Select file
Updated at：2025-11-03
The BOS Java SDK provides the SelectObject API, which is used to execute SQL statements on specified objects in the bucket and return the selected content. Please refer to [Select Object](BOS/API Reference/Object-Related Interface/Select scanning/SelectObject.md). Currently, supported object types are CSV (including TSV and other CSV-like files), JSON and Parquet files:
For the sample code, please refer to File Selection Demo
- Select CSV files
- Select JSON files
Select CSV files
For selecting CSV files with the Java SDK, please refer to the following code:
Java
1final String csvContent = "header1,header2,header3\r\n" +
2 "1,2,3.4\r\n" +
3 "a,b,c\r\n" +
4 "\"d\",\"e\",\"f\"\r\n" +
5 "true,false,true\r\n" +
6 "2006-01-02 15:04:06,2006-01-02 16:04:06,2006-01-02 17:04:06";
7client.putObject("bucketName", "test-csv", new ByteArrayInputStream(csvContent.getBytes()));
8SelectObjectRequest request = new SelectObjectRequest("bucketName", "test-csv")
9 .withSelectType("csv")
10 .withExpression("select * from BosObject limit 3")
11 .withInputSerialization(new InputSerialization()
12 .withCompressionType("NONE")
13 .withFileHeaderInfo("NONE")
14 .withRecordDelimiter("\r\n")
15 .withFieldDelimiter(",")
16 .withQuoteCharacter("\"")
17 .withCommentCharacter("#"))
18 .withOutputSerialization(new OutputSerialization()
19 .withOutputHeader(false)
20 .withQuoteFields("ALWAYS")
21 .withRecordDelimiter("\n")
22 .withFieldDelimiter(",")
23 .withQuoteCharacter("\""))
24 .withRequestProgress(false);
25SelectObjectResponse response = client.selectObject(request);
26 // Output the returned records
27SelectObjectResponse.Messages messages = response.getMessages();
28while (messages.hasNext()) {
29 SelectObjectResponse.CommonMessage message = messages.next();
30 if (message.Type.equals("Records")) {
31 for (String record: message.getRecords()) {
32 System.out.println(record);
33 }
34 }
35}Results of selecting CSV files:
Java
1"header1","header2","header3"
2"1","2","3.4"
3"a","b","c"Note:
- In Unix/Linux systems, each line ends with only a "
", i.e., "\n"; - In Windows systems, each line ends with a "
", i.e., "\r\n"; - In Mac systems, each line ends with a "
", i.e., "\n". Only Mac OS before version 9 uses '\r'. - Set the recordDelimiter appropriately based on the file content.
Select JSON files
For selecting JSON files with the Java SDK, please refer to the following code:
Java
1final String jsonContent = "{\n" +
2 "\t\"name\": \"Smith\",\n" +
3 "\t\"age\": 16,\n" +
4 "\t\"org\": null\n" +
5 "}\n" +
6 "{\n" +
7 "\t\"name\": \"charles\",\n" +
8 "\t\"age\": 27,\n" +
9 "\t\"org\": \"baidu\"\n" +
10 "}\n" +
11 "{\n" +
12 "\t\"name\": \"jack\",\n" +
13 "\t\"age\": 35,\n" +
14 "\t\"org\": \"bos\"\n" +
15 "}";
16client.putObject("bucketName", "test-json", new ByteArrayInputStream(jsonContent.getBytes()));
17SelectObjectRequest request = new SelectObjectRequest("bucketName", "test-json")
18 .withSelectType("json")
19 .withExpression("select * from BosObject where age > 20")
20 .withInputSerialization(new InputSerialization()
21 .withCompressionType("NONE")
22 .withJsonType("LINES"))
23 .withOutputSerialization(new OutputSerialization()
24 .withRecordDelimiter("\n"))
25 .withRequestProgress(false);
26SelectObjectResponse response = client.selectObject(request);
27 // Output the returned records
28SelectObjectResponse.Messages messages = response.getMessages();
29while (messages.hasNext()) {
30 SelectObjectResponse.CommonMessage message = messages.next();
31 if (message.Type.equals("Records")) {
32 for (String record: message.getRecords()) {
33 System.out.println(record);
34 }
35 }
36}Results of selecting JSON files:
Java
1{"name":"charles","age":27,"org":"baidu"}
2{"name":"jack","age":35,"org":"bos"}Select Parquet files
For selecting Parquet files with the Java SDK, please refer to the following code:
Java
1/*
2 Content parsed from Parquet files
3{"Name":"StudentName","Age":20,"Id":0,"Weight":50,"Sex":true,"Day":19240,"Scores":{"computer":80,"math":90,"physics":90}}
4{"Name":"StudentName","Age":21,"Id":1,"Weight":50.1,"Sex":false,"Day":19240,"Scores":{"computer":81,"math":91,"physics":91}}
5{"Name":"StudentName","Age":22,"Id":2,"Weight":50.2,"Sex":true,"Day":19240,"Scores":{"computer":82,"math":92,"physics":92}}
6{"Name":"StudentName","Age":23,"Id":3,"Weight":50.3,"Sex":false,"Day":19240,"Scores":{"computer":83,"math":93,"physics":90}}
7{"Name":"StudentName","Age":24,"Id":4,"Weight":50.4,"Sex":true,"Day":19240,"Scores":{"computer":84,"math":94,"physics":91}}
8{"Name":"StudentName","Age":20,"Id":5,"Weight":50.5,"Sex":false,"Day":19240,"Scores":{"computer":85,"math":90,"physics":92}}
9{"Name":"StudentName","Age":21,"Id":6,"Weight":50.6,"Sex":true,"Day":19240,"Scores":{"computer":86,"math":91,"physics":90}}
10{"Name":"StudentName","Age":22,"Id":7,"Weight":50.7,"Sex":false,"Day":19240,"Scores":{"computer":87,"math":92,"physics":91}}
11{"Name":"StudentName","Age":23,"Id":8,"Weight":50.8,"Sex":true,"Day":19240,"Scores":{"computer":88,"math":93,"physics":92}}
12{"Name":"StudentName","Age":24,"Id":9,"Weight":50.9,"Sex":false,"Day":19240,"Scores":{"computer":89,"math":94,"physics":90}}
13*/
14SelectObjectRequest request = new SelectObjectRequest("bucketName", "test-parquet")
15 .withSelectType("parquet")
16 .withExpression("select * from BosObject s where s.Scores.computer > 85")
17 .withInputSerialization(new InputSerialization()
18 .withCompressionType("NONE"))
19 .withOutputSerialization(new OutputSerialization()
20 .withRecordDelimiter("\n"))
21 .withRequestProgress(false);
22SelectObjectResponse response = client.selectObject(request);
23 // Output the returned records
24SelectObjectResponse.Messages messages = response.getMessages();
25while (messages.hasNext()) {
26 SelectObjectResponse.CommonMessage message = messages.next();
27 if (message.Type.equals("Records")) {
28 for (String record: message.getRecords()) {
29 System.out.println(record);
30 }
31 }
32}Results of selecting Parquet files:
Java
1{"Name":"StudentName","Age":21,"Id":6,"Weight":50.6,"Sex":true,"Day":19240,"Scores":{"computer":86,"math":91,"physics":90}}
2{"Name":"StudentName","Age":22,"Id":7,"Weight":50.7,"Sex":false,"Day":19240,"Scores":{"computer":87,"math":92,"physics":91}}
3{"Name":"StudentName","Age":23,"Id":8,"Weight":50.8,"Sex":true,"Day":19240,"Scores":{"computer":88,"math":93,"physics":92}}
4{"Name":"StudentName","Age":24,"Id":9,"Weight":50.9,"Sex":false,"Day":19240,"Scores":{"computer":89,"math":94,"physics":90}}Note that when querying CSV, JSON and Parquet files, the parameters for initializing SelectObjectRequest differ significantly. For detailed parameter settings, please refer to [SelectObject API](BOS/API Reference/Object-Related Interface/Select scanning/SelectObject.md).