Question

Spring Expression Language是否支持IN运算符？与SQL IN子句类似。

public class Security {
 private secTyp1;
 public Security (String aSecTyp1) {
  secTyp1 = aSecTyp1;
 }
}

Security security = new Security("BOND");
StandardEvaluationContext context = new StandardEvaluationContext(security);
ExpressionParser parser = new SpelExpressionParser();
// This should return true
boolean result = parser.parseExpression("secTyp1 **IN** {'BOND','SWPI'}").getValue(context, Boolean.class); 
// This should return false
result = parser.parseExpression("secTyp1 **IN** {'FUT','SWPI'}").getValue(context, Boolean.class);

我收到以下异常

org.springframework.expression.spel.SpelParseException: EL1041E:(pos 8): After parsing a valid expression, there is still more data in the expression: 'IN'
    at org.springframework.expression.spel.standard.InternalSpelExpressionParser.doParseExpression(InternalSpelExpressionParser.java:118)
    at org.springframework.expression.spel.standard.SpelExpressionParser.doParseExpression(SpelExpressionParser.java:56)
    at org.springframework.expression.spel.standard.SpelExpressionParser.doParseExpression(SpelExpressionParser.java:1)
    at org.springframework.expression.common.TemplateAwareExpressionParser.parseExpression(TemplateAwareExpressionParser.java:66)
    at org.springframework.expression.common.TemplateAwareExpressionParser.parseExpression(TemplateAwareExpressionParser.java:56)
    at com.rules.AssignableSecurityRule.evaluateInCondition(AssignableSecurityRule.java:48)
    at com.rules.AssignableSecurityRuleTest.testINCondition(AssignableSecurityRuleTest.java:43)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
    at java.lang.reflect.Method.invoke(Method.java:597)
    at org.junit.runners.model.FrameworkMethod$1.runReflectiveCall(FrameworkMethod.java:44)
    at org.junit.internal.runners.model.ReflectiveCallable.run(ReflectiveCallable.java:15)
    at org.junit.runners.model.FrameworkMethod.invokeExplosively(FrameworkMethod.java:41)
    at org.junit.internal.runners.statements.InvokeMethod.evaluate(InvokeMethod.java:20)
    at org.junit.internal.runners.statements.RunBefores.evaluate(RunBefores.java:28)
    at org.junit.runners.BlockJUnit4ClassRunner.runNotIgnored(BlockJUnit4ClassRunner.java:79)
    at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:71)
    at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:49)
    at org.junit.runners.ParentRunner$3.run(ParentRunner.java:193)
    at org.junit.runners.ParentRunner$1.schedule(ParentRunner.java:52)
    at org.junit.runners.ParentRunner.runChildren(ParentRunner.java:191)
    at org.junit.runners.ParentRunner.access$000(ParentRunner.java:42)
    at org.junit.runners.ParentRunner$2.evaluate(ParentRunner.java:184)
    at org.junit.runners.ParentRunner.run(ParentRunner.java:236)
    at org.eclipse.jdt.internal.junit4.runner.JUnit4TestReference.run(JUnit4TestReference.java:49)
    at org.eclipse.jdt.internal.junit.runner.TestExecution.run(TestExecution.java:38)
    at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:467)
    at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:683)
    at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.run(RemoteTestRunner.java:390)
    at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.main(RemoteTestRunner.java:197)

Answer 1

它不支持IN运算符，因为您不需要它。您可以改为使用Method invokation功能。

因此，在列表上调用.contains（..）可以达到你想要的效果。

您可以尝试这两种解决方案

    @Test
    public void solutionOneTest() {
      final Security security = new Security("BOND");
      final EvaluationContext context = new StandardEvaluationContext(security);

      Boolean contains = PARSER.parseExpression("{'BOND','SWPI'}.contains(#root.secTyp1)").getValue(context, Boolean.class);
      Assert.assertTrue(contains);

      contains = PARSER.parseExpression("{'FUT','SWPI'}.contains(#root.secTyp1)").getValue(context, Boolean.class);
      Assert.assertFalse(contains);
    }

    @Test
    public void solutionTwoTest() {
      final Security security = new Security("BOND");
      final EvaluationContext context = new StandardEvaluationContext();
      context.setVariable("sec", security);

      Boolean contains = PARSER.parseExpression("{'BOND','SWPI'}.contains(#sec.secTyp1)").getValue(context, Boolean.class);
      Assert.assertTrue(contains);

      contains = PARSER.parseExpression("{'FUT','SWPI'}.contains(#sec.secTyp1)").getValue(context, Boolean.class);
      Assert.assertFalse(contains);
    }

Answer 2

除了直接在micfra的答案中调用方法之外，SpEL还支持一些非常强大的集合过滤表达式。 Collection Selection允许您过滤掉匹配值的子列表，然后可以测试大小：

!{'BOND','SWPI'}.?[#this == 'BOND'].empty

这非常方便的是过滤复杂对象的列表：

!securities.?[secTyp1 == 'BOND'].empty

Spring Expression Language是否支持IN运算符？

2 个答案: