如何使用spring从属性文件中加载地图

Question

I am trying to load a map from .properties file into a HashMap

the properties file has the following:

try.map= one=1,\
two=2

The code:

@org.springframework.beans.factory.annotation.Value("${try.map}")
HashMap<String, String> tryMap;

And loading the property to the map results in :

 java.lang.IllegalStateException: Cannot convert value of type [java.lang.String] to required type [java.util.HashMap]: no matching editors or conversion strategy found

Any ideas how to create a mapping strategy for this?

Answer 1

i got this error too. If you want to resolve it without doing much efforts, just check your imports properly. Mostly you will get this error if you import wrong files. In case of you, I think you are importing wrong HashMap in your file. Check it should be java.util.HashMap.

Answer 2

There is no default converter for that. So you have to write your own converter and register it to the conversationService.

Here an annotation-based example:

@Bean(name="conversionService") 
public static ConversionService getConversionService(){
    ConversionServiceFactoryBean conversionServiceFactoryBean = new ConversionServiceFactoryBean();
    Set<Converter<?,?>> converters = new HashSet<Converter<?,?>>();
    converters.add(new StringToHashMapConverter());
    conversionServiceFactoryBean.setConverters(converters);
    conversionServiceFactoryBean.afterPropertiesSet();
    return conversionServiceFactoryBean.getObject();
}

The Converter:

import java.util.HashMap;

import org.springframework.core.convert.converter.Converter;

public class StringToHashMapConverter implements Converter<String,HashMap> {

    @Override
    public HashMap convert(String paramS) {
           //do the coversion
    }

}

Answer 3

This works for me:

try.map= {\
  one: 1,\
  two: 2\
}

The code:

@org.springframework.beans.factory.annotation.Value("#{${try.map}}")
HashMap<String, String> tryMap;

Yes, the syntax is quite odd.

This SO post has more info: How to fill HashMap from java property file with Spring @Value