O Framework CLDC, não suporta APIs JDBC. Dessa forma, para conectar um bancos de dados a dispositivos que têm configuração CLDC, você precisa chamar um Servlet de MIDLets. A Conexão com o banco de dados, executa as queries, e outras funcionalidades precisam ser implementadas no Servlet.
O exemplo abaixo pega o nome do banco de dados, nome de usuário e senha do MIDlet que executa no dispositivo J2ME e passa isto para o Servlet. O estado de conexão é passado para o MIDlet:
import java.io.*;
import java.util.*;
import javax.microedition.midlet.*;
import javax.microedition.lcdui.*;
import javax.microedition.io.*;
public class testMySQL extends MIDlet implements CommandListener {
private String username;
private String url =
"http://localhost:8080/servlets-examples/servlet/getConnection";
private Display display;
private Command exit = new Command("EXIT", Command.EXIT, 1);;
private Command connect = new Command("Connect", Command.SCREEN, 1);
private TextField tb;
private Form menu;
private TextField tb1;
private TextField tb2;
DB db;
public testMySQL() throws Exception {
display = Display.getDisplay(this);
}
public void startApp() {
displayMenu();
}
public void displayMenu() {
menu = new Form("Conexao");
tb = new TextField("Informe o banco de dados: ","",30,
TextField.ANY );
tb1 = new TextField("Informe o nome de usuario: ","",30,
TextField.ANY);
tb2 = new TextField("Informe a senha: ","",30,
TextField.PASSWORD);
menu.append(tb);
menu.append(tb1);
menu.append(tb2);
menu.addCommand(exit);
menu.addCommand(connect);
menu.setCommandListener(this);
display.setCurrent(menu);
}
public void pauseApp() {}
public void destroyApp(boolean unconditional) {}
public void commandAction(Command command, Displayable screen) {
if (command == exit) {
destroyApp(false);
notifyDestroyed();
} else if (command == connect) {
db = new DB(this);
db.start();
db.connectDb(tb.getString(),tb1.getString(),tb2.getString());
}
}
public class DB implements Runnable {
testMySQL midlet;
private Display display;
String db;
String user;
String pwd;
public DB(testMySQL midlet) {
this.midlet = midlet;
display = Display.getDisplay(midlet);
}
public void start() {
Thread t = new Thread(this);
t.start();
}
public void run() {
StringBuffer sb = new StringBuffer();
try {
HttpConnection c = (HttpConnection) Connector.open(url);
c.setRequestProperty(
"User-Agent","Profile/MIDP-1.0, Configuration/CLDC-1.0");
c.setRequestProperty("Content-Language","en-US");
c.setRequestMethod(HttpConnection.POST);
DataOutputStream os =
(DataOutputStream)c.openDataOutputStream();
os.writeUTF(db.trim());
os.writeUTF(user.trim());
os.writeUTF(pwd.trim());
os.flush();
os.close();
// Obtenha a resposta da servlet page.
DataInputStream is =(DataInputStream)c.openDataInputStream();
//is = c.openInputStream();
int ch;
sb = new StringBuffer();
while ((ch = is.read()) != -1) {
sb.append((char)ch);
}
showAlert(sb.toString());
is.close();
c.close();
} catch (Exception e) {
showAlert(e.getMessage());
}
}
/* Este método leva os dados de usuário como db,usuario e senha
e passa para o servlet */
public void connectDb(String db,String user,String pwd) {
this.db = db;
this.user = user;
this.pwd = pwd;
}
/* Mostra um erro na tela*/
private void showAlert(String err) {
Alert a = new Alert("mensagem de erro");
a.setString(err);
a.setTimeout(Alert.FOREVER);
display.setCurrent(a);
}
};
}
import java.io.*;
import java.text.*;
import java.util.*;
import javax.servlet.*;
import javax.servlet.http.*;
import java.sql.*;
public class getConnection extends HttpServlet {
public void init() {
}
public void doPost(HttpServletRequest request,
HttpServletResponse response) throws ServletException,
IOException {
DataInputStream in = new DataInputStream(
(InputStream)request.getInputStream());
String db = in.readUTF();
String user = in.readUTF();
String pwd = in.readUTF();
String message ="jdbc:mysql://localhost:3306/"+db+","+user+","+pwd;
try {
connect(db.toLowerCase().trim(),user.toLowerCase().trim(),
pwd.toLowerCase().trim());
message += "100 ok";
} catch (Throwable t) {
message += "200 " + t.toString();
}
response.setContentType("text/plain");
response.setContentLength(message.length());
PrintWriter out = response.getWriter();
out.println(message);
in.close();
out.close();
out.flush();
}
public void doGet(HttpServletRequest request,
HttpServletResponse response) throws ServletException,
IOException {
doPost(request,response);
}
/* Este método faz conexão com o MYSQL*/
private void connect(String db, String user,String pwd)
throws Exception {
//Estabelece conexão JDBC com MYSQL.
//Class.forName("org.gjt.mm.mysql.Driver");
Class.forName("com.mysql.jdbc.Driver").newInstance();
Connection conn = DriverManager.getConnection(
"jdbc:mysql://localhost:3306/"+db,user,pwd);
//Estabelece conexão JDBC com Oracle
//DriverManager.registerDriver(new oracle.jdbc.OracleDriver());
//Connection conn = DriverManager.getConnection(
// "jdbc:oracle:thin:@localhost:1521:"+db,user,pwd);
//Estabelece conexão JDBC com o SQL.
//Class.forName("net.sourceforge.jtds.jdbc.Driver");
//Connection conn = DriverManager.getConnection(
// "jdbc:jtds:sqlserver://localhost:1433/"+db,user,pwd);
}
}
