bufferedinputstream转换速度优化
对于下述代码，当图片大小为5mb时，加载时间耗时8秒。如何提升其加载速度？
url url = new url(imageurl);httpurlconnection connection = (httpurlconnection) url.openconnection();connection.setrequestmethod("get");connection.setconnecttimeout(5000);bufferedinputstream bis = new bufferedinputstream(connection.getinputstream());bytearrayoutputstream baos = new bytearrayoutputstream();byte[] buffer = new byte[1024];int len;while ((len = bis.read(buffer)) != -1) { baos.write(buffer, 0, len);}outputstream outputstream = response.getoutputstream();response.setcontenttype("image/jpg");outputstream.write(baos.tobytearray());outputstream.flush();outputstream.close();
优化方案
该代码存在以下优化点：
内存占用高：读取数据后全部存放在内存中，当文件较大时会造成内存溢出。阻塞读取：阻塞读取数据后才执行写入，造成资源浪费。连接未复用：未复用http连接，增加开销。资源未释放：未释放http连接和response流，造成内存泄露。
优化方案一：原始流复制
优化原始流复制，通过增大缓冲区，提高效率：
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httpurlconnection connection = null;try { url url = new url(imageurl); connection = (httpurlconnection) url.openconnection(); connection.setrequestmethod("get"); connection.setconnecttimeout(5000); try (inputstream bis = new bufferedinputstream(connection.getinputstream()); outputstream out = response.getoutputstream()) { response.setcontenttype("image/jpg"); // buffer 越大，效率越快 byte[] buffer = new byte[1024]; int len; while ((len = bis.read(buffer)) != -1) { out.write(buffer, 0, len); out.flush(); } }} catch (exception e) { throw new runtimeexception(e);} finally { if(null != connection){ connection.disconnect(); }}
优化方案二：使用复制工具
使用第三方库提供的方法复制流，减少代码复杂度：
httpurlconnection connection = null;try { url url = new url(imageurl); connection = (httpurlconnection) url.openconnection(); connection.setrequestmethod("get"); connection.setconnecttimeout(5000); try (inputstream bis = new bufferedinputstream(connection.getinputstream()); outputstream out = response.getoutputstream()) { response.setcontenttype("image/jpg"); ioutil.copy(bis, out); }} catch (exception e) { throw new runtimeexception(e);} finally { if(null != connection){ connection.disconnect(); }}
优化方案三：使用nio非阻塞传输
使用nio非阻塞传输，减少系统开销，提升效率：
HttpURLConnection connection = null;try { URL url = new URL(imageUrl); connection = (HttpURLConnection) url.openConnection(); connection.setRequestMethod("GET"); connection.setConnectTimeout(5000); try (ReadableByteChannel in = Channels.newChannel(new BufferedInputStream(connection.getInputStream())); WritableByteChannel out = Channels.newChannel(response.getOutputStream())) { response.setContentType("image/jpg"); ByteBuffer byteBuffer = ByteBuffer.allocate(8192); while (in.read(byteBuffer) != -1) { // 写转读 byteBuffer.flip(); out.write(byteBuffer); byteBuffer.clear(); } }} catch (Exception e) { throw new RuntimeException(e);} finally { if (null != connection) { connection.disconnect(); }}
以上就是5MB图片加载耗时8秒，如何优化BufferedInputStream的转换速度？的详细内容，更多请关注创想鸟其它相关文章！
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