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Polish @Value documentation in the Reference Manual

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See gh-23052
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Sam Brannen
2019-06-11 23:07:23 +03:00
parent 6ac68391c1
commit 74d520fbfa
1 changed files with 20 additions and 14 deletions
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34
src/docs/asciidoc/core/core-beans.adoc
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@@ -5263,6 +5263,7 @@ named "customerPreferenceDao" and then falls back to a primary type match for th
----
With the following configuration:
[source,java,indent=0]
[subs="verbatim,quotes"]
----
@@ -5272,6 +5273,7 @@ With the following configuration:
----
And the following `application.properties` file:
[source,java,indent=0]
[subs="verbatim,quotes"]
----
@@ -5282,7 +5284,7 @@ In that case, the `catalog` parameter and field will be equal to the `MovieCatal
A default lenient embedded value resolver is provided by Spring. It will try to resolve the
property value and if it cannot be resolved, the property name (for example `${catalog.name}`)
will be injected as the value. If you want to maintain strict control over non existent
will be injected as the value. If you want to maintain strict control over nonexistent
values, you should declare a `PropertySourcesPlaceholderConfigurer` bean, as the following
example shows:
@@ -5293,22 +5295,26 @@ example shows:
public class AppConfig {
@Bean
public PropertySourcesPlaceholderConfigurer propertyPlaceholderConfigurer() {
public static PropertySourcesPlaceholderConfigurer propertyPlaceholderConfigurer() {
return new PropertySourcesPlaceholderConfigurer();
}
}
----
Using the above configuration ensures Spring initialization failure if any of `${}`
NOTE: When configuring a `PropertySourcesPlaceholderConfigurer` using JavaConfig, the
`@Bean` method must be `static`.
Using the above configuration ensures Spring initialization failure if any `${}`
placeholder could not be resolved. It is also possible to use methods like
`setPlaceholderPrefix`, `setPlaceholderSuffix` or `setValueSeparator` to customize placeholders.
`setPlaceholderPrefix`, `setPlaceholderSuffix`, or `setValueSeparator` to customize
placeholders.
NOTE: Spring Boot configures by default a `PropertySourcesPlaceholderConfigurer` bean that
will get properties from `application.properties` and `application.yml` files.
Built-in converter support provided by Spring allows simple type conversion (to `Integer`
or `int` for example) to be automatically handled. Multiple comma separated values parameter
can be automatically converted to String array without extra effort.
or `int` for example) to be automatically handled. Multiple comma-separated values can be
automatically converted to String array without extra effort.
It is possible to provide a default value as following:
@@ -5326,10 +5332,10 @@ It is possible to provide a default value as following:
}
----
Spring BeanPostProcessor uses ConversionService instance behind the scene to handle the
process from converting `@Value` value to the target type. If you want to provide conversion
support for your own custom type, you can provide your own ConversionService bean instance
as the following example shows:
A Spring `BeanPostProcessor` uses a `ConversionService` behind the scene to handle the
process for converting the String value in `@Value` to the target type. If you want to
provide conversion support for your own custom type, you can provide your own
`ConversionService` bean instance as the following example shows:
[source,java,indent=0]
[subs="verbatim,quotes"]
@@ -5346,8 +5352,8 @@ as the following example shows:
}
----
<<expressions, `SpEL` expression>> built-in support allows dynamically computed `@Value`
at runtime as in the following example shows:
When `@Value` contains a <<expressions, `SpEL` expression>> the value will be dynamically
computed at runtime as the following example shows:
[source,java,indent=0]
[subs="verbatim,quotes"]
@@ -5357,13 +5363,13 @@ at runtime as in the following example shows:
private final String catalog;
public MovieRecommender(@Value("#{systemProperties['user.catalog'] + 'Catalog' }") String catalog){
public MovieRecommender(@Value("#{systemProperties['user.catalog'] + 'Catalog' }") String catalog) {
this.catalog = catalog;
}
}
----
SpEL also enables to use more complex data structure:
SpEL also enables the use of more complex data structures:
[source,java,indent=0]
[subs="verbatim,quotes"]