+person.getEmail());
    }

An error is found after running ：

Caused by: org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'person': Injection of autowired dependencies failed; nested exception is java.lang.IllegalArgumentException: Could not resolve placeholder 'person.email' in value "${person.email}"

But if you get one of these values, there will be no problem ：

  Running results ：

 4 Specify profile

In actual development , There is a lot of content that needs configuration management , It is impossible to put all the information in the same configuration file , This is neither safe nor convenient for maintenance , We can SpringBoot Irrelevant configurations are put into other configuration files separately , When you need these JavaBean It can be used on ,SpringBoot Provides @PropertySource annotation .

Create a new file ：

Before application.properties Paste the contents of the file into the file .

Entity class plus corresponding path ：

  After the test, it is found that the value can still be obtained normally