Struts2 文件上传和文件下载

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一.单个文件上传

文件上传需要两个jar包：

首先制作一个简单的页面，用于实现文件上传

<h1>单个文件上传</h1>
<s:form action="upload.action" enctype="multipart/form-data"
method="post" namespace="/">
<s:textfield name="title" lable="标题"></s:textfield>
<s:file name="upload" lable="选择文件"></s:file>
<s:submit value="上传文件"></s:submit>
</s:form>

开发实现文件上传的Action

package cn.action;import java.io.File;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.IOException;import org.apache.struts2.ServletActionContext;import com.opensymphony.xwork2.ActionSupport;public class UploadAction extends ActionSupport{
//封装上传文件属性
private File upload; //封装上传文件的类型
private String uploadContentType; //封装上传文件名称
private String uploadFileName; //封装文件上传的路径
private String savePath; public String execute(){
byte[] buffer=new byte[1024];
try {
FileInputStream fis=new FileInputStream(getUpload());
FileOutputStream fos=new FileOutputStream(getSavePath()+"\\"+this.getUploadFileName());
int length=fis.read(buffer);
while(length>0){
fos.write(buffer, 0, length);
length=fis.read(buffer);
}
fos.flush();
fos.close();
fis.close();
} catch (FileNotFoundException e) { e.printStackTrace();
} catch (IOException e) { e.printStackTrace();
}
System.out.println("========================");
return SUCCESS;
} public File getUpload() {
return upload;
} public void setUpload(File upload) {
this.upload = upload;
} public String getUploadContentType() {
return uploadContentType;
} public void setUploadContentType(String uploadContentType) {
this.uploadContentType = uploadContentType;
} public String getUploadFileName() {
return uploadFileName;
} public void setUploadFileName(String uploadFileName) {
this.uploadFileName = uploadFileName;
} public String getSavePath() {
return ServletActionContext.getServletContext().getRealPath(savePath);
} public void setSavePath(String savePath) {
this.savePath = savePath;
}}

在Action中使用了三个属性封装文件信息

File类型的XXX属性，与表单的File控件的name属性一样，用于封装File控件对应的文件内容

String类型的xxxFileName属性，该属性名称由前面的File类型属性和FileName组合，是固定的语法，是封装File控件对应文件的文件名

String类型的XXXContentType属性，同样由xxx属性和ContentType组合而成，是固定语法，封装File控件对应文件的文件类型

配置Action

<action name="upload" class="cn.action.UploadAction">

<param name="savePath">/upload</param>
<result name="success">success.jsp</result>
</action>

效果图：

二.多个文件上传

只需在上传Action中将原本处理单个文件的操作改成对集合操作即可。

其他的都跟单个上传的一样

页面

<action name="someupload" class="cn.action.SomeUploadAction">

<param name="savePath">/upload</param>
<result name="success">success.jsp</result>
</action>

开发实现文件上传的Action

package cn.action;import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;import org.apache.struts2.ServletActionContext;import com.opensymphony.xwork2.ActionSupport;public class SomeUploadAction extends ActionSupport {
//封装上传文件属性
private File[] upload; //封装上传文件的类型
private String[] uploadContentType; //封装上传文件名称
private String[] uploadFileName; //封装文件上传的路径
private String savePath; public String execute() throws Exception{
byte[] buffer=new byte[1024];
for (int i = 0; i < upload.length; i++) {
FileInputStream fis=new FileInputStream(getUpload()[i]);
FileOutputStream fos=new FileOutputStream(getSavePath()+"\\"+this.getUploadFileName()[i]);
int length=fis.read(buffer);
while(length>0){
fos.write(buffer, 0, length);
length=fis.read(buffer);
}
fos.flush();
fos.close();
fis.close();
}
return SUCCESS;
} public File[] getUpload() {
return upload;
} public void setUpload(File[] upload) {
this.upload = upload;
} public String[] getUploadContentType() {
return uploadContentType;
} public void setUploadContentType(String[] uploadContentType) {
this.uploadContentType = uploadContentType;
} public String[] getUploadFileName() {
return uploadFileName;
} public void setUploadFileName(String[] uploadFileName) {
this.uploadFileName = uploadFileName;
} public String getSavePath() {
return ServletActionContext.getServletContext().getRealPath(savePath);
} public void setSavePath(String savePath) {
this.savePath = savePath;
}}

配置Action

效果：

三.文件下载

文件下载需要InputStream，首先在文件下载Action中提供一个获得InputStream的方法，通过输入流可以获取希望下载的文件内容

package cn.action;import java.io.BufferedInputStream;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.InputStream;import org.apache.struts2.ServletActionContext;import com.opensymphony.xwork2.ActionSupport;public class FileDownAction extends ActionSupport {
//读取下载文件的目录
private String inputPath; //下载文件的文件名
private String fileName; //读取下载文件的输入流
private InputStream inputStream; //下载文件的类型
private String conetntType; public String execute(){
return SUCCESS; } public String getInputPath() {
return inputPath;
} public void setInputPath(String inputPath) {
this.inputPath = inputPath;
} public String getFileName() {
return fileName;
} public void setFileName(String fileName) {
this.fileName = fileName;
}
//创建InputStream输入流
public InputStream getInputStream() throws Exception {
String path=ServletActionContext.getServletContext().getRealPath(inputPath);
BufferedInputStream stream = new BufferedInputStream(new FileInputStream(path+"\\"+fileName));
return stream;
} public void setInputStream(InputStream inputStream) {
this.inputStream = inputStream;
} public String getConetntType() {
return conetntType;
} public void setConetntType(String conetntType) {
this.conetntType = conetntType;
}}

通过Context得到下载文件的实际路径，构建一个InputStream输入流实现文件的下载读取。

在配置文件中，同样对Action进行配置，并对stream结果类型的参数进行设置。

<action name="download" class="cn.action.FileDownAction">
<param name="inputPath">/upload</param>
<result name="success" type="stream">
<param name="contentType">application/octet-stream</param>
<param name="inputName">inputStream</param>
<param name="contentDisposition">
attachment;filename="${fileName}"
</param>
<param name="bufferSize">4096</param>
</result>
</action>

ContentType参数决定了下载文件的类型，不同的文件类型对应的参数值也是不同的。