Property Injection

Injection in springboot

• Basic Property Injection @Value
• Object Mode Injection @ConfigurationProperties
• Comparison of two injection modes
• Injection Details
• Profile Injection Value Data Check@Validated
• Load the specified configuration file @PropertySource
• Import Spring's Configuration File@ImportResource
• Profile Placeholder

SpringBoot uses a global profile with a fixed profile name:

• application.properties
• application.yml

The role of configuration files: modify the default values of SpringBoot auto-configuration; SpringBoot is automatically configured for us at the bottom level;

Two injection methods are provided in springboot: basic property injection, object injection

Basic properties include int, String, Date, String[], List, Map, and so on.

Basic property injection: use the comment @Value("$")

@RestController @RequestMapping("hello") public class HelloController { @Value("$") private int port; @Value("$") private String str; @Value("$") private Date bir; @Value("$") private String[] strs; @Value("$") private List<String> list; @Value("#{$}") // map injection value is a bit special private Map<String, String> maps; @GetMapping("hello") public String hello() { // port = 8989 System.out.println("port = " + port); // str = zhenyu System.out.println("str= " + str); // time = Wed Dec 12 12:12:12 CST 2012 System.out.println("time = " + bir); // aa // bb // cc for (String str : strs) { System.out.println(str); } // zhangsan // lisi // wangwu list.forEach( v -> System.out.println(v)); // k = aa, v = xiaoyi // k = bb, v = xiaoer // k = cc, v = xiaosan maps.forEach((k, v) -> { System.out.println("k = " + k + ", v = " + v); }); return "hello spring boot!"; } }

Application.propertiesConfiguration in:

server.port = 8989 # Attribute Injection str = zhenyu bir = 2012/12/12 12:12:12 strs = aa, bb, cc list = zhangsan, lisi, wangwu maps = {'aa':'xiaoyi', 'bb':'xiaoer', 'cc':'xiaosan'}

Annotation for use of object-mode injection: @ConfigurationProperties(prefix="prefix")

@ConfigurationProperties tells SpringBoot that all properties in this class are bound in the configuration file;

• Only if this component is a component in a container can the @ConfigurationProperties function provided by the container, so @Component is required

@ToString @Data // necessary @Component // @Configuration is also possible @ConfigurationProperties(prefix = "user") // necessary public class User { private String id; private String name; private Integer age; private Date bir; }

Use: @Autowired in the controller to complete auto-injection;

@RestController @RequestMapping("hello") public class HelloController { @Autowired private User user; @GetMapping("hello") public String hello() { System.out.println(user); // User(id=1721, name=yusael, age=20, bir=Wed Dec 12 12:12:12 CST 2012) return "hello spring boot!"; } }

Application.propertiesConfiguration in:

# Custom Object Property Injection user.id = 1721 user.name = zhenyu user.age = 20 user.bir = 2012/12/12 12:12:12

Note: Custom injection metadata can be built by introducing a dependency-profile processor.

• This means that when you introduce this dependency, you will be prompted to write injection objects in the configuration file, and it won't affect you much if you don't.

<dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-configuration-processor</artifactId> <optional>true</optional> </dependency>

If we just need to get a value in the configuration file in some business logic, use @Value;

If we wrote a javaBean specifically to map to the configuration file, we would use @ConfigurationProperties directly.

Profile Injection Value Data Check@Validated

@Component @ConfigurationProperties(prefix = "person") @Validated // Configuration File Injection Value Data Check public class Person { /** * <bean> * <property name="lastName" value="Literal /$ Gets the value from environment variables, configuration files /#'></property> * <bean/> */ //lastName must be in mailbox format @Email //@Value("$") private String lastName; //@Value("#") private Integer age; //@Value("true") private Boolean boss; private Date birth; private Map<String,Object> maps; private List<Object> lists; private Dog dog;

Load the specified configuration file @PropertySource

@PropertySource loads the specified configuration file;

// Load the specified profile @PropertySource(value = {"classpath:person.properties"}) @Component @ConfigurationProperties(prefix = "person") public class Person { private String lastName; private Integer age; private Boolean boss; }

Import Spring's Configuration File@ImportResource

@ImportResource: Import Spring's profile to make the contents of the profile effective;

• There are no Spring profiles in Spring Boot, and the profiles we write ourselves cannot be automatically identified.
  For Spring's profile to take effect, load it; @ImportResource is labeled on a configuration class;

// Import Spring's profile to make it work @ImportResource(locations = {"classpath:beans.xml"})

Then write a configuration file for Spring:

<?xml version="1.0" encoding="UTF-8"?> <beans xmlns="http://www.springframework.org/schema/beans" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd"> <bean id="helloService"></bean> </beans>

Profile Placeholder

Random number:

${random.uuid} ${random.value} ${random.int} ${random.long} ${random.int(10)} ${random.int[1024,65536]}

: Specify the default value in the placeholder:

person.last-name=Zhang San ${random.uuid} # random number person.age=${random.int} # random number person.birth=2017/12/15 person.boss=false person.maps.k1=v1 person.maps.k2=14 person.lists=a,b,c person.dog.name=${person.hello:hello}_dog # Specify default values person.dog.age=15