SSH与SSM学习之SSH实现CRM练习12——文件上传原理

一、主要说明

其实文件上传&＃xff0c;主要就是通过 FileUploadInterceptor 这个拦截器&＃xff0c;配合 ParametersInterceptor来完成的。

FileUploadInterceptor 把上传的文件 添加到值栈中&＃xff0c;ParametersInterceptor 取出添加的值&＃xff0c;赋值到对应的Action的属性中。

下面我们具体来看一下。

二、查看 struts-default.xml

我使用的是 struts 2.5
如下地址&＃xff1a;

web\WEB-INF\lib\struts2-core-2.5.13.jar!\struts-default.xml

主要看到下面

.....<interceptors>.......<interceptor name&＃61;"fileUpload" class&＃61;"org.apache.struts2.interceptor.FileUploadInterceptor"/><interceptor name&＃61;"i18n" class&＃61;"org.apache.struts2.interceptor.I18nInterceptor"/><interceptor name&＃61;"logger" class&＃61;"com.opensymphony.xwork2.interceptor.LoggingInterceptor"/><interceptor name&＃61;"modelDriven" class&＃61;"com.opensymphony.xwork2.interceptor.ModelDrivenInterceptor"/><interceptor name&＃61;"scopedModelDriven" class&＃61;"com.opensymphony.xwork2.interceptor.ScopedModelDrivenInterceptor"/><interceptor name&＃61;"params" class&＃61;"com.opensymphony.xwork2.interceptor.ParametersInterceptor"/>.......<interceptor-stack name&＃61;"defaultStack">.......<interceptor-ref name&＃61;"fileUpload"/><interceptor-ref name&＃61;"checkbox"/><interceptor-ref name&＃61;"datetime"/><interceptor-ref name&＃61;"multiselect"/><interceptor-ref name&＃61;"staticParams"/><interceptor-ref name&＃61;"actionMappingParams"/><interceptor-ref name&＃61;"params"/>.......interceptor-stack>.......interceptors>.....


上面我们可以看到&＃xff0c;默认的拦截器栈中&＃xff0c;先调用 fileUpload&＃xff0c;然后才是 params

三、FileUploadInterceptor.java

主要就是完成&＃xff0c;获取文件、文件名、文件的ContentType 添加到值栈中&＃xff0c;最后会调用到 ParametersInterceptor&＃xff0c;赋值给Action中对应的属性。


public class FileUploadInterceptor extends AbstractInterceptor {public String intercept(ActionInvocation invocation) throws Exception {.......// bind allowed FilesEnumeration fileParameterNames &＃61; multiWrapper.getFileParameterNames();while (fileParameterNames !&＃61; null && fileParameterNames.hasMoreElements()) {// get the value of this input tag//获取文件的对应的属性名String inputName &＃61; (String) fileParameterNames.nextElement();// get the content typeString[] contentType &＃61; multiWrapper.getContentTypes(inputName);if (isNonEmpty(contentType)) {// get the name of the file from the input tagString[] fileName &＃61; multiWrapper.getFileNames(inputName);if (isNonEmpty(fileName)) {// get a File object for the uploaded FileUploadedFile[] files &＃61; multiWrapper.getFiles(inputName);if (files !&＃61; null && files.length > 0) {List acceptedFiles &＃61; new ArrayList<>(files.length);List acceptedContentTypes &＃61; new ArrayList<>(files.length);List acceptedFileNames &＃61; new ArrayList<>(files.length);//拼接文件的ContentType属性名String contentTypeName &＃61; inputName &＃43; "ContentType";//拼接文件名的属性名String fileNameName &＃61; inputName &＃43; "FileName";for (int index &＃61; 0; index if (acceptFile(action, files[index], fileName[index], contentType[index], inputName, validation)) {acceptedFiles.add(files[index]);acceptedContentTypes.add(contentType[index]);acceptedFileNames.add(fileName[index]);}}if (!acceptedFiles.isEmpty()) {Map newParams &＃61; new HashMap<>();//把文件添加到值栈中newParams.put(inputName, new Parameter.File(inputName, acceptedFiles.toArray(new UploadedFile[acceptedFiles.size()])));//把文件的ContentType添加到值栈中newParams.put(contentTypeName, new Parameter.File(contentTypeName, acceptedContentTypes.toArray(new String[acceptedContentTypes.size()])));//把文件名添加到值栈中newParams.put(fileNameName, new Parameter.File(fileNameName, acceptedFileNames.toArray(new String[acceptedFileNames.size()])));ac.getParameters().appendAll(newParams);}}} else {if (LOG.isWarnEnabled()) {LOG.warn(getTextMessage(action, "struts.messages.invalid.file", new String[]{inputName}));}}} else {if (LOG.isWarnEnabled()) {LOG.warn(getTextMessage(action, "struts.messages.invalid.content.type", new String[]{inputName}));}}}return invocation.invoke();}}