Apesar de estar um pouco atrasado este post, gostaria de mesmo assim de mostrar a listagem dos artigos da ultima edição da revista MundoJava.
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Arquivo para Maio 12th, 2008
Revista Mundo Java Abril 2008
Escrito por wpjr2 em Maio 12, 2008
Enviado em Noticias | Tagged: Mundo Java, Revista | Nenhum comentário »
AWT, Swing e SWT: Comparação
Escrito por wpjr2 em Maio 12, 2008
Segue abaixo alguns links interessantes sobre as principais bibliotecas de interface gráfica no JavaSE:
Comparação:
SWT:
- SWT Homepage
- Widgets do SWT
- SWT Programming with Eclipse
- Constructing SWT Layouts
- Configuração do SWT No Eclipse e fora dele com exemplos
Outras alternativas:
Enviado em Curso de Programação Java | Tagged: Swing, AWT, SWT | Nenhum comentário »
JDBC: Tipos de Drivers
Escrito por wpjr2 em Maio 12, 2008
JDBC driver types
JDBC drivers are divided into four types or levels. Each type defines a JDBC driver implementation with increasingly higher levels of platform independence, performance, and deployment administration. The four types are:
- Type 1: JDBC-ODBC Bridge
- Type 2: Native-API/partly Java driver
- Type 3: Net-protocol/all-Java driver
- Type 4: Native-protocol/all-Java driver
Type 1: JDBC-ODBC Bridge
The type 1 driver, JDBC-ODBC Bridge, translates all JDBC calls into ODBC (Open DataBase Connectivity) calls and sends them to the ODBC driver. As such, the ODBC driver, as well as, in many cases, the client database code, must be present on the client machine. Figure 1 shows a typical JDBC-ODBC Bridge environment.
Figure 1. Type 1: JDBC-ODBC Bridge
Pros
The JDBC-ODBC Bridge allows access to almost any database, since the database’s ODBC drivers are already available. Type 1 drivers may be useful for those companies that have an ODBC driver already installed on client machines.
Cons
- The performance is degraded since the JDBC call goes through the bridge to the ODBC driver, then to the native database connectivity interface. The result comes back through the reverse process. Considering the performance issue, type 1 drivers may not be suitable for large-scale applications.
- The ODBC driver and native connectivity interface must already be installed on the client machine. Thus any advantage of using Java applets in an intranet environment is lost, since the deployment problems of traditional applications remain.
Type 2: Native-API/partly Java driver
JDBC driver type 2 — the native-API/partly Java driver — converts JDBC calls into database-specific calls for databases such as SQL Server, Informix, Oracle, or Sybase. The type 2 driver communicates directly with the database server; therefore it requires that some binary code be present on the client machine.
Figure 2. Type 2: Native-API/partly Java driver
Pros
Type 2 drivers typically offer significantly better performance than the JDBC-ODBC Bridge.
Cons
The vendor database library needs to be loaded on each client machine. Consequently, type 2 drivers cannot be used for the Internet. Type 2 drivers show lower performance than type 3 and type 4 drivers.
Type 3: Net-protocol/all-Java driver
JDBC driver type 3 — the net-protocol/all-Java driver — follows a three-tiered approach whereby the JDBC database requests are passed through the network to the middle-tier server. The middle-tier server then translates the request (directly or indirectly) to the database-specific native-connectivity interface to further the request to the database server. If the middle-tier server is written in Java, it can use a type 1 or type 2 JDBC driver to do this.
Figure 3. Type 3: Net-protocol/all-Java driver
Pros
The net-protocol/all-Java driver is server-based, so there is no need for any vendor database library to be present on client machines. Further, there are many opportunities to optimize portability, performance, and scalability. Moreover, the net protocol can be designed to make the client JDBC driver very small and fast to load. Additionally, a type 3 driver typically provides support for features such as caching (connections, query results, and so on), load balancing, and advanced system administration such as logging and auditing.
Cons
Type 3 drivers require database-specific coding to be done in the middle tier. Additionally, traversing the recordset may take longer, since the data comes through the backend server.
Type 4: Native-protocol/all-Java driver
The native-protocol/all-Java driver (JDBC driver type 4) converts JDBC calls into the vendor-specific database management system (DBMS) protocol so that client applications can communicate directly with the database server. Level 4 drivers are completely implemented in Java to achieve platform independence and eliminate deployment administration issues.
Figure 4. Type 4: Native-protocol/all-Java driver
Pros
Since type 4 JDBC drivers don’t have to translate database requests to ODBC or a native connectivity interface or to pass the request on to another server, performance is typically quite good. Moreover, the native-protocol/all-Java driver boasts better performance than types 1 and 2. Also, there’s no need to install special software on the client or server. Further, these drivers can be downloaded dynamically.
Cons
With type 4 drivers, the user needs a different driver for each database.
Enviado em Curso de Programação Java | Tagged: JDBC, SQL, Type | Nenhum comentário »
Ferramentas: Eclipse 3.3 WTP + Visual Editor
Escrito por wpjr2 em Maio 12, 2008
Disponibilizei o Eclipse 3.3 WTP que utilizamos no curso de programação Java para quem quiser baixá-lo.
Nele está incluso:
- Plugins de desenvolvimento JavaEE (não foi utilizado no curso de programação Java)
- Framework JUnit para testes unitários (usado pela primeira vez no curso de programação Java)
- Visual Editor para construção de interfaces gráficas (telas) via drag and drop.
- Dentre outras
Links:
http://rapidshare.com/files/108481688/33_europaWTP.part1.rar
http://rapidshare.com/files/108477968/33_europaWTP.part2.rar
Enviado em Aplicativos | Tagged: Eclipse WTP, Visual Editor | Nenhum comentário »
Aplicação Tela Calculadora
Escrito por wpjr2 em Maio 12, 2008
Nas últimas duas turmas do curso de programação em Java, iniciamos no último
capítulo do curso a construção de uma aplicação bem simples utilizando o
plug-in do Eclipse chamado Eclipse Visual Editor para a construção de
interfaces gráficas.
O conceito que usamos foi a criação de uma calculadora que fizesse as
operações básicas de soma, subtração, multiplicação e divisão.
Segue abaixo um link contendo o projeto Eclipse de um exemplo de implementação com a calculadora funcionando. É provável que haja bugs ainda.
O processo de importação é o mesmo que fizemos em sala de aula (FILE,
IMPORT, PROJECT, EXISTING PROJECTS INTO WORKSPACE, ARCHIVE FILE, selecionar
o zip, clicar em OK).
Quem quiser extendê-la, fique a vontade. Algumas das funcionalidades
adicionais interessantes incluem:
- botão para casas decimais
- raiz quadrada, elevar um número ao quadrado, elevar um numero a n potência
- trigonométricas (seno, coseno, tag, etc).
- registros de armazenamento (botão M)
Para quem não conseguir baixar o arquivo zip contendo o projeto, o link para o arquivo no grupo está abaixo:
http://groups.google.com/group/cursojavaoo/web/calculadora.zip
Enviado em Curso de Programação Java | Tagged: Swing, AWT, Calculadora | Nenhum comentário »
