How do I load properties from XML file?

By Wayan in Core API, Util Package 0 Comment

Reading XML properties can be easily done using the java.util.Properties.loadFromXML() method. Just like reading the properties from a file that contains a key=value pairs, the XML file will also contain a key and value wrapped in the following XML format.

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE properties SYSTEM "http://java.sun.com/dtd/properties.dtd">
<properties>
    <comment>Application Configuration</comment>
    <entry key="data.folder">D:\AppData</entry>
    <entry key="jdbc.url">jdbc:mysql://localhost/kodejava</entry>
</properties>

package org.kodejava.util;

import java.util.Properties;

public class LoadXmlProperties {
    public static void main(String[] args) {
        LoadXmlProperties demo = new LoadXmlProperties();
        try {
            Properties properties = demo.readProperties();

            //Display all properties information
            properties.list(System.out);

            // Read the value of data.folder and jdbc.url configuration
            String dataFolder = properties.getProperty("data.folder");
            System.out.println("data.folder = " + dataFolder);
            String jdbcUrl = properties.getProperty("jdbc.url");
            System.out.println("jdbc.url    = " + jdbcUrl);
        } catch (Exception e) {
            e.printStackTrace();
        }
    }

    private Properties readProperties() throws Exception {
        Properties properties = new Properties();
        properties.loadFromXML(getClass().getResourceAsStream("/configuration.xml"));
        return properties;
    }
}

The result of the code snippet above:

-- listing properties --
data.folder=D:\AppData
jdbc.url=jdbc:mysql://localhost/kodejava
data.folder = D:\AppData
jdbc.url    = jdbc:mysql://localhost/kodejava

How do I convert InputStream to String?

By Wayan in Core API, IO 1 Comment

This example will show you how to convert an InputStream into String. In the code snippet below we read a data.txt file, could be from common directory or from inside a jar file.

package org.kodejava.io;

import java.io.*;
import java.nio.charset.StandardCharsets;

public class StreamToString {

    public static void main(String[] args) throws Exception {
        StreamToString demo = new StreamToString();

        // Get input stream of our data file. This file can be in
        // the root of your application folder or inside a jar file
        // if the program is packed as a jar.
        InputStream is = demo.getClass().getResourceAsStream("/student.csv");

        // Call the method to convert the stream to string
        System.out.println(demo.convertStreamToString(is));
    }

    private String convertStreamToString(InputStream stream) throws IOException {
        // To convert the InputStream to String we use the
        // Reader.read(char[] buffer) method. We iterate until the
        // Reader return -1 which means there's no more data to
        // read. We use the StringWriter class to produce the string.
        if (stream != null) {
            Writer writer = new StringWriter();

            char[] buffer = new char[1024];
            try (stream) {
                Reader reader = new BufferedReader(new InputStreamReader(stream,
                        StandardCharsets.UTF_8));
                int length;
                while ((length = reader.read(buffer)) != -1) {
                    writer.write(buffer, 0, length);
                }
            }
            return writer.toString();
        }
        return "";
    }
}

How do I convert string into InputStream?

By Wayan in Core API, IO 0 Comment

Here you will find how to convert string into java.io.InputStream object using java.io.ByteArrayInputStream class.

package org.kodejava.io;

import java.io.*;
import java.nio.charset.StandardCharsets;

public class StringToStream {
    public static void main(String[] args) {
        String text = "Converting String to InputStream Example";

        // Convert String to InputStream using ByteArrayInputStream
        // class. This class constructor takes the string byte array
        // which can be done by calling the getBytes() method.
        InputStream stream = new ByteArrayInputStream(text.getBytes(StandardCharsets.UTF_8));
    }
}

How do I determine bean’s property type?

By Wayan in Apache Commons, Commons Beanutils 0 Comment

Using the PropertyUtils.getPropertyType() we can determine the bean property type. This method return a Class object of bean’s property type.

package org.kodejava.commons.beanutils;

import org.apache.commons.beanutils.PropertyUtils;
import org.kodejava.commons.beanutils.support.Record;

public class PropertyType {
    public static void main(String[] args) {
        Record record = new Record();
        record.setTitle("Magical Mystery Tour");

        try {
            /*
             * Using PropertyUtils.getPropertyType() to determine the type of
             * title property.
             */
            Class<?> type = PropertyUtils.getPropertyType(record, "title");
            System.out.println("type = " + type.getName());

            String value = (String) PropertyUtils.getProperty(record, "title");
            System.out.println("value = " + value);
        } catch (Exception e) {
            e.printStackTrace();
        }
    }
}

package org.kodejava.commons.beanutils.support;

import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;

public class Record {
    private Long id;
    private String title;
    private List<Track> tracks = new ArrayList<>();
    private Map<String, Track> mapTracks = new HashMap<>();

    public Long getId() {
        return id;
    }

    public void setId(Long id) {
        this.id = id;
    }

    public String getTitle() {
        return title;
    }

    public void setTitle(String title) {
        this.title = title;
    }

    public List<Track> getTracks() {
        return tracks;
    }

    public void setTracks(List<Track> tracks) {
        this.tracks = tracks;
    }

    public void setMapTracks(Map<String, Track> mapTracks) {
        this.mapTracks = mapTracks;
    }

    public Map<String, Track> getMapTracks() {
        return mapTracks;
    }
}

The output of the code snippet above:

type = java.lang.String
value = Magical Mystery Tour

Maven Dependencies

<dependency>
    <groupId>commons-beanutils</groupId>
    <artifactId>commons-beanutils</artifactId>
    <version>1.9.4</version>
</dependency>

Maven Central

How do I read mapped bean’s property value?

By Wayan in Apache Commons, Commons Beanutils 0 Comment

In this example you’ll see how to read mapped property value of a bean. We use PropertyUtils.getMappedProperty() method the read the mapped property of the Record object that consist of Track objects.

package org.kodejava.commons.beanutils;

import org.apache.commons.beanutils.PropertyUtils;
import org.kodejava.commons.beanutils.support.Track;
import org.kodejava.commons.beanutils.support.Record;

import java.util.HashMap;
import java.util.Map;

public class ReadMapProperty {
    public static void main(String[] args) {
        Record record = new Record();
        record.setTitle("Abbey Road");

        Track track1 = new Track();
        track1.setTitle("Come Together");

        Track track2 = new Track();
        track2.setTitle("Something");

        Map<String, Track> tracks = new HashMap<>();
        tracks.put("1", track1);
        tracks.put("2", track2);

        record.setMapTracks(tracks);

        try {
            Track track = (Track) PropertyUtils.getMappedProperty(record, "mapTracks(1)");
            System.out.println("track.getTitle() = " + track.getTitle());
        } catch (Exception e) {
            e.printStackTrace();
        }
    }
}

package org.kodejava.commons.beanutils;

import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;

public class Record {
    private Long id;
    private String title;
    private List<Track> tracks = new ArrayList<>();
    private Map<String, Track> mapTracks = new HashMap<>();

    public Long getId() {
        return id;
    }

    public void setId(Long id) {
        this.id = id;
    }

    public String getTitle() {
        return title;
    }

    public void setTitle(String title) {
        this.title = title;
    }

    public List<Track> getTracks() {
        return tracks;
    }

    public void setTracks(List<Track> tracks) {
        this.tracks = tracks;
    }

    public void setMapTracks(Map<String, Track> mapTracks) {
        this.mapTracks = mapTracks;
    }

    public Map<String, Track> getMapTracks() {
        return mapTracks;
    }
}

And here is the result of our program.

track.getTitle() = Come Together

Maven Dependencies

<dependency>
    <groupId>commons-beanutils</groupId>
    <artifactId>commons-beanutils</artifactId>
    <version>1.9.4</version>
</dependency>

Maven Central