cocos_creator_framework/assets/Script/res/ResPool.ts

import ResLoader, { resLoader, CompletedCallback, ProcessCallback, LoadResArgs } from "./ResLoader";
import { NodePool } from "./NodePool";

/**
 * ResPool，可提高资源缓存的效率，
 * 当超过警戒水位时，每次加载新的资源都会自动检查可释放的资源进行释放
 * 也可以手动调用releaseUnuseRes，自动释放可释放的资源
 * 
 * 2020-1-19 by 宝爷
 */

export class ResPool {
    private _useKey: string;
    private _urls: string[] = [];
    private _waterMark: number = 32;

    constructor() {
        this._useKey = `@ResPool${resLoader.nextUseKey()}`;
    }

    /**
     * 开始加载资源
     * @param url           资源url
     * @param type          资源类型，默认为null
     * @param onProgess     加载进度回调
     * @param onCompleted   加载完成回调
     * @param use           资源使用key，根据makeUseKey方法生成
     */
    public loadRes(url: string, use?: string);
    public loadRes(url: string, onCompleted: CompletedCallback, use?: string);
    public loadRes(url: string, onProgess: ProcessCallback, onCompleted: CompletedCallback, use?: string);
    public loadRes(url: string, type: typeof cc.Asset, use?: string);
    public loadRes(url: string, type: typeof cc.Asset, onCompleted: CompletedCallback, use?: string);
    public loadRes(url: string, type: typeof cc.Asset, onProgess: ProcessCallback, onCompleted: CompletedCallback, use?: string);
    public loadRes() {
        this.autoCheck();
        let resArgs: LoadResArgs = ResLoader.makeLoadResArgs.apply(this, arguments);
        let SaveCompleted = resArgs.onCompleted;
        resArgs.onCompleted = (error: Error, resource: any) => {
            let url = resLoader.getUrlByAsset(resource);
            if (!error && url) {
                this.addNewResUrl(url);
            }
            if (SaveCompleted) {
                SaveCompleted(error, resource);
            }
        };
    }

    /**
     * 设置监控水位
     * @param waterMakr 水位
     */
    public setWaterMark(waterMakr: number) {
        this._waterMark = waterMakr;
    }

    /**
     * 是否缓存了某url（这里的url为resloader的_resMap的key，可能不等于加载的url）
     * @param url 
     */
    public hasResUrl(url: string) : boolean {
        for (let i = 0; i < this._urls.length; ++i) {
            if (url == this._urls[i]) {
                return true;
            }
        }
        return false;
    }

    /**
     * 加载完成后添加一个use
     * @param url 
     */
    private addNewResUrl(url: string) {
        if (!this.hasResUrl(url) && resLoader.addUse(url, this._useKey)) {
            this._urls[this._urls.length] = url;
        }
    }

    /**
     * 自动检测是否需要释放资源，需要则自动释放资源
     */
    public autoCheck() {
        if (this._urls.length > this._waterMark) {
            this.autoReleaseUnuseRes();
        }
    }

    /**
     * 自动释放资源
     */
    public autoReleaseUnuseRes() {
        for (let i = this._urls.length; i >= 0; --i) {
            if (resLoader.canRelease(this._urls[i], this._useKey)) {
                resLoader.releaseRes(this._urls[i], this._useKey);
                this._urls.splice(i, 1);
            }
        }
    }

    /**
     * 清空该ResPool
     */
    public destroy() {
        for (let i = this._urls.length; i >= 0; --i) {
            resLoader.releaseRes(this._urls[i], this._useKey);
        }
        this._urls.length = 0;
    }

    /**
     * 调试打印缓存的urls
     */
    public dump() {
        console.log(this._urls);
    }
}