Servlet 起航 文件上传 中文文件名下载

@WebServlet(name = "ticketServlet",urlPatterns = {"/tickets"},loadOnStartup = 1)
@MultipartConfig(fileSizeThreshold = 5242880,
maxFileSize = 20971520L,//20MB
maxRequestSize = 41943040L//40MB
)
public class TicketServlet extends HttpServlet{
    //线程可见性
    private volatile int TICKET_ID_SEQUENCE = 1;
    private Map<Integer,Ticket> ticketDatabase = new LinkedHashMap<>();

    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws IOException {
       //使用请求参数做了一个菜单
        String action = req.getParameter("action");
        if (action == null){
            action = "list";//默认ticket列表
        }
        switch (action){
            case "create":
                this.showTicketForm(resp);//展示表单
                break;
            case "view":
                this.viewTicket(req,resp);//具体一张
                break;
            case  "download":
                this.downloadAttachment(req,resp);//下载附件
                break;
            default:
                this.listTickets(resp);//展示ticket
                break;
        }
    }

    @Override
    protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        String action = req.getParameter("action");
        if(action == null){
            action = "list";
        }
        switch (action){
            case "create":
                this.createTicket(req,resp);//表单提交实际创建方法
                break;
            case "list":
            default:
                resp.sendRedirect("tickets");//重定向 get
                break;

        }

    }


    private void listTickets(HttpServletResponse response) throws IOException {
        PrintWriter writer = this.writeHeader(response);

        writer.append("<h2>Tickets</h2>\r\n");
        //createTicket入口 先展示一个表单
        writer.append("<a href=\"tickets?action=create\">Create Ticket")
                .append("</a><br/><br/>\r\n");

        if(this.ticketDatabase.size() == 0)
            writer.append("<i>There are no tickets in the system.</i>\r\n");
        else
        {
            for(int id : this.ticketDatabase.keySet())
            {
                String idString = Integer.toString(id);
                Ticket ticket = this.ticketDatabase.get(id);
                writer.append("Ticket #").append(idString)
                        .append(": <a href=\"tickets?action=view&ticketId=")
                        .append(idString).append("\">").append(ticket.getSubject())
                        .append("</a> (customer: ").append(ticket.getCustomerName())
                        .append(")<br/>\r\n");
            }
        }

        this.writeFooter(writer);
    }

    private void viewTicket(HttpServletRequest request, HttpServletResponse response) throws IOException {
        //从ticket列表进入某张ticket所需要id
        String idString = request.getParameter("ticketId");
        Ticket ticket = this.getTicket(idString, response);
        if(ticket == null)
            return;

        PrintWriter writer = this.writeHeader(response);

        writer.append("<h2>Ticket #").append(idString)
                .append(": ").append(ticket.getSubject()).append("</h2>\r\n");
        writer.append("<i>Customer Name - ").append(ticket.getCustomerName())
                .append("</i><br/><br/>\r\n");
        writer.append(ticket.getBody()).append("<br/><br/>\r\n");

        if(ticket.getNumberOfAttachments() > 0)
        {
            writer.append("Attachments: ");
            int i = 0;
            for(Attachment attachment : ticket.getAttachments())
            {
                if(i++ > 0)
                    writer.append(", ");
                writer.append("<a href=\"tickets?action=download&ticketId=")
                        .append(idString).append("&attachment=")
                        .append(attachment.getName()).append("\">")
                        .append(attachment.getName()).append("</a>");
            }
            writer.append("<br/><br/>\r\n");
        }

        writer.append("<a href=\"tickets\">Return to list tickets</a>\r\n");

        this.writeFooter(writer);
    }

    private Ticket getTicket(String id, HttpServletResponse response) throws IOException {
        //id.len == ''  一般合法性检查  有没有
        if (id == null || id.length()==0){
            response.sendRedirect("tickets");
            return null;
        }
        try {
            Ticket ticket = this.ticketDatabase.get(Integer.parseInt(id));
            if (ticket == null) {
                response.sendRedirect("tickets");
                return null;
            }
            return ticket;
        }catch (Exception e){
            response.sendRedirect("tickets");
            return null;
        }
    }

    private void showTicketForm(HttpServletResponse resp) throws IOException {
        PrintWriter writer = this.writeHeader(resp);
        writer.append("<h2>Create a Ticket</h2>\r\n");
        writer.append("<form method=\"POST\" action=\"tickets\" ")
                .append("enctype=\"multipart/form-data\">\r\n");//编码类型multipart/form-data
        writer.append("<input type=\"hidden\" name=\"action\" ")//隐藏域提交 action value = create
                .append("value=\"create\"/>\r\n");
        writer.append("Your Name<br/>\r\n");
        writer.append("<input type=\"text\" name=\"customerName\"/><br/><br/>\r\n");
        writer.append("Subject<br/>\r\n");
        writer.append("<input type=\"text\" name=\"subject\"/><br/><br/>\r\n");
        writer.append("Body<br/>\r\n");
        writer.append("<textarea name=\"body\" rows=\"5\" cols=\"30\">")
                .append("</textarea><br/><br/>\r\n");
        writer.append("<b>Attachments</b><br/>\r\n");
        writer.append("<input type=\"file\" name=\"file1\"/><br/><br/>\r\n");
        writer.append("<input type=\"submit\" value=\"Submit\"/>\r\n");
        writer.append("</form>\r\n");

        this.writeFooter(writer);
    }


    private void downloadAttachment(HttpServletRequest request, HttpServletResponse response) throws IOException {
       //下载某一个attachment
        String idString = request.getParameter("ticketId");
        Ticket ticket = this.getTicket(idString, response);
        if(ticket == null)
            return;

        String name = request.getParameter("attachment");
        if(name == null)
        {
            response.sendRedirect("tickets?action=view&ticketId=" + idString);
            return;
        }

        Attachment attachment = ticket.getAttachment(name);
        if(attachment == null)
        {
            response.sendRedirect("tickets?action=view&ticketId=" + idString);
            return;
        }
        //header 内容位置   文件名
        response.setHeader("Content-Disposition",
                "attachment; filename=" + attachment.getName());

        response.setContentType("application/octet-stream");
        //流
        ServletOutputStream stream = response.getOutputStream();
        stream.write(attachment.getContents());
    }


    private void createTicket(HttpServletRequest req, HttpServletResponse resp) throws IOException, ServletException {
        Ticket ticket = new Ticket();
        ticket.setCustomerName(req.getParameter("customerName"));
        ticket.setSubject(req.getParameter("subject"));
        ticket.setBody(req.getParameter("body"));

        Part filePart = req.getPart("file1");
        if (filePart!=null){
            Attachment attachment = this.processAttachment(filePart);
            if (attachment!=null)
                ticket.addAttachment(attachment);
        }
        int id;
        synchronized (this){
            id = this.TICKET_ID_SEQUENCE++;
            this.ticketDatabase.put(id,ticket);
        }
        resp.sendRedirect("tickets?action=view&ticketId="+id);
    }

    private Attachment processAttachment(Part filePart) throws IOException {
        InputStream inputStream = filePart.getInputStream();//用户输入流
        ByteArrayOutputStream outputStream = new ByteArrayOutputStream();//写入attachment做准备

        int read;
        final byte[] bytes  = new byte[1024];//buffer
        while((read=inputStream.read(bytes))!=-1){//有多少
            outputStream.write(bytes,0,read);//写多少
        }

        Attachment attachment = new Attachment();
        attachment.setName(filePart.getSubmittedFileName());
        attachment.setContents(outputStream.toByteArray());

        return attachment;
    }

    private PrintWriter writeHeader(HttpServletResponse response)
            throws IOException
    {
        response.setContentType("text/html");
        response.setCharacterEncoding("UTF-8");

        PrintWriter writer = response.getWriter();
        writer.append("<!DOCTYPE html>\r\n")
                .append("<html>\r\n")
                .append("    <head>\r\n")
                .append("        <title>Customer Support</title>\r\n")
                .append("    </head>\r\n")
                .append("    <body>\r\n");

        return writer;
    }

    private void writeFooter(PrintWriter writer)
    {
        writer.append("    </body>\r\n").append("</html>\r\n");
    }

}

 

 

【文件下载细节】

//header 内容位置   文件名
response.setHeader("Content-Disposition",
        "attachment; filename=" +
                new String(attachment.getName().getBytes("UTF-8"),"ISO8859-1"));//浏览器支持的编码是ISO8859-1
response.setContentType("application/octet-stream");
//流
ServletOutputStream stream = response.getOutputStream();
stream.write(attachment.getContents());