db.java

这是一个连接数据库的类

package connect;


import java.sql.*;
import java.util.logging.Level;
import java.util.logging.Logger;

public class DB {

    private PreparedStatement pstmt;

    public Connection getConn() throws IllegalAccessException, InstantiationException {
        Connection conn = null;

        try {
            try {
                Class.forName(DBConst.CLASSNAME).newInstance();
            } catch (ClassNotFoundException ex) {
                Logger.getLogger(DB.class.getName()).log(Level.SEVERE, null, ex);
            }
            conn = DriverManager.getConnection(DBConst.URL, DBConst.NAME, DBConst.PWD);

        } catch (SQLException e) {
            e.printStackTrace();
        }
        return conn;
    }

    public void add(String addSQL) {
        try {
            pstmt = getConn().prepareStatement(addSQL);
            System.out.println(pstmt);
        } catch (Exception ex) {
            System.out.println(ex);
        }

    }

    public Statement getStatement(Connection conn) {
        Statement stmt = null;
        try {
            if (conn != null) {
                stmt = conn.createStatement();
            }
        } catch (SQLException e) {
            e.printStackTrace();
        }
        return stmt;
    }

    public PreparedStatement getPstmt() {
        return pstmt;
    }

    public void setPstmt(PreparedStatement pstmt) {
        this.pstmt = pstmt;
    }

    public ResultSet getResultSet(Statement stmt, String sql) {
        ResultSet rs = null;
        try {
            if (stmt != null) {
                rs = stmt.executeQuery(sql);
            }
        } catch (SQLException e) {
            e.printStackTrace();
        }
        return rs;
    }

    public void closeConn(Connection conn) {
        try {
            if (conn != null) {
                conn.close();
                conn = null;
            }
        } catch (SQLException e) {
            e.printStackTrace();
        }
    }

    public void closeStmt(Statement stmt) {
        try {
            if (stmt != null) {
                stmt.close();
                stmt = null;
            }
        } catch (SQLException e) {
            e.printStackTrace();
        }
    }
public void closePreStmt(PreparedStatement pstmt) {
        try {
            if (pstmt != null) {
                pstmt.close();
                pstmt = null;
            }
        } catch (SQLException e) {
            e.printStackTrace();
        }
    }
    public void closeRs(ResultSet rs) {
        try {
            if (rs != null) {
                rs.close();
                rs = null;
            }
        } catch (SQLException e) {
            e.printStackTrace();
        }
    }
}