揭秘Java ARchive：50个实用jar调用案例，轻松提升编程技能

引言

Java Archive（JAR）文件是一种用于存储和分发Java类文件、源代码、文档和资源文件的归档格式。JAR文件可以包含多个类文件，以及相关的资源文件和元数据。在Java编程中，JAR文件的使用非常广泛，许多第三方库和框架都通过JAR文件提供。本文将介绍50个实用的JAR调用案例，帮助读者提升编程技能。

1. Apache Commons Lang

Apache Commons Lang是一个提供常用Java类库的JAR，包括字符串处理、日期处理、反射等。

import org.apache.commons.lang3.StringUtils;

public class CommonsLangExample {
    public static void main(String[] args) {
        String str = "Hello, World!";
        System.out.println("Original String: " + str);
        System.out.println("Uppercase String: " + StringUtils.upperCase(str));
        System.out.println("Lowercase String: " + StringUtils.lowerCase(str));
    }
}

2. Apache Commons IO

Apache Commons IO提供文件读写、文件过滤、文件比较等功能。

import org.apache.commons.io.FileUtils;

public class CommonsIOExample {
    public static void main(String[] args) {
        try {
            String content = FileUtils.readFileToString(new File("example.txt"), "UTF-8");
            System.out.println("File Content: " + content);
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
}

3. Google Guava

Google Guava是一个开源的Java库，提供集合操作、并发工具、字符串处理等功能。

import com.google.common.collect.Lists;

public class GuavaExample {
    public static void main(String[] args) {
        List<String> list = Lists.newArrayList("Apple", "Banana", "Cherry");
        System.out.println("Original List: " + list);
        Collections.sort(list);
        System.out.println("Sorted List: " + list);
    }
}

4. Jackson

Jackson是一个JSON处理库，用于将Java对象序列化为JSON字符串，以及将JSON字符串反序列化为Java对象。

import com.fasterxml.jackson.databind.ObjectMapper;

public class JacksonExample {
    public static void main(String[] args) {
        ObjectMapper mapper = new ObjectMapper();
        Person person = new Person("John", 30);
        try {
            String json = mapper.writeValueAsString(person);
            System.out.println("JSON String: " + json);
        } catch (JsonProcessingException e) {
            e.printStackTrace();
        }
    }
}

5. Apache HttpClient

Apache HttpClient是一个用于发送HTTP请求的客户端库。

import org.apache.http.client.methods.CloseableHttpResponse;
import org.apache.http.client.methods.HttpGet;
import org.apache.http.impl.client.CloseableHttpClient;
import org.apache.http.impl.client.HttpClients;
import org.apache.http.util.EntityUtils;

public class HttpClientExample {
    public static void main(String[] args) {
        CloseableHttpClient httpClient = HttpClients.createDefault();
        HttpGet httpGet = new HttpGet("http://www.example.com");
        try {
            CloseableHttpResponse response = httpClient.execute(httpGet);
            String content = EntityUtils.toString(response.getEntity());
            System.out.println("Response Content: " + content);
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
}

6. Log4j

Log4j是一个Java日志库，用于记录程序运行过程中的信息。

import org.apache.log4j.Logger;

public class Log4jExample {
    private static final Logger logger = Logger.getLogger(Log4jExample.class);

    public static void main(String[] args) {
        logger.info("This is an info message");
        logger.error("This is an error message");
    }
}

7. JUnit

JUnit是一个单元测试框架，用于测试Java代码。

import org.junit.Test;
import static org.junit.Assert.assertEquals;

public class JUnitExample {
    @Test
    public void testAdd() {
        assertEquals(2, 1 + 1);
    }
}

8. Hibernate

Hibernate是一个对象关系映射（ORM）框架，用于将Java对象映射到数据库表。

import org.hibernate.Session;
import org.hibernate.SessionFactory;
import org.hibernate.cfg.Configuration;

public class HibernateExample {
    public static void main(String[] args) {
        SessionFactory sessionFactory = new Configuration().configure().buildSessionFactory();
        Session session = sessionFactory.openSession();
        session.beginTransaction();
        // Perform database operations
        session.getTransaction().commit();
        session.close();
    }
}

9. Spring Framework

Spring Framework是一个开源的Java企业级应用开发框架，提供依赖注入、事务管理、AOP等功能。

import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;

public class SpringExample {
    public static void main(String[] args) {
        ApplicationContext context = new ClassPathXmlApplicationContext("applicationContext.xml");
        MyBean myBean = context.getBean("myBean", MyBean.class);
        myBean.sayHello();
    }
}

10. Apache POI

Apache POI是一个用于处理Microsoft Office文档的Java库。

import org.apache.poi.ss.usermodel.*;
import org.apache.poi.xssf.usermodel.XSSFWorkbook;

public class POIExample {
    public static void main(String[] args) {
        Workbook workbook = new XSSFWorkbook();
        Sheet sheet = workbook.createSheet("Sheet1");
        Row row = sheet.createRow(0);
        Cell cell = row.createCell(0);
        cell.setCellValue("Hello, World!");
        try {
            FileOutputStream fileOut = new FileOutputStream("example.xlsx");
            workbook.write(fileOut);
            fileOut.close();
            workbook.close();
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
}

11. Google Guice

Google Guice是一个依赖注入框架，用于管理对象之间的依赖关系。

import com.google.inject.Guice;
import com.google.inject.Injector;
import com.google.inject.Module;

public class GuiceExample {
    public static void main(String[] args) {
        Module module = new Module() {
            @Override
            public void configure(Binder binder) {
                binder.bind(MyBean.class).to(MyBeanImpl.class);
            }
        };
        Injector injector = Guice.createInjector(module);
        MyBean myBean = injector.getInstance(MyBean.class);
        myBean.sayHello();
    }
}

12. Apache Commons Collections

Apache Commons Collections提供集合操作、迭代器、映射等功能。

import org.apache.commons.collections4.ListUtils;

public class CollectionsExample {
    public static void main(String[] args) {
        List<String> list1 = Lists.newArrayList("Apple", "Banana");
        List<String> list2 = Lists.newArrayList("Cherry", "Date");
        List<String> combinedList = ListUtils.union(list1, list2);
        System.out.println("Combined List: " + combinedList);
    }
}

13. Apache Commons Math

Apache Commons Math提供数学计算和统计功能。

import org.apache.commons.math3.stat.descriptive.DescriptiveStatistics;

public class MathExample {
    public static void main(String[] args) {
        double[] values = {1.0, 2.0, 3.0, 4.0, 5.0};
        DescriptiveStatistics stats = new DescriptiveStatistics(values);
        System.out.println("Mean: " + stats.getMean());
        System.out.println("Standard Deviation: " + stats.getStandardDeviation());
    }
}

14. Apache Commons Validator

Apache Commons Validator提供数据验证功能。

import org.apache.commons.validator.routines.EmailValidator;

public class ValidatorExample {
    public static void main(String[] args) {
        String email = "example@example.com";
        EmailValidator validator = EmailValidator.getInstance();
        if (validator.isValid(email)) {
            System.out.println("Valid email address");
        } else {
            System.out.println("Invalid email address");
        }
    }
}

15. Apache Commons BeanUtils

Apache Commons BeanUtils提供JavaBean操作功能。

import org.apache.commons.beanutils.BeanUtils;

public class BeanUtilsExample {
    public static void main(String[] args) {
        Person person = new Person("John", 30);
        try {
            String name = (String) BeanUtils.getProperty(person, "name");
            System.out.println("Name: " + name);
        } catch (IllegalAccessException | InvocationTargetException | NoSuchMethodException e) {
            e.printStackTrace();
        }
    }
}

16. Apache Commons Net

Apache Commons Net提供网络操作功能。

import org.apache.commons.netimap.FtpClient;

public class NetExample {
    public static void main(String[] args) {
        FtpClient ftpClient = new FtpClient();
        try {
            ftpClient.connect("ftp.example.com", 21);
            ftpClient.login("username", "password");
            // Perform FTP operations
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
}

17. Apache Commons Lang3

Apache Commons Lang3是Apache Commons Lang的升级版，提供更多功能。

import org.apache.commons.lang3.math.NumberUtils;

public class Lang3Example {
    public static void main(String[] args) {
        String numberStr = "123";
        int number = NumberUtils.toInt(numberStr, 0);
        System.out.println("Parsed Number: " + number);
    }
}

18. Apache Commons CSV

Apache Commons CSV提供CSV文件读写功能。

import org.apache.commons.csv.CSVFormat;
import org.apache.commons.csv.CSVParser;
import org.apache.commons.csv.CSVPrinter;

public class CSVExample {
    public static void main(String[] args) {
        String csvFile = "example.csv";
        try (CSVParser parser = new CSVParser(new FileReader(csvFile), CSVFormat.DEFAULT)) {
            for (CSVRecord record : parser) {
                System.out.println(record.get(0) + ", " + record.get(1));
            }
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
}

19. Apache Commons Text

Apache Commons Text提供文本处理功能。

import org.apache.commons.text.StringEscapeUtils;

public class TextExample {
    public static void main(String[] args) {
        String text = "<script>alert('Hello');</script>";
        String escapedText = StringEscapeUtils.escapeHtml4(text);
        System.out.println("Escaped Text: " + escapedText);
    }
}

20. Apache Commons IO FileUtils

Apache Commons IO FileUtils提供文件操作功能。

import org.apache.commons.io.FileUtils;

public class FileUtilsExample {
    public static void main(String[] args) {
        File file = new File("example.txt");
        try {
            String content = FileUtils.readFileToString(file, "UTF-8");
            System.out.println("File Content: " + content);
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
}

21. Apache Commons IO FilenameUtils

Apache Commons IO FilenameUtils提供文件名操作功能。

import org.apache.commons.io.FilenameUtils;

public class FilenameUtilsExample {
    public static void main(String[] args) {
        String fileName = "example.txt";
        String baseName = FilenameUtils.getBaseName(fileName);
        String extension = FilenameUtils.getExtension(fileName);
        System.out.println("Base Name: " + baseName);
        System.out.println("Extension: " + extension);
    }
}

22. Apache Commons IO IOUtils

Apache Commons IO IOUtils提供输入输出流操作功能。

import org.apache.commons.io.IOUtils;

public class IOUtilsExample {
    public static void main(String[] args) {
        String input = "Hello, World!";
        try {
            String output = IOUtils.toString(new ByteArrayInputStream(input.getBytes()), "UTF-8");
            System.out.println("Output: " + output);
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
}

23. Apache Commons IO FileCopyUtils

Apache Commons IO FileCopyUtils提供文件复制功能。

import org.apache.commons.io.FileCopyUtils;

public class FileCopyUtilsExample {
    public static void main(String[] args) {
        File sourceFile = new File("source.txt");
        File destFile = new File("dest.txt");
        try {
            FileCopyUtils.copy(sourceFile, destFile);
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
}

24. Apache Commons IO InputValidator

Apache Commons IO InputValidator提供输入验证功能。

import org.apache.commons.io.input.InputValidator;

public class InputValidatorExample {
    public static void main(String[] args) {
        InputValidator validator = new InputValidator() {
            @Override
            public boolean validate(InputStream input) throws IOException {
                return input.available() > 0;
            }
        };
        try {
            System.out.println("Input is valid: " + validator.validate(new FileInputStream("example.txt")));
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
}

25. Apache Commons IO LineIterator

Apache Commons IO LineIterator提供行迭代器功能。

import org.apache.commons.io.LineIterator;

public class LineIteratorExample {
    public static void main(String[] args) {
        try (LineIterator iterator = IOUtils.lineIterator(new FileReader("example.txt"), "UTF-8")) {
            while (iterator.hasNext()) {
                String line = iterator.nextLine();
                System.out.println(line);
            }
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
}

26. Apache Commons IO LineReader

Apache Commons IO LineReader提供行读取器功能。

import org.apache.commons.io.LineReader;

public class LineReaderExample {
    public static void main(String[] args) {
        try (LineReader reader = new LineReader(new FileReader("example.txt"), "UTF-8")) {
            String line;
            while ((line = reader.readLine()) != null) {
                System.out.println(line);
            }
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
}

27. Apache Commons IO Reader

Apache Commons IO Reader提供字符读取器功能。

import org.apache.commons.io.Reader;

public class ReaderExample {
    public static void main(String[] args) {
        try (Reader reader = new FileReader("example.txt")) {
            int c;
            while ((c = reader.read()) != -1) {
                System.out.print((char) c);
            }
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
}

28. Apache Commons IO Writer

Apache Commons IO Writer提供字符写入器功能。

import org.apache.commons.io.Writer;

public class WriterExample {
    public static void main(String[] args) {
        try (Writer writer = new FileWriter("example.txt")) {
            writer.write("Hello, World!");
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
}

29. Apache Commons IO BufferedReader

Apache Commons IO BufferedReader提供缓冲读取器功能。

import org.apache.commons.io.BufferedReader;

public class BufferedReaderExample {
    public static void main(String[] args) {
        try (BufferedReader reader = new BufferedReader(new FileReader("example.txt"))) {
            String line;
            while ((line = reader.readLine()) != null) {
                System.out.println(line);
            }
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
}

30. Apache Commons IO BufferedWriter

Apache Commons IO BufferedWriter提供缓冲写入器功能。

import org.apache.commons.io.BufferedWriter;

public class BufferedWriterExample {
    public static void main(String[] args) {
        try (BufferedWriter writer = new BufferedWriter(new FileWriter("example.txt"))) {
            writer.write("Hello, World!");
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
}

31. Apache Commons IO InputStream

Apache Commons IO InputStream提供输入流功能。

import org.apache.commons.io.InputStream;

public class InputStreamExample {
    public static void main(String[] args) {
        try (InputStream input = new FileInputStream("example.txt")) {
            int c;
            while ((c = input.read()) != -1) {
                System.out.print((char) c);
            }
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
}

32. Apache Commons IO OutputStream

Apache Commons IO OutputStream提供输出流功能。

import org.apache.commons.io.OutputStream;

public class OutputStreamExample {
    public static void main(String[] args) {
        try (OutputStream output = new FileOutputStream("example.txt")) {
            output.write("Hello, World!".getBytes());
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
}

33. Apache Commons IO InputSource

Apache Commons IO InputSource提供输入源功能。

import org.apache.commons.io.InputSource;

public class InputSourceExample {
    public static void main(String[] args) {
        try (InputSource inputSource = new InputSource(new FileReader("example.txt"))) {
            String content = inputSource.getCharacterStream().toString();
            System.out.println("Content: " + content);
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
}

34. Apache Commons IO OutputSource

Apache Commons IO OutputSource提供输出源功能。

import org.apache.commons.io.OutputSource;

public class OutputSourceExample {
    public static void main(String[] args) {
        try (OutputSource outputSource = new OutputSource()) {
            outputSource.setCharacterStream(new StringWriter());
            outputSource.getWriter().write("Hello, World!");
            String content = outputSource.toString();
            System.out.println("Content: " + content);
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
}

35. Apache Commons IO ReaderInputStream

Apache Commons IO ReaderInputStream提供读取器输入流功能。

import org.apache.commons.io.ReaderInputStream;

public class ReaderInputStreamExample {
    public static void main(String[] args) {
        try (ReaderInputStream readerInputStream = new ReaderInputStream(new FileReader("example.txt"))) {
            int c;
            while ((c = readerInputStream.read()) != -1) {
                System.out.print((char) c);
            }
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
}

36. Apache Commons IO InputStreamReader

Apache Commons IO InputStreamReader提供输入流读取器功能。

import org.apache.commons.io.InputStreamReader;

public class InputStreamReaderExample {
    public static void main(String[] args) {
        try (InputStreamReader inputStreamReader = new InputStreamReader(new FileInputStream("example.txt"), "UTF-8")) {
            int c;
            while ((c = inputStreamReader.read()) != -1) {
                System.out.print((char) c);
            }
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
}

37. Apache Commons IO OutputStreamWriter

Apache Commons IO OutputStreamWriter提供输出流写入器功能。

”`java import org.apache.commons.io.OutputStreamWriter;

public class OutputStreamWriterExample {

public static void