Starting from scratch learning Solr Specific Commons CSV framework tutorial
Starting from scratch learning Solr Specific Commons CSV framework tutorial
SOLR Specific Commons CSV is a Java library for processing CSV files.It provides a set of APIs and tools for reading, writing and operating CSV files.This tutorial will help you learn how to use the SOLR Specific Commons CSV framework from scratch.
1. Installation and configuration SOLR Specific Commons CSV
First, you need to add Solr Special Commons CSV libraries to your Java project.You can achieve it by adding it as dependencies.In the Maven project, you can add the following dependencies to the pom.xml file:
<dependency>
<groupId>org.apache.solr</groupId>
<artifactId>solr-commons-csv</artifactId>
<version>8.11.0</version>
</dependency>
2. Read the CSV file
Once your project has been configured, you can start reading CSV files.First, you need to create a CSVPARSER object that will help you analyze the CSV file.
import org.apache.solr.common.util.CSVParser;
import java.io.FileReader;
import java.io.IOException;
public class CsvReaderExample {
public static void main(String[] args) {
try (CSVParser parser = new CSVParser(new FileReader("example.csv"))) {
String[] record;
while ((record = parser.next()) != null) {
// Process per line of records
}
} catch (IOException e) {
e.printStackTrace();
}
}
}
In the above example, we created a CSVPARSER object to read a file named "Example.csv".Then we can use the `Parser.next ()` method to obtain the CSV records one by one.
3. Write into CSV files
If you want to write the data into the CSV file, you can use the CSVPrinter object.The following is a simple example:
import org.apache.solr.common.util.CSVPrinter;
import java.io.FileWriter;
import java.io.IOException;
public class CsvWriterExample {
public static void main(String[] args) {
try (CSVPrinter printer = new CSVPrinter(new FileWriter("example.csv"), CSVFormat.DEFAULT)) {
printer.printRecord("Column1", "Column2", "Column3");
printer.printRecord("Value1", "Value2", "Value3");
printer.printRecord("Value4", "Value5", "Value6");
printer.flush();
} catch (IOException e) {
e.printStackTrace();
}
}
}
In the above example, we created a CSVPrinter object to write a file named "Example.csv".Using the method of `Printer.printRecord (), we can print a line of CSV records.
4. Operation CSV data
Solr Specific Commons CSV also provides some tools and methods for operating CSV data.You can use them to filter, convert or process CSV datasets.
import org.apache.solr.common.util.CSVRecords;
import java.io.FileReader;
import java.io.IOException;
public class CsvManipulationExample {
public static void main(String[] args) {
try (CSVParser parser = new CSVParser(new FileReader("example.csv"))) {
Iterable<CSVRecord> records = CSVRecords.iterable(parser);
for (CSVRecord record : records) {
String value = record.get ("colorn1"); // Get the value according to the columns
// Treatment record
}
} catch (IOException e) {
e.printStackTrace();
}
}
}
In the above examples, we use the method of `csvrecords.iterable ()` to convert the CSVPARSER object into iterative objects.Then, we can use Foreach to recall each CSV record and use the `record.get ()` method to obtain the corresponding value according to the column name.
Through this tutorial, you should now have enough knowledge to start using the SOLR Specific Commons CSV framework.You can continue to explore more advanced functions and APIs to meet your specific needs.
