做1个接口，处理前端请求图片跨域的问题。由于前端拿图片的时候，有跨域问题，所以让后台先拿到图片，然后再写给前台。本来下面的代码没什么太大的问题，但是如果前台请求的图片一多（1个页面中有很多图片），有些请求就会报错：java.io.IOException: Broken pipe…

import lombok.extern.slf4j.Slf4j;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;
import org.springframework.util.StreamUtils;
import org.springframework.web.context.ServletContextAware;import javax.servlet.ServletContext;
import javax.servlet.http.HttpServletResponse;
import java.io.InputStream;
import java.net.URL;
import java.net.URLConnection;@Slf4j
@Service
public class FileServiceImpl implements IFileService {@Autowiredprivate HttpServletResponse response;@Overridepublic void getImg(String imageUrl) {URL target = null;try {target = new URL(imageUrl);URLConnection urlConnection = target.openConnection();//获取输入流InputStream inputStream = urlConnection.getInputStream();byte[] bytes = StreamUtils.copyToByteArray(inputStream);StreamUtils.copy(bytes, response.getOutputStream());response.getOutputStream().close();} catch (Exception e) {log.error("获取图片失败, 图片url: {}, 异常信息: {}", imageUrl, e);}}}

因此，需要加上Content-Length响应头，由于没有告知客户端响应是否写完（当前返回的数据响应体大小），客户端就可能随时主动断开连接

import lombok.extern.slf4j.Slf4j;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;
import org.springframework.util.StreamUtils;
import org.springframework.web.context.ServletContextAware;import javax.servlet.ServletContext;
import javax.servlet.http.HttpServletResponse;
import java.io.InputStream;
import java.net.URL;
import java.net.URLConnection;@Slf4j
@Service
public class FileServiceImpl implements IFileService, ServletContextAware {@Autowiredprivate HttpServletResponse response;private ServletContext servletContext;@Overridepublic void getImg(String imageUrl) {URL target = null;try {target = new URL(imageUrl);URLConnection urlConnection = target.openConnection();response.setHeader("Content-Type",servletContext.getMimeType(imageUrl));//获取输入流InputStream inputStream = urlConnection.getInputStream();byte[] bytes = StreamUtils.copyToByteArray(inputStream);// 必须告诉浏览器客户端当前数据的大小, 否则客户端可能会断开连接, 导致broke pipe异常response.setContentLength(bytes.length);StreamUtils.copy(bytes, response.getOutputStream());response.getOutputStream().close();} catch (Exception e) {log.error("获取图片失败, 图片url: {}, 异常信息: {}", imageUrl, e);}}@Overridepublic void setServletContext(ServletContext servletContext) {this.servletContext = servletContext;}
}