以Jar形式为Web项目提供资源文件（JS、CSS与图片）

目录[-]

一、背景

二、分析

1、把我需要的JS、CSS与图片等资源copy到Web工程中。

2、通过程序采用流的方式读取Jar中的资源流再输出到页面流。

三、分析结果

四、核心代码开发（Jar端）

1、org.noahx.jarresource.TagLibResourceFilter（程序内逻辑详见注释）

2、pom.xml

五、核心代码开发（Web端）

1、web.xml

2、index.jsp（资源使用样例，JS、CSS与图片）

3、pom.xml

六、Web工程两种模式的Filter日志

1、目录部署方式

2、War包部署方式

七、总结

八、源程序下载

一、背景

最近正在编写TagLib，在开发的过程中遇到一个资源文件引用问题。因为我开发的TagLib最终是以Jar包的形式提供给项目来用的，所以Jar包中必须包含我开发TagLib所需的JS、CSS与图片等资源。问题就是Tag是在项目的Web工程中运行，如何访问到jar中的资源。

二、分析

我想了一下，应该有两种方式：

1、把我需要的JS、CSS与图片等资源copy到Web工程中。

    好处：

• 通过原生的Web服务器来访问，速度与性能上讲会好一些。

    缺点：

• Web工程必须以目录方式部署。（非war）
• 存放资源的目录名需要与Web工程明确约定。（防止对原Web项目文件进行覆盖）

2、通过程序采用流的方式读取Jar中的资源流再输出到页面流。

    好处：

• 不依赖Web工程的部署方式。
• 不会复制文件到Web工程。

    缺点：

• 以流的方式实时从Jar中读取。（速度与性能上讲并非最优）
• 页面流输出时需要指定内容类型Content-Type。（前者会由Web服务器来维护）

三、分析结果

最终我准备将1、2两种情况接合使用，默认会采用1复制文件到Web工程的方式。如果发现Web工程无法复制文件则采用2流读取方式。

四、核心代码开发（Jar端）

为了进行两种方式的切换定义一个Filter非常适合，可以拦截请求干扰行为，又可以在init初始化时进行资源文件的复制。

从下面的目录结构可以看出主程序就是一个Filter类，org.noahx.jarresource.resource包下的内容就是我需要的资源目录。Filter会自动判断Web工程的部署方式（目录与War）来决定复制资源目录还是直接流读取。

1、org.noahx.jarresource.TagLibResourceFilter（程序内逻辑详见注释）

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packageorg.noahx.jarresource;

 

importorg.apache.commons.io.FileUtils;

importorg.apache.commons.io.FilenameUtils;

importorg.apache.commons.io.IOUtils;

importorg.apache.commons.lang.StringUtils;

importorg.slf4j.Logger;

importorg.slf4j.LoggerFactory;

importsun.net.www.protocol.file.FileURLConnection;

 

importjavax.servlet.*;

importjavax.servlet.http.HttpServletRequest;

importjavax.servlet.http.HttpServletResponse;

importjava.io.File;

importjava.io.IOException;

importjava.io.InputStream;

importjava.net.JarURLConnection;

importjava.net.URL;

importjava.net.URLConnection;

importjava.util.Enumeration;

importjava.util.HashMap;

importjava.util.Map;

importjava.util.jar.JarEntry;

importjava.util.jar.JarFile;

 

/**

 * Created with IntelliJ IDEA.

 * User: noah

 * Date: 6/24/13

 * Time: 8:18 PM

 * To change this template use File | Settings | File Templates.

 */

publicclass TagLibResourceFilter implementsFilter {

 

    privatestatic final String RESOURCE_PACKAGE_PATH = "/org/noahx/jarresource/resource";

 

    privatestatic final String RESOURCE_CHARSET = "UTF-8";

 

    privatestatic final String DEFAULT_MINE_TYPE = "application/octet-stream";

 

    privatestatic String resourcePath;

 

    privatefinal Logger logger = LoggerFactory.getLogger(this.getClass());

 

    privateResourceMode resourceMode;

 

    privatestatic enum ResourceMode {

        Dir, Jar

    }

 

    privatestatic final Map<String, String> MINE_TYPE_MAP;

 

    static{

        MINE_TYPE_MAP = newHashMap<String, String>();

        MINE_TYPE_MAP.put("js","application/javascript;charset="+ RESOURCE_CHARSET);

        MINE_TYPE_MAP.put("css","text/css;charset="+ RESOURCE_CHARSET);

        MINE_TYPE_MAP.put("gif","image/gif");

        MINE_TYPE_MAP.put("jpg","image/jpeg");

        MINE_TYPE_MAP.put("jpeg","image/jpeg");

        MINE_TYPE_MAP.put("png","image/png");

 

    }

 

    publicstatic String getResourcePath() {

        returnTagLibResourceFilter.resourcePath;

    }

 

    privatestatic void setResourcePath(String resourcePath) {

        TagLibResourceFilter.resourcePath = resourcePath;

    }

 

    @Override

    publicvoid init(FilterConfig filterConfig) throwsServletException {

        String resPath = filterConfig.getInitParameter("resourcePath");

 

        if(!resPath.startsWith("/")) {

            resPath = "/"+ resPath;

        }

 

        setResourcePath(resPath);

 

        String rootPath = filterConfig.getServletContext().getRealPath("/");

        if(rootPath != null) {   //如果web工程是目录方式运行

 

            String dirPath = filterConfig.getServletContext().getRealPath(resPath);

            File dir = null;

            try{

                dir = newFile(dirPath);

                FileUtils.deleteQuietly(dir);//清除老资源

                FileUtils.forceMkdir(dir);  //重新创建资源目录

 

                if(logger.isDebugEnabled()){

                    logger.debug("create dir '"+dirPath+"'");

                }

            }catch(Exception e) {

                logger.error("Error creating TagLib Resource dir", e);

            }

 

            try{

                copyResourcesRecursively(this.getClass().getResource(RESOURCE_PACKAGE_PATH), dir); //复制classpath中的资源到目录

            }catch(Exception e) {

                logger.error(e.getMessage(), e);

            }

 

            resourceMode = ResourceMode.Dir;   //设置为目录模式

        }else{

            resourceMode = ResourceMode.Jar;    //设置为jar包模式

        }

 

        if(logger.isDebugEnabled()){

            logger.debug("ResourceMode:"+resourceMode);

        }

    }

 

    @Override

    publicvoid doFilter(ServletRequest request, ServletResponse response, FilterChain chain) throwsIOException, ServletException {

 

        switch(resourceMode) {

            caseDir:

                chain.doFilter(request, response);

                break;

            caseJar: {

                HttpServletRequest req = (HttpServletRequest) request;

                String path = req.getRequestURI().substring(req.getContextPath().length());  //uri去掉web上下文

 

                HttpServletResponse rep = (HttpServletResponse) response;

 

                if(path.startsWith(getResourcePath() + "/")) {  //resourcePath必须与url-pattern一致

 

                    path = path.substring(getResourcePath().length());     //uri去掉resourcePath

 

                    try{

                        URL resource = this.getClass().getResource(RESOURCE_PACKAGE_PATH + path);    //可能存在潜在安全问题

                        if(resource == null) {      //如果在类路径中没有找到资源->404

                            rep.sendError(HttpServletResponse.SC_NOT_FOUND);

                        }else{

                            InputStream inputStream = readResource(resource);

                            if(inputStream != null) {  //有inputstream说明已经读到jar中内容

                                String ext = FilenameUtils.getExtension(path).toLowerCase();

                                String contentType = MINE_TYPE_MAP.get(ext);

                                if(contentType == null) {

                                    contentType = DEFAULT_MINE_TYPE;

                                }

                                rep.setContentType(contentType);   //设置内容类型

 

                                ServletOutputStream outputStream = rep.getOutputStream();

                                try{

                                    intsize = IOUtils.copy(inputStream, outputStream);  //向输出流输出内容

                                    rep.setContentLength(size);

                                }finally{

                                    IOUtils.closeQuietly(inputStream);

                                    IOUtils.closeQuietly(outputStream);

                                }

                            }else{   //没有inputstream->404

                                rep.sendError(HttpServletResponse.SC_NOT_FOUND);

                            }

                        }

 

                    }catch(Exception e) {

                        logger.error(e.getMessage(), e);

                        rep.sendError(HttpServletResponse.SC_INTERNAL_SERVER_ERROR);

                    }

                }else{

                    logger.error("MUST set url-pattern=\"" + resourcePath + "/*\"!!");

                    rep.sendError(HttpServletResponse.SC_INTERNAL_SERVER_ERROR);

                }

 

            }

            break;

        }

 

 

    }

 

    @Override

    publicvoid destroy() {

    }

 

 

    privateInputStream readResource(URL originUrl) throwsException {

        InputStream inputStream = null;

        URLConnection urlConnection = originUrl.openConnection();

        if(urlConnection instanceofJarURLConnection) {

            inputStream = readJarResource((JarURLConnection) urlConnection);

        }elseif (urlConnection instanceofFileURLConnection) {

            File originFile = newFile(originUrl.getPath());

            if(originFile.isFile()) {

                inputStream = originUrl.openStream();

            }

        }else{

            thrownew Exception("URLConnection["+ urlConnection.getClass().getSimpleName() +

                    "] is not a recognized/implemented connection type.");

        }

 

        returninputStream;

    }

 

    privateInputStream readJarResource(JarURLConnection jarConnection) throwsException {

        InputStream inputStream = null;

        JarFile jarFile = jarConnection.getJarFile();

        if(!jarConnection.getJarEntry().isDirectory()) { //如果jar中内容为目录则不返回inputstream

            inputStream = jarFile.getInputStream(jarConnection.getJarEntry());

        }

        returninputStream;

    }

 

    privatevoid copyResourcesRecursively(URL originUrl, File destination) throwsException {

 

        URLConnection urlConnection = originUrl.openConnection();

        if(urlConnection instanceofJarURLConnection) {

            copyJarResourcesRecursively(destination, (JarURLConnection) urlConnection);

        }elseif (urlConnection instanceofFileURLConnection) {

            FileUtils.copyDirectory(newFile(originUrl.getPath()), destination); //如果不是jar则采用目录copy

            if(logger.isDebugEnabled()){

                logger.debug("copy dir '"+originUrl.getPath()+"' --> '"+destination.getPath()+"'");

            }

        }else{

            thrownew Exception("URLConnection["+ urlConnection.getClass().getSimpleName() +

                    "] is not a recognized/implemented connection type.");

        }

    }

 

    privatevoid copyJarResourcesRecursively(File destination, JarURLConnection jarConnection) throwsIOException {

        JarFile jarFile = jarConnection.getJarFile();

        Enumeration<JarEntry> entries = jarFile.entries();

        while(entries.hasMoreElements()) {    //遍历jar内容逐个copy

            JarEntry entry = entries.nextElement();

            if(entry.getName().startsWith(jarConnection.getEntryName())) {

                String fileName = StringUtils.removeStart(entry.getName(), jarConnection.getEntryName());

                File destFile = newFile(destination, fileName);

                if(!entry.isDirectory()) {

                    InputStream entryInputStream = jarFile.getInputStream(entry);

                    FileUtils.copyInputStreamToFile(entryInputStream, destFile);

                    if(logger.isDebugEnabled()){

                        logger.debug("copy jarfile to file '"+entry.getName()+"' --> '"+destination.getPath()+"'");

                    }

                }else{

                    FileUtils.forceMkdir(destFile);

                    if(logger.isDebugEnabled()){

                        logger.debug("create dir '"+destFile.getPath()+"'");

                    }

                }

            }

        }

    }

}

补充：Filter中提供了静态方法getResourcePath()来获得当前的资源路径，我的TagLib中就可以通过该方法获得资源URI。

2、pom.xml

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<?xmlversion="1.0"encoding="UTF-8"?>

<projectxmlns="http://maven.apache.org/POM/4.0.0"

         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"

         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">

    <modelVersion>4.0.0</modelVersion>

 

    <groupId>org.noahx.jarresource</groupId>

    <artifactId>resource</artifactId>

    <version>1.0-SNAPSHOT</version>

 

    <packaging>jar</packaging>

 

    <dependencies>

 

        <dependency>

            <groupId>commons-io</groupId>

            <artifactId>commons-io</artifactId>

            <version>2.4</version>

        </dependency>

 

        <dependency>

            <groupId>org.slf4j</groupId>

            <artifactId>slf4j-api</artifactId>

            <version>1.7.5</version>

        </dependency>

 

        <dependency>

            <groupId>commons-lang</groupId>

            <artifactId>commons-lang</artifactId>

            <version>2.6</version>

        </dependency>

 

        <dependency>

            <groupId>javax.servlet</groupId>

            <artifactId>servlet-api</artifactId>

            <version>2.5</version>

            <scope>provided</scope>

        </dependency>

 

    </dependencies>

</project>

使用了commons-io与commons-lang第三方类包

五、核心代码开发（Web端）

作为Jar文件的使用端，只需要在web.xml中配置一个filter，就可以访问到Jar中的资源。

1、web.xml

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<web-appxmlns="http://java.sun.com/xml/ns/javaee"

         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"

         xsi:schemaLocation="http://java.sun.com/xml/ns/javaee

          http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd"

         version="2.5">

    <display-name>jar resource web</display-name>

 

    <filter>

        <filter-name>tagLibResourceFilter</filter-name>

        <filter-class>org.noahx.jarresource.TagLibResourceFilter</filter-class>

        <init-param>

            <param-name>resourcePath</param-name>

            <param-value>/tagres</param-value>

        </init-param>

    </filter>

 

    <filter-mapping>

        <filter-name>tagLibResourceFilter</filter-name>

        <url-pattern>/tagres/*</url-pattern>

    </filter-mapping>

 

    <welcome-file-list>

        <welcome-file>index.jsp</welcome-file>

    </welcome-file-list>

</web-app>

注意：由于Servlet 3.0以下无法通过程序获得url-pattern，所以在filter的参数中指定了一个同名路径来使用。filter会用这个路径名称在Web工程下创建资源目录（目录部署）。

2、index.jsp（资源使用样例，JS、CSS与图片）

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<%@ page contentType="text/html;charset=UTF-8" language="java" %>

<html>

<head>

    <title></title>

    <linkrel="stylesheet"type="text/css"href="tagres/css.css"/>

    <script type="text/javascript"src="tagres/example.js"></script>

</head>

<body>

     <imgsrc="tagres/imgs/star-hover4.png"/>star-hover4.png<br/>

     <buttononclick="example();">example.js (example)</button><br/>

     <divclass="redbox">css.css redbox</div>

</body>

</html>

tagres/中的内容就是Jar工程中所提供的资源。（下图为显示效果）

3、pom.xml

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<?xmlversion="1.0"encoding="UTF-8"?>

<projectxmlns="http://maven.apache.org/POM/4.0.0"

         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"

         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">

    <modelVersion>4.0.0</modelVersion>

 

    <groupId>org.noahx.jarresource</groupId>

    <artifactId>web</artifactId>

    <version>1.0-SNAPSHOT</version>

 

    <packaging>war</packaging>

 

    <dependencies>

        <dependency>

            <groupId>org.noahx.jarresource</groupId>

            <artifactId>resource</artifactId>

            <version>1.0-SNAPSHOT</version>

        </dependency>

 

        <dependency>

            <groupId>org.slf4j</groupId>

            <artifactId>slf4j-log4j12</artifactId>

            <version>1.7.5</version>

            <scope>runtime</scope>

        </dependency>

 

    </dependencies>

 

</project>

六、Web工程两种模式的Filter日志

1、目录部署方式

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[JAR-RES] 2013-06-26 13:11:13,132 DEBUG [org.noahx.jarresource.TagLibResourceFilter] - createdir'/nautilus/develop/jar-resource/web/target/web-1.0-SNAPSHOT/tagres' (TagLibResourceFilter.java:93)

[JAR-RES] 2013-06-26 13:11:13,146 DEBUG [org.noahx.jarresource.TagLibResourceFilter] - createdir'/nautilus/develop/jar-resource/web/target/web-1.0-SNAPSHOT/tagres/' (TagLibResourceFilter.java:240)

[JAR-RES] 2013-06-26 13:11:13,147 DEBUG [org.noahx.jarresource.TagLibResourceFilter] - createdir'/nautilus/develop/jar-resource/web/target/web-1.0-SNAPSHOT/tagres/imgs' (TagLibResourceFilter.java:240)

[JAR-RES] 2013-06-26 13:11:13,152 DEBUG [org.noahx.jarresource.TagLibResourceFilter] - copy jarfile tofile'org/noahx/jarresource/resource/imgs/star-hover4.png' --> '/nautilus/develop/jar-resource/web/target/web-1.0-SNAPSHOT/tagres'(TagLibResourceFilter.java:235)

[JAR-RES] 2013-06-26 13:11:13,153 DEBUG [org.noahx.jarresource.TagLibResourceFilter] - copy jarfile tofile'org/noahx/jarresource/resource/example.js' --> '/nautilus/develop/jar-resource/web/target/web-1.0-SNAPSHOT/tagres'(TagLibResourceFilter.java:235)

[JAR-RES] 2013-06-26 13:11:13,154 DEBUG [org.noahx.jarresource.TagLibResourceFilter] - copy jarfile tofile'org/noahx/jarresource/resource/css.css' --> '/nautilus/develop/jar-resource/web/target/web-1.0-SNAPSHOT/tagres'(TagLibResourceFilter.java:235)

[JAR-RES] 2013-06-26 13:11:13,154 DEBUG [org.noahx.jarresource.TagLibResourceFilter] - ResourceMode:Dir (TagLibResourceFilter.java:111)

可以看到copy资源文件的过程

2、War包部署方式

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[JAR-RES] 2013-06-26 13:12:25,287 DEBUG [org.noahx.jarresource.TagLibResourceFilter] - ResourceMode:Jar (TagLibResourceFilter.java:111)

从Jar中直接读取，并没有copy资源的过程。

七、总结

这个Filter很好的解决了我在开发TagLib时遇到的资源引用问题，对我来说应该够用了。

我们项目中一般采用目录方式部署，我也更希望通过Web服务器来直接访问资源。

并没有采用maven来组织资源，因为我需要提供给非maven工程使用。

一些流行的mvc中也有类似的手法，可能是采用流方式读取（猜测），感兴趣的朋友可以查看这些mvc的代码。

八、源程序下载

下载包中提供了源代码以及打包后（target目录）的工程。

http://sdrv.ms/11Mp5gF