Random number setting and reference between parameters

stay Spring Boot When setting properties in the configuration file , In addition to the configuration property values shown in the previous example , You can also use random values and references between parameters to set attribute values . below , This paper explains how to set these two property values in the configuration file

1、 Random value setting

stay Spring Boot In profile , Random value setting uses Spring Boot embedded RandomValuePropertySource class , Inject random values into some hidden attribute values or test case attribute values. The syntax format of random values is ${random.xx},xx Indicates that the type and range of generated random numbers need to be specified , It can generate random integers 、uuid Or a string , The sample code is as follows  

my.secret=${random.value} // Configure random values
my.number=${random.int} // Configure random integers
my.bignumber=${random.long} // Configure random long Number of types
my.uuid=${random.uuid} // Configure random uuid Number of types
my.number.less.than.ten=${random.int(10)} // Configuration less than 10 Random integer of
my.number.in.range=${random.int[1024,65536]} // The configuration range is [1024,65536] Random integer between  

In the above code , Use RandomValuePropertySource Class random The random number type provided , Examples of setting different types of random values are shown  

2、 Reference between parameters

stay Spring Boot In profile , The property values of configuration files can also be referenced between parameters , That is, the previously defined attribute is directly referenced in the attribute value of the latter configuration , In this way, the attribute values can be directly parsed .

The advantage of using references between parameters is , In multiple configuration properties that are associated with each other , You only need to pre configure one of these properties , Other places can quote , It saves the trouble of many subsequent modifications .

The syntax format of references between parameters is ${xx},xx Represents the property name that has been previously configured in the configuration file , The sample code is as follows  

 app.name=MyApp
app.description=${app.name} is a Spring Boot application

In the example of reference setting between the above parameters , First set up “app.name=MyApp”, take app.name The property value of the property is set to MyApp; next , stay app.description Property configuration , Use ${app.name} The previous attribute value is referenced

Next , Through a case to demonstrate the specific use and effect of property setting by using random value setting and reference between parameters , The specific steps are as follows

（1） open Spring Boot project resources In the catalog application.properties The configuration file , In this configuration file, two test attributes are configured through random value setting and reference between parameters , The sample code is as follows  

 # Random value setting and parameter reference configuration
tom.age=${random.int[10,20]}
tom.description=tom My age may be ${tom.age}

In the above application.properties In profile , First use random values to set tom.age Property value of property , The attribute value is set to [10,20] Between , Then we use the reference between parameters to configure tom.description attribute

（2） open \ Test class of the project , Add string type in this test class description attribute , And in the configuration file tom.description Property to inject , Then add a new test method for output test , The sample code is as follows  

@Value("${tom.description}")
private String description;
@Test
public void placeholderTest() {
    System.out.println(description);
}

In the above code , adopt @Value("${tom.description}") The annotation will be in the configuration file tom.description Property values are injected into the corresponding description Properties of the , In the test method placeholderTest() The attribute value is printed out in .

Perform test methods placeholderTest() , Check the console output  

It can be seen that , The test method placeholderTest() The successful running , And print out the attributes description The content of the injection , This content is consistent with the property values configured in the configuration file . next , Repeat the test method placeholderTest(), The age displayed in the output statement of the console will be [10,20] Random display between