本文介绍如何使用Java SDK的SelectObject查询CSV和JSON文件。
说明
本文示例由阿里云用户bin提供，仅供参考。
以下代码用于查询CSV文件和JSON文件：
import com.aliyun.oss.ClientBuilderConfiguration;
import com.aliyun.oss.ClientException;
import com.aliyun.oss.OSS;
import com.aliyun.oss.OSSClientBuilder;
import com.aliyun.oss.common.auth.CredentialsProviderFactory;
import com.aliyun.oss.common.auth.EnvironmentVariableCredentialsProvider;
import com.aliyun.oss.common.comm.SignVersion;
import com.aliyun.oss.model.*;
import java.io.*;
import java.nio.charset.StandardCharsets;
/**
* 本程序演示如何使用阿里云OSS SDK对CSV和JSON文件进行查询操作。
* 主要功能包括：
* 1. 获取CSV文件的元数据信息，包括总行数和分片数量。
* 2. 查询CSV文件内容，并输出查询结果。
* 3. 查询简单JSON文件内容，并将结果保存到本地文件。
* 4. 查询复杂JSON文件内容，并将结果保存到本地文件。
*
* 注意事项：
* - 请确保在环境变量中设置了阿里云的Access Key ID和Access Key Secret。
* - 请确保OSS Bucket名称和区域配置正确。
*/
public class selectobject {
private static final String CSV_KEY = "test.csv"; // CSV文件路径
private static final String ENDPOINT = "http://oss-cn-hangzhou.aliyuncs.com";
private static final String BUCKET_NAME = "examplebucket"; // Bucket名称
private static final String REGION = "cn-hangzhou"; // bucket所在地域
/**
* 创建OSS客户端实例。
*
* @return OSS客户端实例
*/
private static OSS createOSSClient() throws com.aliyuncs.exceptions.ClientException {
// 从环境变量中获取凭证
EnvironmentVariableCredentialsProvider credentialsProvider = CredentialsProviderFactory.newEnvironmentVariableCredentialsProvider();
// 使用credentialsProvider进行后续操作...
ClientBuilderConfiguration clientBuilderConfiguration = new ClientBuilderConfiguration();
clientBuilderConfiguration.setSignatureVersion(SignVersion.V4);
return OSSClientBuilder.create()
.endpoint(ENDPOINT)
.credentialsProvider(credentialsProvider)
.clientConfiguration(clientBuilderConfiguration)
.region(REGION)
.build();
}
/**
* 程序入口
*/
public static void main(String[] args) {
try {
createCsvSelectObjectMetadata(); // 获取CSV文件元数据
selectCsv(); // 查询CSV文件内容
selectSimpleJson(); // 查询简单JSON文件内容
selectComplexJson(); // 查询复杂JSON文件内容
} catch (ClientException ex) {
System.out.println("ClientException: " + ex.getMessage());
}
}
/**
* 获取CSV文件的元数据信息，包括总行数和分片数量。
*/
public static void createCsvSelectObjectMetadata() {
OSS ossClient = null; // 创建OSS客户端实例
try {
ossClient = createOSSClient();
} catch (com.aliyuncs.exceptions.ClientException e) {
throw new RuntimeException(e);
}
String content = "name,school,company,age\n" +
"Lora Francis,School A,Staples Inc,27\n" +
"Eleanor Little,School B,\"Conectiv, Inc\",43\n" +
"Rosie Hughes,School C,Western Gas Resources Inc,44\n" +
"Lawrence Ross,School D,MetLife Inc.,24";
// 将CSV内容上传到OSS
ossClient.putObject(BUCKET_NAME, CSV_KEY, new ByteArrayInputStream(content.getBytes()));
// 创建SelectObjectMetadata请求并获取元数据
SelectObjectMetadata selectObjectMetadata = ossClient.createSelectObjectMetadata(
new CreateSelectObjectMetadataRequest(BUCKET_NAME, CSV_KEY)
.withInputSerialization(
new InputSerialization().withCsvInputFormat(
new CSVFormat().withHeaderInfo(CSVFormat.Header.Use)
.withRecordDelimiter("\n"))));
// 输出CSV文件的总行数和分片数量
int splits = selectObjectMetadata.getCsvObjectMetadata().getSplits();
System.out.println("CSV被拆分成了 " + splits + " 份。");
ossClient.shutdown(); // 关闭OSS客户端
}
/**
* 查询CSV文件内容，并输出查询结果。
*/
public static void selectCsv() {
OSS ossClient = null; // 创建OSS客户端实例
try {
ossClient = createOSSClient();
} catch (com.aliyuncs.exceptions.ClientException e) {
throw new RuntimeException(e);
}
try {
// 创建SelectObjectRequest并设置查询条件
SelectObjectRequest selectObjectRequest =
new SelectObjectRequest(BUCKET_NAME, CSV_KEY)
.withInputSerialization(
new InputSerialization().withCsvInputFormat(
new CSVFormat().withHeaderInfo(CSVFormat.Header.Use)
.withRecordDelimiter("\n")))
.withOutputSerialization(new OutputSerialization().withCsvOutputFormat(new CSVFormat()));
// 设置SQL表达式，查询总记录数和年龄的最大值、最小值
selectObjectRequest.setExpression("select count(*), max(cast(_4 as int)), min(cast(_4 as int)) from ossobject");
// 执行查询并读取结果
OSSObject ossObject = ossClient.selectObject(selectObjectRequest);
BufferedReader reader = new BufferedReader(new InputStreamReader(ossObject.getObjectContent(), StandardCharsets.UTF_8));
String line;
while ((line = reader.readLine()) != null) {
System.out.println("CSV文件的查询结果为："+line);
}
} catch (Exception ex) {
System.out.println(ex.getMessage());
} finally {
ossClient.shutdown(); // 关闭OSS客户端
}
}
/**
* 查询简单JSON文件内容，并将结果保存到本地文件。
*/
public static void selectSimpleJson() {
String key = "simple.json"; // 自定义JSON文件路径
OSS ossClient = null; // 创建OSS客户端实例
try {
ossClient = createOSSClient();
} catch (com.aliyuncs.exceptions.ClientException e) {
throw new RuntimeException(e);
}
final String content = "{\n" +
"\t\"name\": \"Lora Francis\",\n" +
"\t\"age\": 27,\n" +
"\t\"company\": \"Staples Inc\"\n" +
"}\n" +
"{\n" +
"\t\"name\": \"Eleanor Little\",\n" +
"\t\"age\": 43,\n" +
"\t\"company\": \"Conectiv, Inc\"\n" +
"}\n" +
"{\n" +
"\t\"name\": \"Rosie Hughes\",\n" +
"\t\"age\": 44,\n" +
"\t\"company\": \"Western Gas Resources Inc\"\n" +
"}\n" +
"{\n" +
"\t\"name\": \"Lawrence Ross\",\n" +
"\t\"age\": 24,\n" +
"\t\"company\": \"MetLife Inc.\"\n" +
"}";
// 将JSON内容上传到OSS
try {
ossClient.putObject(BUCKET_NAME, key, new ByteArrayInputStream(content.getBytes()));
// 创建SelectObjectRequest并设置查询条件
SelectObjectRequest selectObjectRequest =
new SelectObjectRequest(BUCKET_NAME, key)
.withInputSerialization(new InputSerialization()
.withCompressionType(CompressionType.NONE)
.withJsonInputFormat(new JsonFormat().withJsonType(JsonType.LINES)))
.withOutputSerialization(new OutputSerialization()
.withCrcEnabled(true)
.withJsonOutputFormat(new JsonFormat()))
.withExpression("select * from ossobject as s where s.age > 40");
// 执行查询并保存结果到本地文件
OSSObject ossObject = ossClient.selectObject(selectObjectRequest);
// 指定保存路径
String outputPath = "D:\\\\localpath\\\\result.simple.json";
writeToFile(ossObject.getObjectContent(), outputPath);
System.out.println("simple json的查询结果已保存到: " + outputPath);
} catch (Exception ex) {
System.out.println(ex.getMessage());
} finally {
ossClient.shutdown(); // 关闭OSS客户端
}
}
/**
* 查询复杂JSON文件内容，并将结果保存到本地文件。
*/
public static void selectComplexJson() {
String key = "complex.json"; // 自定义JSON文件路径
OSS ossClient = null; // 创建OSS客户端实例
try {
ossClient = createOSSClient();
} catch (com.aliyuncs.exceptions.ClientException e) {
throw new RuntimeException(e);
}
String content = "{\n" +
" \"contacts\":[\n" +
"{\n" +
" \"firstName\": \"John\",\n" +
" \"lastName\": \"Smith\",\n" +
" \"isAlive\": true,\n" +
" \"age\": 27,\n" +
" \"address\": {\n" +
" \"streetAddress\": \"21 2nd Street\",\n" +
" \"city\": \"New York\",\n" +
" \"state\": \"NY\",\n" +
" \"postalCode\": \"10021-3100\"\n" +
" },\n" +
" \"phoneNumbers\": [\n" +
" {\n" +
" \"type\": \"home\",\n" +
" \"number\": \"212 555-1234\"\n" +
" },\n" +
" {\n" +
" \"type\": \"office\",\n" +
" \"number\": \"646 555-4567\"\n" +
" },\n" +
" {\n" +
" \"type\": \"mobile\",\n" +
" \"number\": \"123 456-7890\"\n" +
" }\n" +
" ],\n" +
" \"children\": [],\n" +
" \"spouse\": null\n" +
"}\n" +
"]}";
try {
// 将JSON内容上传到OSS
ossClient.putObject(BUCKET_NAME, key, new ByteArrayInputStream(content.getBytes()));
// 创建SelectObjectRequest并设置查询条件
SelectObjectRequest selectObjectRequest =
new SelectObjectRequest(BUCKET_NAME, key)
.withInputSerialization(new InputSerialization()
.withCompressionType(CompressionType.NONE)
.withJsonInputFormat(new JsonFormat().withJsonType(JsonType.LINES)))
.withOutputSerialization(new OutputSerialization()
.withCrcEnabled(true)
.withJsonOutputFormat(new JsonFormat()))
.withExpression("select * from ossobject.contacts[*] s where s.age = 27");
// 执行查询并保存结果到本地文件
OSSObject ossObject = ossClient.selectObject(selectObjectRequest);
// 指定本地保存路径
String outputPath = "D:\\\\localpath\\\\result.complex.json";
writeToFile(ossObject.getObjectContent(), outputPath);
System.out.println("complex json的查询结果已保存到: " + outputPath);
} catch (Exception ex) {
System.out.println(ex.getMessage());
} finally {
ossClient.shutdown(); // 关闭OSS客户端
}
}
/**
* 将输入流写入指定的本地文件。
*
* @param in 输入流
* @param file 文件路径
*/
private static void writeToFile(InputStream in, String file) {
try (BufferedOutputStream outputStream = new BufferedOutputStream(new FileOutputStream(file))) {
byte[] buffer = new byte[1024];
int bytesRead;
while ((bytesRead = in.read(buffer)) != -1) {
outputStream.write(buffer, 0, bytesRead);
}
} catch (IOException ex) {
ex.printStackTrace();
}
}
}SelectObject的更多详情，请参考SelectObject。
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