一. HTTP gzip壓縮,概述
- request
- header中聲明Accept-Encoding : gzip，告知服務器客戶端接受gzip的數據
- response
- body，同時加入以下header：Content-Encoding: gzip：表明body是gzip過的數據
- Content-Length:117：表示body gzip壓縮后的數據大小，便于客戶端使用
- 或Transfer-Encoding: chunked：分塊傳輸編碼
二. 如何使用gzip進行壓縮
Tomcat開啟壓縮（gzip）
tomcat server.xml
<Connector
compression="on" # 表示開啟壓縮
noCompressionUserAgents="gozilla, traviata"
compressionMinSize="2048" # 表示會對大于2KB的文件進行壓縮
compressableMimeType="text/html,text/xml,text/css,text/JAVAscript,image/gif,image/jpg" # 是指將進行壓縮的文件類型
/>
- 弊端
對HTTP傳輸內容進行壓縮是改良前端響應性能的可用方法之一，大型網站都在用。但是也有缺點，就是壓縮過程占用cpu的資源，客戶端瀏覽器解析也占據了一部分時間。但是隨著硬件性能不斷的提高，這些問題正在不斷的弱化。
程序壓縮/解壓
GZIPInputStream(解壓) / GZIPOutputStream(壓縮)
- netflix.zuul相關示例
# org.springframework.cloud.netflix.zuul.filters.post.SendResponseFilter#writeResponse()
is = context.getResponseDataStream();
InputStream inputStream = is;
if (is != null) {
if (context.sendZuulResponse()) {
// if origin response is gzipped, and client has not requested gzip,
// decompress stream
// before sending to client
// else, stream gzip directly to client
if (context.getResponseGZipped() && !isGzipRequested) {
// If origin tell it's GZipped but the content is ZERO bytes,
// don't try to uncompress
final Long len = context.getOriginContentLength();
if (len == null || len > 0) {
try {
inputStream = new GZIPInputStream(is);
}catch (java.util.zip.ZipException ex) {
log.debug("gzip expected but not "+ "received assuming unencoded response "+ RequestContext.getCurrentContext()
.getRequest().getRequestURL()
.toString());
inputStream = is;
}
}else {
// Already done : inputStream = is;
}
}else if (context.getResponseGZipped() && isGzipRequested) {
servletResponse.setHeader(ZuulHeaders.CONTENT_ENCODING, "gzip");
}
writeResponse(inputStream, outStream);
}
}
# com.netflix.zuul.http.HttpServletRequestWrApper.UnitTest#handlesGzipRequestBody
@Test
public void handlesGzipRequestBody() throws IOException {
// creates string, gzips into byte array which will be mocked as InputStream of request
final String body = "hello";
final byte[] bodyBytes = body.getBytes();
// in this case the compressed stream is actually larger - need to allocate enough space
final ByteArrayOutputStream byteOutStream = new ByteArrayOutputStream(0);
final GZIPOutputStream gzipOutStream = new GZIPOutputStream(byteOutStream);
gzipOutStream.write(bodyBytes);
gzipOutStream.finish();
gzipOutStream.flush();
body(byteOutStream.toByteArray());
final HttpServletRequestWrapper wrapper = new HttpServletRequestWrapper(request);
assertEquals(body, IOUtils.toString(new GZIPInputStream(wrapper.getInputStream())));
}
示例: 網關主動對response進行壓縮響應(可減少帶寬) GZIPOutputStream
- 簡單實現示例.實際情況需考慮更新情況,如是否已經被壓縮等
InputStream inputStream = okResponse.body().byteStream();
try {
// 網關主動對response進行壓縮響應(可減少帶寬)
HttpServletRequest request = RequestContext.getCurrentContext().getRequest();
boolean isGatewayGZIP = Boolean.parseBoolean(request.getHeader("x-gateway-gzip"));
if (!isGatewayGZIP) {
isGatewayGZIP = Boolean.parseBoolean(request.getParameter("x-gateway-gzip"));
}
if (isGatewayGZIP) {
final ByteArrayOutputStream byteOutStream = new ByteArrayOutputStream(0);
final GZIPOutputStream gzipOutStream = new GZIPOutputStream(byteOutStream);
gzipOutStream.write(okResponse.body().bytes());
gzipOutStream.finish();
gzipOutStream.flush();
inputStream = new ServletInputStreamWrapper(byteOutStream.toByteArray());
httpHeaders.add(ZuulHeaders.CONTENT_ENCODING, "gzip");
}
} catch (Exception e) {
logger.error("GatewayGZIP error:", e);
}
三.okhttp 壓縮相關處理
okHttp 解壓gzip,條件: Content-Encoding = gizp
- okio.GzipSource
if (transparentGzip
&& "gzip".equalsIgnoreCase(networkResponse.header("Content-Encoding"))
&& HttpHeaders.hasBody(networkResponse)) {
GzipSource responseBody = new GzipSource(networkResponse.body().source());
Headers strippedHeaders = networkResponse.headers().newBuilder()
.removeAll("Content-Encoding")
.removeAll("Content-Length")
.build();
responseBuilder.headers(strippedHeaders);
String contentType = networkResponse.header("Content-Type");
responseBuilder.body(new RealResponseBody(contentType, -1L, Okio.buffer(responseBody)));
}
okhttp gzip壓縮/解壓 (示例)
//zip壓縮
GzipSink gzipSink = new GzipSink(Okio.sink(file));
BufferedSink bufferedSink = Okio.buffer(gzipSink);
bufferedSink.writeUtf8("this is zip file");
bufferedSink.flush();
bufferedSink.close();
//讀取zip
GzipSource gzipSource = new GzipSource(Okio.source(file));
BufferedSource bufferedSource = Okio.buffer(gzipSource);
String s = bufferedSource.readUtf8();
okhttp框架－如何對請求(request)數據進行GZIP壓縮-GzipRequestInterceptor
OkHttpClient okHttpClient = new OkHttpClient.Builder()
.addInterceptor(new GzipRequestInterceptor())//開啟Gzip壓縮
...
.build();
GzipRequestInterceptor
https://github.com/square/okhttp\issues/350#issuecomment-123105641
class GzipRequestInterceptor implements Interceptor {
@Override
public Response intercept(Chain chain) throws IOException {
Request originalRequest = chain.request();
if (originalRequest.body() == null || originalRequest.header("Content-Encoding") != null) {
return chain.proceed(originalRequest);
}
Request compressedRequest = originalRequest.newBuilder()
.header("Content-Encoding", "gzip")
.method(originalRequest.method(), forceContentLength(gzip(originalRequest.body())))
.build();
return chain.proceed(compressedRequest);
}
/** https://github.com/square/okhttp\issues/350 */
private RequestBody forceContentLength(final RequestBody requestBody) throws IOException {
final Buffer buffer = new Buffer();
requestBody.writeTo(buffer);
return new RequestBody() {
@Override
public MediaType contentType() {
return requestBody.contentType();
}
@Override
public long contentLength() {
return buffer.size();
}
@Override
public void writeTo(BufferedSink sink) throws IOException {
sink.write(buffer.snapshot());
}
};
}
private RequestBody gzip(final RequestBody body) {
return new RequestBody() {
@Override
public MediaType contentType() {
return body.contentType();
}
@Override
public long contentLength() {
return -1; // We don't know the compressed length in advance!
}
@Override
public void writeTo(BufferedSink sink) throws IOException {
BufferedSink gzipSink = Okio.buffer(new GzipSink(sink));
body.writeTo(gzipSink);
gzipSink.close();
}
};
}
}
okhttp框架－如何對請求數據進行GZIP壓縮
https://cloud.tencent.com/info/61307ab74137a46628c2ea2ca42a6eb4.html
Okhttp3請求網絡開啟Gzip壓縮 - CSDN博客
https://blog.csdn.net/aiynmimi/article/details/77453809
四. Nginx的Gzip可以對服務器端響應內容進行壓縮從而減少一定的客戶端響應時間
gzip on;
gzip_min_length 1k;
gzip_buffers 4 32k;
gzip_types text/plain application/x-JavaScript application/javascript text/xml text/css;
gzip_vary on;
API網關那些兒 | I'm Yunlong
http://ylzheng.com/2017/03/14/the-things-about-api-gateway
source: //liuxiang.github.io/2018/08/13/HTTP%20gzip壓縮
