HarmonyOS 代码转化问题

let textEncoder = new util.TextEncoder("utf-8"); 
let buffer = new ArrayBuffer(20); 
let imageUrl = new Uint8Array(buffer); 
try { 
 imageUrl = textEncoder.encodeInto(url); 
 let result = util.TextDecoder.create('utf-8'); 
 let rststr = result.decodeWithStream(imageUrl); 
 console.log('解码后---', rststr); 
} catch (err) { 
}