The technical principle interpretation of the CSVEED framework in the Java library
The CSVEED framework is a Java class library for processing the CSV (comma separation value) file. It can easily read and write the CSV file.This article will introduce the technical principles of the CSVEED framework in the Java class library and provide some Java code examples.
The technical principles of the CSVEED framework are mainly based on the reflex mechanism and annotation processor.It uses Java's reflection mechanism to analyze the lines and columns of the CSV file and map it to the Java object.By using the annotation processor, developers can use annotations to define the mapping relationship between CSV files and Java objects, so that the framework can analyze and generate automated CSV files based on annotations.
First of all, we need to use the @CSVPROPERTY annotation on the field of the Java object to mark the corresponding position of the field in the CSV file.For example, if the first column of the CSV file is the name and the second column is the age, we can use the fields of the Java object with @CSVPROPERTY (Index = 0) and @csvproperty (index = 1).
public class Person {
@CsvProperty(index = 0)
private String name;
@CsvProperty(index = 1)
private int age;
// omit the getter and setter method
}
We can then use the CSVReader class to read the CSV file and convert it to the Java object.The following is an example code:
import com.codepoetics.ambivalence.CsvReader;
public class Main {
public static void main(String[] args) {
CsvReader<Person> csvReader = new CsvReader<>(Person.class);
try {
List <person> Persons = csvreader.read ("data.csv"); // Read csv file
for (Person person : persons) {
System.out.println(person.getName() + " - " + person.getAge());
}
} catch (IOException e) {
e.printStackTrace();
}
}
}
In the above code, we created a CSVReader object and passed the Person.class as a parameter to it.Then, we call the read method to read the CSV file named Data.csv and convert it to a list of the Person object.Finally, we can print the data in the CSV file by iteration list and call the object method of the object.
In addition, the CSVEED framework also provides the function of writing CSV files.Use the CSVWriter class to write a list of the Java object into the CSV file.The following is an example code:
import com.codepoetics.ambivalence.CsvWriter;
public class Main {
public static void main(String[] args) {
List<Person> persons = new ArrayList<>();
persons.add(new Person("John", 25));
persons.add(new Person("Alice", 30));
try {
CsvWriter<Person> csvWriter = new CsvWriter<>(Person.class);
csvwriter.write ("Output.csv", Persons); // Write into csv files
} catch (IOException e) {
e.printStackTrace();
}
}
}
In the above code, we created a CSVWriter object and passed the Person.class as a parameter to it.We then call the WRITE method to write the Persons list into the CSV file named output.csv.
Through the CSVEED framework, we can easily handle CSV files, especially when you need to read and write CSV files frequently.It simplifies the conversion process between Java objects and CSV files, and improves the readability and maintenance of the code.
