java常用sql处理函数类

java常用sql处理函数类

使用jdbc操作

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;
import java.util.HashMap;


//封装了数据库的增删改查操作

public class Sqlutil {
    /** * 连接数据库 * @param url * @param user * @param passwd * @return */
    public static Connection connect(String url, String user, String passwd) {
        Connection conn = null;
        try {
            Class.forName("com.mysql.jdbc.Driver");
        } catch (ClassNotFoundException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
        try {
            conn = DriverManager.getConnection(url, user, passwd);
        } catch (SQLException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
        return conn;
    }

/** * 查一条 * @param conn * @param sql * @return */
    public static HashMap<String, String> fetchOne(Connection conn, String sql) {
        Statement stat = null;
        ResultSet res = null;
        HashMap<String, String> map = new HashMap<>();
        try {
            stat = conn.createStatement();
            res = stat.executeQuery(sql);
            int col = res.getMetaData().getColumnCount();
            res.next();
            for (int i = 1; i < col; i++) {
                map.put(res.getMetaData().getColumnName(i), res.getString(i));
            }
        } catch (SQLException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
        return map;
    }

    /** * 查多条 * @param conn * @param sql * @return */
    public static HashMap<Integer, HashMap<String, String>> fetchAll(Connection conn, String sql) {
        Statement stat = null;
        ResultSet res = null;
        HashMap<Integer,HashMap<String, String>> map = new HashMap<>();
        try {
            stat = conn.createStatement();
            res = stat.executeQuery(sql);
            int col = res.getMetaData().getColumnCount();
            int j = 0;
            while (res.next()) {
                HashMap<String, String> tmap = new HashMap<>();
                for (int i = 1; i < col; i++) {
                    tmap.put(res.getMetaData().getColumnName(i), res.getString(i));
                }
                map.put(j, tmap);
                j++;
            }
        } catch (SQLException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
        return map;
    }

    /** * 增删改 * @param conn * @param sql * @return */
    public static int update(Connection conn, String sql) {
        Statement stat;
        int res = 0;
        try {
            stat = conn.createStatement();
            res = stat.executeUpdate(sql);
        } catch (SQLException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
        return res;
    }

}