跳过网络，从内存中取图片

library/src/main/ets/components/imageknife/ImageKnife.ets

@@ -41,6 +41,9 @@ import common from '@ohos.app.ability.common'
 import HashMap from '@ohos.util.HashMap'
 import LinkedList from '@ohos.util.LinkedList'
 import { MemoryLruCache } from '../cache/MemoryLruCache'
+import { BusinessError } from '@ohos.base'
+import { IParseImage } from './interface/IParseImage'
+import { ParseImageUtil } from './utils/ParseImageUtil'
 
 export class ImageKnife {
   static readonly SEPARATOR: string = '/'
@@ -70,9 +73,10 @@ export class ImageKnife {
   defaultLifeCycle: IDrawLifeCycle | undefined = undefined;
   // 开发者可配置全局缓存
   engineKeyImpl: EngineKeyInterface;
+  private mParseImageUtil: IParseImage<PixelMap>;
 
   private constructor() {
-
+    this.mParseImageUtil = new ParseImageUtil();
     this.runningMaps = new EasyLinkedHashMap();
     this.pendingMaps = new EasyLinkedHashMap();
     this.pausedMaps = new EasyLinkedHashMap();
@@ -99,6 +103,7 @@ export class ImageKnife {
 
 
   }
+
   //全局设置请求头调用方法
   addHeader(key: string, value: Object) {
     this.headerMap.set(key, value);
@@ -214,6 +219,106 @@ export class ImageKnife {
     // }
   }
 
+
+  public isUrlExist(url: string): Promise<PixelMap> {
+
+    return new Promise((resolve, reject) => {
+      let request1 = new RequestOption();
+      request1.loadSrc = url;
+      let request = this.loadResourcesCaches(request1);
+
+      let loadComplete = (ImageKnifeData: ImageKnifeData) => {
+        let pixelMap: PixelMap | undefined;
+        pixelMap = ImageKnifeData?.drawPixelMap?.imagePixelMap;
+        resolve(pixelMap as PixelMap);
+      }
+      let loadError = (err ?: BusinessError | string) => {
+        reject(undefined);
+      }
+      this.loadMemoryCacheAndDiskFrom(request, loadComplete, loadError);
+    })
+  }
+
+  loadMemoryCacheAndDiskFrom(request: RequestOption, onComplate: (ImageKnifeData: ImageKnifeData) => void | PromiseLike<ImageKnifeData>, onError: (err?: BusinessError | string) => void) {
+    let cache = this.memoryCache.get(request.generateCacheKey);
+    if (cache == null || typeof cache == 'undefined') {
+      let cached = this.diskMemoryCache.get(request.generateDataKey);
+      if (cached == null) {
+        //4.加载磁盘缓存 原图
+        cached = this.diskMemoryCache.get(request.generateResourceKey);
+      }
+      if (cached != null) {
+        //5.磁盘有数据，解析错误返回onError
+        let success = (value: PixelMap) => {
+          let imageKnifeData = ImageKnifeData.createImagePixelMap(ImageKnifeType.PIXELMAP, value);
+          this.memoryCache.put(request.generateCacheKey, imageKnifeData);
+          onComplate(imageKnifeData);
+        }
+        this.mParseImageUtil.parseImage(cached, success, onError)
+      } else {
+        //6.磁盘无数据，返回onError
+        onError("网络缓存and磁盘缓存无数据！")
+      }
+    } else {
+      //需要清理状态
+      cache.waitSaveDisk = false;
+      //2.网络缓存有数据，返回
+      onComplate(cache);
+    }
+  }
+
+  loadResourcesCaches(request: RequestOption) {
+    let factories: EngineKeyInterface;
+    let cacheKey: string;
+    let transferKey: string;
+    let dataKey: string;
+    if (this.engineKeyImpl) {
+      factories = this.engineKeyImpl;
+    } else {
+      factories = new EngineKeyFactories();
+    }
+    // 生成内存缓存key 内存 变换后磁盘
+
+    let loadKey = '';
+    if (typeof request.loadSrc == 'string') {
+      loadKey = request.loadSrc;
+    } else {
+      loadKey = JSON.stringify(request.loadSrc);
+    }
+
+    let size = JSON.stringify(request.size);
+
+    let transformed = '';
+    if (request && request.transformations) {
+      for (let i = 0; i < request.transformations.length; i++) {
+        if (i == request.transformations.length - 1) {
+          transformed += request.transformations[i].getName() + "";
+        } else {
+          transformed += request.transformations[i].getName() + ",";
+        }
+      }
+    }
+
+    let dontAnimateFlag = request.dontAnimateFlag;
+
+    let signature = request.signature;
+
+    cacheKey = factories.generateMemoryCacheKey(loadKey, size, transformed, dontAnimateFlag, signature);
+
+    // 生成磁盘缓存变换后数据key 变换后数据保存在磁盘
+    transferKey = factories.generateTransformedDiskCacheKey(loadKey, size, transformed, dontAnimateFlag, signature);
+
+    // 生成磁盘缓存源数据key 原始数据保存在磁盘
+    dataKey = factories.generateOriginalDiskCacheKey(loadKey, signature);
+
+    request.generateCacheKey = cacheKey;
+    request.generateResourceKey = transferKey;
+    request.generateDataKey = dataKey;
+
+    return request;
+  }
+
+
   // 预加载 resource资源一级缓存，string资源实现二级缓存
   preload(request: RequestOption): void {
     // 每个request 公共信息补充
@@ -308,6 +413,7 @@ export class ImageKnife {
     return this.parseSource(request);
   }
 
+
   loadResources(request: RequestOption) {
     let factories: EngineKeyInterface;
     let cacheKey: string;
@@ -375,8 +481,6 @@ export class ImageKnife {
   private keyEqualPendingToRun(nextPending: RequestOption) {
 
 
-
-
     this.pendingMaps.remove(nextPending.uuid)
     this.runningMaps.put(nextPending.uuid, nextPending);