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深入理解OGNL - 附录详析

最编程 2024-02-09 20:10:37

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参考：http://commons.apache.org/proper/commons-ognl/language-guide.html

操作符

Operator	`getValue()` Notes	`setValue()` Notes
`e1``,` `e2` Sequence operator	Both `e1` and `e2` are evaluated with the same source object, and the result of `e2` is returned.	`getValue` is called on `e1`, and then `setValue` is called on `e2`.
`e1` `=` `e2` Assignment operator	`getValue` is called on `e2`, and then `setValue` is called on `e1` with the result of `e2` as the target object.	Cannot be the top-level expression for `setValue`.
`e1` `?` `e2` `:` `e3` Conditional operator	`getValue` is called on `e1` and the result is interpreted as a boolean. `getValue` is then called on either `e2` or `e3`, depending on whether the result of `e1` was `true` or `false` respectively, and the result is returned.	`getValue` is called on `e1`, and then `setValue` is called on either `e2` or `e3`.
`e1` `\|\|` `e2`, e1 `or` `e2` Logical `or` operator	`getValue` is called on `e1` and the result is interpreted as a boolean. If `true`, that result is returned; if `false`, `getValue` is called on `e2` and its value is returned.	`getValue` is called on `e1`; if `false`, `setValue` is called on `e2`. Note that `e1` being `true` prevents any further setting from taking place.
`e1` `&&` `e2`, `e1` `and` `e2` Logical `and` operator	`getValue` is called on `e1` and the result is interpreted as a boolean. If `false`, that result is returned; if true, `getValue` is called on e2 and its value is returned.	`getValue` is called on `e1`; if `true`, `setValue` is called on `e2`. Note that `e1` being `false` prevents any further setting from taking place.
`e1` `\|` `e2`, `e1` `bor` `e2` Bitwise `or` operator	`e1` and `e2` are interpreted as integers and the result is an integer.	Cannot be the top-level expression passed to `setValue`.
`e1` `^` `e2`, `e1` `xor` `e2` Bitwise exclusive-or operator	`e1` and `e2` are interpreted as integers and the result is an integer.	Cannot be the top-level expression passed to `setValue`.
`e1` `&` `e2`, `e1` `band` `e2` Bitwise and operator	`e1` and `e2` are interpreted as integers and the result is an integer.	Cannot be the top-level expression passed to `setValue`.
`e1` `==` `e2`, `e1` `eq` `e2` Equality test `e1` `!=` `e2`, `e1` `neq` `e2` Inequality test	Equality is tested for as follows. If either value is `null`, they are equal if and only if both are `null`. If they are the same object or the `equals()` method says they are equal, they are equal. If they are both `Number`s, they are equal if their values as double-precision floating point numbers are equal. Otherwise, they are not equal. These rules make numbers compare equal more readily than they would normally, if just using the equals method.	Cannot be the top-level expression passed to `setValue`.
`e1` `<` `e2`, `e1` `lt` `e2` Less than comparison `e1` `<=` `e2`, `e1` `lte` `e2` Less than or equals comparison `e1` `>` `e2`, `e1` `gt` `e2` Greater than comparison `e1` `>=` `e2`, `e1` `gte` `e2` Greater than or equals comparison `e1` `in` `e2` List membership comparison `e1` `not in` `e2` List non-membership comparison	The ordering operators compare with `compareTo()` if their arguments are non-numeric and implement `Comparable`; otherwise, the arguments are interpreted as numbers and compared numerically. The in operator is not from Java; it tests for inclusion of e1 in e2, where e2 is interpreted as a collection. This test is not efficient: it iterates the collection. However, it uses the standard OGNL equality test.	Cannot be the top-level expression passed to `setValue`.
`e1` `<<` `e2`, `e1` `shl` `e2` Bit shift left `e1` `>>` `e2`, `e1` `shr` `e2` Bit shift right `e1` `>>>` `e2`, `e1` `ushr` `e2` Logical shift right	`e1` and `e2` are interpreted as integers and the result is an integer.	Cannot be the top-level expression passed to `setValue`.
`e1` `+` `e2` Addition `e1` `-` `e2` Subtraction	The plus operator concatenates strings if its arguments are non-numeric; otherwise it interprets its arguments as numbers and adds them. The minus operator always works on numbers.	Cannot be the top-level expression passed to `setValue`.
`e1``` `e2`* Multiplication `e1` `/` `e2` Division `e1` `%` `e2` Remainder	Multiplication, division, which interpret their arguments as numbers, and remainder, which interprets its arguments as integers.	Cannot be the top-level expression passed to `setValue`.
`+` `e` Unary plus `-` `e` Unary minus `!` `e`, `not` `e` Logical not `~` `e` Bitwise not `e` `instanceof` `class` Class membership	Unary plus is a no-op, it simply returns the value of its argument. Unary minus interprets its argument as a number. Logical not interprets its argument as a boolean. Bitwise not interprets its argument as an integer. The `class` argument to instanceof is the fully qualified name of a Java class.	Cannot be the top-level expression passed to `setValue`.
`e``.``method``(``args``)` Method call `e``.``property` Property `e1``[` `e2` `]` Index `e1``.{` `e2` `}` Projection `e1``.{?` `e2` `}` Selection `e1``.(``e2``)` Subexpression evaluation `e1``(``e2``)` Expression evaluation	Generally speaking, navigation chains are evaluated by evaluating the first expression, then evaluating the second one with the result of the first as the source object.	Some of these forms can be passed as top-level expressions to `setValue` and others cannot. Only those chains that end in property references (e.property), indexes (`e1[e2]`), and subexpressions (`e1.(e2)`) can be; and expression evaluations can be as well. For the chains, `getValue` is called on the left-hand expression (`e` or `e1`), and then `setValue` is called on the rest with the result as the target object.
`constant` Constant `(` `e` `)` Parenthesized expression `method``(``args``)` Method call `property` Property reference `[` `e` `]` Index reference `{` `e``,` … `}` List creation `#``variable` Context variable reference `@``class``@``method``(``args``)` Static method reference `@``class``@``field` Static field reference `new` `class``(``args``)` Constructor call `new` `array-component-class``[] {` `e``,` … `}` Array creation `#{` `e1` `:` `e2``,` … `}` Map creation `#@``classname``@{` `e1` `:` `e2``,` … `}` Map creation with specific subclass `:[` `e` `]` Lambda expression definition	Basic expressions	Only property references (`property`), indexes (`[e]`), and variable references (`#variable`) can be passed as top-level expressions to `setValue`. For indexes, `getValue` is called on `e`, and then the result is used as the property “name” (which might be a `String` or any other kind of object) to set in the current target object. Variable and property references are set more directly.

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