使用ResponseEntity实现文件下载

使用ResponseEntity实现对jar内部和外部的数据文件实现下载。
ResponseEntity的泛型可以设置自定义返回值，也可以使用自带的返回值。

import org.springframework.core.io.ClassPathResource;
import org.springframework.core.io.InputStreamResource;
import org.springframework.core.io.Resource;
import org.springframework.http.HttpHeaders;
import org.springframework.http.MediaType;
import org.springframework.http.ResponseEntity;
import org.springframework.web.bind.annotation.PostMapping;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;

import java.io.IOException;
import java.nio.file.Files;
import java.nio.file.Path;
import java.nio.file.Paths;

@RestController
@RequestMapping("/test")
public class TestController {

    // 设置返回值
    class MyResult<T>{
        private int code;
        private String msg;
        private T data;

        public int getCode() {
            return code;
        }

        public void setCode(int code) {
            this.code = code;
        }

        public String getMsg() {
            return msg;
        }

        public void setMsg(String msg) {
            this.msg = msg;
        }

        public T getData() {
            return data;
        }

        public void setData(T data) {
            this.data = data;
        }
    }

    @PostMapping("/download/out")
    public ResponseEntity<Object> downloadOut(){

        try {
            // Set the file name
            String fileName = "my.xlsx";

            // 工程的目录
            String prefixPath = System.getProperty("user.dir");
            // 文件路径
            String filePath = "/data/"+fileName;

            // 设置头信息
            HttpHeaders headers = new HttpHeaders();
            // 设置文件名称
            headers.setContentDispositionFormData("attachment", fileName);

            // 转化文件
            Path path = Paths.get(prefixPath + "/" + filePath);
            Resource resource = new InputStreamResource(Files.newInputStream(path));

            // 设置返回值
            return ResponseEntity.ok()
                    .headers(headers)
                    .contentLength(Files.size(path))
                    .contentType(MediaType.APPLICATION_OCTET_STREAM)
                    .body(resource);
        } catch (IOException e) {
            System.out.println("下载文件失败");

            MyResult<String> result = new MyResult<>();
            result.setCode(-1);
            result.setMsg("下载文件失败");

            // 返回实体值
            return ResponseEntity.ok(result);
        }
    }

    @PostMapping("/download/in")
    public ResponseEntity<Object> downloadIn(){

        System.out.println("test");
        try {
            // Set the file name
            String fileName = "my.xlsx";

            // 文件路径
            String filePath = "/data/"+fileName;

            // 设置头信息
            HttpHeaders headers = new HttpHeaders();
            // 设置文件名称
            headers.setContentDispositionFormData("attachment", fileName);

            System.out.println(filePath);

            // 获取资源jar包下的数据文件
            ClassPathResource classPathResource = new ClassPathResource(filePath);
            Resource resource = new InputStreamResource(classPathResource.getInputStream());

            // 设置返回值
            return ResponseEntity.ok()
                    .headers(headers)
                    .contentLength(classPathResource.contentLength())
                    .contentType(MediaType.APPLICATION_OCTET_STREAM)
                    .body(resource);
        } catch (IOException e) {
            System.out.println("下载文件失败");

            MyResult<String> result = new MyResult<>();
            result.setCode(-2);
            result.setMsg("下载文件失败");

            // 返回实体值
            return ResponseEntity.ok(result);
        }

    }

}