如何用断点续传的方式下载文件

let config: request.agent.Config = { 
action: request.agent.Action.DOWNLOAD, 
url: 'https://test.com/jdk-21_linux-aarch64_bin.tar.gz', 
title: 'taskOnTest', 
description: 'Sample code for event listening', 
mode: request.agent.Mode.FOREGROUND, 
overwrite: false, 
method: "GET", 
data: '', 
saveas: "./", 
network: request.agent.Network.WIFI, 
metered: false, 
roaming: true, 
retry: true, 
redirect: true, 
index: 0, 
begins: 0, 
ends: -1, 
gauge: false, 
precise: false, 
token: "it is a secret" 
}; 
request.agent.create(getContext(), config).then((task: request.agent.Task) => { 
task.on('progress', (progress: request.agent.Progress) => { 
console.info('upload task progress:' + progress); 
}); 
task.on('completed', (progress: request.agent.Progress) => { 
console.info('upload task completed:' + progress); 
}); 
task.on('failed', (progress: request.agent.Progress) => { 
console.info('upload task failed:' + progress); 
}); 
task.start(() => { 
console.info('start task success'); 
}) 
console.info(`Succeeded in creating a upload task. result: ${task.tid}`); 
}).catch((err: BusinessError) => { 
console.error(`Failed to create a upload task, Code: ${err.code}, message: ${err.message}`); 
});