java - Spring Security 中的 Spring Expression Language (SpEL) 比较对象使用 equals() 或 ==?

Question

Spring Security 中的 Spring 表达式语言 (SpEL) 比较对象使用 equals() 或 ==?

例如(方法equals()没有被调用!):

class SecurityObject {      
   public boolean equals(Object obj) {
  //...
   }
 }

@PreAuthorize(" #secObject == #otherSecObject ") 
public void securityMethod(SecurityObject secObject, SecurityObject otherSecObject) {                        
   //...        
}

这很正常!？我需要到处使用@PreAuthorize("#secObject.equals(#otherSecObject) ") 吗？

更新

为什么在第一种情况下 Spring Security 调用 .equals() 而在第二种情况下不调用？

      //TestObject 

      public class TestObject {

      private static final Logger log = LoggerFactory.getLogger(TestObject.class);

      private Long id;

      public TestObject(Long id) {
           this.id = id;
      }

       @Override
       public int hashCode() {
           int hash = 7;
           hash = 71 * hash + Objects.hashCode(this.id);
           return hash;
       }

       @Override
       public boolean equals(Object obj) {

       log.info("equals");

       if (obj == null) {
          return false;
       }

       if (getClass() != obj.getClass()) {
         return false;
       }
       final TestObject other = (TestObject) obj;
       if (!Objects.equals(this.id, other.id)) {
         return false;
       }
      return true;
  }               
}

//TestService

@PreAuthorize(" #one == #two ")
public String testEqualsInAnnotation(Long one, Long two) {        
    //...
}

@Override
@PreAuthorize(" #one == #two ")
public String testEqualsInAnnotation(TestObject one, TestObject two) {
    //...
}

//Test

    log.info("for Long");
    Long one = new Long(500);
    Long two = new Long(500);        

    log.info("one == two: {}", (one==two)? true : false); // print false
    log.info("one equals two: {}", (one.equals(two))? true : false); // print true

    testService.testEqualsInAnnotation(one, two); //OK

    log.info("for TestObject");

    TestObject oneObj = new TestObject(new Long(500));
    TestObject twoObj = new TestObject(new Long(500));              

    log.info("oneObj == twoObj: {}", (oneObj==twoObj)? true : false); // print false
    log.info("oneObj equals twoObj: {}", (oneObj.equals(twoObj))? true : false); // print true

    testService.testEqualsInAnnotation(oneObj, twoObj); // AccessDeniedException: Access is denied

更新 2

equals() 从未被调用过

           package org.springframework.expression.spel.ast;

           import org.springframework.expression.EvaluationException;
           import org.springframework.expression.spel.ExpressionState;
           import org.springframework.expression.spel.support.BooleanTypedValue;

/**
 * Implements equality operator.
 *
 * @author Andy Clement
 * @since 3.0
 */
public class OpEQ extends Operator {

    public OpEQ(int pos, SpelNodeImpl... operands) {
        super("==", pos, operands);
    }

    @Override
    public BooleanTypedValue getValueInternal(ExpressionState state) throws EvaluationException {
        Object left = getLeftOperand().getValueInternal(state).getValue();
        Object right = getRightOperand().getValueInternal(state).getValue();
        if (left instanceof Number && right instanceof Number) {
            Number op1 = (Number) left;
            Number op2 = (Number) right;
            if (op1 instanceof Double || op2 instanceof Double) {
                return BooleanTypedValue.forValue(op1.doubleValue() == op2.doubleValue());
            } else if (op1 instanceof Long || op2 instanceof Long) {
                return BooleanTypedValue.forValue(op1.longValue() == op2.longValue());
            } else {
                return BooleanTypedValue.forValue(op1.intValue() == op2.intValue());
            }
        }
        if (left!=null && (left instanceof Comparable)) {
            return BooleanTypedValue.forValue(state.getTypeComparator().compare(left, right) == 0);
        } else {
            return BooleanTypedValue.forValue(left==right);
        }
    }

}

Answer 1

根据 spEL 文档，您需要创建 ExpressionParser 实例，创建一个 Expression 实例并获取如下值

String name = "Nikola Tesla";
Expression exp = parser.parseExpression("name == 'Nikola Tesla'");
boolean result = exp.getValue(Boolean.class); 

结果评估为“真”。也就是说，当我们需要比较任意两个对象时，我们需要覆盖 equals() 方法并将两个对象传递给 parser#parseExpression("obj1 == obj2") 然后调用exp#getValue(Boolean.class) 进行评估。类似地，Expression 实例也可以有包含Obj1.equals(Obj2) 的表达式字符串，用于检查是否相等。因此，这两种检查相等性的方法都可以使用 spEL。