官术网_书友最值得收藏!

Custom converters

If your application defines Java types that do not provide any of these three cases covered by the automatic converters, MicroProfile Config can still provide conversion using custom converters that extend the org.eclipse.microprofile.config.spi.Converter interface defined in the following:

public interface Converter<T> {
    /**
     * Configure the string value to a specified type
     * @param value the string representation of a property value.
     * @return the converted value or null
     *
     * @throws IllegalArgumentException if the value cannot be converted to 
the specified type. */ T convert(String value);

You have to write an implementation of org.eclipse.microprofile.config.spi.Converter, then add its name to the /META-INF/services/org.eclipse.microprofile.config.spi.Converter file and put that file in your application archive. For your reference, here is an example of the implementation of a custom converter that supports a named number concept:

package io.packt.sample.config;

import org.eclipse.microprofile.config.spi.Converter;

public class NamedNumberConverter implements Converter<NamedNumber> {
/**
* Parses an assignment type of expression into a name and number value
* @param value name=Number expression
* @return NamedNumber instance
*/
@Override
public NamedNumber convert(String value) {
String[] parts = value.split("="); // 1
return new NamedNumber(parts[0], parts[1]);
}
}

package io.packt.sample.config;

public class NamedNumber {
private String name;
private Number number;

public NamedNumber(String name, Number number) {
this.name = name;
this.number = number;
}

...
}

The converter takes a string and splits it based on a comma separator to extract the name and corresponding value to build the NamedNumber instance.

You would then specify a named number in your configuration, as shown here:

# microprofile-config.properties NamedNumber example
injected.namedNumber
=jdoe,2.0

The addition of NamedNumberConverter allows us to use the NamedNumber type as a configuration type that can be injected. Here is an example that would match the configuration setting shown previously:

@Inject
@ConfigProperty(name="injected.namedNumber")
NamedNumber configuredNumber;

With the base MicroProfile Config feature covered, let's move onto another feature, MicroProfile Fault Tolerance.

主站蜘蛛池模板: 台湾省| 永嘉县| 南昌市| 道孚县| 乌兰察布市| 唐河县| 阜阳市| 即墨市| 林芝县| 儋州市| 烟台市| 奈曼旗| 乐东| 财经| 夏河县| 南康市| 敦煌市| 丰城市| 丹棱县| 新干县| 蒲江县| 高尔夫| 中方县| 岐山县| 桐城市| 宾川县| 阜阳市| 虞城县| 威远县| 共和县| 福建省| 庆元县| 淮阳县| 永州市| 泸西县| 尖扎县| 雅江县| 永顺县| 綦江县| 临潭县| 裕民县|