1. 单个文件上传

1.1 创建上传单个文件的JSP页面、显示提交结果的JSP页面

uploadTest1.jsp

<%@ page language="java" import="java.util.*" pageEncoding="utf-8"%>
<%@ page isELIgnored="false"%>
<%@ taglib uri="/struts-tags" prefix="s"%>

<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
    <head>
    </head>
    <body>
        <s:form action="uploadT1" method="post" enctype="multipart/form-data">
            <s:file name="uploadFile"></s:file>
            <br />
            <s:submit value="提交"></s:submit>
        </s:form>
    </body>
</html>

注意：代码中加入了enctype="multipart/form-data"；而且使用了<s:file/>标签，尤其注意<s:file/>的name属性。

showResult1.jsp

<%@ page language="java" import="java.util.*" pageEncoding="utf-8"%>
<%@ page isELIgnored="false"%>
<%@ taglib uri="/struts-tags" prefix="s"%>

<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
    <body>
        您上传的文件名为：<s:property value="uploadFileFileName" />，存放目录：<s:property value="#request.storeDir"/>
        <br />
        <br/>
        <!--下载上下文路径-->
        <s:a href="%{#request.get('javax.servlet.forward.context_path')}/upload/%{uploadFileFileName}">点击这里下载</s:a>
        <br />
    </body>
</html>

1.2 生成Action类

package com.clzhang.struts2.demo12;

import java.io.File;
import java.io.IOException;
import org.apache.commons.io.FileUtils;
import org.apache.struts2.ServletActionContext;
import com.opensymphony.xwork2.ActionSupport;

public class UploadTest1Action extends ActionSupport {
    public static final long serialVersionUID = 1;

    private File uploadFile;
    private String uploadFileFileName;

    public File getUploadFile() {
        return uploadFile;
    }
    public void setUploadFile(File uploadFile) {
        this.uploadFile = uploadFile;
    }
    public String getUploadFileFileName() {
        return uploadFileFileName;
    }
    public void setUploadFileFileName(String uploadFileFileName) {
        this.uploadFileFileName = uploadFileFileName;
    }

    public String execute() throws IOException {
        // 上传物理路径
        String targetDirectory = ServletActionContext.getServletContext().getRealPath("/upload");
        // 生成上传的File对象
        File target = new File(targetDirectory, uploadFileFileName);
        // 复制File对象，从而实现上传文件
        FileUtils.copyFile(uploadFile, target);
        
        ServletActionContext.getRequest().setAttribute("storeDir", targetDirectory);

        return SUCCESS;
    }
}

Action实例中File变量命名规则：

数据类型为File的变量uploadFile和JSP页面中的<s:file/>标签的name属性值要一致，这样才可以使用Struts2的拦截器进行属性值的自动封装。
Action实例中有uploadFileFileName变量，对应于上传文件的文件名，它的命名规则就是File的变量名后加FileName。

1.3 设置上传文件相关参数（struts.properties）

struts.multipart.maxSize=2048000000
struts.multipart.saveDir=/upload

通常此文件存放于WEB-INFclasses目录下。

1.4 修改struts.xml文件

        <action name="uploadT1" class="com.clzhang.struts2.demo12.UploadTest1Action">
            <result>/struts2/demo12/showResult1.jsp</result>
        </action>

1.5 测试

打开IE，输入地址：http://127.0.0.1:8080/st/struts2/demo12/uploadTest1.jsp

结果如下：

选择任意一个文件提交后，结果如下：

一个，显示了服务器物理存储地址；二个，提供了下载链接。

2. 多个文件上传（属性驱动）

Struts2支持多文件批量上传，将上面的代码中的File类型改成File[]即可。

2.1 创建上传多个文件的JSP页面、显示提交结果的JSP页面

uploadTest2.jsp

<%@ page language="java" import="java.util.*" pageEncoding="utf-8"%>
<%@ page isELIgnored="false"%>
<%@ taglib uri="/struts-tags" prefix="s"%>

<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
    <head>
    </head>
    <body>
        <s:form action="uploadT2" method="post" enctype="multipart/form-data">
            username:<s:textfield name="fileUploadTools.username"></s:textfield>
            <br />
            <s:file name="fileUploadTools.uploadFile"></s:file>
            <br />
            <s:file name="fileUploadTools.uploadFile"></s:file>
            <br />
            <s:file name="fileUploadTools.uploadFile"></s:file>
            <br />
            <s:submit value="提交"></s:submit>
        </s:form>
    </body>
</html>

注意：因为是属性驱动，所以表单元素的命名需要以fileUploadTools打头。

showResult2.jsp

<%@ page language="java" import="java.util.*" pageEncoding="utf-8"%>
<%@ page isELIgnored="false"%>
<%@ taglib uri="/struts-tags" prefix="s"%>

<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
    <body>
        您上传的文件名列表：
        <br/>
        <!--对Action中对象（fileUploadTools）包含的数组（uploadFileFileName）的遍历-->
        <s:iterator value="fileUploadTools.uploadFileFileName" status="st">
            <s:iterator value="fileUploadTools.uploadFileFileName[#st.index]"> 
                <s:property />
                <br/>
            </s:iterator>
        </s:iterator>
        <br />
    </body>
</html>

2.2 生成Action类及属性驱动类

UploadTest2Action.java

package com.clzhang.struts2.demo12;

import java.io.IOException;

import com.opensymphony.xwork2.ActionSupport;

public class UploadTest2Action extends ActionSupport {
    public static final long serialVersionUID = 1;

    // 声明封装了File上传的FileUploadTools类的实例
    // FileUploadTools类也封装了上传的属性及get和set方法
    private FileUploadTools fileUploadTools = new FileUploadTools();

    public FileUploadTools getFileUploadTools() {
        return fileUploadTools;
    }
    public void setFileUploadTools(FileUploadTools fileUploadTools) {
        this.fileUploadTools = fileUploadTools;
    }

    @Override
    public String execute() throws IOException {
        fileUploadTools.beginUpload();
        
        return SUCCESS;
    }
}

FileUploadTools.java

package com.clzhang.struts2.demo12;

import java.io.File;
import java.io.IOException;
import java.text.SimpleDateFormat;
import java.util.Date;

import org.apache.commons.io.FileUtils;
import org.apache.struts2.ServletActionContext;

public class FileUploadTools {
    private String username;
    private File uploadFile[];// 上传的文件是数组类型
    private String uploadFileFileName[];// 文件名是数组类型
    private String uploadFileContentType[];

    public String getUsername() {
        return username;
    }
    public void setUsername(String username) {
        this.username = username;
    }
    // 上传的ContentType文件类型也是数组类型
    // 必须要加上对ContentType的声明，否则会出现异常
    public String[] getUploadFileContentType() {
        return uploadFileContentType;
    }
    public void setUploadFileContentType(String[] uploadFileContentType) {
        this.uploadFileContentType = uploadFileContentType;
    }
    public File[] getUploadFile() {
        return uploadFile;
    }
    public void setUploadFile(File[] uploadFile) {
        this.uploadFile = uploadFile;
    }
    public String[] getUploadFileFileName() {
        return uploadFileFileName;
    }
    public void setUploadFileFileName(String[] uploadFileFileName) {
        this.uploadFileFileName = uploadFileFileName;
    }

    public String beginUpload() throws IOException {
        System.out.println("用户名：" + username);

        String targetDirectory = ServletActionContext.getServletContext().getRealPath("/upload");
        for (int i = 0; i < uploadFile.length; i++) {
            File target = new File(targetDirectory, new SimpleDateFormat("yyyy_MM_dd_HH_mm_ss")
                    .format(new Date()).toString() + System.nanoTime() + uploadFileFileName[i]);

            FileUtils.copyFile(uploadFile[i], target);
        }

        return "success";
    }
}

2.3 设置上传文件相关参数（struts.properties），同上

2.4 修改struts.xml文件

        <action name="uploadT2" class="com.clzhang.struts2.demo12.UploadTest2Action">
            <result>/struts2/demo12/showResult2.jsp</result>
        </action>

2.5 测试

打开IE，输入地址：http://127.0.0.1:8080/st/struts2/demo12/uploadTest2.jsp

结果如下：

任意选择三个文件后，提交，结果如下：