log4j.rootLogger=ERROR,stdout,file,D,MAIL
log4j.category.org.yuna=DEBUG

log4j.appender.stdout = org.apache.log4j.ConsoleAppender
log4j.appender.stdout.Target = System.out
log4j.appender.stdout.layout = org.apache.log4j.PatternLayout
log4j.appender.stdout.layout.ConversionPattern =  %-d{yyyy-MM-dd HH:mm:ss}  [ %t:%r ] - [ %p ]  %m%n

log4j.appender.file=org.apache.log4j.DailyRollingFileAppender
log4j.appender.file.File=logs/yuna.log
log4j.appender.file.Append = true
log4j.appender.file.Threshold = DEBUG
log4j.appender.file.layout=org.apache.log4j.PatternLayout
log4j.appender.file.layout.ConversionPattern=%-d{yyyy-MM-dd HH:mm:ss}  [ %t:%r ] - [ %p ]  %m%n

log4j.appender.D = org.apache.log4j.DailyRollingFileAppender
log4j.appender.D.File = logs/error.log 
log4j.appender.D.Append = true
log4j.appender.D.Threshold = ERROR
log4j.appender.D.layout = org.apache.log4j.PatternLayout
log4j.appender.D.layout.ConversionPattern = %-d{yyyy-MM-dd HH:mm:ss}  [ %t:%r ] - [ %p ]  %m%n

log4j.appender.MAIL=org.apache.log4j.net.SMTPAppender
log4j.appender.MAIL.Threshold=ERROR
log4j.appender.MAIL.BufferSize=1
log4j.appender.MAIL.SMTPUsername=main_shorttime@yahoo.cn
log4j.appender.MAIL.SMTPPassword=alibaba
log4j.appender.MAIL.SMTPHost=smtp.mail.yahoo.com.cn
log4j.appender.MAIL.Subject=Yuna Has Error
log4j.appender.MAIL.SMTPDebug=false
log4j.appender.MAIL.LocationInfo=true
log4j.appender.MAIL.SendOnClose=true
log4j.appender.MAIL.From=main_shorttime@yahoo.cn
log4j.appender.MAIL.To=tengfei.fangtf@alibaba-inc.com,steven.lin@alibaba-inc.com
log4j.appender.MAIL.layout=org.apache.log4j.PatternLayout
log4j.appender.MAIL.layout.ConversionPattern=[framework] %d - %c -%-4r [%t] %-5p %c %x - %m%n

import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.context.ServletContextAware;

import javax.servlet.ServletContext;
import javax.servlet.ServletOutputStream;
import javax.servlet.http.HttpServletResponse;
import java.io.*;

@Controller
public class FileController implements ServletContextAware{
    //Spring这里是通过实现ServletContextAware接口来注入ServletContext对象
    private ServletContext servletContext;


    @RequestMapping("file/download")
    public void fileDownload(HttpServletResponse response){
        //获取网站部署路径(通过ServletContext对象)，用于确定下载文件位置，从而实现下载
        String path = servletContext.getRealPath("/");

        //1.设置文件ContentType类型，这样设置，会自动判断下载文件类型
        response.setContentType("multipart/form-data");
        //2.设置文件头：最后一个参数是设置下载文件名(假如我们叫a.pdf)
        response.setHeader("Content-Disposition", "attachment;fileName="+"a.pdf");
        ServletOutputStream out;
        //通过文件路径获得File对象(假如此路径中有一个download.pdf文件)
        File file = new File(path + "download/" + "download.pdf");

        try {
            FileInputStream inputStream = new FileInputStream(file);

            //3.通过response获取ServletOutputStream对象(out)
            out = response.getOutputStream();

            int b = 0;
            byte[] buffer = new byte[512];
            while (b != -1){
                b = inputStream.read(buffer);
                //4.写到输出流(out)中
                out.write(buffer,0,b);
            }
            inputStream.close();
            out.close();
            out.flush();

        } catch (IOException e) {
            e.printStackTrace();
        }
    }

    @Override
    public void setServletContext(ServletContext servletContext) {
        this.servletContext = servletContext;
    }
}