SpringMVC下载文件

import org.junit.Test;
import org.springframework.http.HttpHeaders;
import org.springframework.http.HttpStatus;
import org.springframework.http.ResponseEntity;

import javax.servlet.http.HttpSession;
import java.io.File;
import java.io.FileInputStream;
import java.io.IOException;

public class TestDownControlelr {


    @Test
    public ResponseEntity<byte[]> down(HttpSession session) throws IOException {

        //获取下载文件的路径
        String realPath = session.getServletContext().getRealPath("img");
        String finalPath = realPath + File.separator + "2.jpg";
        FileInputStream is = new FileInputStream(finalPath);
        //available(): 获取输入流所读取的文件的最大字节数
        byte[] b = new byte[is.available()];
        is.read(b);

        //设置请求头
        HttpHeaders headers = new HttpHeaders();
        headers.add("Content-Disposition","attachment;filename=zzz.jpg");
        //设置响应状态
        HttpStatus statusCode = HttpStatus.OK;
        ResponseEntity<byte[]> entity = new ResponseEntity<byte[]>(b, headers, statusCode);

        return entity;
    }

}