java struts2入门学习实例－－使用struts2快速实现上传

一、文件上传快速入门

１）、关于上传表单三要素

>>尽量以POST请求方式上传，因为GET支持文件大小是有限制的。

>>必须要加上enctype="multipart/form-data"表示上传的文件，以随着请求体经过特殊编码后，一同传入服务器

>>每个表单项，必须取一个名字(name)，因为服务器端便于通过名字(name)收集信息.

2)、fileUpload拦截器文件上传拦截器，自动注入三个参数，如下所示：

    private String uploadContentType;//上传文件的类型,(Fileupload拦截器传入的参数)
    private File upload;//上传的文件,(Fileupload拦截器传入的参数)
    private String uploadFileName;//上传文件的真实文件名，(Fileupload拦截器传入的参数)

与jsp页面中的name相对应.

注意：upload和表单项与<s:file>中的name属性一致

　　 upload拼上contentType其中C要大写.

<%@ page language="java" contentType="text/html; charset=UTF-8"
    pageEncoding="UTF-8"%>
<%@ taglib uri="/struts-tags" prefix="s"  %>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
<title>Insert title here</title>
</head>
<body>
    <s:form action="UploadAction" enctype="multipart/form-data" method="POST">
        <s:textfield name="username"/>
        <s:file name="upload" />
        <s:submit value="提交"/>
    </s:form>
</body>
</html>

３）框架自身有fileUpload文件上传拦截器

　　在默认栈中，有一个fileUpload文件上传拦截器，但是没有下载拦截器，源码参见struts2-core-2.3.16-sources.jar/struts-default.xml

４）、代码分析

UploadAction.java

package action;

import java.io.File;

import com.opensymphony.xwork2.ActionSupport;

/**
 * @ClassName: UploadAction
 * @Description: 文件上传
 * @author: amosli
 * @email:amosli@infomorrow.com
 * @date Jan 14, 2014 1:50:28 AM
 */
public class UploadAction extends ActionSupport {
    private static final long serialVersionUID = -8920466592471253212L;
    private String username;// 用户名
    private String uploadContentType;// 上传文件的类型,(Fileupload拦截器传入的参数)
    private File upload;// 上传的文件,(Fileupload拦截器传入的参数)
    private String uploadFileName;// 上传文件的真实文件名，(Fileupload拦截器传入的参数)

    public void setUsername(String username) {
        this.username = username;
    }

    public void setUploadContentType(String uploadContentType) {
        this.uploadContentType = uploadContentType;
    }

    public void setUpload(File upload) {
        this.upload = upload;
    }

    public String getUsername() {
        return username;
    }

    public String getUploadContentType() {
        return uploadContentType;
    }

    public File getUpload() {
        return upload;
    }

    public String getUploadFileName() {
        return uploadFileName;
    }

    public void setUploadFileName(String uploadFileName) {
        this.uploadFileName = uploadFileName;
    }

    public String uploadMethod() {

        return SUCCESS;
    }

}

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