OGNL小应用-动态数学公式计算

KimShen

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Java Servlet JSP

OGNL解析器:

import ognl.Ognl;
import ognl.OgnlContext;
import ognl.OgnlException;
public class OgnlExpression {
/* 表达式 */
private Object expression;
/* expressionString为OGNL表达式 */
public OgnlExpression(String expressionString) throws OgnlException {
super();
/* Ognl存放表达式,此时还没有解析 */
expression = Ognl.parseExpression(expressionString);
}
/* 获得表达式 */
public Object getExpression() {
return expression;
}
/* 获取Ognl结果 */
//参数1:上下文.
//参数2:对象
public Object getValue(OgnlContext context, Object rootObject)throws OgnlException {
/* 开始解析 */
return Ognl.getValue(getExpression(), context, rootObject);
}
}

测试Servlet:

import java.io.IOException;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import ognl.OgnlContext;
public class Test extends HttpServlet {
public void doPost(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
try {
// 创建OGNL上下文
OgnlContext context = new OgnlContext();
// 需要全类名
OgnlExpression expr = new OgnlExpression(request.getParameter("test"));
/* 指定表达式在指定上下文和根目录时返回的结果 */
System.out.println(expr.getValue(context, context));
System.out.println("表达式是：" + expr.getExpression());
} catch (Exception e) {
throw new RuntimeException();
}
}
}

测试JSP:

<%@ page language="java" import="java.util.*" pageEncoding="utf-8"%>
<html>
<head>
<title>My JSP 'index.jsp' starting page</title>
</head>
<body>
<form action="test" method="post">
<input type="text" name="test" />
<input type="submit" />
</form>
</body>
</html>

测试用例:
(1.12+13.4)/3.1*1.7
结果:
7.96258064516129

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