Spring 表达式expression

1、引入依赖

 <dependencies>
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-expression</artifactId>
            <version>5.2.8.RELEASE</version>
        </dependency>

        <dependency>
            <groupId>junit</groupId>
            <artifactId>junit</artifactId>
            <version>4.13.2</version>
        </dependency>
    </dependencies>

2、demo

public class SpringExpressionTest {
   

    @Test
    public void testSqEL() {
   

        //创建表达式列表
        ArrayList<String> list = new ArrayList<>();
        list.add("#A == 1");
        list.add("#B == 1");
        list.add("#C == 1 && #D == 1");
        list.add("#B == 1 && #D == 1");

        //创建参数map
        HashMap<String, Object> map = new HashMap<>();
        map.put("A", 1);
        map.put("B", 2);
        map.put("C", 1);
        map.put("D", 1);

        System.out.print("参数值:");
        System.out.println(map.toString());

        //创建ExpressionParser解析表达式
        ExpressionParser parser = new SpelExpressionParser();
        //创建一个虚拟的容器EvaluationContext
        StandardEvaluationContext context = new StandardEvaluationContext();
        for (Map.Entry e : map.entrySet()) {
   
            String key = (String) e.getKey();
            Integer value = (Integer) e.getValue();
            //向容器内添加变量
            context.setVariable(key, value);
        }

        list.stream().forEach(expression -> {
   
            System.out.print("expression : " + expression);
            //getValue有参数context，从新的容器中根据SpEL表达式获取所需的值
            Boolean flag = parser.parseExpression(expression).getValue(context, Boolean.class);
            System.out.println("\t结果:" + flag);
        });
    }
}