Java 實現String語句的執行（Jexl）

https://www.jianshu.com/p/1000719e49fa

1.maven 導入庫

<dependency>
<groupId>org.apache.commons</groupId>
<artifactId>commons-jexl</artifactId>
<version>2.0</version>
</dependency>

2.代碼實例

import org.apache.commons.jexl2.Expression; import org.apache.commons.jexl2.JexlContext; import org.apache.commons.jexl2.JexlEngine; import org.apache.commons.jexl2.MapContext; import java.util.HashMap; import java.util.Map; /** * A Camel Application */ public class MainApp { /** * A main() so we can easily run these routing rules in our IDE */ public static Object convertToCode(String jexlExp, Map<String, Object> map) { //創建或檢索引擎 JexlEngine jexl = new JexlEngine(); //創建一個表達式 Expression e = jexl.createExpression(jexlExp); //創建上下文並添加數據 JexlContext jc = new MapContext(); for (String key : map.keySet()) { jc.set(key, map.get(key)); } //現在評估表達式，得到結果 if (null == e.evaluate(jc)) { return ""; } return e.evaluate(jc); } public static void main(String... args) throws Exception { try { Map<String, Object> map = new HashMap<String, Object>(16); map.put("money", 6100); String expression = "money>=2000&&money<=4000"; Object code = convertToCode(expression, map); System.out.println((Boolean) code); } catch (Exception e) { // TODO Auto-generated catch block e.printStackTrace(); } } } 

3. 補充：c# Asp.net

using System.Web.Script.Serialization;

 public static object EvalJscript(string str) { object Result = null; str = str.Replace("OR", "||"); str = str.Replace("AND", "&&"); if (ve == null) { ve = Microsoft.JScript.Vsa.VsaEngine.CreateEngine(); } Result = Microsoft.JScript.Eval.JScriptEvaluate(str, ve); return Result; }

作者：咖啡機an
鏈接：https://www.jianshu.com/p/1000719e49fa
來源：簡書
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