The Java class library uses Solr Specific Commons CSV to implement CSV file processing
The Java class library uses Solr Specific Commons CSV to implement CSV file processing
Overview:
CSV (COMMA-SEPARATED VALUES) is a commonly used file format for storing structured data.In Java programming, we can use the Solr Specific Commons CSV library to process CSV files.This article will introduce how to use this class library to realize the reading and writing operation of the CSV file.
Step 1: Introduce SOLR Specific Commons CSV library
First, you need to introduce Solr Specific Commons CSV libraries in your Java project.You can use the following dependencies in the Maven project, add the following code to the pom.xml file:
<dependency>
<groupId>org.apache.solr</groupId>
<artifactId>solr-solrj</artifactId>
<version>7.7.3</version>
</dependency>
Step 2: Read the CSV file
Next, we will demonstrate how to read a CSV file with Solr Specific Commons CSV library.Suppose we have a CSV file called "data.csv", which contains the following data:
Name, age, gender
Zhang San, 25, male
Li Si, 30, male
Wang Wu, 28, female
The following code will show how to read this file and store the data into a two -dimensional array:
import org.apache.solr.common.StringUtils;
import org.apache.solr.common.StringUtils.CSVStrategy;
import java.io.FileReader;
import java.util.List;
public class CSVReaderExample {
public static void main(String[] args) {
String filePath = "data.csv";
CSVStrategy csvStrategy = new CSVStrategy(',', '"', '#');
try (FileReader reader = new FileReader(filePath)) {
List<String[]> data = StringUtils.streamCSV(reader, csvStrategy).toList();
for (String[] row : data) {
for (String value : row) {
System.out.print(value + " ");
}
System.out.println();
}
} catch (Exception e) {
e.printStackTrace();
}
}
}
In the above code, we first specify the path "data.csv" of the CSV file, and then use the `FileRereader` to read the file.Next, we use the `StreamCSV` method in the` StringUtils` class to read the CSV files one by one and store each row of data into a two -dimensional array.Finally, we traversed this two -dimensional array and printed the data of each line.
Step 3: Write into CSV files
Now, let's demonstrate how to use the Solr Specific Commons CSV library to write the CSV file.We read the data obtained in step 2 and write it into a new CSV file.
import org.apache.solr.common.StringUtils;
import org.apache.solr.common.StringUtils.CSVStrategy;
import java.io.FileWriter;
import java.util.ArrayList;
import java.util.List;
public class CSVWriterExample {
public static void main(String[] args) {
String filePath = "output.csv";
CSVStrategy csvStrategy = new CSVStrategy(',', '"', '#');
try (FileWriter writer = new FileWriter(filePath)) {
List<String[]> data = new ArrayList<>();
data.add (new string [] {"name", "age", "gender"});
data.add (New String [] {"Zhang San", "25", "Male"});
data.add (new string [] {"Li Si", "30", "Male"});
data.add (new string [] {"Wang Five", "28", "female"});
StringUtils.writeCSV(data, writer, csvStrategy);
} catch (Exception e) {
e.printStackTrace();
}
}
}
In the above code, we first specify the path "output.csv" of the written CSV file, and then use the `FileWriter` to create a new file.Next, we create a `list <string []` `and store the data of the CSV file into the list.Finally, we use the `` WRITECSV` method in the `StringUtils` class to write the data into the CSV file.
Summarize:
Through SOLR Specific Commons CSV library, we can easily handle CSV files and realize the reading and writing operation of files.The above code example shows how to read and write the CSV file with this class of libraries.I hope this article will help you understand how to use the Solr Specific Commons CSV library.
