js 动态调用 applet 内的方法
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js 动态调用 applet 内的方法
js 动态调用 applet 内的方法示例程序下载链接
js、applet（java） 都是客户端脚本语言，在客户端与用户进行着一些信息交互。然而它们并不是独立的，它们也可以协作工作，互相调用来完成一些复杂的客户端操作。本文从一个项目实战例子，演示了如何使用 js 动态调用 applet 内封装的各种方法。
本文仅贴出了 FileApplet 中被调用的方法，因为 FileUploadApplet extends FileApplet，所以这些方法（public）被直接继承。
/**
* added by Defonds
* @param filesInfo
* File Name1|File Flag Public1|File Document Language1|File Description1|File Operating System1|File Store1|File Title1|File Flag Exp1
*/
public void addFileInfomation(String filesInfo,String directoryInfo,String formatInfo){
System.out.println("the file info str gived to applet is:" + filesInfo);
String fileName = "",fileFlagPublic = "",fileDocomentLanguage = "",fileDescription = "",
fileOperatingSystem = "",fileStore = "",fileTitle = "",fileFlagExp = "";
String[] filesInfoArr = filesInfo.split("|");
if(filesInfoArr.length > 0){
fileName = filesInfoArr[0];
fileFlagPublic = filesInfoArr[1];
fileDocomentLanguage = filesInfoArr[2];
fileDescription = filesInfoArr[3];
fileOperatingSystem = filesInfoArr[4];
fileStore = filesInfoArr[5];
fileTitle = filesInfoArr[6];
fileFlagExp = filesInfoArr[7];
}
java.io.File checkinFile = new java.io.File(directoryInfo);
FileInfo file = new FileInfo(checkinFile);
file.setFileStore(fileStore);
file.setFormat(formatInfo);
file.setFileFlagPublic(fileFlagPublic);
file.setFileFlagEXP(fileFlagExp);
file.setFileDocumentLanguage(fileDocomentLanguage);
System.out.println("applet-filename=" + file.getFileName());
addFile(file);
System.out.println("a file added successfully!");
}
/**
* @added by Defonds
* @param directoryStr
* D:/tmp/tmp/AppDevGuide1071.pdf@@@D:/tmp/tmp/AppDevGuide1072.pdf@@@...
* @return
* D:/tmp/tmp/AppDevGuide1071.pdf@@@D:/tmp/tmp/AppDevGuide1072.pdf...
* @note
* only return the directories which are valid
*/
public synchronized String directoryValid(String directoryStr){
System.out.println("the file directory info give to applet is:" + directoryStr);
_fileValidStr = directoryStr;
FileValidRunner runner = new FileValidRunner();
AccessController.doPrivileged(runner);
System.out.println("applet return value is:" + _fileValidStrRe);
return _fileValidStrRe;
}
/**
* @author defonds
*/
class FileValidRunner implements PrivilegedAction {
public Object run() {
String[] direArrs = _fileValidStr.split("@@@");
if(direArrs.length > 0){
for(int i = 0;i < direArrs.length;i ++){
String tmpName = direArrs[i];
java.io.File tmpFile = new java.io.File(tmpName);
if(tmpFile.exists()){//only return the directories which are invalid
if(_fileValidStrRe.equals("")){//the first one
_fileValidStrRe = tmpName;
}else{//not the first one
_fileValidStrRe += "@@@" + tmpFile;
}
}
}
}
return null;
}
FileValidRunner() {
}
}
addFileInfomation 是 js 向 applet 传递一些服务器提供的文件信息，诸如文件名（含完整的路径信息）、文件格式、文件内容语言、操作系统…
directoryValid 是 js 调用 applet 方法，对一系列的文件路径进行验证，applet 把有效的（即本地确实存在此文件）文件路径进行返回。
本文仅演示 js 调用 applet 的 directoryValid 方法对文件路径进行验证的例子，addFileInfomation 方法的例子、directoryValid 被调用的完整例子都可以去示例程序下载链接进行下载。
步骤一：
编写并编译 applet 程序，然后打包并进行数字签名后把 jar 包放在项目中的自定义目录 common 下。详细过程可以参考作者的博客《一次 applet 客户端打印 jasperreport 报表任务笔记》，这里不再赘述。
步骤二：
jsp 中编写 java 脚本，提供 addApplet 方法，以备服务器添加客户端的 applet 应用：
<%!
void addApplet(JspWriter out, String plugInCodeBase, String appletClass,String name,String codeBase,String jarFiles, int width, int height,HashMap props ) throws Exception
{
// load java plug-in using dynamic versioning
// if installed version of the plug in is 1.4 or above then do not download
// else download from the URl specified by codebase property
out.println("<OBJECT classid = 'clsid:8AD9C840-044E-11D1-B3E9-00805F499D93'");
out.println(" name = '" + name + "'");
out.println("codebase='" + plugInCodeBase + "#Version=1,4,0,0'" );
out.println("WIDTH ='" + width + "' HEIGHT ='" + height + "'>");
out.println("<PARAM NAME='java_code' VALUE ='" + appletClass + "'>");
out.println("<PARAM NAME='java_codebase' value='" + codeBase + "'>");
out.println("<PARAM NAME='java_archive' value='" + jarFiles + "'>");
out.println("<PARAM NAME='type' VALUE ='application/x-java-applet;version=1.4'>");
out.println("<PARAM NAME='scriptable' VALUE ='true'>");
String key;
out.println("<COMMENT>");
out.println("<EMBED type ='application/x-java-applet;version=1.4'");
out.println(" CODE ='" + appletClass + "'");
out.println(" name ='" + name + "'");
out.println(" java_code='" + appletClass + "' java_codebase='" + codeBase + "' java_archive='" + jarFiles + "'");
out.println(" WIDTH ='" + width + "' HEIGHT ='" + height + "' scriptable =true");
out.println("pluginspage = 'http://java.sun.com/products/plugin/index.html#download'>");
out.println("<NOEMBED>");
out.println("alt='Your browser understands the <APPLET> tag but isn/'t running the applet, for some reason.'");
out.println("Your browser is completely ignoring the <APPLET> tag!");
out.println("</noembed></embed></COMMENT></OBJECT>");
}
%>
步骤三：
jsp 中编写 java 脚本，调用 addApplet 方法添加客户端 applet 服务：
String codeBase = Framework.getFullClientSideURL(request,response,"") + "/common";
String plugInCodeBase = null;
String jarFiles = "";
jarFiles = "asbAttachmentUploadApplet.jar";
String userAgent = request.getHeader("User-Agent");
userAgent = userAgent.toLowerCase();
if(userAgent.indexOf("x11") != -1 || userAgent.indexOf("hp-ux") != -1 || userAgent.indexOf("sunos") != -1){
plugInCodeBase = (String)FrameworkProperties.getProperty("emxFramework.Unix.JavaPlugInURL");
if(plugInCodeBase == null || "".equals(plugInCodeBase) || "null".equals(plugInCodeBase)){
plugInCodeBase = "http://java.sun.com/j2se/1.4.2/download.html";
}
}else{
plugInCodeBase = (String)FrameworkProperties.getProperty("emxFramework.Windows.JavaPlugInURL");
if(plugInCodeBase == null || "".equals(plugInCodeBase) || "null".equals(plugInCodeBase)){
plugInCodeBase = "http://java.sun.com/products/plugin/autodl/jinstall-1_4-windows-i586.cab";
}
}
int appletWidth = 0;
int appletHeight = 0;
addApplet(out, plugInCodeBase, "com.matrixone.fcs.applet.FileUploadApplet","upload",codeBase,jarFiles,appletWidth,appletHeight,null);
步骤四：
js 中编写 getApplet 方法，获取 applet 对象：
function getApplet(){
if (document.applets.length > 0){
return document.applets[0];
}else if(document.embeds.length > 0){
return document.embeds[0];
}else{
alert("<emxUtil:i18nScript localize="i18nId">emxComponents.Common.CanNotStartApplet</emxUtil:i18nScript>");
return "";
}
}
步骤五：
js 中对 applet 中封装的方法的调用：
function next(){
var numOfValid = <%=numOfValidFiles%>;
if(numOfValid < 1){
alert('There is no file valid to upload!');
return;
}
var validDirs = getApplet().directoryValid('<%=directoryStr%>');
parent.document.location = "asbEngrDocumentImportCheckinAppletsFS.jsp?xyz=xyz&validDirs=" + validDirs;
}
注：applet 中 directoryValid 返回的是 String 对象，弱类型语言的 js 得到这个对象时会进行自动转换。applet 中要被 js 调用的方法一定是为 public 权限。其它权限的诸如 private、default、protected 方法应该不能够被 js 调用。作者没有去尝试，如果读者有兴趣的话可以亲自动手去测试一下，如果成功的话，记得也告诉我一下哈：）
