S3 need to implement policy to limit file size

[gao2009ss]

版本1.90

问题一：

例如正确地址
http://127.0.0.1:8333/testbucket/file/topic/2020-08-19/image/93380c2d1739420d88ad743ed9ed02c0a16d44128a84c4e56b67cc8bf77d07bbc.jpg

使用listObjectsV2查询返回地址

http://127.0.0.1:8333/testbucket/file/topic/2020-08-19/image93380c2d1739420d88ad743ed9ed02c0a16d44128a84c4e56b67cc8bf77d07bbc.jpg

对比发现在文件名前面少了一个斜杆

查询代码：

`S3Client s3Client = ...

ListObjectsV2Request listObjectsReqManual = ListObjectsV2Request.builder()
.bucket("testbucket")
.maxKeys(6)
.prefix("file/topic/")
.build();

boolean done = false;
while (!done) {
ListObjectsV2Response listObjResponse = s3Client.listObjectsV2(listObjectsReqManual);
for (S3Object content : listObjResponse.contents()) {
System.out.println(content.key());
}

		if (listObjResponse.nextContinuationToken() == null) {
		    done = true;
		}
		System.out.println("分页");
		listObjectsReqManual = listObjectsReqManual.toBuilder()
		       .continuationToken(listObjResponse.nextContinuationToken())
		       .build();

}`

问题二：建议S3接口实现Policy功能
使用S3接口就是需要它的预签名功能，Policy里的content-length-range属性可以限制上传文件大小,这样在客户端使用预签名URL直传就不会让文件上传大小超出限制

参照API
https://docs.aws.amazon.com/AmazonS3/latest/API/sigv4-HTTPPOSTConstructPolicy.html
https://docs.aws.amazon.com/zh_cn/AmazonS3/latest/dev/HTTPPOSTExamples.html
https://docs.aws.amazon.com/AmazonS3/latest/API/sigv4-post-example.html

[chrislusf]

fixed the first one

[chrislusf]

Implemented PostPolicy.