Struts 查看文件内容功能

1.Action 代码

/* 
* $Id: ShowFileAction.java 471754 2006-11-06 14:55:09Z husted $ 
* 
* Licensed to the Apache Software Foundation (ASF) under one 
* or more contributor license agreements.    See the NOTICE file 
* distributed with this work for additional information 
* regarding copyright ownership.    The ASF licenses this file 
* to you under the Apache License, Version 2.0 (the 
* "License"); you may not use this file except in compliance 
* with the License.    You may obtain a copy of the License at 
* 
*    http://www.apache.org/licenses/LICENSE-2.0 
* 
* Unless required by applicable law or agreed to in writing, 
* software distributed under the License is distributed on an 
* "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY 
* KIND, either express or implied.    See the License for the 
* specific language governing permissions and limitations 
* under the License. 
*/ 

package org.apache.struts.webapp.validator; 

import javax.servlet.http.HttpServletRequest; 
import javax.servlet.http.HttpServletResponse; 

import java.io.InputStream; 
import java.io.InputStreamReader; 

import org.apache.struts.action.Action; 
import org.apache.struts.action.ActionForm; 
import org.apache.struts.action.ActionForward; 
import org.apache.struts.action.ActionMapping; 
import org.apache.commons.logging.LogFactory; 
import org.apache.commons.logging.Log; 

/** 
* Action which retrieves a file specified in the parameter 
* and stores its contents in the request, so that they 
* can be displayed. 
*/ 
public class ShowFileAction extends Action { 

        /** Logging Instance. */ 
        private static final Log log = LogFactory.getLog(ShowFileAction.class); 

        public ActionForward execute(ActionMapping mapping, 
                                                                 ActionForm form, 
                                                                 HttpServletRequest request, 
                                                                 HttpServletResponse response) 
                                                    throws Exception { 

                // Get the file name 
                String fileName = mapping.getParameter(); 
                StringBuffer fileContents = new StringBuffer(); 

                if(fileName != null) { 

                        InputStream input = servlet.getServletContext().getResourceAsStream(fileName); 
                        if (input == null) { 
                                log.warn("File Not Found: "+fileName); 
                        } else { 
                                InputStreamReader inputReader = new InputStreamReader(input); 
                                char[] buffer = new char[1000]; 
                                while (true) { 
                                        int lth = inputReader.read(buffer); 
                                        if (lth < 0) { 
                                                break; 
                                        } else { 
                                                fileContents.append(buffer, 0, lth); 
                                        } 
                                } 
                        } 
                } else { 
                        log.error("No file name specified."); 
                } 


                // Store the File contents and name in the Request 
                request.setAttribute("fileName", fileName); 
                request.setAttribute("fileContents", fileContents.toString()); 

                return mapping.findForward("success"); 
        } 
} 

分析：

 

 String fileName = mapping.getParameter();

其中mapping 是ActionMapping 对象，是ActionConfig的子对象。 其中ActionConfig封装了Struts-config.xml 中的配置信息。

 

inputStream input = servlet.getServletContext().getResourceAsStream(fileName);

每个Web应用程序都是一个独立的Servlet容器，每个Web应用程序分别用一个ServletContext对象。ServletContext对象包含在ServletConfig对象中，

调用ServletConfig.getServletContext()方法获取ServletContext对象。
1、    getResourcePath    返回一个包含该目录和文件路径名称的Set集合
2、    getResource        返回映射到资源上的URL对象。
3、    getResourceAsStream 返回连接到某资源上的InputStream对象

 

 

 InputStreamReader inputReader = new InputStreamReader(input);

需要重新包装成字符处理。

 

【2】配置文件

        <!-- Show validations.xml --> 
        <action path="/showValidation"    
                        type="org.apache.struts.webapp.validator.ShowFileAction"    
                        scope="request"    
                        parameter="/WEB-INF/validator/validation.xml"> 
                <forward name="success" path="/showFile.jsp" /> 
        </action>

 

通过传递不同的parameter，读取不同的文件。

 

【3】在JSP页面 读取信息

    <body bgcolor="white"> 

        <h2>File: <i><bean:write name="fileName" scope="request" /></i></h2> 
        <hr /> 
        <pre> 
                <bean:write name="fileContents" scope="request" filter="true"/> 
        </pre> 
        <hr /> 
    </body>

 

bean:write 标签 有个filter属性。如果为true 的话，则表示

将把输出内容中的特殊HTML符号作为普通字符串来显示；如果filter属性为false,则不会把输出内容中的HTML符号转化为普通字符串． 

本文转自 randy_shandong 51CTO博客，原文链接：http://blog.51cto.com/dba10g/241235，如需转载请自行联系原作者