Using Spring internal Spel Expression Parser

Question

Do you know how to use Spring internal Spel Expression Parser in order to parse a String that contains bean reference of the Spring Application Context ?

I have already seen that SpelExpressionParser could be use with a StandardEvaluationContext that define somes explicit user variables.

I'm looking for a solution to directly use the Spring internal Spel Expression Parser binding to the whole Spring Application Context. The idea is to use a string template with the same capabilities of @Value SPEL annotations.

Marat Bukharov · Accepted Answer · 2018-06-11 17:05:48Z

2

You can use EmbeddedValueResolver to achieve the same capabilities as for @Value annotations:

// can be autowired or fetched from ConfigurableApplicationContext.getBeanFactory()
ConfigurableBeanFactory configurableBeanFactory; 

EmbeddedValueResolver embeddedValueResolver = new EmbeddedValueResolver(configurableBeanFactory);
System.out.println(embeddedValueResolver.resolveStringValue("${someProperty}");
System.out.println(embeddedValueResolver.resolveStringValue("#{@foo.calcValue(123)}");

answered Jun 11, 2018 at 17:05

Marat Bukharov

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user3849838 · Accepted Answer · 2017-03-01 17:18:41Z

1

I found the solution by using :

private Object resolveExpression(String expression) {
    String placeholdersResolved = applicationContext.getBeanFactory().resolveEmbeddedValue(expression);
    BeanExpressionResolver expressionResolver = applicationContext.getBeanFactory().getBeanExpressionResolver();
    return expressionResolver.evaluate(placeholdersResolved, new BeanExpressionContext(applicationContext.getBeanFactory(), null));
}

resolveEmbeddedValue replace ${} expression with properties place holder.

evaluate resolve #{} expression with Application Context Bean Factory

answered Mar 1, 2017 at 17:18

user3849838

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Dhrumil Shah · Accepted Answer · 2020-04-17 06:56:14Z

0

public class CustomClass{
    @Autowired
    private ConfigurableApplicationContext configurableApplicationContext;

    public String evaluateExpression(String myString) {
        ConfigurableListableBeanFactory beanFactory =
              configurableApplicationContext.getBeanFactory();
          StringValueResolver str = new EmbeddedValueResolver(beanFactory);
          return str.resolveStringValue(myString);
          //Put Above statement in Try catch .. Worked for me
    }
}

It will work with Any of the environment variable Example

application.properties

data.myenv=10

/etc/profile

export DATA_MYENV=10

edited Apr 17, 2020 at 6:56

answered Apr 17, 2020 at 6:50

Dhrumil Shah

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Using Spring internal Spel Expression Parser

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