方式一:通过responseentity 方式来下载
@apioperation(value = "下载数据文档模板") @getmapping("/download-template/1") public responseentity<resource> downloadfile01(httpservletrequest request) { try { resource resource = new classpathresource("templates/ubuntu-20.04.6-desktop-amd64.iso"); // 检查资源是否存在 if (resource.exists() || resource.isreadable()) { return responseentity.ok() .header(httpheaders.content_length, string.valueof(resource.contentlength())) .header(httpheaders.content_disposition, "attachment; filename=" + encodefilename(request, resource.getfilename())) .contenttype(mediatypefactory.getmediatype(resource).orelse(mediatype.application_octet_stream)) .body(resource); } else { return responseentity.notfound().build(); } } catch (exception e) { log.error("文件模板下载失败!", e); return responseentity.internalservererror().build(); } } /** * 根据浏览器类型编码文件名 * @param request 请求对象 * @param filename 原始文件名 * @return 编码后的文件名 */ private static string encodefilename(httpservletrequest request, string filename) { string useragent = request.getheader("user-agent"); // 处理ie及edge浏览器 if (useragent.contains("msie") || useragent.contains("trident") || useragent.contains("edge")) { return cn.hutool.core.net.urlencoder.createdefault().encode(filename, standardcharsets.utf_8); } // 其他浏览器使用iso-8859-1编码 return new string(filename.getbytes(standardcharsets.utf_8), standardcharsets.iso_8859_1); }
方式二:通过responseentity 方式来下载
@apioperation(value = "下载数据文档模板") @getmapping("/download-template/2") public responseentity<streamingresponsebody> downloadfile02(httpservletrequest request) { try { resource resource = new classpathresource("templates/ubuntu-20.04.6-desktop-amd64.iso"); streamingresponsebody body = outputstream -> { fileutil.writetostream(resource.getfile(), outputstream); }; // 检查资源是否存在 if (resource.exists() || resource.isreadable()) { return responseentity.ok() .header(httpheaders.content_length, string.valueof(resource.contentlength())) // 省略 encodefilename 方法 .header(httpheaders.content_disposition, "attachment; filename=" + encodefilename(request, resource.getfilename())) .contenttype(mediatypefactory.getmediatype(resource).orelse(mediatype.application_octet_stream)) .body(body); } else { return responseentity.notfound().build(); } } catch (exception e) { log.error("文件模板下载失败!", e); return responseentity.internalservererror().build(); } }
方式三:通过servlet原生下载
@apioperation(value = "下载数据文档模板") @getmapping("/download-template/3") public void downloadfile03(httpservletrequest request, httpservletresponse response) throws ioexception { resource resource = new classpathresource("templates/ubuntu-20.04.6-desktop-amd64.iso"); // 设置响应头 response.setcontenttype(mediatypefactory.getmediatype(resource).orelse(mediatype.application_octet_stream).tostring()); response.setheader("content-disposition", "attachment; filename=" + encodefilename(request, resource.getfilename())); // 这里是关键,如果设置 response.setcontentlength() 则下载的文件只能是 50 多兆 response.setcontentlengthlong(resource.contentlength()); fileutil.writetostream(resource.getfile(), response.getoutputstream()); }
方式四:通过responseentity<byte[]> 方式来下载
@apioperation(value = "下载数据文档模板") @getmapping("/download-template/4") public responseentity<byte[]> downloadfile04(httpservletrequest request, httpservletresponse response) throws ioexception { try { resource resource = new classpathresource("templates/ubuntu-20.04.6-desktop-amd64.iso"); // 检查资源是否存在 if (resource.exists() || resource.isreadable()) { return responseentity.ok() .header(httpheaders.content_length, string.valueof(resource.contentlength())) .header(httpheaders.content_disposition, "attachment; filename=" + encodefilename(request, resource.getfilename())) .contenttype(mediatypefactory.getmediatype(resource).orelse(mediatype.application_octet_stream)) .body(fileutil.readbytes(resource.getfile())); } else { return responseentity.notfound().build(); } } catch (exception e) { log.error("文件模板下载失败!", e); return responseentity.internalservererror().build(); } }
四种下载方式的对比
1、核心特性对比
方式 | 内存占用 | 适用场景 | 流式支持 | 资源管理 | 代码复杂度 |
---|---|---|---|---|---|
responseentity<byte[]> | 高(全量加载) | 小文件(<10mb)如配置文件、图片 | ❌ | 自动释放内存 | 低(简单封装) |
responseentity<resource> | 中(按需加载) | 动态资源(如jar内文件、数据库blob) | ✅(需手动关闭流) | 需显式关闭inputstream | 中(需处理流) |
responseentity<streamingresponsebody> | 极低(分块传输) | 超大文件(视频、日志等) | ✅(自动分块) | 自动处理流生命周期 | 高(需分块逻辑) |
servlet原生下载 | 低(手动控制) | 需要精细控制响应头/流的场景 | ✅(手动实现) | 需手动关闭流 | 高(冗余代码) |
2、典型场景推荐
- 快速小文件下载:优先使用
responseentity<byte[]>
,直接返回字节数组,无需流控制。 - 动态资源或加密文件:选择
responseentity<resource>
,灵活处理输入流。 - **超大文件(gb级)**:必须用
streamingresponsebody
分块传输,避免oom。 - 兼容旧系统或特殊需求:
servlet原生下载
(如需要自定义响应头逻辑)
完整的代码
import cn.hutool.core.io.fileutil; import io.swagger.annotations.apioperation; import lombok.extern.slf4j.slf4j; import org.springframework.core.io.classpathresource; import org.springframework.core.io.resource; import org.springframework.http.httpheaders; import org.springframework.http.mediatype; import org.springframework.http.mediatypefactory; import org.springframework.http.responseentity; import org.springframework.stereotype.controller; import org.springframework.web.bind.annotation.getmapping; import org.springframework.web.bind.annotation.requestmapping; import org.springframework.web.servlet.mvc.method.annotation.streamingresponsebody; import javax.servlet.http.httpservletrequest; import javax.servlet.http.httpservletresponse; import java.io.ioexception; import java.nio.charset.standardcharsets; /** * description * * @author lijin * @since 2025-08-12 14:05 */ @slf4j @controller @requestmapping("/cycle-data/document01") public class downloadcontroller { @apioperation(value = "下载数据文档模板") @getmapping("/download-template/1") public responseentity<resource> downloadfile01(httpservletrequest request) { try { resource resource = new classpathresource("templates/ubuntu-20.04.6-desktop-amd64.iso"); // 检查资源是否存在 if (resource.exists() || resource.isreadable()) { return responseentity.ok() .header(httpheaders.content_length, string.valueof(resource.contentlength())) .header(httpheaders.content_disposition, "attachment; filename=" + encodefilename(request, resource.getfilename())) .contenttype(mediatypefactory.getmediatype(resource).orelse(mediatype.application_octet_stream)) .body(resource); } else { return responseentity.notfound().build(); } } catch (exception e) { log.error("文件模板下载失败!", e); return responseentity.internalservererror().build(); } } @apioperation(value = "下载数据文档模板") @getmapping("/download-template/2") public responseentity<streamingresponsebody> downloadfile02(httpservletrequest request) { try { resource resource = new classpathresource("templates/ubuntu-20.04.6-desktop-amd64.iso"); streamingresponsebody body = outputstream -> { fileutil.writetostream(resource.getfile(), outputstream); }; // 检查资源是否存在 if (resource.exists() || resource.isreadable()) { return responseentity.ok() .header(httpheaders.content_length, string.valueof(resource.contentlength())) .header(httpheaders.content_disposition, "attachment; filename=" + encodefilename(request, resource.getfilename())) .contenttype(mediatypefactory.getmediatype(resource).orelse(mediatype.application_octet_stream)) .body(body); } else { return responseentity.notfound().build(); } } catch (exception e) { log.error("文件模板下载失败!", e); return responseentity.internalservererror().build(); } } @apioperation(value = "下载数据文档模板") @getmapping("/download-template/3") public void downloadfile03(httpservletrequest request, httpservletresponse response) throws ioexception { resource resource = new classpathresource("templates/ubuntu-20.04.6-desktop-amd64.iso"); // 设置响应头 response.setcontenttype(mediatypefactory.getmediatype(resource).orelse(mediatype.application_octet_stream).tostring()); response.setheader("content-disposition", "attachment; filename=" + encodefilename(request, resource.getfilename())); response.setcontentlengthlong(resource.contentlength()); fileutil.writetostream(resource.getfile(), response.getoutputstream()); } @apioperation(value = "下载数据文档模板") @getmapping("/download-template/4") public responseentity<byte[]> downloadfile04(httpservletrequest request, httpservletresponse response) throws ioexception { try { resource resource = new classpathresource("templates/ubuntu-20.04.6-desktop-amd64.iso"); // 检查资源是否存在 if (resource.exists() || resource.isreadable()) { return responseentity.ok() .header(httpheaders.content_length, string.valueof(resource.contentlength())) .header(httpheaders.content_disposition, "attachment; filename=" + encodefilename(request, resource.getfilename())) .contenttype(mediatypefactory.getmediatype(resource).orelse(mediatype.application_octet_stream)) .body(fileutil.readbytes(resource.getfile())); } else { return responseentity.notfound().build(); } } catch (exception e) { log.error("文件模板下载失败!", e); return responseentity.internalservererror().build(); } } /** * 根据浏览器类型编码文件名 * @param request 请求对象 * @param filename 原始文件名 * @return 编码后的文件名 */ private static string encodefilename(httpservletrequest request, string filename) { string useragent = request.getheader("user-agent"); // 处理ie及edge浏览器 if (useragent.contains("msie") || useragent.contains("trident") || useragent.contains("edge")) { return cn.hutool.core.net.urlencoder.createdefault().encode(filename, standardcharsets.utf_8); } // 其他浏览器使用iso-8859-1编码 return new string(filename.getbytes(standardcharsets.utf_8), standardcharsets.iso_8859_1); } }
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