struts2的文件下传与上载
struts2的文件上传与下载
针对与struts2的文件上传与下载是非常简单的。对于upload来讲：struts2在defaultStack这个拦截器栈已经提供了支持了，对于upload来说大致一个完成过程如下：
1）书写JSP，上传数据的时候要记得form的method为post，enctype为multipart/form-data
2）书写action： 配置file，fileFiileName,fileContentType. struts2帮我们封装文件名，与文件类型。分别为他们提供setter和getter方法.
3）execute方法的书写简单的代码如下：
public String execute() throws Exception {
// TODO Auto-generated method stub
FileInputStream inputStream = new FileInputStream(file);
String path = ServletActionContext.getRequest().getRealPath("/upload");
System.out.println(path);
FileOutputStream out = new FileOutputStream(new File(path,this.getFileFileName()));
int length = 0;
byte [] buffer = new byte[1024];
while((length=inputStream.read(buffer))!=-1){
out.write(buffer,0,length);
out.flush();
}
out.close();
inputStream.close();
return SUCCESS;
}
我们打开struts-default.xml这个配置文件，有如下代码片段：
<interceptors>
<interceptor name="alias" class="com.opensymphony.xwork2.interceptor.AliasInterceptor"/>
<interceptor name="autowiring" class="com.opensymphony.xwork2.spring.interceptor.ActionAutowiringInterceptor"/>
<interceptor name="chain" class="com.opensymphony.xwork2.interceptor.ChainingInterceptor"/>
<interceptor name="conversionError" class="org.apache.struts2.interceptor.StrutsConversionErrorInterceptor"/>
<interceptor name="cookie" class="org.apache.struts2.interceptor.CookieInterceptor"/>
<interceptor name="clearSession" class="org.apache.struts2.interceptor.ClearSessionInterceptor" />
<interceptor name="createSession" class="org.apache.struts2.interceptor.CreateSessionInterceptor" />
<interceptor name="debugging" class="org.apache.struts2.interceptor.debugging.DebuggingInterceptor" />
<interceptor name="externalRef" class="com.opensymphony.xwork2.interceptor.ExternalReferencesInterceptor"/>
<interceptor name="execAndWait" class="org.apache.struts2.interceptor.ExecuteAndWaitInterceptor"/>
<interceptor name="exception" class="com.opensymphony.xwork2.interceptor.ExceptionMappingInterceptor"/>
<interceptor name="fileUpload" class="org.apache.struts2.interceptor.FileUploadInterceptor"/>
<interceptor name="i18n" class="com.opensymphony.xwork2.interceptor.I18nInterceptor"/>
<interceptor name="logger" class="com.opensymphony.xwork2.interceptor.LoggingInterceptor"/>
<interceptor name="modelDriven" class="com.opensymphony.xwork2.interceptor.ModelDrivenInterceptor"/>
<interceptor name="scopedModelDriven" class="com.opensymphony.xwork2.interceptor.ScopedModelDrivenInterceptor"/>
<interceptor name="params" class="com.opensymphony.xwork2.interceptor.ParametersInterceptor"/>
<interceptor name="actionMappingParams" class="org.apache.struts2.interceptor.ActionMappingParametersInteceptor"/>
<interceptor name="prepare" class="com.opensymphony.xwork2.interceptor.PrepareInterceptor"/>
<interceptor name="staticParams" class="com.opensymphony.xwork2.interceptor.StaticParametersInterceptor"/>
<interceptor name="scope" class="org.apache.struts2.interceptor.ScopeInterceptor"/>
<interceptor name="servletConfig" class="org.apache.struts2.interceptor.ServletConfigInterceptor"/>
<interceptor name="sessionAutowiring" class="org.apache.struts2.spring.interceptor.SessionContextAutowiringInterceptor"/>
<interceptor name="timer" class="com.opensymphony.xwork2.interceptor.TimerInterceptor"/>
<interceptor name="token" class="org.apache.struts2.interceptor.TokenInterceptor"/>
<interceptor name="tokenSession" class="org.apache.struts2.interceptor.TokenSessionStoreInterceptor"/>
可以看见一个fileUpload的拦截器。我们打开这个拦截器的源代码：如下：
public class FileUploadInterceptor extends AbstractInterceptor {
private static final long serialVersionUID = -4764627478894962478L;
protected static final Log log = LogFactory.getLog(FileUploadInterceptor.class);
private static final String DEFAULT_DELIMITER = ",";
private static final String DEFAULT_MESSAGE = "no.message.found";
protected Long maximumSize;
protected String allowedTypes;
protected Set allowedTypesSet = Collections.EMPTY_SET;
/**
* Sets the allowed mimetypes
*
* @param allowedTypes A comma-delimited list of types
*/
public void setAllowedTypes(String allowedTypes) {
this.allowedTypes = allowedTypes;
// set the allowedTypes as a collection for easier access later
allowedTypesSet = getDelimitedValues(allowedTypes);
}
/**
可以看见一些成员变量，表示上传文件的最大size以及允许上传的文件类型。需要说明的是最大容量的现在是以字节为单位的，文件类型也不是文件的后缀名：例如.txt文件他的文件类型应该是：text/plain。这些都可以在tomcat的web.xml文件中找到。 下面我们将刚刚的两个属性配置到xml文件中去：配置如下：
<action name="upload" class="com.wh.struts2.action.FileUploadAction">
<result name="success">/index.jsp</result>
<interceptor-ref name="fileUpload">
<param name="maximumSize">5242880</param>
<param name="allowedTypes">text/plain</param>
</interceptor-ref>
<interceptor-ref name="defaultStack"></interceptor-ref>
</action>
这里需要的注意到是当你应该了一个单独的拦截器之后，struts2就不会在去附加默认的拦截器了，因此我们还需要手动的在引用一次默认拦截器栈。
二) 文件的下载：
1）简单的不能在简单的JSP：
<body>
<a href="downLoad.action">下载</a>
</body>
2）简单的action：
package com.wh.struts2.action;
import java.io.InputStream;
import org.apache.struts2.ServletActionContext;
import com.opensymphony.xwork2.ActionSupport;
public class DownLoadAction extends ActionSupport {
public InputStream getInputStream(){
return ServletActionContext.getServletContext().getResourceAsStream("/upload/spring.doc");
}
@Override
public String execute() throws Exception {
// TODO Auto-generated method stub
return SUCCESS;
}
}
3）简单的配置：
<action name="downLoad" class="com.wh.struts2.action.DownLoadAction">
<result type="stream" name="success">
<param name="contentType">application/msword</param>
<param name="contentDisposition">filename="spring.doc"</param>
<param name="inputName">inputStream</param>
</result>
</action>
对于文件的下载，在action需要提供一个返回一个输入流的方法，方法名可以任意的。应该满足PO的书写规范。配置xml文件的时候inputName的值，就是刚刚提供的方法的名称。 文件下载的时候type必须是stream，那么这些配置的属性又是如何找到的？ 同样是struts-default.xml，有如下片段：
<result-types>
<result-type name="chain" class="com.opensymphony.xwork2.ActionChainResult"/>
<result-type name="dispatcher" class="org.apache.struts2.dispatcher.ServletDispatcherResult" default="true"/>
<result-type name="freemarker" class="org.apache.struts2.views.freemarker.FreemarkerResult"/>
<result-type name="httpheader" class="org.apache.struts2.dispatcher.HttpHeaderResult"/>
<result-type name="redirect" class="org.apache.struts2.dispatcher.ServletRedirectResult"/>
<result-type name="redirectAction" class="org.apache.struts2.dispatcher.ServletActionRedirectResult"/>
<result-type name="stream" class="org.apache.struts2.dispatcher.StreamResult"/>
<result-type name="velocity" class="org.apache.struts2.dispatcher.VelocityResult"/>
<result-type name="xslt" class="org.apache.struts2.views.xslt.XSLTResult"/>
<result-type name="plainText" class="org.apache.struts2.dispatcher.PlainTextResult" />
</result-types>
我们可以看见结果类型中有个对于stream。我们查看下这个类的原代码：
public class StreamResult extends StrutsResultSupport {
private static final long serialVersionUID = -1468409635999059850L;
protected static final Log log = LogFactory.getLog(StreamResult.class);
public static final String DEFAULT_PARAM = "inputName";
protected String contentType = "text/plain";
protected String contentLength;
protected String contentDisposition = "inline";
protected String inputName = "inputStream";
protected InputStream inputStream;
protected int bufferSize = 1024;
public StreamResult() {
super();
}
public StreamResult(InputStream in) {
this.inputStream = in;
}
/**
就可以看见配置的文件是哪里的了吧。 呵呵，简单的介绍到这里了。