These methods are useful for programmer that do not knows wich characters represents file separator and path separator at OS that supports your application.

Linux/Unix, the methods File.separator and File.pathSeparator returns “/” and “.”, while in Windows, these methods returns “\” (or “\\” – escape) and “;”.

In recent case, the code below threw exception FileNotFoundException running over Linux, but not running over Windows:

String appPath = ctx.getRealPath();
String filePath = appPath + "\\" + "WEB-INF/classes/my/application/packages/";

File file = new File(filePath, "report.pdf");
OutputStream out = new FileOutputStream(file);
...

Worked in both systems after to replace “\\” by File.separator in line 2:

String appPath = ctx.getRealPath();
String filePath = appPath + File.separator + "WEB-INF/classes/my/application/packages/";

File file = new File(filePath, "report.pdf");
OutputStream out = new FileOutputStream(file);
...

Utilization of these methods, besides a good practice, is very usefull when same version of an application is running over differents operacional systems.

At MySQL, for example, this field is called MEMO.

Writing CLOB field

The method setAsciiStream of PreparedStatement allow to pass data to a CLOB.

ps.setAsciiStream(bindPosition, inputStream, textLength);

bindPosition – Position in PreparedStatment’s CLOB field.
inputStream – Used to pass data.
textLength – Data (text) length.

Full code:

String sql = "INSERT INTO TABLE (text) VALUES(?)";
		try{
			String txt = readTxtFile();
			ByteArrayInputStream bais = new ByteArrayInputStream(txt.getBytes());

			PreparedStatement ps = conexao.prepareStatement(sql);
			//CLOB is '?' at first position
			ps.setAsciiStream(1, bais, txt.length());

			ps.execute();

			ps.close();
		}catch (Exception e) {
			e.printStackTrace();
		}

Retrieving CLOB data

We’re using SELECT clause, this clause returns a ResultSet to fetch data and, calling getClob method, passing column name or your position in the query, it give to you a Clob object.

rs.getClob("xml");

Full code:

String sql = "SELECT xml FROM TEST";
		try{
			PreparedStatement ps = conexao.prepareStatement(sql);
			ResultSet rs = ps.executeQuery();

			while(rs.next()){
				Clob clob = rs.getClob("xml");
				BufferedReader reader = new BufferedReader(clob.getCharacterStream());
				StringBuffer strBuf = new StringBuffer();

				String linha = null;
				while((linha = reader.readLine()) != null){
					strBuf.append(linha);
//Character.LINE_SEPARATOR insert break line
					strBuf.append((char)Character.LINE_SEPARATOR);
				}

				System.out.println("=========== CLOB ===========");
				System.out.println(strBuf.toString());
			}

			rs.close();
			ps.close();
		}catch (Exception e) {
			e.printStackTrace();
		}

That’s it! Easy and painless

Download full code here

To write a BLOB see this tutorial.

After some tries I found two solutions to solve my access problem: first was pass as Java parameters the proxy’s configurations.

$ java -Dhttp.proxyHost=serv -Dhttp.proxyPort=port -Dhttp.proxyUser=user -Dhttp.proxyPassword=pass  ClassJava

-Dhttp.proxyHost = IP or host name of server proxy
-Dhttp.proxyPort = Proxy port
-Dhttp.proxyUser = User
-Dhttp.proxyPassword = Password

This way the class ClassJava will have access to internet through proxy server.

Another way, was insert the settings in own class:

public static void main(String[] args){
...
System.getProperties().put("proxySet", "true");
System.getProperties().put("http.proxyHost", "serv");
System.getProperties().put("http.proxyPort", "port");
System.getProperties().put("http.proxyUser", "user");
System.getProperties().put("http.proxyPassword", "password");
...
}

proxySet = Connect, or not, through proxy server
http.proxyHost = IP or host name of server proxy
http.proxyPortt = Proxy port
http.proxyUse = User
http.proxyPassword = Password

Using this resource you can set your application to access the internet through proxy server.

I hope help you.  Bye!

Building a transparent window

To make a Window (JFrame, JDialog …) with alpha effect, you should invoke the method AWTUtilities.setWindowOpacity. This method parameters are: the window to apply transparency and transparency degree, that can be between 0 (zero) and 1, being 0 invisible and 1 totally visible.

JFrame  window = new JFrame("My Window");

//70% of transparency
AWTUtilities.setWindowOpacity(window, .7f);
window.setSize(800,600);
window.setVisible(true);

The result will be:

Changing window shape

To change the window shape you should use the method AWTUtilities.setWindowShape. This method parameters are: window that will be changed and the new shape (java.awt.Shape) of the window.

The most efficiently form to use is to implement the method componentResized(), cause you may recompute the window and components size

Here I’ll use a triangle with 70% of transparency.

final JFrame  window = new JFrame("My Window");

try {
	//Add the ComponentListener to implement componentResized method
	window.addComponentListener(new ComponentAdapter(){
		@Override
		//building componentResized
		public void componentResized(ComponentEvent e) {
			int[] x = {0,400,800}; //Pontos X do polígono
			int[] y = {600,0,600}; //Pontos Y do polígono

			//Triangle with 800 w x 600 h
			Shape shape = new Polygon(x, y, 3);

			AWTUtilities.setWindowShape(window, shape);

			//70% of transparency
			AWTUtilities.setWindowOpacity(window, 0.7f);
		}
	});
} catch (SecurityException e) {
	// TODO Auto-generated catch block
	e.printStackTrace();
} catch (IllegalArgumentException e) {
	// TODO Auto-generated catch block
	e.printStackTrace();
}

window.setUndecorated(true); //removing title bar
window.setSize(800,600);
window.setVisible(true);

Notice that the method setUndecorated( ) was invoked with true as value. This method are responsible by hide the title bar (one with icon and the maximize, minimize and close buttons). This is really necessary, because with title bar visible the window are not be shaped.

The result:

I hope you enjoy…

PreparedStatemente.setBinaryStream(int index, Inputstream is, int length);

In sample, we set a table called FILEthat contains BLOB column called BIN.

//Normal connection, as any JDBC connection
Class.forName("oracle.jdbc.driver.OracleDriver");
Connection conn = DriverManager.getConnection("jdbc:oracle:thin:@<IP>:<PORT>:<SID>","<USER>","<PASSWORD>");

//Reading the file and retrieving an InputStream
File file= new File("<COMPLETE_FILE_PATH>");
FileInputStream fis = new FileInputStream(file);

//Preparing statement
PreparedStatement ps = conn.prepareStatement("INSERT INTO FILE(bin) VALUES(?)");

//Passing InputStream and file length
ps.setBinaryStream(1, fis, (int)file.length());

ps.execute();

ps.close();
conn.close();

I used Oracle 8i to execute this sample. I haven’t a MySQL/PostgreSQL/MS SQL Server in my dispose, then you’ll responsible for testing in this data bases and send me the results, OK

Thanks! Until next time!

To retrieve the cursor you should declare him how a REF CURSOR in Package spec.

  --Creating the REF CURSOR type
  type g_cursor is ref cursor;

In both, spec and body, you need declare an out REF CURSOR variable in procedure signature, how cited above.

  procedure PRO_RETURN_CARS(
    i_id     in     tbl_car.car_id%type,
    o_cursor in out g_cursor);

The cursor must be opened in procedure’s body to return, this way:

open o_cursor for
          select car_id, company, model, color, hp, price
          from tbl_car
          where car_id = i_id;

The complete Package:

create or replace package PAC_CURSOR is
  --Creating REF CURSOR type
  type g_cursor is ref cursor;

  --Procedure that return the cursor
  procedure PRO_RETURN_CARS(
    i_id     in     tbl_car.car_id%type,
    o_cursor in out g_cursor); -- Our cursor

end PAC_CURSOR;
/

create or replace package body PAC_CURSOR is
  procedure PRO_RETURN_CARS(
    i_id     in     tbl_car.car_id%type,
    o_cursor in out g_cursor) is

       begin
        --Opening the cursor to return matched rows
        open o_cursor for
          select car_id, company, model, color, hp, price
          from tbl_car
          where car_id = i_id;

  end PRO_RETURN_CARS;

end PAC_CURSOR;

We have Oracle side ready, now we need create Java call

How the cursors are being returned by a procedure, we’ll used a java.sql.CallableStatement instance.

CallableStatement cs = conn.prepareCall("{call PAC_CURSOR.PRO_RETURN_CARS(?,?)}");

The registerOutParameter will obtain oracle.jdbc.OracleTypes.CURSOR type and return a java.sql.ResultSet instance. We can iterate the ResultSet like a common Iterator.
Each row column returned by SELECT will be represented how a map, using correspondent getter. For example, we will call getString(<column name>) method when value of column is a varchar, getDate(<column name>) when is a date and etc.

The complete code will be like this:

//Calling Oracle procedure
CallableStatement cs = conn.prepareCall("{call PAC_CURSOR.PRO_RETURN_CARS(?,?)}");

//Defining type of return
cs.registerOutParameter("o_cursor", OracleTypes.CURSOR);
cs.setLong("i_id", id);

cs.execute();//Running the call

//Retrieving the cursor as ResultSet
ResultSet rs = (ResultSet)cs.getObject("o_cursor");

//Iterating the returned rows
while(rs.next()){
	//Getting column values
	System.out.println("ID: " + rs.getLong("car_id"));
	System.out.println("Manufacturer: " + rs.getString("company"));
	System.out.println("Model: " + rs.getString("model"));
	System.out.println("Color: " + rs.getString("color"));
	System.out.println("HP: " + rs.getString("hp"));
	System.out.println("Price: " + rs.getFloat("price"));
}

In the end you will get any value returned in a SELECT clause.

See ya!

I’ve been there too, then I found a easy and with many resources solution: JSmooth

This software allow you “transform” your JAR file in an executable (EXE), but, of course, will need the JVM already installed and running.

Here I only have mentioned the settings that I consider important, then let’s go!

After install (or unzip, this depends of file that you have downloaded) run him;

In the side menu, click in “Skeleton”;

In the “Skeleton Selection” screen you need define how application will be run, select “Window Wrapper”.

In “Skeleton Properties”, you need define a message when user have no JVM installed (“Message” field) and where can be downloaded (“URL” field).

The “Launch java app in the exe process” field define if JAR file will be executed in same process of EXE (only the executable process will be displayed in Windows Task Manager), otherwise the javaw.exe will be displayed too.

The “Single Instance” field define if more than one instance can be opened.

“Debug Console” open the EXE from prompt window, displaying possibles outputs.

Now click in “Executable”

In “Executable Setting” you inform where EXE will be builded (“Executable Binary” field), the EXE’s icon (“Executable Icon” filed) and what will be the application execution directory.

Click in “Application”

First, click in the icon and select JAR that contains the main class.

After, select the main class in the field “Main Class” clicking in button .

In the field “Application arguments” you can inform necessaries parameters for your main class.

“Embedded JAR” field allows you to aggregate your JAR file in EXE file, in other words, only EXE file will be necessarie, because the JAR will be uncompressed by EXE in each execution.

Now click in “JVM Selection”.

Here you can define the minimum and maximum version of JVM that your application support.

The “JVM Serach Sequence” inform the seek order of javaw.exe file, in this case, he search in resgistry first, after in JAVA_HOME enviroment and so.

Click in “JVM Configuration”.

Here the maximum and minimum memory available for your application can be configured, as the options that can passed to JVM.

Until here we only have configured the JSmooth. To build the EXE file click in button . If you don’t have saved the project, a new window will open to choose the place to save. Done it, the EXE file will be create in directory mentioned in “Executable Binary” field of “Executable” screen.

Now just execute the EXE file and your application will be run!

To more information visit http://jsmooth.sourceforge.net/

I hope you enjoyed, feel free to comment!

Until next!

For this tutorial, we’ll need create the table TBL_CLASS and add your primary key as foreign key in TBL_USER table.

--num class is PK and desc_class description
create table TBL_CLASS (num_class number, desc_class varchar(100));
alter table TBL_CLASS add primary key(num_class);

alter table TBL_USER add num_class number;
alter table TBL_USER add constraint FK_CLASS foreign key(num_class) references tbl_class(num_class);

Now we need to include the new types:

create or replace type class_type as object (num_class number, desc_class varchar2(100), users arr_users);
/
create or replace type arr_class as table of class_type;
/

The class_type type will be the Java Object. Notice that in your signature was included the arr_users type, that will be our collection of user_type (read previous post for more information), the arr_class type will be the class_type collection.

Now we’ll include the procedure that returns our class_type collection.

procedure pro_select_class(clas in class_type, class_return in out arr_class)is
  class_ref_cur ref_cur;
  --class_type array
  classes arr_class := arr_class();

  begin
    open class_ref_cur for
      select cast(
                multiset(
                  select num_class,
                         desc_class,
                         (select cast(
                                  multiset(
                                    select user_name,
                                           height,
                                           b_date
                                    from tbl_user
                                    --JOIN with TBL_USER
                                    where tbl_user.num_class = tbl_class.num_class
                                  ) as arr_users)
                          from dual) users
                  from tbl_class
                  --Using num_class attribute of in parameter
                  where num_class = clas.num_class) as arr_class
      ) classes
    from dual;

    --including the return in array
    fetch class_ref_cur into classes;
    --transferring arrar to variable out
    class_return := classes;
end pro_select_class;

Notice that procedure receive class_type as parameter in and returns arr_class type.

Separating code charge back and set up our objects, we have:

--Mount return
select cast(
        multiset(

          --Will returns the objects class_type and your attributes
          select num_class,
                 desc_class,

                 --Populate user_type collection
                 (select cast(
                          multiset(
                            select user_name,
                                   height,
                                   b_date
                            from tbl_user
                            where tbl_user.num_class = tbl_class.num_class
                          ) as arr_users)

                  from dual) users

          from tbl_class
          where num_class = clas.num_class) as arr_class
) classes
from dual;

Oracle objects done, now the Java code!

We’ll create the object that will be interpreted by the Oracle. Called TypeClass:

public class TypeClass implements SQLData{
	public static final String ORACLE_OBJECT_NAME = "CLASS_TYPE"; //Type name in Oracle
	public static final String ORACLE_CLASS_ARRAY_NAME = "ARR_CLASS"; //Array name in Oracle

        //Attibutes of TBL_CLASS table
	private Long number;
	private String desc;
	private Array users; //This will be user_type collection (or TypeUser in Java)

	public String getSQLTypeName() throws SQLException {
		return ORACLE_OBJECT_NAME;
	}

	public void readSQL(SQLInput stream, String typeName) throws SQLException {
		setNumber(stream.readLong());
		setDesc(stream.readString());
		setUsers(stream.readArray());//Used by JDBC driver to read the collection
	}

	public void writeSQL(SQLOutput stream) throws SQLException {
		stream.writeLong(getNumber());
		stream.writeString(getDesc());
		stream.writeArray(getUsers());//Used by JDBC driver to write the collection
	}
	//Getters and setters omitted
}

We need to map types interpreted in request, this way:

Map> typeMaps = connection.getTypeMap();
typeMaps.put(TypeUser.ORACLE_OBJECT_NAME, TypeUser.class);
typeMaps.put(TypeClass.ORACLE_OBJECT_NAME, TypeClass.class);

We need to map the arrays too:

typeMaps.put(TypeClass.ORACLE_CLASS_ARRAY_NAME, TypeClass[].class);//returned by procedure
typeMaps.put(TypeUser.ORACLE_USER_ARRAY_NAME, TypeUser[].class);//returned by class_type collection

For request, we do:

cs = conn.prepareCall("{call PAC_BEAN.PRO_SELECT_CLASS(?,?)}");
//registering out type, that will be a TypeClass array
cs.registerOutParameter("class_return", OracleTypes.ARRAY, TypeClass.ORACLE_CLASS_ARRAY_NAME);

//passing parameter object
cs.setObject("clas", classQry);

cs.execute();
//retrieving and looping the TypeClass array
Object[] array = (Object[])cs.getArray("class_return").getArray();

for(Object obj : array){
	TypeClass objClass = ((TypeClass)obj);

	System.out.println("Description: "+objClass.getDesc());

        //Here we obtains user_type(TypeUser) array returned by query.
	Object[] userArray = (Object[])objClass.getUsers().getArray();
	for(Object user : userArray){
		System.out.println("\tName: " + ((TypeUser)user).getName());
		System.out.println("\tHeight: " + ((TypeUser)user).getHeight());
		System.out.println("\tBirth: " + sdf.format(((TypeUser)user).getBirth())+ "\r\n");
	}
}

In the end you’ll have a java.sql.Array of TypeUser in getUsers() attribute of TypeClass.

Here I fulfilled my promise. Download the source code of this sample (with previous post sample too) here.

Until next time!

I thinking about the complexity of a class that takes screen shots and store the files in hard disk and, asking to “uncle G”, I fonded the class Robot, that provide createScreenCapture method.

Now I’ll show how to implement this functionality:

Robot robot = new Robot();
//Setting the rectangle that mark capture area. In this case, will be all screen..
Rectangle rect = new Rectangle(Toolkit.getDefaultToolkit().getScreenSize());

BufferedImage img = robot.createScreenCapture(rect);

Here we defined capture area and obtained a BufferedImage, our image. Now, we needed to persist in hard disk.

//Capturing the ImageWriter and ImageWriterParam
ImageWriter writer = ImageIO.getImageWritersByFormatName("jpeg").next();
ImageWriteParam iwp = writer.getDefaultWriteParam();

//Setting compression mode and the image quality
iwp.setCompressionMode(ImageWriteParam.MODE_EXPLICIT);
iwp.setCompressionQuality(1);

//Persisting the image
writer.setOutput(new FileImageOutputStream(arquivo));

IIOImage iioimage = new IIOImage(img, null, null);

writer.write(null, iioimage, iwp);
writer.dispose();

We captured the ImageWriter and ImageWriterParam to set the compression method and the image quality.

In line 07 we defined the image quality as 1, where the value can be between 0 (zero), more compression and less quality and 1 (one), less compression and more quality. Then we have kept the file in HD.

We’ve done! Simple, isn’t?

Download this sample here.

See ya!

public class MaxLengthTextDocument extends PlainDocument {
	//Store maximum characters permitted
	private int maxChars;

	@Override
	public void insertString(int offs, String str, AttributeSet a)
			throws BadLocationException {
		if(str != null && (getLength() + str.length() < maxChars)){
			super.insertString(offs, str, a);
		}
	}

	//getter e setter omitted
}

Here we defined one class called MaxLengthTextDocument that extends PlainDocument. In insertString attribute, we checked if quantity of characters minor than maxChars attribute, inserting in String if true.

After this, only insert our implementation in JTextField, this way:

	...
	MaxLengthTextDocument maxLength = new MaxLengthTextDocument();
	maxLength.setMaxChars(50);//50 is a maximum number of character 

	jTextField.setDocument(maxLength);
	...

And voilà!

See ya!

...
JLabel jLabel = new JLabel("My JLabel");
//Border used as padding
Border paddingBorder = BorderFactory.createEmptyBorder(10,10,10,10);

jLabel.setBorder(BorderFactory.createCompoundBorder(border,paddingBorder));
...

Here, the JLabel contains a padding with 10 pixels in top, right, bottom and left, respectively.

If you want to put border around the JLabel, you can use a CompoundBorder, setting Border and EmptyBorder (padding):

...
JLabel jLabel = new JLabel("Meu JLabel");
//Border used as padding
Border paddingBorder = BorderFactory.createEmptyBorder(10,10,10,10);
//JLabel will be involved for this border
Border border = BorderFactory.createLineBorder(Color.BLUE);

jLabel.setBorder(BorderFactory.createCompoundBorder(border,paddingBorder));
...

Download the source code of this sample here.

Setting iBatis

Unlike another frameworks, to configure iBatis you need only one XML file, called SqlMapConfig.

The mains sections of XML are:

<properties resource="tuto/ibatis/config/SqlMap.properties"/>

This code is optional and specifies the .properties file that’ll be used to declare variables used in configuration.

<typeAlias alias="car" type="tuto.ibatis.beans.Car"/>

Defines the JavaBean used and your alias. You can set much lines, depending of modeling complexity.
In example, we’ll Car bean below:

public class Car {
	private Long carId;
	private String company;
	private String model;
	private String color;
	private Integer	hp;
	private Float price;

	//Setters and getters omitted
}

<transactionManager type="JDBC">
    <dataSource type="SIMPLE">
        <property name="JDBC.Driver" value="${driver}"/>
        <property name="JDBC.ConnectionURL" value="${url}"/>
        <property name="JDBC.Username" value="${username}"/>
        <property name="JDBC.Password" value="${password}"/>
    </dataSource>
</transactionManager>

Parameters used in database connection. The variables ${driver}, ${url}, ${username} and ${password} are defined in .properties file in section properties. If you prefer, can put the values directly in fields.

See the complete file:

<?xml version="1.0" encoding="UTF-8"?>

<!DOCTYPE sqlMapConfig PUBLIC "-//ibatis.apache.org//DTD SQL Map Config 2.0//EN"
        "http://ibatis.apache.org/dtd/sql-map-config-2.dtd">

<sqlMapConfig>
    <properties resource="tuto/ibatis/config/SqlMap.properties"/>

    <settings
        cacheModelsEnabled="true"
        enhancementEnabled="true"
        lazyLoadingEnabled="true"
        maxRequests="32"
        maxSessions="10"
        maxTransactions="5"
        useStatementNamespaces="false" />

    <typeAlias alias="car" type="tuto.ibatis.beans.Car"/>

    <transactionManager type="JDBC">
        <dataSource type="SIMPLE">
            <property name="JDBC.Driver" value="${driver}"/>
            <property name="JDBC.ConnectionURL" value="${url}"/>
            <property name="JDBC.Username" value="${username}"/>
            <property name="JDBC.Password" value="${password}"/>
        </dataSource>
    </transactionManager>

    <sqlMap resource="tuto/ibatis/sqlmaps/CarSqlMap.xml"/>
</sqlMapConfig>

The properties have this content:

driver=oracle.jdbc.OracleDriver
url=jdbc:oracle:thin:@<host>:<porta>:<sid>
username=<login>
password=<senha>

Next you need to configure the SqlMap. This XML contains the querys used in application and your name need be equals described in sqlMap section of SqlMapConfig, in our case will be CarSqlMap.xml

In example only we will see utilization of tags select, insert, update and delete.

<select id="getCars" resultClass="tuto.ibatis.beans.Car"
	parameterClass="java.lang.Long">
    SELECT COMPANY  as company,
           MODEL    as model,
           COLOR    as color,
           HP       as hp,
           PRICE    as price
    FROM TBL_CAR
    WHERE CAR_ID = #var#
</select>

Execute the select statement can return a single object or one collection of objects, the type is same of resultClass attribute, o parameterClass is the type sent to execute the query and the id is the query identification call.

We will use the SqlMap below:

<?xml version="1.0" encoding="UTF-8"?>

<!DOCTYPE sqlMap PUBLIC "-//ibatis.apache.org//DTD SQL Map 2.0//EN"
	"http://ibatis.apache.org/dtd/sql-map-2.dtd">

<sqlMap namespace="Car">
    <select id="getCars" resultClass="tuto.ibatis.beans.Car"
    parameterClass="java.lang.Long">
        SELECT COMPANY  as company,
               MODEL    as model,
               COLOR    as color,
               HP       as hp,
               PRICE    as price
        FROM TBL_CAR
        WHERE CAR_ID = #var#
    </select>

    <insert id="addCar" parameterClass="tuto.ibatis.beans.Car">
        INSERT INTO TBL_CAR (CAR_ID, COMPANY, MODEL, COLOR, HP, PRICE)
        VALUES (#carId#, #company#, #model#, #color#, #hp#, #price#)
    </insert>

    <delete id="delCar" parameterClass="java.lang.Long">
        DELETE FROM TBL_CAR WHERE CAR_ID = #var#
    </delete>

    <update id="updCar" parameterClass="tuto.ibatis.beans.Car">
        UPDATE TBL_CAR
          SET COMPANY = #company#,
              MODEL = #model#,
              COLOR = #color#,
              HP = #hp#,
              PRICE = #price#
        WHERE CAR_ID = #carId#
    </update>
</sqlMap>

Data base connection configured, now we will implements the singleton class the will used as SqlMapClient, called OracleMapConfig.

package tuto.ibatis.connection;

import java.io.Reader;

import com.ibatis.common.resources.Resources;
import com.ibatis.sqlmap.client.SqlMapClient;
import com.ibatis.sqlmap.client.SqlMapClientBuilder;

public class OracleMapConfig {
	private static final SqlMapClient sqlMapClient;

	static{
		try{
			//Defining path of SqlMapConfig and creating reader
			String res = "tuto/ibatis/config/SqlMapConfig.xml";
			Reader reader = Resources.getResourceAsReader(res);

			//Retrieving the client to SqlMap
			sqlMapClient = SqlMapClientBuilder.buildSqlMapClient(reader);
		} catch(Exception e){
			e.printStackTrace();
			throw new RuntimeException(e);
		}
	}

	//Method used to retrieve the client
	public static SqlMapClient getSqlMapClient(){
		return sqlMapClient;
	}
}

The client is responsible for execute the querys configured in SqlMap and return the results.

Executing Querys and treating the return

To call any query is too simple, only execute the correspondent method of client class.

The select can be called this way:

OracleMapConfig.getSqlMapClient().queryForObject("<id>", <parâmetro>);

Theid need be equals of id specified in SqlMap

Only one line is return in code above, to get all lines change to queryForList, this way:

OracleMapConfig.getSqlMapClient().queryForList("<id>", <parâmetro>);

Will be returned a Collection containing the objects;

Select

try{
	Car car = (Car)OracleMapConfig.getSqlMapClient().queryForObject("getCars",
		new Long(readKeyboard()));

	System.out.println("Company: "+car.getCompany());
	System.out.println("Model: "+car.getModel());
	System.out.println("Color: "+car.getColor());
	System.out.println("HP: "+car.getHp());
	System.out.println("Price: "+car.getPrice());
}catch (Exception e) {
	e.printStackTrace();
}

The id “getCars” are defined in select attributes of SqlMap, providing one Long type and retrieving a Car type, both defined in line <select id=”getCars” resultClass=”tuto.ibatis.beans.Car” parameterClass=”java.lang.Long“>.

Insert

try{
	OracleMapConfig.getSqlMapClient().insert("addCar", newCar);
}catch (Exception e) {
	e.printStackTrace();
}

Now we will provide as parameter a Car type, <insert id=”addCar” parameterClass=”tuto.ibatis.beans.Car“>, and call the methods using sharp (#), this way:

INSERT INTO TBL_CAR (CAR_ID, COMPANY, MODEL, COLOR, HP, PRICE)
VALUES (#carId#, #company#, #model#, #color#, #hp#, #price#)

Delete

try{
	int lines = OracleMapConfig.getSqlMapClient().delete("delCar",
		new Long(readKeyboard()));

	System.out.println(lines + " lines deleted");
}catch (Exception e) {
	e.printStackTrace();
}

The method delete of client return a type int, this represents the number of rows deleted.

Update

try{
	int lines = OracleMapConfig.getSqlMapClient().update("updCar", car);

	System.out.println(lines + " cars updated");
}catch (Exception e) {
	e.printStackTrace();
}

Update return a type int, this represents the number of rows affected by update.

How you see, with only three XML and three classes we built a simple storage management and price consulting system.

You can download the source code of this tutorial clicking here.

Until next post!

This tutorial only work with Oracle9i , or above, and using the JDBC driver ojdbc14g, or above.

First, we create the tables, objects and procedures. Remember: the types tbl_users and user_type must be declared out of packages, as global types:

-- Creating table
create table tbl_user(user_name varchar2(100), height number, b_date date);
/
--Creating type user_type (own bean)
create or replace type user_type as object (user_name varchar2(100), height number, birth_date date);
/
--Creating type arr_users, table of user_type (array of user_type)
create or replace type arr_users as table of user_type;
/

Creating specification and body of package.

--Spec
create or replace package PAC_BEAN is
  type ref_cur is ref cursor;

  -- Procedure used to insert values
  procedure pro_insert_user(usu in user_type);

  -- Procedure used to select
  procedure pro_select_user(usu in user_type, user_return in out arr_users);
end PAC_BEAN;
/

--Body
create or replace package body PAC_BEAN is
  --The insert procedure will receive user_type and put him into table tbl_user.
  procedure pro_insert_user(usu in user_type) is
    begin
      insert into tbl_user (user_name, height, b_date)
      values (usu.user_name, usu.height, usu.birth_date);

      commit;
    exception
      when others then
        rollback;
  end pro_insert_user;

  --The procedure used for select will receive a user_type (where clause) and will return the array arr_users
  procedure pro_select_user(usu in user_type, user_return in out arr_users)is
    user_ref_cur ref_cur;

    --Instancing the array
    users arr_users := arr_users();

    begin
      --Opening the cursor that will return the array
      open user_ref_cur for
        select cast(
                 multiset(
                   select user_name,
                          height,
                          b_date
                   from tbl_user
                   where user_name like '%'||usu.user_name||'%'
                 ) as arr_users
              ) arr
        from dual;

      --Putting the cursor into arr_users instance.
      fetch user_ref_cur into users;

      --Returning the instance through OUT variable
      user_return := users;
  end pro_select_user;
end PAC_BEAN;
/

See CAST and MULTISET about how they work.

Built database objects, we need prepare the JavaBean. It’ll an implementation of java.sql.SQLData, because it will be necessary to implement the methods:

getSQLTypeName() – Getter used to obtain the name of type.

readSQL(SQLInput, String) – Used to convert an object in Java object.

writeSQL(SQLOutput stream) – Used to mount a SQL object, used byJDBC Driver.

public class TypeUser implements SQLData{
	//Name declared in Oracle
	public static final String ORACLE_OBJECT_NAME = "USER_TYPE";
	//Array name declared in Oracle
	public static final String ORACLE_USER_ARRAY_NAME = "ARR_USERS";

	//The attributes
	private String name;
	private Float height;
	private Date birth;

	public TypeUser() {
		height = 0F;
	}

	public String getSQLTypeName() throws SQLException {
		return ORACLE_OBJECT_NAME;
	}

	public void readSQL(SQLInput stream, String typeName) throws SQLException {
		setName(stream.readString());
		setHeight(stream.readFloat());
		setBirth(stream.readDate());
	}

	public void writeSQL(SQLOutput stream) throws SQLException {
		stream.writeString(getName());
		stream.writeFloat(getHeight());
		stream.writeDate(getBirth() != null ?
				new java.sql.Date(getBirth().getTime()) : null);
	}

        //getters and setters omitted
}

To define a type that can will be send to procedure be necessary add him  into type map through Connection.getTypeMap(). This method return the Map<String,Class<?>>, where type name is the key and class of SQLData implementation is the value, in own case the type TypeUser. Sample:

Map<String,Class<?>> typeMaps = connection.getTypeMap();
typeMaps.put(TypeUser.ORACLE_OBJECT_NAME, TypeUser.class);

Then the connection will be:

//Making connection
Class.forName("oracle.jdbc.driver.OracleDriver");
connection = DriverManager.getConnection("jdbc:oracle:thin:@localhost:1521:<host>:<port>:<db>","<user>","<pass>");

//Mapping necessary tipes
Map<String,Class<?>> typeMaps = connection.getTypeMap();
typeMaps.put(TypeUser.ORACLE_OBJECT_NAME, TypeUser.class);

Now, we create the insert method, it receive an instance of TypeUser and Connection:

CallableStatement cs = null;
try {
	//call the procedure
	cs = conn.prepareCall("{call PAC_BEAN.PRO_INSERT_USER(?)}");

	//defining the instance of TypeUser as variable IN "usu"
	cs.setObject("usu", typeUser);

	cs.execute();
} catch (SQLException e) {
	e.printStackTrace();
}

Now, the select method. This method return a object array, then be necessary insert the type of array in Connection TypeMap. The name passed as key should be equals of Oracle’s array name and the values will be the array class, like this:

connection.getTypeMap().put(TypeUser.ORACLE_USER_ARRAY_NAME, TypeUser[].class);

To call procedure and registerOutParameter:

cs = conn.prepareCall("{call PAC_BEAN.PRO_SELECT_USER(?,?)}");
cs.registerOutParameter("user_return", OracleTypes.ARRAY, TypeUser.ORACLE_USER_ARRAY_NAME);
cs.setObject("usu", typeUserQry);

cs.execute();

To obtain the array, do it:

//user_return is the OUT variable name
Object[] array = (Object[])cs.getArray("user_return").getArray();

If until here is alright, smile, to obtain array values just iterate him and cast each index to Type User.

for(Object obj : array){
	System.out.println("Nome: " + ((TypeUser)obj).getName());
	System.out.println("Altura: " + ((TypeUser)obj).getHeight());
	System.out.println("Data de Nascimento: " + sdf.format(((TypeUser)obj).getBirth()));
}

So we can pass and retrieve simple Java objects of a Oracle procedure or function. The next step, Retrieving objects collection from Oracle procedure.

See ya!

Download the source code of this tutorial here.

<host>:<porta>:<bd>","<usuario>","<senha>"

ArrayList
The ArrayList Collection allow to store objects and null values, but your access is unordered, the first object inserted, can be a last to retrieve.

LinkedList
This implementation of Collection is like ArrayList, but the difference is in access to objects stored, where each object is returned in your inserted order.

TreeSet
If you want retrieve the objects of your Collection in specified order, this Collection can do the work! Insert values in TreeSet is equal previously classes, but your return depends of Comparable implemented in values. It sort your object values using result of compareTo method, inherited of Comparable Interface.

For more information, visits Collection Javadoc.

Thanks for Roberto Furutani!

Enjoy!

To obtain the hard drives or removable devices, use File.listRoots(). This code return a File array, where each index of array is a removable device or hard disk unit.

Follow this sample:

File[] units = File.listRoots();

for(File unit : units){
    System.out.println(unit.getAbsolutePath());
}

The code below will show you how to get any information of MP3 file:

try {
    MP3File mp3 = new MP3File("D:\\Musics\\MP3\\ACDC\\ACDC - Back In Black.mp3");
    System.out.println("Album:" + mp3.getID3v2Tag().getAlbumTitle());
    System.out.println("Band:" + mp3.getID3v2Tag().getLeadArtist());
    System.out.println("Composer:" + mp3.getID3v2Tag().getAuthorComposer());
    System.out.println("Year:" + mp3.getID3v2Tag().getYearReleased());
} catch (Exception e) {
	e.printStackTrace();
}

The result:

Album: Back in Black
Band: AC/DC
Composer: Angus Young/Brian Johnson/Malcolm Young
Year:

To change any information of any ID3 tags, try the code bellow:

mp3.getID3v2Tag().setYearReleased("1980");
mp3.save();

This library has many methods that help you to customize any MP3 file.