BAEL-1484: Synchronous OpenCSV (#3784)

* BAEL-1484: Synchronous OpenCSV

* corrected pom.xml and package

* Refactored for future async example

* Resource Link

libraries/README.md

@@ -63,6 +63,7 @@
 - [A Docker Guide for Java](http://www.baeldung.com/docker-java-api)
 - [Exceptions in Netty](http://www.baeldung.com/netty-exception-handling)
 - [Creating and Configuring Jetty 9 Server in Java](http://www.baeldung.com/jetty-java-programmatic)
+- [Introduction To OpenCSV](http://www.baeldung.com/opencsv)
 - [Introduction to Akka Actors in Java] (http://www.baeldung.com/akka-actors-java)
 - [Asynchronous HTTP with async-http-client in Java](https://github.com/eugenp/tutorials/tree/master/libraries)
 - [Introduction to Smooks](http://www.baeldung.com/smooks)

libraries/pom.xml

@@ -43,6 +43,12 @@
             <artifactId>cglib</artifactId>
             <version>${cglib.version}</version>
         </dependency>
+        <!-- https://mvnrepository.com/artifact/com.opencsv/opencsv -->
+        <dependency>
+            <groupId>com.opencsv</groupId>
+            <artifactId>opencsv</artifactId>
+            <version>${opencsv.version}</version>
+        </dependency>
         <dependency>
             <groupId>commons-beanutils</groupId>
             <artifactId>commons-beanutils</artifactId>
@@ -858,9 +864,9 @@
         <tomcat.version>8.5.24</tomcat.version>
         <async.http.client.version>2.2.0</async.http.client.version>
         <infinispan.version>9.1.5.Final</infinispan.version>
+        <opencsv.version>4.1</opencsv.version>
         <unirest.version>1.4.9</unirest.version>
         <commons-codec-version>1.10.L001</commons-codec-version>
         <jets3t-version>0.9.4.0006L</jets3t-version>
     </properties>
-
-</project>
+</project>

libraries/src/main/java/com/baeldung/opencsv/Application.java

@@ -0,0 +1,108 @@
+package com.baeldung.opencsv;
+
+import com.baeldung.opencsv.beans.NamedColumnBean;
+import com.baeldung.opencsv.beans.SimplePositionBean;
+import com.baeldung.opencsv.examples.sync.BeanExamples;
+import com.baeldung.opencsv.examples.sync.CsvReaderExamples;
+import com.baeldung.opencsv.examples.sync.CsvWriterExamples;
+import com.baeldung.opencsv.helpers.Helpers;
+
+import java.io.Reader;
+import java.nio.file.Files;
+import java.nio.file.Path;
+
+public class Application {
+
+        /*
+         *  Bean Examples.
+         */
+
+    public static String simpleSyncPositionBeanExample() {
+        Path path = null;
+        try {
+            path = Helpers.twoColumnCsvPath();
+        } catch (Exception ex) {
+            Helpers.err(ex);
+        }
+        return BeanExamples.beanBuilderExample(path, SimplePositionBean.class).toString();
+    }
+
+    public static String namedSyncColumnBeanExample() {
+        Path path = null;
+        try {
+            path = Helpers.namedColumnCsvPath();
+        } catch (Exception ex) {
+            Helpers.err(ex);
+        }
+        return BeanExamples.beanBuilderExample(path, NamedColumnBean.class).toString();
+    }
+
+    public static String writeSyncCsvFromBeanExample() {
+        Path path = null;
+        try {
+            path = Helpers.fileOutBeanPath();
+        } catch (Exception ex) {
+            Helpers.err(ex);
+        }
+        return BeanExamples.writeCsvFromBean(path);
+    }
+
+        /*
+         *  CSV Reader Examples.
+         */
+
+    public static String oneByOneSyncExample() {
+        Reader reader = null;
+        try {
+            reader = Files.newBufferedReader(Helpers.twoColumnCsvPath());
+        } catch (Exception ex) {
+            Helpers.err(ex);
+        }
+        return CsvReaderExamples.oneByOne(reader).toString();
+    }
+
+    public static String readAllSyncExample() {
+        Reader reader = null;
+        try {
+            reader = Files.newBufferedReader(Helpers.twoColumnCsvPath());
+        } catch (Exception ex) {
+            Helpers.err(ex);
+        }
+        return CsvReaderExamples.readAll(reader).toString();
+    }
+
+         /*
+         *  CSV Writer Examples.
+         */
+
+
+    public static String csvWriterSyncOneByOne() {
+        Path path = null;
+        try {
+            path = Helpers.fileOutOnePath();
+        } catch (Exception ex) {
+            Helpers.err(ex);
+        }
+        return CsvWriterExamples.csvWriterOneByOne(Helpers.fourColumnCsvString(), path);
+    }
+
+    public static String csvWriterSyncAll() {
+        Path path = null;
+        try {
+            path = Helpers.fileOutAllPath();
+        } catch (Exception ex) {
+            Helpers.err(ex);
+        }
+        return CsvWriterExamples.csvWriterAll(Helpers.fourColumnCsvString(), path);
+    }
+
+    public static void main(String[] args) {
+        simpleSyncPositionBeanExample();
+        namedSyncColumnBeanExample();
+        writeSyncCsvFromBeanExample();
+        oneByOneSyncExample();
+        readAllSyncExample();
+        csvWriterSyncOneByOne();
+        csvWriterSyncAll();
+    }
+}

libraries/src/main/java/com/baeldung/opencsv/Constants.java

@@ -0,0 +1,17 @@
+package com.baeldung.opencsv;
+
+public class Constants {
+
+    public static final String GENERIC_EXCEPTION = "EXCEPTION ENCOUNTERED: ";
+    public static final String GENERIC_SUCCESS = "SUCCESS";
+
+    public static final String TWO_COLUMN_CSV = "csv/twoColumn.csv";
+    public static final String FOUR_COLUMN_CSV = "csv/fourColumn.csv";
+    public static final String NAMED_COLUMN_CSV = "csv/namedColumn.csv";
+
+    public static final String CSV_All = "csv/writtenAll.csv";
+    public static final String CSV_BEAN = "csv/writtenBean.csv";
+    public static final String CSV_ONE = "csv/writtenOneByOne.csv";
+
+
+}

libraries/src/main/java/com/baeldung/opencsv/beans/CsvBean.java

@@ -0,0 +1,3 @@
+package com.baeldung.opencsv.beans;
+
+public class CsvBean { }

libraries/src/main/java/com/baeldung/opencsv/beans/NamedColumnBean.java

@@ -0,0 +1,31 @@
+package com.baeldung.opencsv.beans;
+
+import com.opencsv.bean.CsvBindByName;
+
+public class NamedColumnBean extends CsvBean {
+
+    @CsvBindByName(column = "name")
+    private String name;
+
+    //Automatically infer column name as Age
+    @CsvBindByName
+    private int age;
+
+    public String getName() {
+        return name;
+    }
+
+    public void setName(String name) {
+        this.name = name;
+    }
+
+    public int getAge() {
+        return age;
+    }
+
+    public void setAge(int age) {
+        this.age = age;
+    }
+
+
+}

libraries/src/main/java/com/baeldung/opencsv/beans/SimplePositionBean.java

@@ -0,0 +1,29 @@
+package com.baeldung.opencsv.beans;
+
+import com.opencsv.bean.CsvBindByPosition;
+
+public class SimplePositionBean extends CsvBean {
+
+    @CsvBindByPosition(position = 0)
+    private String exampleColOne;
+
+    @CsvBindByPosition(position = 1)
+    private String exampleColTwo;
+
+    public String getExampleColOne() {
+        return exampleColOne;
+    }
+
+    private void setExampleColOne(String exampleColOne) {
+        this.exampleColOne = exampleColOne;
+    }
+
+    public String getExampleColTwo() {
+        return exampleColTwo;
+    }
+
+    private void setExampleCsvTwo (String exampleColTwo) {
+        this.exampleColTwo = exampleColTwo;
+    }
+
+}

libraries/src/main/java/com/baeldung/opencsv/beans/WriteExampleBean.java

@@ -0,0 +1,40 @@
+package com.baeldung.opencsv.beans;
+
+public class WriteExampleBean extends CsvBean {
+
+    private String colA;
+
+    private String colB;
+
+    private String colC;
+
+    public WriteExampleBean(String colA, String colB, String colC) {
+        this.colA = colA;
+        this.colB = colB;
+        this.colC = colC;
+    }
+
+    public String getColA() {
+        return colA;
+    }
+
+    public void setColA(String colA) {
+        this.colA = colA;
+    }
+
+    public String getColB() {
+        return colB;
+    }
+
+    public void setColB(String colB) {
+        this.colB = colB;
+    }
+
+    public String getColC() {
+        return colC;
+    }
+
+    public void setColC(String colC) {
+        this.colC = colC;
+    }
+}

libraries/src/main/java/com/baeldung/opencsv/examples/sync/BeanExamples.java

@@ -0,0 +1,61 @@
+package com.baeldung.opencsv.examples.sync;
+
+import com.baeldung.opencsv.beans.CsvBean;
+import com.baeldung.opencsv.beans.WriteExampleBean;
+import com.baeldung.opencsv.helpers.Helpers;
+import com.baeldung.opencsv.pojos.CsvTransfer;
+import com.opencsv.CSVWriter;
+import com.opencsv.bean.*;
+
+import java.io.FileWriter;
+import java.io.Reader;
+import java.io.Writer;
+import java.nio.file.Files;
+import java.nio.file.Path;
+import java.util.ArrayList;
+import java.util.List;
+
+public class BeanExamples {
+
+    public static List<CsvBean> beanBuilderExample(Path path, Class clazz) {
+        CsvTransfer csvTransfer = new CsvTransfer();
+        try {
+            ColumnPositionMappingStrategy ms = new ColumnPositionMappingStrategy();
+            ms.setType(clazz);
+
+            Reader reader = Files.newBufferedReader(path);
+            CsvToBean cb = new CsvToBeanBuilder(reader)
+                    .withType(clazz)
+                    .withMappingStrategy(ms)
+                    .build();
+
+            csvTransfer.setCsvList(cb.parse());
+            reader.close();
+
+        } catch (Exception ex) {
+            Helpers.err(ex);
+        }
+        return csvTransfer.getCsvList();
+    }
+
+    public static String writeCsvFromBean(Path path) {
+        try {
+            Writer writer  = new FileWriter(path.toString());
+
+            StatefulBeanToCsv sbc = new StatefulBeanToCsvBuilder(writer)
+                    .withSeparator(CSVWriter.DEFAULT_SEPARATOR)
+                    .build();
+
+            List<CsvBean> list = new ArrayList<>();
+            list.add(new WriteExampleBean("Test1", "sfdsf", "fdfd"));
+            list.add(new WriteExampleBean("Test2", "ipso", "facto"));
+
+            sbc.write(list);
+            writer.close();
+
+        } catch (Exception ex) {
+            Helpers.err(ex);
+        }
+        return Helpers.readFile(path);
+    }
+}

libraries/src/main/java/com/baeldung/opencsv/examples/sync/CsvReaderExamples.java

@@ -0,0 +1,63 @@
+package com.baeldung.opencsv.examples.sync;
+
+import com.baeldung.opencsv.helpers.Helpers;
+import com.opencsv.CSVParser;
+import com.opencsv.CSVParserBuilder;
+import com.opencsv.CSVReader;
+import com.opencsv.CSVReaderBuilder;
+
+import java.io.Reader;
+import java.util.ArrayList;
+import java.util.List;
+
+public class CsvReaderExamples {
+
+    public static List<String[]> readAll(Reader reader) {
+
+        CSVParser parser = new CSVParserBuilder()
+                .withSeparator(',')
+                .withIgnoreQuotations(true)
+                .build();
+
+        CSVReader csvReader = new CSVReaderBuilder(reader)
+                .withSkipLines(0)
+                .withCSVParser(parser)
+                .build();
+
+        List<String[]> list = new ArrayList<>();
+        try {
+            list = csvReader.readAll();
+            reader.close();
+            csvReader.close();
+        } catch (Exception ex) {
+            Helpers.err(ex);
+        }
+        return list;
+    }
+
+    public static List<String[]> oneByOne(Reader reader) {
+        List<String[]> list = new ArrayList<>();
+        try {
+            CSVParser parser = new CSVParserBuilder()
+                    .withSeparator(',')
+                    .withIgnoreQuotations(true)
+                    .build();
+
+            CSVReader csvReader = new CSVReaderBuilder(reader)
+                    .withSkipLines(0)
+                    .withCSVParser(parser)
+                    .build();
+
+            String[] line;
+            while ((line = csvReader.readNext()) != null) {
+                list.add(line);
+            }
+            reader.close();
+            csvReader.close();
+        } catch (Exception ex) {
+            Helpers.err(ex);
+        }
+        return list;
+    }
+
+}

libraries/src/main/java/com/baeldung/opencsv/examples/sync/CsvWriterExamples.java

@@ -0,0 +1,35 @@
+package com.baeldung.opencsv.examples.sync;
+
+import com.baeldung.opencsv.helpers.Helpers;
+import com.opencsv.CSVWriter;
+
+import java.io.FileWriter;
+import java.nio.file.Path;
+import java.util.List;
+
+public class CsvWriterExamples {
+
+    public static String csvWriterOneByOne(List<String[]> stringArray, Path path) {
+        try {
+            CSVWriter writer = new CSVWriter(new FileWriter(path.toString()));
+            for (String[] array : stringArray) {
+                writer.writeNext(array);
+            }
+            writer.close();
+        } catch (Exception ex) {
+            Helpers.err(ex);
+        }
+        return Helpers.readFile(path);
+    }
+
+    public static String csvWriterAll(List<String[]> stringArray, Path path) {
+        try {
+            CSVWriter writer = new CSVWriter(new FileWriter(path.toString()));
+            writer.writeAll(stringArray);
+            writer.close();
+        } catch (Exception ex) {
+            Helpers.err(ex);
+        }
+        return Helpers.readFile(path);
+    }
+}

libraries/src/main/java/com/baeldung/opencsv/helpers/Helpers.java

@@ -0,0 +1,108 @@
+package com.baeldung.opencsv.helpers;
+
+import com.baeldung.opencsv.Constants;
+
+import java.io.BufferedReader;
+import java.io.FileReader;
+import java.net.URI;
+import java.net.URISyntaxException;
+import java.nio.file.Path;
+import java.nio.file.Paths;
+import java.util.ArrayList;
+import java.util.List;
+
+public class Helpers {
+
+    /**
+     * Write Files
+     */
+
+    public static Path fileOutAllPath() throws URISyntaxException {
+        URI uri = ClassLoader.getSystemResource(Constants.CSV_All).toURI();
+        return Paths.get(uri);
+    }
+
+    public static Path fileOutBeanPath() throws URISyntaxException {
+        URI uri = ClassLoader.getSystemResource(Constants.CSV_BEAN).toURI();
+        return Paths.get(uri);
+    }
+
+    public static Path fileOutOnePath() throws URISyntaxException {
+        URI uri = ClassLoader.getSystemResource(Constants.CSV_ONE).toURI();
+        return Paths.get(uri);
+    }
+
+    /**
+     * Read Files
+     */
+
+    public static Path twoColumnCsvPath() throws URISyntaxException {
+        URI uri = ClassLoader.getSystemResource(Constants.TWO_COLUMN_CSV).toURI();
+        return Paths.get(uri);
+    }
+
+    public static Path fourColumnCsvPath() throws URISyntaxException {
+        URI uri = ClassLoader.getSystemResource(Constants.FOUR_COLUMN_CSV).toURI();
+        return Paths.get(uri);
+    }
+
+    public static Path namedColumnCsvPath() throws URISyntaxException {
+        URI uri = ClassLoader.getSystemResource(Constants.NAMED_COLUMN_CSV).toURI();
+        return Paths.get(uri);
+    }
+
+    /**
+     * Simple File Reader
+     */
+
+    public static String readFile(Path path) {
+        String response = "";
+        try {
+            FileReader fr = new FileReader(path.toString());
+            BufferedReader br = new BufferedReader(fr);
+            String strLine;
+            StringBuffer sb = new StringBuffer();
+            while ((strLine = br.readLine()) != null) {
+                sb.append(strLine);
+            }
+            response = sb.toString();
+            System.out.println(response);
+            fr.close();
+            br.close();
+        } catch (Exception ex) {
+            Helpers.err(ex);
+        }
+        return response;
+    }
+
+    /**
+     * Dummy Data for Writing.
+     */
+
+    public static List<String[]> twoColumnCsvString() {
+        List<String[]> list = new ArrayList<>();
+        list.add(new String[]{"ColA", "ColB"});
+        list.add(new String[]{"A", "B"});
+        return list;
+    }
+
+    public static List<String[]> fourColumnCsvString() {
+        List<String[]> list = new ArrayList<>();
+        list.add(new String[]{"ColA", "ColB", "ColC", "ColD"});
+        list.add(new String[]{"A", "B", "A", "B"});
+        list.add(new String[]{"BB", "AB", "AA", "B"});
+        return list;
+    }
+
+    /**
+     * Message Helpers
+     */
+
+    public static void print(String msg) {
+        System.out.println(msg);
+    }
+
+    public static void err(Exception ex) {
+        System.out.println(Constants.GENERIC_EXCEPTION + " " + ex);
+    }
+}

libraries/src/main/java/com/baeldung/opencsv/pojos/CsvTransfer.java

@@ -0,0 +1,38 @@
+package com.baeldung.opencsv.pojos;
+
+import com.baeldung.opencsv.beans.CsvBean;
+
+import java.util.ArrayList;
+import java.util.List;
+
+public class CsvTransfer {
+
+    private List<String[]> csvStringList;
+
+    private List<CsvBean> csvList;
+
+    public CsvTransfer() {}
+
+    public List<String[]> getCsvStringList() {
+        if (csvStringList != null) return csvStringList;
+        return new ArrayList<String[]>();
+    }
+
+    public void addLine(String[] line) {
+        if (this.csvList == null) this.csvStringList = new ArrayList<>();
+        this.csvStringList.add(line);
+    }
+
+    public void setCsvStringList(List<String[]> csvStringList) {
+        this.csvStringList = csvStringList;
+    }
+
+    public void setCsvList(List<CsvBean> csvList) {
+        this.csvList = csvList;
+    }
+
+    public List<CsvBean> getCsvList() {
+        if (csvList != null) return csvList;
+        return new ArrayList<CsvBean>();
+    }
+}

libraries/src/main/resources/csv/fourColumn.csv

@@ -0,0 +1,5 @@
+ColA,ColB,ColC,ColD
+A,B,B,B
+C,D,W,W
+G,G,E,E
+G,F,Q,Q

libraries/src/main/resources/csv/namedColumn.csv

@@ -0,0 +1,5 @@
+name,age
+adam,1000
+martin,27
+gigi,41
+seraphine,30

libraries/src/main/resources/csv/twoColumn.csv

@@ -0,0 +1,5 @@
+ColA,ColB
+A,B
+C,D
+G,G
+G,F

libraries/src/test/java/com/baeldung/opencsv/OpenCsvTest.java

@@ -0,0 +1,66 @@
+package com.baeldung.opencsv;
+
+import com.baeldung.opencsv.helpers.Helpers;
+import org.junit.After;
+import org.junit.Before;
+import org.junit.Test;
+
+public class OpenCsvTest {
+
+    private Object testReadCsv(Object result) {
+        assert (result != null);
+        assert (result instanceof String);
+        assert (!((String) result).isEmpty());
+        System.out.println(result);
+        return result;
+    }
+
+    private Object testWriteCsv(Object result) {
+        assert (result instanceof String);
+        assert (!((String) result).isEmpty());
+        return result;
+    }
+
+    @Before
+    public void setup() {
+    }
+
+    @Test
+    public void positionExampleTest() {
+        testReadCsv(Application.simpleSyncPositionBeanExample());
+    }
+
+    @Test
+    public void namedColumnExampleTest() {
+        testReadCsv(Application.namedSyncColumnBeanExample());
+    }
+
+    @Test
+    public void writeCsvUsingBeanBuilderTest() {
+        testWriteCsv(Application.writeSyncCsvFromBeanExample());
+    }
+
+    @Test
+    public void oneByOneExampleTest() {
+        testReadCsv(Application.oneByOneSyncExample());
+    }
+
+    @Test
+    public void readAllExampleTest() {
+        testReadCsv(Application.readAllSyncExample());
+    }
+
+    @Test
+    public void csvWriterOneByOneTest() {
+        testWriteCsv(Application.csvWriterSyncOneByOne());
+    }
+
+    @Test
+    public void csvWriterAllTest() {
+        testWriteCsv(Application.csvWriterSyncAll());
+    }
+
+    @After
+    public void close() {
+    }
+}

libraries/src/test/resources/csv/fourColumn.csv

@@ -0,0 +1,5 @@
+ColA,ColB,ColC,ColD
+A,B,B,B
+C,D,W,W
+G,G,E,E
+G,F,Q,Q

libraries/src/test/resources/csv/namedColumn.csv

@@ -0,0 +1,5 @@
+name,age
+adam,1000
+martin,27
+gigi,41
+seraphine,30

libraries/src/test/resources/csv/twoColumn.csv

@@ -0,0 +1,5 @@
+ColA,ColB
+A,B
+C,D
+G,G
+G,F