André L. S.

The default implementation of JTextField not allow set maximum number of characters. To enable this resource you need implements a Document, overriding insertString method.

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!

To insert padding into a JLabel we should use an EmptyBorder, where the attribute ‘width’ will be our padding. Like this:

...
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.

When we talk about the persistence framework, we think in Hibernate/JPA. Recently I was presented to iBatis, a framework that so easy to install, to configure and to use. You can download it in your sponsor site, Apache, clicking 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!

In the enterprise where I work was a discussion about possibility to pass a Java objects into an Oracle procure or function, then I looked for and here is a simple solution to reach this objective.

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>"

I’m initiating in J2ME world, specifically games developing for mobile phones, using Eclipse with EclipseME plug-in. In my first application was presented with “Couldn’t load zayitlib.dll library” error message when tried to start J2ME Sony Ericsson W200 Emulator.

The solution founded to solve this problem was:

In the Programs Files\VoiceAge folder you’il see many files, between them, four specifics dlls called SPOTCorePlayer_51.dll, SPOTxdePlayerDLL.dll, VaAce.dll and VaMp_50.dll.

Copy this files to SonyEricsson\JavaME_SDK_CLDC\PC_Emulation\WTK2\bin folder.

Try to start the emulator again.