Apache Commons Exec

Giriş

Bir shell script veya başar bir uygulamayı çalıştırıp çıktısını okumak için kullanılır

DefaultExecutor harici uygulamayı çalıştırır

PumpStreamHandler çıktıyı toparlar

Gradle

Şu satırı dahil ederiz

implementation group: 'org.apache.commons', name: 'commons-exec', version: '1.3'

HttpComponents HttpClientBuilder Sınıfı

Giriş
Şu satırı dahil ederiz.

import org.apache.http.impl.client.HttpClientBuilder;

setDefaultRequestConfig metodu

Tüm client için timeout ayarları yapılabilir.

Örnek

Şöyle yaparız

import org.apache.http.client.config.RequestConfig;
import org.apache.http.client.methods.HttpGet;
import org.apache.http.impl.client.CloseableHttpClient;
import org.apache.http.impl.client.HttpClientBuilder;

HttpGet request = new HttpGet("https://httpbin.org/get");

// 5 seconds timeout
RequestConfig requestConfig = RequestConfig.custom()
  .setConnectionRequestTimeout(5_000)
  .setConnectTimeout(5_000)
  .setSocketTimeout(5_000)
  .build();

try (CloseableHttpClient httpClient = HttpClientBuilder.create()
  .setDefaultRequestConfig(requestConfig)
  .build();
   CloseableHttpResponse response = httpClient.execute(request)) {
  ...
}

setUserAgent metodu

Şöyle yaparız.

CloseableHttpClient httpClient = HttpClients.custom()
  .setUserAgent(HTTP_USER_AGENT).
  .build();
HttpGet request = new HttpGet(url);
HttpResponse response = httpClient.execute(request);

setSSLSocketFactory metodu

Örnek

Şöyle yaparız

HttpClientBuilder builder = HttpClients.custom();
javax.net.ssl.SSLContext sslContext = SSLContext.getInstance("TLSv1.1");
javax.net.ssl.KeyManager[] clientKeyManagers = ...;
javax.net.ssl.TrustManager[] clientTrustManagers = ...;
sslContext.init(clientKeyManagers, clientTrustManagers, new SecureRandom());

builder.setSSLSocketFactory(
  new org.apache.http.conn.ssl.SSLConnectionSocketFactory(sslContext,
    SSLConnectionSocketFactory.ALLOW_ALL_HOSTNAME_VERIFIER)
);
CloseableHttpClient client = builder.build();




Failable Sınıfı - Lambda İçinde Exception İçindir

Giriş

Şu satırı dahil ederiz

import org.apache.commons.lang3.function.Failable;

Örnek

Şöyle yaparız

Stream<String> stream = Stream.of("...", "...", "...");
Failable.stream(stream)
  //throws a ClassNotFoundException wrapped in an UndeclaredThrowableException at runtime. 
  .map(Class::forName)  
  .forEach(System.out::println);

Camel Choice ve When - Content Based Routing İçindir

Giriş

Açıklaması şöyle

Apache Camel contains a powerful feature called content-based routers. This allows you to process the message differently relying on the content.

They are quite similar to the if/else statement in Java. Regardless, in Camel, the equivalent words are when and otherwise.

Örnek

Şöyle yaparız

import org.apache.camel.builder.RouteBuilder;
import org.springframework.stereotype.Component;

@Component
public class ChoiceWhenRoute extends RouteBuilder {
  @Override
  public void configure() throws Exception {

    from("direct:startWhenChoiceRoute")
      .routeId("direct:startWhenChoiceRoute")
      .log( "${body}")
      .choice()
      .when(body().isNull())
      .log("Message body is empty.")
      .log("${body}")
      .end();
  }
}

Test için şöyle yaparız

import org.apache.camel.CamelContext;
import org.apache.camel.Exchange;
import org.apache.camel.ProducerTemplate;
import org.apache.camel.builder.ExchangeBuilder;

@RestController
public class Controler {

  @Autowired
  private ProducerTemplate producerTemplate;

  @Autowired
  private CamelContext camelContext;

  @GetMapping
  public void function() {
    Exchange requestExchange = ExchangeBuilder
      .anExchange(camelContext)
      .build();

    producerTemplate
      .send("direct:startWhenChoiceRoute",requestExchange);

  }
}

Jena - Semantic Web

Gradle

Şu satırı dahil ederiz

implementation "org.apache.jena:apache-jena-libs:4.0.0"

Örnek

Şöyle yaparız

OntModel model = ModelFactory.createOntologyModel("http://www.w3.org/2000/01/rdf-schema#");
RDFParser.source("https://schema.org/version/latest/schemaorg-current-https.jsonld")
  .parse(model);

Camel Resequence

Giriş

İki çeşit resequence işlemi var

1. Batch resequencing
2. Stream resequencing

2. Stream resequencing
Örnek

Elimizde şöyle bir comparator olsun

import org.apache.camel.Exchange;
import org.apache.camel.Expression;
import org.apache.camel.processor.resequencer.ExpressionResultComparator;

@NoArgsConstructor(staticName = "of")
class CustomPriorityComparator implements ExpressionResultComparator {

  @Override
  public void setExpression(Expression expression) {// do nothing}

  @Override
  public boolean predecessor(Exchange o1, Exchange o2) {return false;}

  @Override
  public boolean successor(Exchange o1, Exchange o2) {return false;}

  @Override
  public boolean isValid(Exchange exchange) {
    return exchange.getMessage().getBody() instanceof String;
  }

  @Override
  public int compare(Exchange exchange1, Exchange exchange2) {
    return getMessageAsString(exchange1).compareTo(getMessageAsString(exchange2));
  }

  private static String getMessageAsString(Exchange exchange) {
    return String.valueOf(exchange.getMessage().getBody());
  }
}

Şöyle yaparız

import org.springframework.stereotype.Component;

@Component
public class ResequenceRoute extends RouteBuilder {

  private static final String TOPIC_TO_CONSUME = "incoming_channel";
  private static final String TOPIC_TO_FORWARD = "outgoing_channel";
  private static final String BOOTSTRAP_URL = "localhost:9092";
  private static final String CONSUMER_GROUP = "resequencer";
  private static final Integer RESEQUENCER_CAPACITY = 100;
  private static final Long RESEQUENCER_TIMEOUT = 5000L;
    

  @Override
  public void configure() {
    from("kafka:" + TOPIC_TO_CONSUME + "?brokers=" + BOOTSTRAP_URL 
         + "&groupId=" + CONSUMER_GROUP)
      .resequence()
      .body()
      .stream()
      .capacity(RESEQUENCER_CAPACITY)
      .timeout(RESEQUENCER_TIMEOUT)
      .comparator(CustomPriorityComparator.of())
      .to("kafka:" + TOPIC_TO_FORWARD + "?brokers=" + BOOTSTRAP_URL);
    }
}

POI Kullanımı

Maven

Şu satırı dahil ederiz

<dependency>
  <groupId>org.apache.poi</groupId>
  <artifactId>poi</artifactId>
  <version>4.1.2</version>
</dependency>
<dependency>
  <groupId>org.apache.poi</groupId>
  <artifactId>poi-ooxml</artifactId>
  <version>4.1.2</version>
</dependency>

Yazma

Her şey XSSWorkbook sınıfı etrafında dönüyor.

Örnek

Şöyle yaparız

ByteArrayOutputStream bos = new ByteArrayOutputStream();

try (Workbook workbook = new XSSFWorkbook()) {
  ...
} catch (Exception e) {
  ...
} finally {
  bos.close();
}
return bos.toByteArray();

Yazarken Font ve fontların kullanılacağı CellStyle nesnelerini oluşturmak gerekir. Şöyle yaparız

//setting up the basic styles for the workbook
Font boldFont = getBoldFont(workbook);
Font genericFont = getGenericFont(workbook);
CellStyle headerStyle = getLeftAlignedCellStyle(workbook, boldFont);
CellStyle currencyStyle = setCurrencyCellStyle(workbook);
CellStyle centerAlignedStyle = getCenterAlignedCellStyle(workbook);
CellStyle genericStyle = getLeftAlignedCellStyle(workbook, genericFont);

Daha sonra bir Sheet oluşturulur. Şöyle yaparız

String sheetName = ...
Sheet sheet = workbook.createSheet(sheetName);

Daha sonra bir başlık oluşturulur. Şöyle yaparız

int tempRowNo = 0;

//set spreadsheet titles
Row mainRow = sheet.createRow(tempRowNo++);

for (int i = 0; i < columnTitles.length; i++) {
  Cell columnTitleCell = mainRow.createCell(i);
  columnTitleCell.setCellStyle(headerStyle);
  columnTitleCell.setCellValue(columnTitles[i]);
}

Daha sonra veriyi sütunlar halinde yazarız. Şöyle yaparız

//looping the dataset
for (T record : data) {
  
  Row mainRow = sheet.createRow(tempRowNo++);
  Cell compositeNewCell = mainRow.createCell(cellIndex);
  cell.setCellValue(...);
  Hyperlink link = workbook.getCreationHelper().createHyperlink(HyperlinkType.URL);
  link.setAddress(...);
  cell.setHyperlink(link);
  ...
}

Tabi bu işleri yaparken bir sürü yardımcı metod gerekiyor. Bunları hep kodlamak lazım

Örnek

Elimizde şöyle bir kod olsun

public class ExcelGenerator {
  private List < Student > studentList = ...;
  private XSSFWorkbook workbook = new XSSFWorkbook();
  private XSSFSheet sheet;

  private void writeHeader() {
    sheet = workbook.createSheet("Student");
    Row row = sheet.createRow(0);
    CellStyle style = workbook.createCellStyle();
    XSSFFont font = workbook.createFont();
    font.setBold(true);
    font.setFontHeight(16);
    style.setFont(font);
    createCell(row, 0, "ID", style);
    createCell(row, 1, "Student Name", style);
    createCell(row, 2, "Email", style);
    createCell(row, 3, "Mobile No.", style);
  }
  private void createCell(Row row, int columnCount, Object valueOfCell,
    CellStyle style) {
    sheet.autoSizeColumn(columnCount);
    Cell cell = row.createCell(columnCount);
    if (valueOfCell instanceof Integer) {
      cell.setCellValue((Integer) valueOfCell);
    } else if (valueOfCell instanceof Long) {
      cell.setCellValue((Long) valueOfCell);
    } else if (valueOfCell instanceof String) {
      cell.setCellValue((String) valueOfCell);
    } else {
      cell.setCellValue((Boolean) valueOfCell);
    }
    cell.setCellStyle(style);
  }
  private void write() {
    int rowCount = 1;
    CellStyle style = workbook.createCellStyle();
    XSSFFont font = workbook.createFont();
    font.setFontHeight(14);
    style.setFont(font);
    for (Student record: studentList) {
      Row row = sheet.createRow(rowCount++);
      int columnCount = 0;
      createCell(row, columnCount++, record.getId(), style);
      createCell(row, columnCount++, record.getStudentName(), style);
      createCell(row, columnCount++, record.getEmail(), style);
      createCell(row, columnCount++, record.getMobileNo(), style);
    }
  }
}

Şöyle yaparız. Burada Excep direkt servlet cevabına yazılıyor

public class ExcelGenerator {
  
  public void generateExcelFile(HttpServletResponse response) throws IOException {
    writeHeader();
    write();
    ServletOutputStream outputStream = response.getOutputStream();
    workbook.write(outputStream);
    workbook.close();
    outputStream.close();
  }
}

Dosya İndirme

Örnek - SpringBoot

Şöyle yaparız

import org.springframework.http.HttpHeaders;
import org.springframework.http.HttpStatus;
import org.springframework.http.MediaType;
import org.springframework.http.ResponseEntity;

@Controller
public class UserController {

  @Autowired
  private UserService userService;

  @RequestMapping(method = RequestMethod.POST, value = "/download-users")
  public ResponseEntity downloadUsersExcel() {
    try {
      final byte[] data = userService.getUserXlsData();
      HttpHeaders header = new HttpHeaders();
      header.setContentType(MediaType.parseMediaType(
      "application/vnd.openxmlformats-officedocument.spreadsheetml.sheet;charset=UTF-8"));
      header.set(HttpHeaders.CONTENT_DISPOSITION, "inline; filename= users.xlsx");
      header.setContentLength(data.length);
      return new ResponseEntity<>(data, header, HttpStatus.OK);
    } catch (Exception e) {
      return new ResponseEntity<>(null, HttpStatus.INTERNAL_SERVER_ERROR);
    }
  }
}