opencsv是什么？one essential tool for managing csv files in java is opencsv. this highly-regarded library comes standard with an easily-navigable api allowing you to read/write files containing headers while utilizing custom delimiters as well as escaping characters - without breaking a sweat! another huge benefit offered by opencsv involves facilitating the simplified mapping of intricately-structured data sets directly onto corresponding bean classes. opencsv provides users with an effective way to create stylish and varied content - perplexity and burliness come together to create an optimal output.
mapping java beans to csv using opencsv使用opencsv将java beans与csv文件进行映射需要四个主要步骤 - 定义、创建、映射和写入。在介绍这四个步骤之前，我们先来看看使用opencsv将java beans映射到csv的四个步骤：定义java bean、创建csvwriter、将java bean映射到csv以及写入csv记录。在定义java bean之后，创建一个csvwriter来处理和处理数据的写入。接下来是将您的java bean映射到csv文件，提供写入器所需的信息。最后，使用csvwriter写入记录，从而确保您的数据以您希望的方式表达出来。通过这四个步骤，您将在掌握使用opencsv将java beans映射到csv的艺术方面迈出坚实的一步。
将opencsv库添加到项目中步骤 1 - 对于 maven 项目，在 pom.xml 文件中包含 opencsv 的 maven 依赖。
<dependency> <groupid>com.opencsv</groupid> <artifactid>opencsv</artifactid> <version>4.1</version></dependency>
step 2 − for gradle project, include the opencsv dependency
compile group: com.opencsv, name: opencsv, version: 4.1
step 3 − you can also download opencsv jar and include it in your project class path.
mapping java beans to csv第一步 - 创建一个writer实例，用于将数据写入csv文件
writer writer =files.newbufferedwriter(paths.get(file_location));
step 2 − create a list of objects which are required to be written in the csv file
step 3 − using columnpositionmappingstrategy map the columns of created objects, to column of csv
columnpositionmappingstrategy mappingstrategy = newcolumnpositionmappingstrategy();mappingstrategy.settype(employee.class);//where employee is the object to be mapped with csv
step 4 − create object of statefulbeantocsv class by calling build method of statefulbeantocsvbuilder class with writer object as a parameter. according to the needs the user might also provide −
使用statefulbeantocsvbuilder对象的withmappingstrategy函数，将columnpositionmappingstrategy应用于。
separator of generated csv file with the help of withseparator function of statefulbeantocsvbuilder object.
通过statefulbeantocsvbuilder对象的withquotechar函数，生成的csv文件的withquotechar。
statefulbeantocsv beantocsv = new statefulbeantocsvbuilder(writer).withmappingstrategy(mappingstrategy). withseparator('#').withquotechar(csvwriter.no_quote_character). build ();
第5步 - 在创建后，可以通过使用statefulbeantocsv对象中的write方法，将对象列表或单个对象添加到csv文件中。
beantocsv.write(employeelist);
example我们的目标是创建一个包含重要属性（如姓名、年龄、公司和薪水）的员工对象的综合列表。然后，我们将生成一个名为employees.csv的csv文件，其中包含员工对象。
employee.java
public class employee { public string name, age, company, salary; public employee(string name, string age, string company, string salary) { super(); name = name; age = age; company = company; salary = salary; } @override public string tostring() { return employee [name= + name + , age= + age + , company= + company + , salary= + salary + ]; }}
beantocsv.java
import java.io.filewriter;import java.io.writer;import java.nio.*;import java.nio.file.files;import java.nio.file.paths;import java.util.*;import com.opencsv.bean.columnpositionmappingstrategy;import com.opencsv.bean.statefulbeantocsv;import com.opencsv.bean.statefulbeantocsvbuilder;public class beantocsv { public static void main(string[] args) { // name of generated csv final string csv_location = employees.csv ; try { // creating writer class to generate // csv file filewriter writer = newfilewriter(csv_location); // create a list of employees list<employee> employeelist = newarraylist<employee>(); employee emp1 = new employee (anurag, 24, htc, 75000); employee emp2 = new employee (amaan, 24, microsoft, 79000); employee emp3 = new employee (rashi, 26, tcs, 39000); employee emp4 = new employee (varun, 22, nggear, 15000); employee emp5 = new employee (pranjal, 29, sath, 51000); employeelist.add(emp1); employeelist.add(emp2); employeelist.add(emp3); employeelist.add(emp4); employeelist.add(emp5); // create mapping strategy to arrange the // column name in order columnpositionmappingstrategy mappingstrategy= new columnpositionmappingstrategy(); mappingstrategy.settype(employee.class); // arrange column name as provided in below array. string[] columns = new string[] { name, age, company, salary }; mappingstrategy.setcolumnmapping(columns); // creating statefulbeantocsv object statefulbeantocsvbuilder<employee> builder= new statefulbeantocsvbuilder(writer); statefulbeantocsv beanwriter = builder.withmappingstrategy(mappingstrategy).build(); // write list to statefulbeantocsv object beanwriter.write(employeelist); // closing the writer object writer.close(); } catch (exception e) { e.printstacktrace(); } }}
outputemployeedata.csvcsv file contains: ----anurag, 24, htc, 75000amaan, 24, microsoft, 79000rashi, 26, tcs, 39000varun, 22, nggear, 15000pranjal, 29, sath, 51000
结论java's open csv is a powerful tool that simplifies reading and writing of csv files, so if you need a simpler way of dealing with complex data structures within your csv files look no further than open csv - the tool which maps java beans into the format. a simple definition of the java bean coupled with mapping it to csv is enough to produce well-written csv record through those few lines of code, and the flexibility and dependability of open csv make it a vital component for effectively managing csv files in data-driven applications.
以上就是使用opencsv将java beans映射到csv文件的详细内容。