spring mvc使用gzip压缩

　　最近接到一个需求，我们要调用其他项目Restful接口，并要求数据传输使用gzip压缩以减小传输过程中的网络开销。  

　　请求中通过添加Header标识Content-Encoding ：gzip 来标识已压缩的请求。

　　整个流程如图：

　　

　1.　调用方采用的是：Spring 的 RestTemplate ，底层是OkHttp的client

　　先声明 RestTemplate 

    @Bean("gzipRestTemplate")
    public RestTemplate restTemplate() {
        OkHttpClient okHttpClient = new OkHttpClient.Builder() 
                .addInterceptor(new GzipRequestInterceptor())//添加gzip拦截器--只过滤header有"Content-Encoding ：gzip "
                .build();
        OkHttp3ClientHttpRequestFactory requestFactory = new OkHttp3ClientHttpRequestFactory(okHttpClient);
        RestTemplate restTemplate = new  RestTemplate(requestFactory);
        restTemplate.getMessageConverters().add(new MappingJackson2HttpMessageConverter()) ;
        return  restTemplate;
    }

　　gzip压缩拦截器（注：只对header中Content-Encoding =gzip的请求压缩）

　　

import java.io.IOException;

import okhttp3.Interceptor;
import okhttp3.MediaType;
import okhttp3.Request;
import okhttp3.RequestBody;
import okhttp3.Response;
import okio.BufferedSink;
import okio.GzipSink;
import okio.Okio;

public class GzipRequestInterceptor implements Interceptor {
    @Override
    public Response intercept(Chain chain) throws IOException {
        Request originalRequest = chain.request();
        String contentEncoding = originalRequest.header("Content-Encoding");
　　　　　//只对有body的请求（比如：PUT POST ）  且 Content-Encoding=gzip进行处理
        if (originalRequest.body() == null || contentEncoding == null || !(contentEncoding.trim().toLowerCase().equals("gzip"))) {
            return chain.proceed(originalRequest);
        }

        Request compressedRequest = originalRequest.newBuilder()
                .header("Content-Encoding", "gzip")
                .method(originalRequest.method(), gzip(originalRequest.body()))
                .build();
        return chain.proceed(compressedRequest);
    }

    private RequestBody gzip(final RequestBody body) {
        return new RequestBody() {
            @Override
            public MediaType contentType() {
                return body.contentType();
            }

            @Override
            public long contentLength() {
                return -1; // 无法提前知道压缩后的数据大小
            }

            @Override
            public void writeTo(BufferedSink sink) throws IOException {
                BufferedSink gzipSink = Okio.buffer(new GzipSink(sink));
                body.writeTo(gzipSink);
                gzipSink.close();
            }
        };
    }
}

　　请求时带着gzip的header

　　

	private HttpHeaders getGzipHeader() {
            HttpHeaders headers = new HttpHeaders();
            headers.set("Content-Encoding", "gzip");
            MediaType type = MediaType.parseMediaType("application/json; charset=UTF-8");
            headers.setContentType(type);
            return  headers;
	}

　　调用代码：

　　

	    List<User>   rs = new ArrayList<>();
	    User testBean = new User();
	    testBean.setAge("12");
	    testBean.setName("Tom11");
	    testBean.setPassword("ccc");
	    rs.add(testBean);
	    String url = "http://localhost:8000/remote/createUser";
    	
        　　HttpEntity<List<User>> entity = new HttpEntity<List<User>>(rs,getGzipHeader());
        　　ParameterizedTypeReference<Result<Integer>>  parameterizedTypeReference = new ParameterizedTypeReference<Result<Integer>>(){};
    	　　ResponseEntity<Result<Integer>> resp = gzipRestTemplate.exchange(url, HttpMethod.POST, entity, parameterizedTypeReference);
	　　System.out.println(resp.getBody());

　　

2.服务提供方

　　请求包装类 实现HttpServletRequestWrapper接口

　　

import java.io.IOException;
import java.util.zip.GZIPInputStream;

import javax.servlet.ReadListener;
import javax.servlet.ServletInputStream;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletRequestWrapper;

import org.slf4j.Logger;

public class GzipRequestWrapper  extends HttpServletRequestWrapper{

    private HttpServletRequest request;  
    private static final Logger LOGGER = org.slf4j.LoggerFactory.getLogger(GzipRequestWrapper.class);

    public GzipRequestWrapper(HttpServletRequest request) {  
        super(request);  
        this.request = request;  
    } 


    @Override  
    public ServletInputStream getInputStream() throws IOException {  
        
        ServletInputStream stream = request.getInputStream();  
        
        String contentEncoding = request.getHeader("Content-Encoding");
        if(null!=contentEncoding) {
        	  contentEncoding =contentEncoding.trim().toLowerCase();
        }
        // 如果对内容进行了压缩，则解压  
        if (null != contentEncoding && contentEncoding.indexOf("gzip") != -1) {  
            try {  
                final GZIPInputStream gzipInputStream = new GZIPInputStream(  
                        stream);  

                ServletInputStream newStream = new ServletInputStream() {  

                    @Override  
                    public int read() throws IOException {  
                        return gzipInputStream.read();  
                    }

                    @Override
                    public boolean isFinished() {
                        return false;
                    }

                    @Override
                    public boolean isReady() {
                        return false;
                    }

                    @Override
                    public void setReadListener(ReadListener arg0) {
                        
                    }  
                };  
                return newStream;  
            } catch (Exception e) {  
                LOGGER.debug("ungzip content fail.", e);  
            }  
        }  
        return stream;  
    }  


}

　　编写过滤器：

　　

import java.io.IOException;
import javax.servlet.Filter;
import javax.servlet.FilterChain;
import javax.servlet.FilterConfig;
import javax.servlet.ServletException;
import javax.servlet.ServletRequest;
import javax.servlet.ServletResponse;
import javax.servlet.annotation.WebFilter;
import javax.servlet.http.HttpServletRequest;

@WebFilter(filterName="gzipFilter",urlPatterns="/")
public class GzipFilter implements Filter {

    @Override
    public void destroy() {
        
    }

    @Override
    public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain)
            throws IOException, ServletException {
        chain.doFilter(new GzipRequestWrapper((HttpServletRequest) request),response); 
    }

    @Override
    public void init(FilterConfig arg0) throws ServletException {
        
    }
}

　　spring  boot  注册过滤器

　　

　　@Bean  
    public FilterRegistrationBean  filterRegistrationBean() {  
        FilterRegistrationBean registrationBean = new FilterRegistrationBean();  
        GzipFilter httpBasicFilter = new GzipFilter();  
        registrationBean.setFilter(httpBasicFilter);  
        List<String> urlPatterns = new ArrayList<String>();  
        urlPatterns.add("/*");  
        registrationBean.setUrlPatterns(urlPatterns);  
        return registrationBean;  
    } 

　　接口定义：

　　

	@RequestMapping(value= "/remote/createUser", method=RequestMethod.POST)
	public Result<Integer> test(@RequestBody  List<User>  data ) {
		System.out.println(JSON.toJSON(data));
		Result<Integer> r = new Result<>();
		r.setData(30);
		r.setStatus(200);
		return r;
	}

　　

至此结束