struts2文件上传和下载

1. struts系统中的拦截器介绍

过滤器：javaweb中的服务器组件，主要针对的请求和响应进行拦截。

拦截器：主要针对方法的调用，进行拦截器，当使用代理对象调用某个方法时候

对方法的调用进行拦截，对拦截到的方法可以进行扩展，增强

Struts2中的拦截器主要针对Action中方法的调用进行拦截

<interceptors>
 <!—声明n个拦截器-->
    <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="params"
        class="com.opensymphony.xwork2.interceptor.ParametersInterceptor" />
    <interceptor name="staticParams"
        class="com.opensymphony.xwork2.interceptor.StaticParametersInterceptor" />
    <interceptor name="token"
        class="org.apache.struts2.interceptor.TokenInterceptor" />
    <interceptor name="tokenSession"
        class="org.apache.struts2.interceptor.TokenSessionStoreInterceptor" />
20 <!—由已经声明的n个拦截器，组成拦截器栈-->
    <interceptor-stack name="defaultStack">
        <interceptor-ref name="exception" />
        <interceptor-ref name="alias" />
        <interceptor-ref name="servletConfig" />
        <interceptor-ref name="i18n" />
        <interceptor-ref name="prepare" />
        <interceptor-ref name="chain" />
        <interceptor-ref name="scopedModelDriven" />
        <interceptor-ref name="modelDriven" />
        <interceptor-ref name="fileUpload" />
        <interceptor-ref name="checkbox" />
        <interceptor-ref name="multiselect" />
        <interceptor-ref name="staticParams" />
        <interceptor-ref name="actionMappingParams" />
        <interceptor-ref name="params">
            <param name="excludeParams">^class..*,^dojo..*,^struts..*,^session..*,^request..*,^application..*,^servlet(Request|Response)..*,^parameters..*,^action:.*,^method:.*
            </param>
        </interceptor-ref>
        <interceptor-ref name="conversionError" />
        <interceptor-ref name="validation">
            <param name="excludeMethods">input,back,cancel,browse</param>
        </interceptor-ref>
        <interceptor-ref name="workflow">
            <param name="excludeMethods">input,back,cancel,browse</param>
        </interceptor-ref>
        <interceptor-ref name="debugging" />
        <interceptor-ref name="deprecation" />
    </interceptor-stack>
</interceptors>
<default-interceptor-ref name="defaultStack" />
</package>
 

拦截器栈：

 a --> b --> c --> execute() --> c --> b --> a

 

2.文件上传

2.1 Action

/*** 处理文件上传的请求 **/
public class FileAction
{
    // org.apache.struts2.interceptor.FileUploadInterceptor
    // 1 定义文件上传需要的特定属性
    private File img; // 上传的文件对象
    private String imgContentType;// 上传的文件的内容的类型
    private String imgFileName;// 上传的文件名称
    private String path; // 文件保存到服务器上的目录

    public String getPath()
    {
        return path;
    }

    public void setPath(String path)
    {
        this.path = path;
    }

    public File getImg()
    {
        return img;
    }

    public void setImg(File img)
    {
        this.img = img;
    }

    public String getImgContentType()
    {
        return imgContentType;
    }

    public void setImgContentType(String imgContentType)
    {
        this.imgContentType = imgContentType;
    }

    public String getImgFileName()
    {
        return imgFileName;
    }

    public void setImgFileName(String imgFileName)
    {
        this.imgFileName = imgFileName;
    }

    /*** 处理文件上传的请求 ****/
    public String uploadFile()
    {
        System.out.println(img);
        System.out.println(imgContentType);
        System.out.println(imgFileName);
        // 修改文件名
        String fname = UUID.randomUUID()
                + imgFileName.substring(imgFileName.lastIndexOf("."));
        // 将上传的文件对象img保存到服务器的指定目录
        // 1获得path的绝对路径
        String pth = ServletActionContext.getServletContext().getRealPath(path);
        // 2在pth下创建文件
        File file = new File(pth, fname);
        // 3将img内容拷贝file中
        try
        {
            FileUtils.copyFile(img, file);
        }
        catch (IOException e)
        {
            e.printStackTrace();
        }
        return Action.SUCCESS;
    }
}

2.2 struts.xml 配置 1 <?xml version="1.0" encoding="UTF-8"?>

 <!DOCTYPE struts PUBLIC
    "-//Apache Software Foundation//DTD Struts Configuration 2.3//EN"
    "http://struts.apache.org/dtds/struts-2.3.dtd">
<struts>
    <package name="file" namespace="/" extends="struts-default">
        <interceptors>
            <!-- 自定义拦截器栈 -->
            <interceptor-stack name="mystack">
                <!-- 引用系统文件上传的拦截器 -->
                <interceptor-ref name="fileUpload">
                    <param name="allowedExtensions">txt,jpg,doc</param>
                    <!-- 其他属性的赋值同理 -->
                </interceptor-ref>
　　　　　　<interceptor-ref name="staticParams"></interceptor-ref>
                <!-- 引用系统基本拦截器栈 -->
                <interceptor-ref name="basicStack" />
            </interceptor-stack>
        </interceptors>
        <action name="fileAction_*" class="com.guangsoft.action.FileAction"
            method="{1}">
            <!-- 引用自定义的拦截器栈 -->
            <interceptor-ref name="mystack"></interceptor-ref>
            <!-- 给path属性赋值 -->
            <param name="path">filedir</param>
            <result>/index.jsp</result>
        </action>
    </package>
</struts>

2.3实现UI页面 

<form action="fileAction_uploadFile.action" method="post"
    enctype="multipart/form-data">
    <input type="file" name="img" />
    <input type="submit" />
</form>

3.文件下载

3.1 Action

//org.apache.struts2.dispatcher.StreamResult
public class DownloadAction
{
    private InputStream inputStream;
    private String fname;// 需要下载的文件的名字

    public InputStream getInputStream()
    {
        System.out.println("----------getInputStream");
        return inputStream;
    }

    public String getFname()
    {
        return fname;
    }

    public void setFname(String fname)
    {
        this.fname = fname;
    }

    /*** 实现文件下载 ***/
    public String download()
    {
        System.out.println("----------download");
        // 获得附件的保存目录
        String path = ServletActionContext.getServletContext().getRealPath(
                "filedir");
        // 将下载的文件封装为InputStream的对象
        try
        {
            inputStream = new FileInputStream(path + "/" + fname);
        }
        catch (FileNotFoundException e)
        {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
        return Action.SUCCESS;
    }
}

3.2 struts.xml 配置： 

<package name="down" namespace="/down" extends="struts-default">
    <action name="downloadAction_*" class="com.guangsoft.action.DownloadAction"
        method="{1}">
        <result type="stream">
            <param name="inputName">inputStream</param>
            <!-- 指定下载的附件的类型 -->
            <param name="contentType">application/octet-stream</param>
            <!-- 指定下载的附件的名称 -->
            <param name="contentDisposition">attachment;filename=${fname}</param>
        </result>
    </action>
</package>