学了才知道，其实，上传与下载并没与我想象中那么难，要想实现上传与下载必须导入下面的包
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前端代码
<body>
<!-- 注意：
可以只写一个servlet页面。其中多写几个方法，用doGet调用
-->
<!-- 简单的下载 -->
<a href="FileServlet?option=download&fileName=index.jsp">下载D:/hello.jsp</a>
<!-- 简单的上传 -->
<%--上传表单必须是post请求方式,必须有enctype="multipart/form-data" --%>
<form action="FileServlet?option=upload" method="post" enctype="multipart/form-data">
<input type="file" value="请选择文件"/>
<input type="submit" value="上传"/>
</form>
</body>
servlet代码
package Servlet;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.FileReader;
import java.io.IOException;
import java.io.OutputStream;
import java.io.Reader;
import java.io.Writer;
import java.sql.SQLException;
import javax.servlet.ServletException;
import javax.servlet.ServletOutputStream;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.jsp.JspFactory;
import com.jspsmart.upload.SmartUpload;
import com.jspsmart.upload.SmartUploadException;
/**
* Servlet implementation class FileServlet
*/
@WebServlet("/FileServlet")
public class FileServlet extends HttpServlet {
private static final long serialVersionUID = 1L;
public FileServlet() {
super();
}
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
request.setCharacterEncoding("utf-8");
response.setCharacterEncoding("utf-8");
//获取前台传入的option的值
String option = request.getParameter("option");
if("download".equals(option)){
download(request, response);
}else if("upload".equals(option)){
upload(request, response);
}
}
protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
doGet(request, response);
}
protected void download(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
/**
* 下载
*/
//方法一：
/*String fileName = request.getParameter("fileName");
System.out.println(fileName);
//拷贝的文件
String path = "d:/"+fileName;
Reader fr = new FileReader(path);
Writer out = response.getWriter();
//通过设置响应头，告知准备回复给客户端的本次响应的处理方式和格式、大小等附加信息
response.setHeader("Content-Disposition", "attachment;filename=\""+fileName+"\"");
response.setHeader("Content-Type", "text/plain");
int data = fr.read();
while(data!=-1){
out.write(data);
data = fr.read();
out.flush();
}
out.close();
fr.close();*/
//方法二：
String fileName = request.getParameter("fileName");
// 拷贝的文件
String path = "d:/"+fileName;
// 读取文件
FileInputStream in = new FileInputStream(path);
// 输出文件
OutputStream out = response.getOutputStream();
//通过设置响应头，告知准备回复给客户端的本次响应的处理方式和格式、大小等附加信息
response.setHeader("Content-Disposition", "attachment;filename=\""+fileName+"\"");
response.setHeader("Content-Type", "text/plain");
int n;
while((n=in.read())!=-1){
out.write(n);
}
in.close();
out.close();
}
protected void upload(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
/**
* 上传
*/
//使用smartupload类实现上传
SmartUpload su = new SmartUpload();
//获取请求页面的资料，初始化上传信息（pageContext）
// pageContext = _jspxFactory.getPageContext(this, request, response,
//null, true, 8192, true);
//是将请求页面index.jsp页面的信息，初始化到smartupload对象中。请求页面中的信息就存到了su对象中
su.initialize(JspFactory.getDefaultFactory().getPageContext(this, request, response, null, true, 8192, true));
try {
//设置不允许上传的类型
su.setDeniedFilesList("java,txt");
//设置最大可以上传5MB文件
su.setMaxFileSize(5*1024*1024);
su.upload();
File saveFile = new File("D:/test");
su.save(saveFile.getPath());
} catch (SmartUploadException e) {
e.printStackTrace();
} catch (SQLException e) {
e.printStackTrace();
}
//String uname = su.getRequest().getParameter("uname");
}
}
完整的项目代码已经上传到github中了，其中包括上面说到的要导入的包，访问地址:github
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在学习的过程中如果遇到什么问题，欢迎大家提问。
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