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Why does API return only 10 messages? Many novices are not very clear about this. In order to help you solve this problem, the following editor will explain it in detail. People with this need can come and learn. I hope you can gain something.

In some API methods that may return a lot of information, in order to better display the information, the information that needs to be returned is usually paged. For example, when querying available images, 40 pieces of data are returned. By default, the result will be divided into 10 pages, a total of 4 pages, and only 1 page of information will be returned at a time, so the returned data is incomplete. You can use PageSize and PageNumber to control these two parameters:

For example, to query images, query the official public images currently available in Hangzhou region. If 39 TotalCount entries are displayed in the query result, the result will be divided into four pages by default. If you want to get it all at once, you can add PageSize to the request and set it to a number greater than 39 (if you use Java SDK, you can set PageSize to a value greater than 39 in the Request object through the setPageSize method), so that 39 images can be returned at a time after the request.

The following is a demonstration of Java SDK:

By default, the PageSize value is 10 (because if Java SDK does not set the value of PageSize, it will return with getPageSize that the null,API server will set PageSize to 10 by default):

The code snippet is as follows:

DescribeImagesRequest describe = new DescribeImagesRequest (); / / describe.setPageSize (50); / / if not set by default, PageSize is 10 describe.setRegionId ("cn-hangzhou"); describe.setImageOwnerAlias ("system"); System.out.println ("PageSize size of the current request:" + describe.getPageSize ()); DescribeImagesResponse response = client.getAcsResponse (describe) System.out.println ("Total number of mirrors:" + response.getTotalCount ()); System.out.println ("number of mirrors in the response =" + response.getImages () .size ()

After setting the PageSize value to 50 using setPageSize, you can return all images at once:

The code snippet is as follows:

DescribeImagesRequest describe = new DescribeImagesRequest (); describe.setPageSize (50); / / here in Request, the number of pages displayed is set to 50 describe.setRegionId ("cn-hangzhou"); describe.setImageOwnerAlias ("system"); System.out.println ("PageSize size of the current request:" + describe.getPageSize ()); try {DescribeImagesResponse response = client.getAcsResponse (describe) System.out.println ("Total number of mirrors:" + response.getTotalCount ()); System.out.println ("number of mirrors in the response =" + response.getImages () .size ()

Description

The maximum value of PageSize is 100. if the result of the query is greater than 100, you need to obtain the data of the next few pages with the help of PageNumber, that is, submit the request many times, and set the PageNumber to 1, 2, 3 each time. To get all the return information You can specify the number of pages to be returned through the setPageNumber () method in the request.

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