Spring EL運算符實例

Spring EL支持大多數標準的數學，邏輯和關係運算符。 例如，

1. 關係運算符 – 等於 (==, eq), 不等於 (!=, ne), 小於 (<, lt), 小於或等於 (<= , le), 大於 (>, gt), 和大於或等於 (>=, ge).
2. 邏輯運算符 – 且, 或, 非 (!).
3. 數學運算符 – 加法(+), 減法 (-), 乘法 (*), 除法(/), 除模(%) 和指數冪 (^).

Spring EL以註解的形式

這個例子說明了如何在 SpEL 中使用運算符。

package com.yiibai.core;

import org.springframework.beans.factory.annotation.Value;
import org.springframework.stereotype.Component;

@Component("customerBean")
public class Customer {

//Relational operators

@Value("#{1 == 1}") //true
private boolean testEqual;

@Value("#{1 != 1}") //false
private boolean testNotEqual;

@Value("#{1 < 1}") //false
private boolean testLessThan;

@Value("#{1 <= 1}") //true
private boolean testLessThanOrEqual;

@Value("#{1 > 1}") //false
private boolean testGreaterThan;

@Value("#{1 >= 1}") //true
private boolean testGreaterThanOrEqual;

//Logical operators , numberBean.no == 999

@Value("#{numberBean.no == 999 and numberBean.no < 900}") //false
private boolean testAnd;

@Value("#{numberBean.no == 999 or numberBean.no < 900}") //true
private boolean testOr;

@Value("#{!(numberBean.no == 999)}") //false
private boolean testNot;

//Mathematical operators

@Value("#{1 + 1}") //2.0
private double testAdd;

@Value("#{'1' + '@' + '1'}") //1@1
private String testAddString;

@Value("#{1 - 1}") //0.0
private double testSubtraction;

@Value("#{1 \* 1}") //1.0
private double testMultiplication;

@Value("#{10 / 2}") //5.0
private double testDivision;

@Value("#{10 % 10}") //0.0
private double testModulus ;

@Value("#{2 ^ 2}") //4.0
private double testExponentialPower;

@Override
public String toString() {
    return "Customer \[testEqual=" + testEqual + ", testNotEqual="
            + testNotEqual + ", testLessThan=" + testLessThan
            + ", testLessThanOrEqual=" + testLessThanOrEqual
            + ", testGreaterThan=" + testGreaterThan
            + ", testGreaterThanOrEqual=" + testGreaterThanOrEqual
            + ", testAnd=" + testAnd + ", testOr=" + testOr + ", testNot="
            + testNot + ", testAdd=" + testAdd + ", testAddString="
            + testAddString + ", testSubtraction=" + testSubtraction
            + ", testMultiplication=" + testMultiplication
            + ", testDivision=" + testDivision + ", testModulus="
            + testModulus + ", testExponentialPower="
            + testExponentialPower + "\]";
}

}

package com.yiibai.core;

import org.springframework.beans.factory.annotation.Value;
import org.springframework.stereotype.Component;

@Component("numberBean")
public class Number {

@Value("999")
private int no;

public int getNo() {
    return no;
}

public void setNo(int no) {
    this.no = no;
}

}

執行

Customer obj = (Customer) context.getBean("customerBean");
System.out.println(obj);

輸出結果

Customer [testEqual=true, testNotEqual=false, testLessThan=false, testLessThanOrEqual=true, testGreaterThan=false, testGreaterThanOrEqual=true, testAnd=false, testOr=true, testNot=false, testAdd=2.0, testAddString=1@1, testSubtraction=0.0, testMultiplication=1.0, testDivision=5.0, testModulus=0.0, testExponentialPower=4.0]

Spring EL以XML形式

請參閱在XML文件定義bean的等效版本。在XML中，類似 < 小於符號不支持，應該使用下面所示文本形式，例如文本等值， ('<' = 'lt') 和 ('<=' = 'le').

<bean id="customerBean" class="com.yiibai.core.Customer">

  <property name="testEqual" value="#{1 == 1}" />
  <property name="testNotEqual" value="#{1 != 1}" />
  <property name="testLessThan" value="#{1 lt 1}" />
  <property name="testLessThanOrEqual" value="#{1 le 1}" />
  <property name="testGreaterThan" value="#{1 > 1}" />
  <property name="testGreaterThanOrEqual" value="#{1 >= 1}" />

  <property name="testAnd" value="#{numberBean.no == 999 and numberBean.no lt 900}" />
  <property name="testOr" value="#{numberBean.no == 999 or numberBean.no lt 900}" />
  <property name="testNot" value="#{!(numberBean.no == 999)}" />

  <property name="testAdd" value="#{1 + 1}" />
  <property name="testAddString" value="#{'1' + '@' + '1'}" />
  <property name="testSubtraction" value="#{1 - 1}" />
  <property name="testMultiplication" value="#{1 \* 1}" />
  <property name="testDivision" value="#{10 / 2}" />
  <property name="testModulus" value="#{10 % 10}" />
  <property name="testExponentialPower" value="#{2 ^ 2}" />

</bean>

<bean id="numberBean" class="com.yiibai.core.Number">
    <property name="no" value="999" />
</bean>

下載代碼 -  http://pan.baidu.com/s/1MLG1w