This is the third article, a summary of YAML configuration files

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SpringBoot takeoff road -HelloWorld

(two) SpringBoot takeoff road – analysis of the principle of entry

(three) SpringBoot takeoff road -YAML configuration summary (entry must know will)

(4) SpringBoot takeoff road – static resource processing

(five) SpringBoot takeoff road -Thymeleaf template engine

(6) SpringBoot takeoff road – integration jdbctemplate-druid-mybatis

(7) SpringBoot launch road – integration of SpringSecurity (Mybatis, JDBC, memory)

(eight) SpringBoot take-off path – integration Shiro detailed tutorial (MyBatis, Thymeleaf)

SpringBoot -Swagger 2 And 3

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(1) SpringBoot configuration file type

In the previous introduction to the Basics, we briefly mentioned some instructions for automatic configuration, and when we demonstrated this, You can easily change the port number by simply writing server.port=9090 to application.properties under SRC \main\ Resources

Properties or Application.yml (application.yaml) configuration if you want to modify SpringBoot

Properties, which we are relatively familiar with, were used a lot in Spring development in the past

This article focuses on the yamL genre

(2) Introduction to YAML

Wikipedia post introduction

YAML is a recursive abbreviation of “YAML Ain’t a Markup Language” (YAML is not a Markup Language). At the time the Language was developed, YAML actually meant “Yet Another Markup Language” (still a Markup Language), but was renamed with a reverse acronym to emphasize the Language’s data-centric, rather than Markup language-centric focus.

Features of wikipedia posts

YAM’s syntax is similar to that of other high-level languages, and it can simply express manifest, hash, scalars, and other data forms. It uses whitespace indentation and a lot of look-and-feel features, making it especially suitable for expressing or editing data structures, various configuration files, printing debugging content, and file size. Although it is more suitable for expressing hierarchical data structures, it also has a sophisticated syntax for expressing relational data. Its most user-friendly feature is the clever avoidance of closed symbols, such as quotation marks and various brackets, which can become complicated and difficult to read in nested structures

Let’s start with an example:

The XML configuration

<server>
    <port>9090<port>
</server>
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The Properties configuration

server.port=9090
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Yaml configuration

Server:
  prot: 9090
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From such a simple example, Properties and Yaml are relatively simple, at least compared to XML, and XML is a nightmare when it comes to complex lists and so on

So, a quick summary: YAML language files, which have a. Yml suffix, are more readable and concise than XML (mainly) or Properties, and are more data-centric than markup language, making them suitable as configuration files for development projects

(3) Basic grammar

(1) Grammar requirements

The space between value and colon cannot be omitted, for example, key: value, ‘:’ can be followed by a space
The indentation indicates the hierarchy, and the data in the left-aligned column is of the same hierarchy
You can’t indent with tabs, you can only indent with blank Spaces
Syntax is case sensitive

(2) Configure common data

Ordinary data here is worth: numbers, booleans, strings, etc

Grammar:

key: value
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Example:

name: ideal
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Normal data values are written directly after colons (followed by Spaces), and usually strings do not require single or double quotation marks
The “” double quote returns an escape character such as” \n “as a newline character
‘ ‘single quotes do not parse escapes, and ‘\n’ is returned as a string

(3) Configure object data and Map data

Grammar:

Basic writing

key: 
  key1: value1
  key2: value2
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Inline writing

key: {key1: value1.key2: value2}
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Example:

user:
  name: Steven
  age:20
  address: beijing
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user: {name:Steven.age: 20.address: beijing}  
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Note: the number of Spaces in front of key1 is not limited, although the default is two, but as long as it is the same indentation, on behalf of the same level, the default can be used, that’s all

(4) Configure array, List and Set data

There is a space between – and value1, etc

Grammar:

Basic writing

key: 
  - value1
  - value2
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Inline writing

key: [value1.value2]
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Example:

province:
  - guangdong
  - hebei
  - sichuan
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province: [guangdong.hebei.sichuan]
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Add: When the elements in the collection are objects, as shown in the following example

user:
  - name: zhangsan
    age: 20
    address: beijing
  - name: lisi
    age: 28
    address: shanghai
  - name: wangwu
    age: 26
    address: shenzhen
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(4) Attribute mapping between configuration files and configuration classes

(1) @ Value mapping

In Spring, we’ve already introduced the @Value annotation, which allows you to map values in a configuration file to fields in a Spring-managed Bean

To demonstrate this, create a simple User class with just three members

@Component
public class User {
    private String name;
    private Integer age;
    privateString address; . Add get, toString method (set can not write)}Copy the code

The tests are all uniform

@Controller
public class UserController {
    @Autowired
    User user;

    @RequestMapping("/testUser")
    @ResponseBody
    public String testUser(a){
       returnuser.toString(); }}Copy the code

Now let’s do it in three ways

A: Direct assignment

@Value("Tom")
private String name;

@Value("20")
private Integer age;

@ Value (" Beijing ")
private String address;
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B: the Properties

application.properties

user1.name=Jack
user1.age=30
user1.address=Beijing
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User

@Value("${user1.name}")
private String name;

@Value("${user1.age}")
private Integer age;

@Value("${user1.address}")
private String address;
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C: Yaml

application.yml

user1:
  name: Steven
  age: 20
  address: Beijing
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User

@Value("${user1.name}")
private String name;

@Value("${user1.age}")
private Integer age;

@Value("${user1.address}")
private String address;
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Take a look at the yamL test results

D:

1 configuration priority

Properties, YAMl, and YML configuration files, if configured at the same time, the configuration information in the three files will take effect, but there is a loading priority problem, and the last loaded file will overwrite the first loaded file. Yml > YAMl >properties is the last file to be loaded, so the priority is :properties> YAMl > yML.

② User naming problem

@value (“${user1.name}”) I used user1 because if user.name is used in Windows, it will get the user name of the current Windows user

(3) application

Properties or application.yaml or application.yml, because the default is to find these configuration files. If the configuration file is named incorrectly, it will not be found

④ Properties garbled characters

If you did not set before, Chinese will certainly be garbled, here is a supplement to set the method

Check the box below and set the Properties encoding to UTF-8

(2) @ ConfigurationProperties mapping

The entity class uses the @ConfigurationProperties annotation (prefix=” prefix of key in the configuration file “), which automatically maps the configuration in the configuration file to the entity

Note: there may be some errors, generally no impact, the solution is placed below the article, if no impact, just do it first

A: Configure the entity class

At sign Value, if you have a lot of members, it’s a little bit more convenient to introduce one, and it’s going to be used a lot in the future, so I’m going to rewrite a little bit more complicated entity, and I’m going to show you a little bit more comprehensively

Note: To implement this using @ConfigurationProperties, you add a set method to its member, which you can do without using the @Value annotation

@Component
@ConfigurationProperties(prefix = "student")
public class Student {

    private String name;
    private Integer age;
    private Date birthday;
    private Boolean graduate;
    private Map<String, Integer> score;
    private List<String> subject;
    privateUser u; . Get set toStringCopy the code

The User class referenced in the Student class

@Component
public class User {
    private String name;
    private Integer age;
    privateString address; . Get set toStringCopy the code

B: YAML configuration

student:
  name: Steven
  age: 20
  birthday: 2020/ 01/01
  graduate: false
  score: {math: 90.english: 88}
  subject:
    - The high number of
    - The British
    - Big things
  u:
    name: Jack
    age: 30
    address: Beijing
Copy the code

(3) Load the specified properties profile

Add one more tip about loading the specified properties configuration file

Spring uses yML configuration by default, but sometimes uses traditional XML or properties configuration. By the way, what if you want to invoke a custom properties configuration?

Use the @propertysource annotation

@Component
@PropertySource(value = "classpath:user.properties")
@ConfigurationProperties(prefix = "usertest")
public class User {
    private String name;
    private Integer age;
    privateString address; . Get set toStringCopy the code

user.properties

usertest.name=Jack
usertest.age=30
usertest.address=Beijing
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(v) Solutions

1. Spring Boot Configuration Annotation Processor not found in classpath error

IDEA prompt, springboot configuration annotation processor is not found, it will give us the address, let us go to see the document, but some documents are not necessarily open, you can go to the official website to find a

Take a look at the instructions on the official website

Generating Your Own Metadata by Using the Annotation Processor

You can easily generate your own configuration metadata file from items annotated with @ConfigurationProperties by using the spring-boot-configuration-processor jar. The jar includes a Java annotation processor which is invoked as your project is compiled. To use the processor, include a dependency on spring-boot-configuration-processor.

With Maven the dependency should be declared as optional, as shown in the following example:

So it’s ok to add dependencies

<dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-configuration-processor</artifactId>
    <optional>true</optional>
</dependency>
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2. Re-run Spring Boot Configuration Annotation Processor to update generated metadata

This problem can be ignored and does not affect the code execution. It should only be a reminder to remind you to restart or recompile if necessary. I have not found a perfect solution to this problem.

Under Setting, search for Spring, find SpringBoot and deselect show Notification Panel

(six) doubt occupied building

For spring-boot-configuration-processor, some say it was used to introduce @propertysource, and some say it was used to enable @ConfigurationProperties

@Component
@PropertySource(value = "classpath:user.properties")
@ConfigurationProperties(prefix = "usertest")
public class User {
    private String name;
    private Integer age;
    privateString address; . Get set toStringCopy the code

However, if you test it, you can use these two annotations without introducing spring-boot-configuration-processor. I haven’t thought about them carefully and ignored them. If you know about them, you can leave a message and communicate with them

(7) Ending

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(three) SpringBoot takeoff road -YAML configuration summary (entry must know will)

(1) SpringBoot configuration file type

(2) Introduction to YAML

(3) Basic grammar

(1) Grammar requirements

(2) Configure common data

(3) Configure object data and Map data

(4) Configure array, List and Set data

(4) Attribute mapping between configuration files and configuration classes

(1) @ Value mapping

A: Direct assignment

B: the Properties

C: Yaml

D:

1 configuration priority

② User naming problem

(3) application

④ Properties garbled characters

(2) @ ConfigurationProperties mapping

A: Configure the entity class

B: YAML configuration

(3) Load the specified properties profile

(v) Solutions

(six) doubt occupied building

(7) Ending

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