工作原理

利用strust2的action通配对保护的图片得到后返回流文件，如果目录下没有找到图片，则返回未找到图片提示；对请求的IP进行对比，如果不在允许的IP列表时则返回没有权限的图片。

首先在struts.properties文件中添加查询后缀，struts的默认为action，可以添加多个，中间用“，”隔开

struts.i18n.encoding = UTF-8
struts.action.extension = html,jpg
struts.devMode=true
struts.custom.i18n.resources=messageResource
struts.locale=zh_CN
struts.multipart.saveDir=javax.servlet.context.tempdir
struts.ui.theme=simple
struts.enable.DynamicMethodInvocation=true

添加action类Test，其中有两个属性：String contentType，InputStream bis，前者是制定输出的流文件类型，后一个是文件流

package test.com.eca.service;import java.io.BufferedInputStream;
import java.io.BufferedOutputStream;
import java.io.FileInputStream;
import java.io.IOException;
import java.util.regex.Matcher;
import java.util.regex.Pattern;import javax.servlet.http.HttpServletRequest;import main.com.eca.util.JsonUtil;import org.apache.struts2.ServletActionContext;
import org.nail.common.BaseAction;import com.opensymphony.xwork2.Action;public class Test extends BaseAction {private BufferedOutputStream bos = null;private BufferedInputStream bis = null;private String imgPath;private String contentType;public String testImg() throws Exception {HttpServletRequest request = ServletActionContext.getRequest();System.out.println("request.getHeader(\"user-agent\")"+ request.getHeader("user-agent"));System.out.println("请求来源于浏览器 ："+BrowseTool.checkBrowse(request.getHeader("user-agent")));// 访问图片后缀StringBuffer requestUrl = request.getRequestURL();String fileType = requestUrl.substring(requestUrl.lastIndexOf("."));// 得到访问的IPString reqIp = IpUtils.getIpAddr(request);System.out.println("img : " + imgPath + fileType);System.out.println("ip : " + reqIp);// 的到允许的IP的Mapif ("127.0.0.1".equals(reqIp)) {bis = new BufferedInputStream(new FileInputStream("D:/images/no_acc_image.jpg"));return Action.SUCCESS;}// 判断是否有权限try {try {bis = new BufferedInputStream(new FileInputStream("D:/images/"+ imgPath + fileType));} catch (Exception e) {// e.printStackTrace();bis = new BufferedInputStream(new FileInputStream("D:/images/no_image.jpg"));}} catch (final IOException e) {e.printStackTrace();} catch (Exception e) {e.printStackTrace();}return Action.SUCCESS;}public static void main(String[] args) throws Exception {System.out.println("abcds".substring("abcds".indexOf("c")));}public BufferedOutputStream getBos() {return bos;}public void setBos(BufferedOutputStream bos) {this.bos = bos;}public BufferedInputStream getBis() {return bis;}public void setBis(BufferedInputStream bis) {this.bis = bis;}public String getImgPath() {return imgPath;}public String getContentType() {return contentType;}public void setContentType(String contentType) {this.contentType = contentType;}public void setImgPath(String imgPath) {this.imgPath = imgPath;}}/*** * @author cc 20120307*/
class BrowseTool {private final static String IE5_5 = "MSIE 5.5";private final static String IE9 = "MSIE 9.0";private final static String IE8 = "MSIE 8.0";private final static String IE7 = "MSIE 7.0";private final static String IE6 = "MSIE 6.0";private final static String MAXTHON = "Maxthon";private final static String QQ = "QQBrowser";private final static String GREEN = "GreenBrowser";private final static String SE360 = "360SE";private final static String FIREFOX = "Firefox";private final static String OPERA = "Opera";private final static String CHROME = "Chrome";private final static String SAFARI = "Safari";private final static String OTHER = "其它";public static String checkBrowse(String userAgent) {if (regex(OPERA, userAgent)) {return OPERA;} else if (regex(CHROME, userAgent)) {return CHROME;} else if (regex(FIREFOX, userAgent)) {return FIREFOX;} else if (regex(SAFARI, userAgent)) {return SAFARI;} else if (regex(SE360, userAgent)) {return SE360;} else if (regex(GREEN, userAgent)) {return GREEN;} else if (regex(QQ, userAgent)) {return QQ;} else if (regex(MAXTHON, userAgent)) {return MAXTHON;} else if (regex(IE9, userAgent)) {return IE9;} else if (regex(IE8, userAgent)) {return IE8;} else if (regex(IE7, userAgent)) {return IE7;} else if (regex(IE6, userAgent)) {return IE6;} else if (regex(IE5_5, userAgent)) {return IE5_5;}return OTHER;}private static boolean regex(String regex, String str) {Pattern p = Pattern.compile(regex, Pattern.MULTILINE);Matcher m = p.matcher(str);return m.find();}
}class IpUtils {public static String getIpAddr(HttpServletRequest request) {String ip = request.getHeader("X-Forwarded-For");if (ip == null || ip.length() == 0 || "unknown".equalsIgnoreCase(ip)) {ip = request.getHeader("Proxy-Client-IP");}if (ip == null || ip.length() == 0 || "unknown".equalsIgnoreCase(ip)) {ip = request.getHeader("WL-Proxy-Client-IP");}if (ip == null || ip.length() == 0 || "unknown".equalsIgnoreCase(ip)) {ip = request.getHeader("HTTP_CLIENT_IP");}if (ip == null || ip.length() == 0 || "unknown".equalsIgnoreCase(ip)) {ip = request.getHeader("HTTP_X_FORWARDED_FOR");}if (ip == null || ip.length() == 0 || "unknown".equalsIgnoreCase(ip)) {ip = request.getRemoteAddr();}return ip;}
}

在actionContext.xml文件中加入bean配置：

<bean id="test" class="test.com.eca.service.Test"parent="baseAction" scope="prototype"></bean>

之后配置action配置

<package name="test" extends="struts-default" namespace="/images"><!-- 测试图片权限管理 --><action name="*" class="test" method="testImg"><param name="imgPath">{1}</param><result type="stream">   <param name="contentType">image/jpeg</param>   <param name="inputName">bis</param><!-- 指定下载的文件名   --><!--<param name="contentDisposition">filename="wjc_lgo.jpg"</param>--><!-- 指定下载文件时的缓冲大小   --><!--<param name="bufferSize">1024</param>--></result></action>
</package>

其中注意，namespace要加入“/”，否则输入地址“http://xxx/images/abc.jpg”则无法找到，平配置意思为地址路径为“http://xxx/images/”开头的，已“.jpg”结尾的所有的请求都转为处理。

例如：“http://xxx/images/abc.jpg”并将“imgPath”作为参数调用action的方法

inputName指定为action的文件流的名称

下载的文件名、缓冲区大小在此不配置也可以

完成后地址栏输入“http://192.168.2.15:5050/ecs/images/tomcat.jpg”后就可以看到成果了