java 从模型下载文件并在春季查看
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Downloading file from model and view in spring
提问by Medioman92
i'm trying to create a page where users can download some .log file. this is the code :
我正在尝试创建一个页面，用户可以在其中下载一些 .log 文件。这是代码：
if(action.equalsIgnoreCase("download")){
String file = (String)request.getParameter("file");
response.setHeader("Content-Disposition",
"attachment;filename="+file+"");
response.setContentType("text/plain");
File down_file = new File("log/"+file);
FileInputStream fileIn = new FileInputStream(down_file);
ServletOutputStream out = response.getOutputStream();
byte[] outputByte = new byte[4096];
//copy binary contect to output stream
while(fileIn.read(outputByte, 0, 4096) != -1)
{
out.write(outputByte, 0, 4096);
}
fileIn.close();
out.flush();
out.close();
return null;
}
where am i doing wrong ? when i click on the download button it correctly ask me to save the file, but it is always a 0 byte file...
我哪里做错了？当我单击下载按钮时，它正确地要求我保存文件，但它始终是一个 0 字节的文件...
回答by Xaerxess
This should do the job:
这应该可以完成这项工作：
public void getFile(final HttpServletResponse response) {
String file = (String) request.getParameter("file");
response.setHeader("Content-Disposition",
"attachment;filename=" + file);
response.setContentType("text/plain");
File down_file = new File("log/" + file);
FileInputStream fileIn = new FileInputStream(down_file);
ByteStreams.copy(fileIn, response.getOutputStream());
response.flushBuffer();
return null;
}
where ByteStreams.copycomes from wonderful Google's Guava library.
其中，ByteStreams.copy来自于美妙的谷歌的番石榴库。
EDIT:
编辑：
Also, if you are using Spring MVC 3.1 you can do it in cleaner way (that's how I do it, turns out to be one-liner ;)):
此外，如果您使用的是 Spring MVC 3.1，您可以以更简洁的方式进行操作（我就是这样做的，结果是单行的 ;)）：
@Controller
public final class TestController extends BaseController {
@RequestMapping(value = "/some/url/for/downloading/files/{file}",
produces = "text/plain")
@ResponseBody
public byte[] getFile(@PathVariable final String file) throws IOException {
return Files.toByteArray(new File("log/" + file));
}
}
and in your servlet.xmladd converter to mvc:message-converters:
并在您的servlet.xml添加转换器中mvc:message-converters：
<mvc:annotation-driven>
<mvc:message-converters>
<bean class="org.springframework.http.converter.ByteArrayHttpMessageConverter" />
</mvc:message-converters>
</mvc:annotation-driven>
so that you can return byte[]from any @Controllermethod annotated with @ResponseBody. Read more hereand here.
这样你就可以byte[]从任何@Controller用@ResponseBody. 在这里和这里阅读更多。
Files.toByteArrayis also from Guava.
Files.toByteArray也来自番石榴。
回答by davioooh
Try with:
尝试：
IOUtils.copy(fileIn, response.getOutputStream());
response.flushBuffer();
you can find Apache Commons IO here: http://commons.apache.org/io/
你可以在这里找到 Apache Commons IO：http: //commons.apache.org/io/
Hereyou find IOUtils.copy()reference.
在这里你可以找到IOUtils.copy()参考。
