相关疑难解决方法(0)

我有一个要求,我需要从网站上下载PDF.PDF需要在代码中生成,我认为这将是freemarker和像iText这样的PDF生成框架的组合.有更好的方法吗？

但是,我的主要问题是如何允许用户通过Spring Controller下载文件？

当我尝试从服务器下载260MB的大文件时,我收到此错误:java.lang.OutOfMemoryError: Java heap space.我确定我的堆大小小于252MB.有没有办法在不增加堆大小的情况下下载大文件？

如何在不解决此问题的情况下下载大文件？我的代码如下:

String path= "C:/temp.zip";   
response.addHeader("Content-Disposition", "attachment; filename=\"test.zip\""); 
byte[] buf = new byte[1024];   
try {   

             File file = new File(path);   
             long length = file.length();   
             BufferedInputStream in = new BufferedInputStream(new FileInputStream(file));   
             ServletOutputStream out = response.getOutputStream();   

             while ((in != null) && ((length = in.read(buf)) != -1)) {   
             out.write(buf, 0, (int) length);   
             }   
             in.close();   
             out.close();

我尝试下载文件.该操作由ajax()发布请求触发.请求以json格式将数据发送到控制器.控制器生成文件(字节)并将其发回.

java脚本:

function getLicenseFile() {
    $.ajax({
        type: 'POST',
        url: '<%=request.getContextPath()%>/licenses/rest/downloadLicenseFile',
        dataType: 'json',
        contentType: 'application/json;charset=UTF-8',
        data: ko.mapping.toJSON(licenseModel),
        success: function (data) {
            console.log("in sucess")
        },
        error:function (xhr, ajaxOptions, thrownError){
            console.log("in error")
        } 
    });
}  

控制器:

@RequestMapping(value = "/licenses/rest/downloadLicenseFile", method = RequestMethod.POST)
@ResponseStatus(value=HttpStatus.OK)
@ResponseBody
public void createLicenseFile(@Valid @RequestBody License license, HttpServletResponse response) throws Exception {

    logger.debug("Contoller License in: "+ license);

    byte[] licensedata = licenseEncodeDefaultService.createLicenseFile(license);
    logger.debug("licenseData: " + new String(licensedata));

    response.setHeader("Content-Disposition", "attachment; filename=\"" + license.getCustomer() + ".license\"");
    response.getOutputStream().write(licensedata);
    response.flushBuffer();
}

问题:
*浏览器应该打开一个下载框,但它不会发生
*响应是在错误中处理的:ajax函数的一部分(但是http状态是OK)

那么我错了什么或者这样做的正确方法是什么？

我测试HttpResponse#flushBuffer及PrintWriter#flush上Tomcat 7下方,但它似乎是回应,而忽略了他们比尽快冲洗过线的内容符合市场预期.

import java.io.IOException;
import java.io.PrintWriter;

import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

@WebServlet("/HelloServlet")
public class HelloServlet extends HttpServlet {

    private static final long serialVersionUID = 1L;

    protected void doGet(HttpServletRequest request,
            HttpServletResponse response) throws ServletException, IOException {

        PrintWriter pw = response.getWriter();
        pw.println("say hi now");
        pw.flush();
        response.flushBuffer();
        try {
            Thread.sleep(5000);
        } catch (Exception e) {
        }
        pw.println("say bye in 5 seconds");

    }

}

在延迟之后,浏览器一起显示"hi"和"bye".这是不正当行为还是打算？

@编辑

根据@Tomasz Nurkiewicz我的建议,我再次测试,curl然后问题就消失了.似乎标准的浏览器和tcp/ip …