Java将一个含有逻辑运算符的字符串转化成逻辑表达式

public class TestA {
    public static void main(String[] args) throws Exception {
        String str = "(a >= 0 && b <= 5)";
        ScriptEngineManager manager = new ScriptEngineManager();
        ScriptEngine engine = manager.getEngineByName("js");
        engine.put("a", 4);
        engine.put("b", 5);
        Object result = engine.eval(str);
        System.out.println("结果类型:" + result.getClass().getName() + ",计算结果:" + result);
    }
}

输出结果:
结果类型:java.lang.Boolean,计算结果:false

还可以使用 commons-jexl3 jar包 

示例:

public static void main(String[] args){
        String expressionString = "1+2+3";

        JexlEngine jexlEngine = new JexlBuilder().create();
        JexlExpression jexlExpression = jexlEngine.createExpression(expressionString);
        Object evaluate = jexlExpression.evaluate(null);
        System.out.println(evaluate);
    }

结果:  6

示例2:

来个复杂点的

public static void main(String[] args){
        //  String expressionString = "1+2+3";

        String expressionString = "100*10-(200+300)";

        JexlEngine jexlEngine = new JexlBuilder().create();
        JexlExpression jexlExpression = jexlEngine.createExpression(expressionString);
        Object evaluate = jexlExpression.evaluate(null);
        System.out.println(evaluate);
    }

结果: 500