求JAVA和JSP连接数据库方法最全的类!

如题！
方法啊。不是连接和关闭啊。
比如里面有直接传一个SQL语句然后就口语直接进行判断的。比如：
public boolean check(String str) {
try {
ResultSet rs = this.executeQuery(str);
if (rs.next()) {
return true;
}
return false;
} catch (SQLException se) {

}
return false;
}
判断数据库里面是否存在搜索数据！

public int execute(String sql) {
int tag = 0;
try {
connect = DriverManager.getConnection(sqlserverUrl, sqlserverUser,
sqlserverPsw);
stmt = connect.createStatement();
tag = stmt.executeUpdate(sql);
connect.commit();
return tag;
} catch (SQLException ex) {
System.err.println(ex.getMessage());
try {
rs.close();
stmt.close();
connect.close();
} catch (Exception em) {
em.getMessage();
}
return 0;
}
}

等等等等这样的。。

package news;

import java.sql.*;

public class DBConnect {
// private String dbUrl = "jdbc:odbc:newsDB";
private String dbUser = "sa";

private String dbPass = "sa";

private Connection conn = null;

private Statement stmt = null;

/**
* 构造数据库的连接
*/
public DBConnect() throws Exception {
Class.forName("com.microsoft.jdbc.sqlserver.SQLServerDriver");
conn = DriverManager
.getConnection(
"jdbc:microsoft:sqlserver://localhost:1433;DatabaseName=newsDB",
dbUser, dbPass);
stmt = conn.createStatement();
}

/**
* 执行SQL语句返回字段集
*
* @param sql
* SQL语句
* @return ResultSet 字段集
*/
public ResultSet executeQuery(String sql) throws SQLException {
if (stmt != null) {
return stmt.executeQuery(sql);
} else