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[Java教程]Java Web项目将word打包zip并提供下载


      该博客记录Java Web项目将word打包zip并提供下载功能的实现和其中遇到的坑,方便后续自己的查看的参照。
      项目架构背景: JQuery + Bootstarp + SpringMvc

1. 后台处理的java 方法

      具体实现思路为,将 word 文档生成到uploadword文件夹下,将压缩包生成到uploadzip文件夹下,(在配置目录的路径的时候记得注意几种不同的服务器上面的路径写法)首先将所有的word生成到uploadword目录下面,然后指定压缩的文件夹为uploadword,并将生成的zip指定到uploadzip文件夹,当时也考虑过在一个文件夹下面,生成word ,然后压缩为一个 zip,但很可惜的时压缩出来的文件,总是莫名奇妙的迭代了很多相同的压缩包,应该是将生成的压缩包,也作为了文件不断循环在压缩,所以果断分开文件夹,在将文件压缩流入压缩包中后,删除原uploadword文件夹中的文件,所以当程序正确执行完后,服务器中的uploadword这个文件夹都是清空的(毕竟这个功能是权限比较大的管理员进行的操作,有且只有一个超级管理员,现在还没有考虑多用户同时并发生成压缩包的情况)

     根据 word 模版生成 word 文书的方法,我已经在前面的博客中总结过,可以看 java动态生成复杂word文件

压缩方法上代码:

 1 /**  2 * @Description: 生成zip包 3 * @param: web请求对象,web返回对象,web后端返回到前端的map 4 * @return: TODO (返回类型和参数描述) 5 */ 6 public void createZip(HttpServletRequest req,HttpServletResponse res,Map<String, Object> retmap) { 7 try { 8 //从配置文件获取生成压缩包的文件夹路径,生成唯一的压缩包名称 9 String zippath = getUploadpath("uploadzip");10 String zipFileName = Functions.now("yyyy-MM-dd-HH-mm-ss") + ".zip";11 String zipFilePath = zippath + zipFileName;12 13 //生成压缩文件,并写入压缩流中14 File zipFile = new File(zipFilePath);15 ZipOutputStream zipOut = new ZipOutputStream(new FileOutputStream(zipFile));16 17 //从配置文件获取待压缩的的文件夹路径,并生成文件夹,准备好读入流,等待进行读入文件进行压缩18 String filepath = getUploadpath("uploadword");19 File file = new File(filepath);20 InputStream input = null;21 22 // 压缩包中文件zip的名称为23 zipOut.setComment(file.getName());24 25 //循环读入uploadword文件夹中文件,写入压缩流中,最后删除对应的文件26 if (file.isDirectory()) {27 File[] files = file.listFiles();28 for (int i = 0; i < files.length; ++i) {29 30 input = new FileInputStream(files[i]);31 zipOut.putNextEntry(new ZipEntry(file.getName()+ File.separator + files[i].getName()));32 33 int temp = 0;34 while ((temp = input.read()) != -1) {35 zipOut.write(temp);36 }37 input.close();38 files[i].delete();39 }40 }41 //关闭压缩流,并将压缩文件夹路径,压缩文件名称,当前服务器类型【tomcat,weblogic】返回给前端用于跳转下载页面时进行传参42 zipOut.close();43 retmap.put("zippath", zipFilePath);44 retmap.put("zipFileName", zipFileName);45 retmap.put("serverName", ServerDetector.getServerId().toUpperCase());46 retmap.put("success", true);47 } catch (Exception e) {48 e.printStackTrace();49 }50 }51 52 /** 53 * @Description: 获取配置文件上传路径(为了可维护性高,路径会配置在配置文件中,然后在代码中进行读,这样会减少后边维护人员的痛苦)54 */55 public String getUploadpath(String param) {56 Properties prop = new Properties();57 String url = this.getClass().getResource("").getPath().replaceAll("%20", " ");58 String path = url.substring(0, url.indexOf("WEB-INF")) + "WEB-INF/Config.properties";59 try {60 prop.load(new FileInputStream(path));61 } catch (Exception e) {62 e.printStackTrace();63 }64 String content = prop.getProperty(param).trim();65 return content;66 }

2. Sping MVC框架实现下载遇到的“坑” 

    可能以前做过这功能朋友的会产生疑问,为什么要跳转到前端的下载页面去,不直接在后端生成下载流,放入HttpServletResponse对象,返回给前端直接在弹出下载框。当时我也是这样想的,但事实总是很残酷。
实现的代码是这样的:

 1 /**  2 * @Description: 实现压缩包下载 3 * @param: TODO (入参描述)压缩文件夹的路径,生成的压缩文件的名称 4 * @return: TODO (返回类型和参数描述) 5 */ 6 public void downFile(HttpServletResponse response, String zippath, String zipFileName) { 7 try { 8  9 String path = zippath + zipFileName;10 File file = new File(path);11 if (file.exists()) {12 InputStream ins = new FileInputStream(path);13 BufferedInputStream bins = new BufferedInputStream(ins);// 放到缓冲流里面14 15 OutputStream outs = response.getOutputStream();// 获取文件输出IO流16 BufferedOutputStream bouts = new BufferedOutputStream(outs);17 18 response.reset();19 response.setContentType("application/x-download");// 设置response内容的类型20 response.setHeader("Content-disposition", "attachment;filename=" + URLEncoder.encode(str, "GBK"));// 设置头部信息21 int bytesRead = 0;22 byte[] buffer = new byte[8192];23 24 while ((bytesRead = bins.read(buffer, 0, 8192)) != -1) {25 bouts.write(buffer, 0, bytesRead);26 }27 bouts.flush();28 ins.close();29 bins.close();30 outs.close();31 bouts.close();32 } else {33 response.sendRedirect("/error.jsp");34 }35 } catch (Exception e) {36 e.printStackTrace();37 }38 }

    加入后台这段代码后,并没有达到我想要的效果,可能是我对Spring Mvc理解的不够,还请各位看官赐教。

3. 生成zip包成功,在前端跳转下载页面

    既然后端不能直接返回下载流,并弹出下载框,在前端接受返回的下载所需(zippath,zipFileName,serverName)的关键参数,跳转到下载JSP页面。

相应跳转(跳转方式多种多样,这里采用表单提交到download.jsp页面):

var theParam = {};theParam.zippath = data.zippath;theParam.zipFileName =data.zipFileName;Param.serverName =data.serverName;var formStr = "<form action='..../download.jsp' method='post' id='form' style='display:none'>";$.each(theParam, function(key, value) {formStr += "<input type='hidden' name='" + key + "' value='" + value + "'/>";});formStr += "</form>";$("body").append(formStr);$("#form").submit();

下载页面:

<%@page import="java.io.OutputStream"%><%@page import="java.net.URLEncoder"%><%@page import="java.io.FileInputStream"%><%@page import="cn.nxcc.nxwb.utils.ServerDetector"%><%@page language="java" contentType="application/x-msdownload" pageEncoding="UTF-8"%><%try {//关于文件下载时采用文件流输出的方式处理://加上response.reset(),并且所有的%>后面不要换行,包括最后一个;response.reset();//可以加也可以不加response.setContentType("application/x-download");String filedownload = request.getParameter("zippath");String filedisplay = request.getParameter("zipFileName");response.addHeader("Content-Disposition", "attachment;filename=" + URLEncoder.encode(filedisplay, "UTF-8"));OutputStream outp = response.getOutputStream();FileInputStream in = new FileInputStream(filedownload);byte[] b = new byte[1024];int i = 0;while ((i = in.read(b)) > 0) {outp.write(b, 0, i);}outp.flush();outp.close();in.close();//Tomcat 需要添加这两局来避免 getOutputStream() 方法,已被调用的异常,weblogic做特殊判断if(request.getParameter("serverName").equals("TOMCAT")){out.clear();out = pageContext.pushBody();}} catch (Exception e) {e.printStackTrace();}%>

4. 流在不同web容器的妥善处理

    刚开始程序在tomcat 上跑时,总出现报错:
org.apache.jasper.JasperException: java.lang.IllegalStateException: getOutputStream() has already been called for this response

    百度一番,发现Body()的作用是保存当前的out对象,并更新PageContext中Page范围内Out对象。JSP容器在处理完成请求后会调用releasePageConter方法释放所有的
PageContestObject,并且同时调用getWriter方法。由于getWriter方法与在JSP页面中使用流相关的getOutputStream方法冲突,解决方法也很简单,重新生成PageContext中Page范围内Out对象,
在代码最后添加
out.clear();
out = pageContext.pushBody();

    好了,自己本地测试不会报错了,将项目打包到weblogic,开始出现了报错:
Servlet failed with Exception java.lang.IllegalStateException: Response already committed at weblogic.servlet.internal.ServletResponseImpl.objectIfCommitted(ServletResponseImpl.java:1602) ......
    虽然不影响功能的使用,还是看着不爽,百度一番,发现是自己添加的上两句的的原因(tomcat 和 weblogic 容器的差异性,应该是weblogic并不会调用releasePageConter方法释放所有的PageContestObject)

    这就是下载页面出现这几行代码的原因:

//Tomcat 需要添加这两局来避免 getOutputStream() 方法,已被调用的异常,weblogic做特殊判断if(request.getParameter("serverName").equals("TOMCAT")){out.clear();out = pageContext.pushBody();}

     如果能判断是在哪个web容器中,然后进行特殊判断就好了,同样是百度一番,发现 portal-kernel.jar中的类ServerDetector.java 能完美判断多达10种以上的容器类型,但我又不想将这个jar 引入到项目中(俺就用一个类,引一个jar,太亏了),然后Jd-Gui反编译,单独拉出这个类,修改修改添加到我的项目中。

上代码(修改完的代码,不依赖任何类,你可以拿来直接用):

 1 /** 2 * @ClassName: ServerDetector 3 * @Description: 判断 Web 容器类型 4 */ 5 public class ServerDetector{ 6 private static ServerDetector _instance = new ServerDetector(); 7 private String _serverId; 8 private Boolean _geronimo; 9 private Boolean _glassfish; 10 private Boolean _jBoss; 11 private Boolean _jetty; 12 private Boolean _jonas; 13 private Boolean _oc4j; 14 private Boolean _resin; 15 private Boolean _tomcat; 16 private Boolean _webLogic; 17 private Boolean _webSphere; 18  19 public static final String GERONIMO_ID = "geronimo"; 20 public static final String GLASSFISH_ID = "glassfish"; 21 public static final String JBOSS_ID = "jboss"; 22 public static final String JETTY_ID = "jetty"; 23 public static final String JONAS_ID = "jonas"; 24 public static final String OC4J_ID = "oc4j"; 25 public static final String RESIN_ID = "resin"; 26 public static final String TOMCAT_ID = "tomcat"; 27 public static final String WEBLOGIC_ID = "weblogic"; 28 public static final String WEBSPHERE_ID = "websphere"; 29  30 public static String getServerId() { 31 ServerDetector sd = _instance; 32 if (sd._serverId == null) { 33 if (isGeronimo()) { 34 sd._serverId = "geronimo"; 35 } else if (isGlassfish()) { 36 sd._serverId = "glassfish"; 37 } else if (isJBoss()) { 38 sd._serverId = "jboss"; 39 } else if (isJOnAS()) { 40 sd._serverId = "jonas"; 41 } else if (isOC4J()) { 42 sd._serverId = "oc4j"; 43 } else if (isResin()) { 44 sd._serverId = "resin"; 45 } else if (isWebLogic()) { 46 sd._serverId = "weblogic"; 47 } else if (isWebSphere()) { 48 sd._serverId = "websphere"; 49 } 50 if (isJetty()) { 51 if (sd._serverId == null) { 52 sd._serverId = "jetty"; 53 } else { 54 sd._serverId += "-jetty"; 55 } 56 } else if (isTomcat()) { 57 if (sd._serverId == null) { 58 sd._serverId = "tomcat"; 59 } else { 60 sd._serverId += "-tomcat"; 61 } 62 } 63 if (sd._serverId == null) { 64 throw new RuntimeException("Server is not supported"); 65 } 66 } 67 return sd._serverId; 68 } 69  70 public static boolean isGeronimo() { 71 ServerDetector sd = _instance; 72 if (sd._geronimo == null) { 73 sd._geronimo = _detect("/org/apache/geronimo/system/main/Daemon.class"); 74 } 75 return sd._geronimo.booleanValue(); 76 } 77  78 public static boolean isGlassfish() { 79 ServerDetector sd = _instance; 80 if (sd._glassfish == null) { 81 String value = System.getProperty("com.sun.aas.instanceRoot"); 82 if (value != null) { 83 sd._glassfish = Boolean.TRUE; 84 } else { 85 sd._glassfish = Boolean.FALSE; 86 } 87 } 88 return sd._glassfish.booleanValue(); 89 } 90  91 public static boolean isJBoss() { 92 ServerDetector sd = _instance; 93 if (sd._jBoss == null) { 94 sd._jBoss = _detect("/org/jboss/Main.class"); 95 } 96 return sd._jBoss.booleanValue(); 97 } 98  99 public static boolean isJetty() {100 ServerDetector sd = _instance;101 if (sd._jetty == null) {102 sd._jetty = _detect("/org/mortbay/jetty/Server.class");103 }104 return sd._jetty.booleanValue();105 }106 107 public static boolean isJOnAS() {108 ServerDetector sd = _instance;109 if (sd._jonas == null) {110 sd._jonas = _detect("/org/objectweb/jonas/server/Server.class");111 }112 return sd._jonas.booleanValue();113 }114 115 public static boolean isOC4J() {116 ServerDetector sd = _instance;117 if (sd._oc4j == null) {118 sd._oc4j = _detect("oracle.oc4j.util.ClassUtils");119 }120 return sd._oc4j.booleanValue();121 }122 123 public static boolean isResin() {124 ServerDetector sd = _instance;125 if (sd._resin == null) {126 sd._resin = _detect("/com/caucho/server/resin/Resin.class");127 }128 return sd._resin.booleanValue();129 }130 131 public static boolean isSupportsComet() {132 return false;133 }134 135 public static boolean isTomcat() {136 ServerDetector sd = _instance;137 if (sd._tomcat == null) {138 sd._tomcat = _detect("/org/apache/catalina/startup/Bootstrap.class");139 }140 if (sd._tomcat == null) {141 sd._tomcat = _detect("/org/apache/catalina/startup/Embedded.class");142 }143 return sd._tomcat.booleanValue();144 }145 146 public static boolean isWebLogic() {147 ServerDetector sd = _instance;148 if (sd._webLogic == null) {149 sd._webLogic = _detect("/weblogic/Server.class");150 }151 return sd._webLogic.booleanValue();152 }153 154 public static boolean isWebSphere() {155 ServerDetector sd = _instance;156 if (sd._webSphere == null) {157 sd._webSphere = _detect("/com/ibm/websphere/product/VersionInfo.class");158 }159 return sd._webSphere.booleanValue();160 }161 162 private static Boolean _detect(String className) {163 try {164 ClassLoader.getSystemClassLoader().loadClass(className);165 return Boolean.TRUE;166 } catch (ClassNotFoundException cnfe) {167 ServerDetector sd = _instance;168 169 Class<?> c = sd.getClass();170 if (c.getResource(className) != null) {171 return Boolean.TRUE;172 }173 }174 return Boolean.FALSE;175 }176 }

    OK ,到此完美解决了 Spring MVC 中zip包下载、避开后端直接写入前端下载流、妥善解决各web容器的差异性。