电子技术论坛_中国专业的电子工程师学习交流社区-中电网技术论坛

标题: Picasso使用简介及分析（8） [打印本页]

作者: look_w 时间: 2019-2-18 19:56 标题: Picasso使用简介及分析（8）

9.以网络图片为例介绍下从硬盘和网络加载图片的流程

@Override
public Response load(Uri uri, int networkPolicy) throws IOException {
   CacheControl cacheControl = null;
   if (networkPolicy != 0) {
      //只走本地缓存
      if (NetworkPolicy.isOfflineOnly(networkPolicy)) {
         cacheControl = CacheControl.FORCE_CACHE;
      } else {
         //自定义缓存策略
         CacheControl.Builder builder = new CacheControl.Builder();
         //不从硬盘读
         if (!NetworkPolicy.shouldReadFromDiskCache(networkPolicy)) {
            builder.noCache();
            }
         //不写入硬盘
         if (!NetworkPolicy.shouldWriteToDiskCache(networkPolicy)) {
            builder.noStore();
         }
         cacheControl = builder.build();
      }
   }
   Request.Builder builder = new Request.Builder().url(uri.toString());
   if (cacheControl != null) {
      builder.cacheControl(cacheControl);
   }
   //重点：调用okhttp或者UrlConnection来执行bitmap的下载任务(拦截器)。
   okhttp3.Response response = client.newCall(builder.build()).execute();
   int responseCode = response.code();
   if (responseCode >= 300) {
      response.body().close();
      throw new ResponseException(responseCode + " " + response.message(), networkPolicy,       responseCode);
      }
   boolean fromCache = response.cacheResponse() != null;
   ResponseBody responseBody = response.body();
   return new Response(responseBody.byteStream(), fromCache, responseBody.contentLength());
   }

欢迎光临电子技术论坛_中国专业的电子工程师学习交流社区-中电网技术论坛 (http://bbs.eccn.com/)