app端獲取本地緩存，清除

// 獲取本地緩存大小
			getStorageSize() {
				let that = this;
				plus.cache.calculate(function(size) {
					let sizeCache = parseInt(size);
					if (sizeCache == 0) {
						that.currentSize = "0B";
					} else if (sizeCache < 1024) {
						that.currentSize = sizeCache + "B";
					} else if (sizeCache < 1048576) {
						that.currentSize = (sizeCache / 1024).toFixed(2) + "KB";
					} else if (sizeCache < 1073741824) {
						that.currentSize = (sizeCache / 1048576).toFixed(2) + "MB";
					} else {
						that.currentSize = (sizeCache / 1073741824).toFixed(2) + "GB";
					}
				});
			},
			// 清理緩存
			clearStorage() {
				let that = this;
				let os = plus.os.name;
				if (os == 'Android') {
					let main = plus.android.runtimeMainActivity();
					let sdRoot = main.getCacheDir();
					let files = plus.android.invoke(sdRoot, "listFiles");
					let len = files.length;
					console.log(files, len)
					for (let i = 0; i < len; i++) {
						let filePath = '' + files[i]; // 沒有找到合適的方法獲取路徑，這樣寫可以轉成文件路徑  
						plus.io.resolveLocalFileSystemURL(filePath, function(entry) {
							if (entry.isDirectory) {
								entry.removeRecursively(function(entry) { //遞歸刪除其下的所有文件及子目錄
									that.files = []
									uni.showToast({
										title: '清除成功',
										duration: 2000
									});
									that.getStorageSize(); // 重新計算緩存  
								}, function(e) {
									console.log(e.message)
								});
							} else {
								entry.remove();
							}
						}, function(e) {
							console.log('文件路徑讀取失敗')
						});
					}
				} else { // ios  
					plus.cache.clear(function() {
						uni.showToast({
							title: '清除成功',
							duration: 2000
						});
						that.getStorageSize();
					});
				}
			},

微信小程序獲取緩存，清除

// 獲取本地緩存大小
			getStorageSize(){
				let that = this;
				uni.getStorageInfo({
					success(res) {
						console.log(res)
						console.log(res.keys);
						console.log(res.limitSize);
						let size = res.currentSize;
						if (size < 1024) {
							that.storageSize = size + ' B';
						} else if (size/1024>=1 && size/1024/1024<1) {
							that.storageSize = Math.floor(size/1024*100)/100 + ' KB';
						} else if (size/1024/1024>=1) {
							that.storageSize = Math.floor(size/1024/1024*100)/100 + ' M';
						}
					}
				})
			},
			// 清理緩存
			clearStorage (){
				let that = this;
				uni.showModal({
					title:'提示',
					content:'確定清除緩存嗎?',
					confirmText:'立即清除',
					success(res) {
						if(res.confirm){
							uni.clearStorageSync();
							//重新獲取并顯示清除后的緩存大小
							that.getStorageSize();
							uni.showToast({
								title:'清除成功'
							})
						}
					}
				})
			}