java中链接数据库的具体操作以及pstmt.setObject(i+1, objects[i])这行代码的意思

package dao;
 
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
 
public class BaseDao {
    private String driver = "com.microsoft.sqlserver.jdbc.SQLServerDriver";
    private String url = "jdbc:sqlserver://localhost:1433;databaseName=EasyBuy"; 
    private String user = "sa";
    private String password = "sa";
 
    /**
     * 获取数据库连接对象
     * 
     * @return
     */
    public Connection getcConnection() {
        Connection conn = null;
        try {
            Class.forName(driver);
            conn = DriverManager.getConnection(url, user, password);
        } catch (Exception e) {
            e.printStackTrace();
        }
        return conn;
    }
    /**
     * 关闭数据库连接对象
     * @param rs
     * @param pstmt
     * @param conn
     */
    public void closeAll(ResultSet rs,PreparedStatement pstmt,Connection conn){
        try {
            if(rs!=null){
                rs.close();
            }
            if(pstmt!=null){
                pstmt.close();
            }
            if(conn!=null){
                conn.close();
            }
        } catch (Exception e) {
            e.printStackTrace();
        }
    }
    /**
     * 增删改方法
     * @param sql
     * @param objects
     * @return
     */
    public int executeUpdate(String sql,Object[] objects){
             int num=0;
             PreparedStatement pstmt=null; 
             Connection conn=getcConnection();
             try {
                pstmt=conn.prepareStatement(sql);
                for (int i = 0; i < objects.length; i++) {
                    pstmt.setObject(i+1,objects[i]); 
                }
                num=pstmt.executeUpdate();
            } catch (Exception e) {
                e.printStackTrace();
            }finally{
                closeAll(null, pstmt, conn);
            }
             return num;
    }
}