okHttp--Retrofit網路快取設定總結

jlanglang發表於2018-01-12
HTTP快取

前言

找了些文章,發現說的都不是很清楚.設定始終有點問題
這個配置,每個人的需求不一樣,實現情況肯定也不一樣.
說說我的需求:
1.有網的時候所有介面不使用快取
2.指定的介面產生快取檔案,其他介面不會產生快取檔案
3.無網的時候指定的介面使用快取資料.其他介面不使用快取資料
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1.網路攔截器(關鍵)

提示:只能快取Get請求

 Interceptor cacheInterceptor = new Interceptor() {
            @Override
            public Response intercept(Chain chain) throws IOException {
                //拿到請求體
                Request request = chain.request();

                //讀介面上的@Headers裡的註解配置
                String cacheControl = request.cacheControl().toString();

                //判斷沒有網路並且新增了@Headers註解,才使用網路快取.
                if (!Utils.isOpenInternet()&&!TextUtils.isEmpty(cacheControl)){
                    //重置請求體;
                    request = request.newBuilder()
                              //強制使用快取
                            .cacheControl(CacheControl.FORCE_CACHE)
                            .build();
                }

             //如果沒有新增註解,則不快取
                if (TextUtils.isEmpty(cacheControl) || "no-store" .contains(cacheControl)) {
                    //響應頭設定成無快取
                    cacheControl = "no-store";
                } else if (Utils.isOpenInternet()) {
                    //如果有網路,則將快取的過期時間,設定為0,獲取最新資料
                    cacheControl = "public, max-age=" + 0;
                }else {
                    //...如果無網路,則根據@headers註解的設定進行快取.
                }
                Response response = chain.proceed(request);
                HLog.i("httpInterceptor", cacheControl);
                return response.newBuilder()
                        .header("Cache-Control", cacheControl)
                        .removeHeader("Pragma")
                        .build();
        };
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具體介面中的使用,新增headers:

 /**
   * 只能快取get請求.
   * 這裡我設定了1天的快取時間
   * 介面隨便寫的.哈哈,除了 @Headers(...),其它程式碼沒啥參考價值.
   */
    @Headers("Cache-Control: public, max-age=" + 24 * 3600)
    @GET("url")
    Observable<?> queryInfo(@Query("userName") String userName);
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關於Cache-Control頭的引數說明:

public	所有內容都將被快取(客戶端和代理伺服器都可快取)

private	內容只快取到私有快取中(僅客戶端可以快取，代理伺服器不可快取)

no-cache	no-cache是會被快取的，只不過每次在向客戶端（瀏覽器）提供響應資料時，快取都要向伺服器評估快取響應的有效性。 

no-store	所有內容都不會被快取到快取或 Internet 臨時檔案中

max-age=xxx (xxx is numeric)	快取的內容將在 xxx 秒後失效, 這個選項只在HTTP 1.1可用, 並如果和Last-Modified一起使用時, 優先順序較高

max-stale和max-age一樣，只能設定在請求頭裡面。

同時設定max-stale和max-age，快取失效的時間按最長的算。(這個其實不用糾結)
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還有2個引數:

CacheControl.FORCE_CACHE 強制使用快取,如果沒有快取資料,則丟擲504(only-if-cached) CacheControl.FORCE_NETWORK 強制使用網路,不使用任何快取.

這兩個設定,不會判斷是否有網.需要自己寫判斷. 設定錯誤會導致,資料不重新整理,或者有網情況下,請求不到資料 這兩個很關鍵..可以根據自己的需求,進行切換.

2.設定OkHttpClient

  OkHttpClient client = new OkHttpClient.Builder()
                //新增log攔截器,列印log資訊,程式碼後面貼出
                .addInterceptor(loggingInterceptor)
                //新增上面程式碼的攔截器,設定快取
                .addNetworkInterceptor(cacheInterceptor)
                //這個也要新增,否則無網的時候,快取設定不會生效
                .addInterceptor(cacheInterceptor)
                //設定快取目錄,以及最大快取的大小,這裡是設定10M
                .cache(new Cache(MyApplication.getContext().getCacheDir(), 10240 * 1024))
                .build();

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3.完整的程式碼:

public class RetrofitUtil {
    /**
     * 伺服器地址
     */
    private static final String API_HOST = Constant.URLS.BASEURL;
  private RetrofitUtil() {

    }

    public static Retrofit getRetrofit() {
        return Instanace.retrofit;
    }

    private static Retrofit getInstanace() {
        HttpLoggingInterceptor loggingInterceptor = new HttpLoggingInterceptor(new HttpLoggingInterceptor.Logger() {
            @Override
            public void log(String message) {
                HLog.i("RxJava", message);
            }
        });
        Interceptor cacheInterceptor = new Interceptor() {
            @Override
            public Response intercept(Chain chain) throws IOException {
                Request request = chain.request();
                //有網的時候,讀介面上的@Headers裡的註解配置
                String cacheControl = request.cacheControl().toString();
                //沒有網路並且新增了註解,才使用快取.
                if (!Utils.isOpenInternet()&&!TextUtils.isEmpty(cacheControl)){
                    //重置請求體;
                    request = request.newBuilder()
                            .cacheControl(CacheControl.FORCE_CACHE)
                            .build();
                }

             //如果沒有新增註解,則不快取
                if (TextUtils.isEmpty(cacheControl) || "no-store" .contains(cacheControl)) {
                    //響應頭設定成無快取
                    cacheControl = "no-store";
                } else if (Utils.isOpenInternet()) {
                    //如果有網路,則將快取的過期事件,設定為0,獲取最新資料
                    cacheControl = "public, max-age=" + 0;
                }else {
                    //...如果無網路,則根據@headers註解的設定進行快取.
                }
                Response response = chain.proceed(request);
                HLog.i("httpInterceptor", cacheControl);
                return response.newBuilder()
                        .header("Cache-Control", cacheControl)
                        .removeHeader("Pragma")
                        .build();
            }
        };
        OkHttpClient client = new OkHttpClient.Builder()
                .addInterceptor(loggingInterceptor)
                .addNetworkInterceptor(cacheInterceptor)
                .addInterceptor(cacheInterceptor)
                .cache(new Cache(MyApplication.getContext().getCacheDir(), 10240 * 1024))
                .build();
        return new Retrofit.Builder()
                .client(client)
                .baseUrl(API_HOST)
                .addConverterFactory(FastjsonConverterFactory.create())
                .addCallAdapterFactory(RxJavaCallAdapterFactory.create())
                .build();

    }

    private static class Instanace {
        private static final Retrofit retrofit = getInstanace();
    }
 }
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附上HttpLoggingInterceptor

/**
 * Created by Sunflower on 2016/1/12.
 */
public class HttpLoggingInterceptor implements Interceptor {
    private static final Charset UTF8 = Charset.forName("UTF-8");

    public enum Level {
        /**
         * No logs.
         */
        NONE,
        /**
         * Logs request and response lines.
         * <p/>
         * Example:
         * <pre>{@code
         * --> POST /greeting HTTP/1.1 (3-byte body)
         * <p/>
         * <-- HTTP/1.1 200 OK (22ms, 6-byte body)
         * }</pre>
         */
        BASIC,
        /**
         * Logs request and response lines and their respective headers.
         * <p/>
         * Example:
         * <pre>{@code
         * --> POST /greeting HTTP/1.1
         * Host: example.com
         * Content-Type: plain/text
         * Content-Length: 3
         * --> END POST
         * <p/>
         * <-- HTTP/1.1 200 OK (22ms)
         * Content-Type: plain/text
         * Content-Length: 6
         * <-- END HTTP
         * }</pre>
         */
        HEADERS,
        /**
         * Logs request and response lines and their respective headers and bodies (if present).
         * <p/>
         * Example:
         * <pre>{@code
         * --> POST /greeting HTTP/1.1
         * Host: example.com
         * Content-Type: plain/text
         * Content-Length: 3
         * <p/>
         * Hi?
         * --> END GET
         * <p/>
         * <-- HTTP/1.1 200 OK (22ms)
         * Content-Type: plain/text
         * Content-Length: 6
         * <p/>
         * Hello!
         * <-- END HTTP
         * }</pre>
         */
        BODY
    }

    public interface Logger {
        void log(String message);

        /**
         * A {@link Logger} defaults output appropriate for the current platform.
         */
        Logger DEFAULT = new Logger() {
            @Override
            public void log(String message) {
                Platform.get().log(Platform.WARN,message,null);
            }
        };
    }

    public HttpLoggingInterceptor() {
        this(Logger.DEFAULT);
    }

    public HttpLoggingInterceptor(Logger logger) {
        this.logger = logger;
    }

    private final Logger logger;

    private volatile Level level = Level.BODY;

    /**
     * Change the level at which this interceptor logs.
     */
    public HttpLoggingInterceptor setLevel(Level level) {
        if (level == null) throw new NullPointerException("level == null. Use Level.NONE instead.");
        this.level = level;
        return this;
    }

    @Override
    public Response intercept(Chain chain) throws IOException {
        Level level = this.level;

        Request request = chain.request();
        if (level == Level.NONE) {
            return chain.proceed(request);
        }

        boolean logBody = level == Level.BODY;
        boolean logHeaders = logBody || level == Level.HEADERS;

        RequestBody requestBody = request.body();
        boolean hasRequestBody = requestBody != null;

        String requestStartMessage = request.method() + ' ' + request.url();
        if (!logHeaders && hasRequestBody) {
            requestStartMessage += " (" + requestBody.contentLength() + "-byte body)";
        }
        logger.log(requestStartMessage);

        if (logHeaders) {

            if (!logBody || !hasRequestBody) {
                logger.log("--> END " + request.method());
            } else if (bodyEncoded(request.headers())) {
                logger.log("--> END " + request.method() + " (encoded body omitted)");
            } else if (request.body() instanceof MultipartBody) {
                //如果是MultipartBody，會log出一大推亂碼的東東
            } else {
                Buffer buffer = new Buffer();
                requestBody.writeTo(buffer);

                Charset charset = UTF8;
                MediaType contentType = requestBody.contentType();
                if (contentType != null) {
                    contentType.charset(UTF8);
                }

                logger.log(buffer.readString(charset));

//                logger.log(request.method() + " (" + requestBody.contentLength() + "-byte body)");
            }
        }

        long startNs = System.nanoTime();
        Response response = chain.proceed(request);
        long tookMs = TimeUnit.NANOSECONDS.toMillis(System.nanoTime() - startNs);
        logger.log(response.code() + ' ' + response.message() + " (" + tookMs + "ms" + ')');

        return response;
    }

    private boolean bodyEncoded(Headers headers) {
        String contentEncoding = headers.get("Content-Encoding");
        return contentEncoding != null && !contentEncoding.equalsIgnoreCase("identity");
    }

    private static String protocol(Protocol protocol) {
        return protocol == Protocol.HTTP_1_0 ? "HTTP/1.0" : "HTTP/1.1";
    }
}

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