Jexl解析表达式

例1:

public static void main(String[] args) {
    Map params =new HashMap<>();
    params.put("id", 1122);
    String sql=" select * from Table where id=${id}";
    JexlContext context = new MapContext(params);
    JexlEngine jexl = new JexlEngine();
    UnifiedJEXL ujexl = new UnifiedJEXL(jexl);
    UnifiedJEXL.Expression expr = ujexl.parse(sql);
    String result = expr.evaluate(context).toString();
  }

sql:

执行前: select * from Table where id=${id}

执行后: select * from Table where id=1122

例2:

public static void main(String[] args) {
    Expression expr;
    JexlContext ctxt = new MapContext();
    JexlEngine jexl = new JexlEngine();
    // 表达式
    String exps = "if(c1>c2) {c3=5}";
    expr = jexl.createExpression(exps);

    ctxt.set("c1", 2);
    ctxt.set("c2", 1);
    expr.evaluate(ctxt);
    System.out.println(ctxt.get("c3"));
  }

ctxt:

执行前: 无c3

执行后: c3 = 5

总结:

JexlEngine  创建表达式

JexlContext  存放参数

需要jar包支持:commons-jexl-2.1.1.jar