JDBC閫氱敤鐨勬暟鎹簱鏁版嵁鎿嶄綔[CRUD]灏佽

Posted 2021-03-04

鏍囩锛?a href='http://www.mamicode.com/so/1/false' title='false'>false   tar   column   tin   statement   椤电爜   ack   鏌ヨ   turn   

package com.lyang.dao;

import java.lang.reflect.Field;
import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.ResultSetMetaData;
import java.sql.SQLException;
import java.util.ArrayList;
import java.util.List;

import com.lyang.util.PageInfo;
import com.lyang.util.JdbcUtil;

/**
 * 閫氱敤鐨勬暟鎹簱鏁版嵁鎿嶄綔绫? */
public class BaseDao {

    /**
     * 閫氱敤鏌ヨ鏁版嵁鍒楄〃
     * @param <T>   鍏蜂綋鐨勭被
     * @param sql   sql鎸囦护
     * @param cls   鍙嶅皠绫?     * @param param 鍙傛暟
     * @return
     */
    public <T> List<T> selectList(String sql, Class<T> cls, Object... param) {
        Connection conn = JdbcUtil.getConn();
        PreparedStatement prep = null;
        ResultSet rs = null;
        List<T> data = new ArrayList<T>();
        try {
            prep = conn.prepareStatement(sql);
            //寰幆璁剧疆鍙傛暟
            for (int i = 0; i < param.length; i++) {
                prep.setObject(i + 1, param[i]);
            }
            //鏌ヨ缁撴灉
            rs = prep.executeQuery();
            while (rs.next()) {
                T bean = rsToBean(rs, cls);
                data.add(bean);
            }
        } catch (Exception e) {
            e.printStackTrace();
        } finally {
            JdbcUtil.close(conn, prep, rs);
        }
        return data;
    }

    /**
     * 鏌ヨ涓€鏉℃暟鎹?     * @param <T>   鍏蜂綋鐨勭被
     * @param sql   sql鎸囦护
     * @param cls   鍙嶅皠绫?     * @param param 鍙傛暟
     * @return
     */
    public <T> T selectOne(String sql, Class<T> cls, Object... param) {
        List<T> list = this.selectList(sql, cls, param);
        if (!list.isEmpty() && list.size() == 1) {
            return list.get(0);
        }
        return null;
    }

    /**
     * 灏哛esultSet 杞寲涓轰换鎰忓搴旂殑JavaBean
     * @param <T> 鍏蜂綋鐨勭被
     * @param rs  缁撴灉闆?     * @param cls 鍙嶅皠绫?     * @return
     */
    public <T> T rsToBean(ResultSet rs, Class<T> cls) {
        T t = null;
        try {
            t = cls.newInstance();
            // 鑾峰彇鏌ヨ缁撴灉鐨勫厓鏁版嵁
            ResultSetMetaData metaData = rs.getMetaData();
            // 鑾峰彇鍒楃殑涓暟 鏌ヨ缁撴灉鐨勫垪鐨勪釜鏁?            int columnCount = metaData.getColumnCount();
            for (int i = 0; i < columnCount; i++) {
                // 鑾峰彇鍒楀悕绉?                String columnLabel = metaData.getColumnLabel(i + 1);
                // 鑾峰彇璇ュ垪瀵瑰簲鐨勫€?                Object value = rs.getObject(columnLabel);
                // 鏍规嵁缁撴灉鍒楀悕绉?鏌ユ壘瀵瑰簲灞炴€?                Field field = cls.getDeclaredField(columnLabel);
                // 璁剧疆鏉冮檺锛屽洜涓哄睘鎬ч兘涓虹鏈夌殑锛屾棤娉曠洿鎺ヨ幏鍙?                field.setAccessible(true);
                // 涓哄睘鎬ц缃€?                field.set(t, value);
            }
        } catch (Exception e) {
            e.printStackTrace();
        }
        return t;
    }

    /**
     * 閫氱敤鍒犻櫎
     * @param sql sql鎸囦护
     * @return
     */
    public boolean deleteById(String sql) {
        Connection conn = JdbcUtil.getConn();
        PreparedStatement prep = null;
        try {
            prep = conn.prepareStatement(sql);
            int m = prep.executeUpdate();
            return m == 1 ? true : false;
        } catch (SQLException e) {
            e.printStackTrace();
        } finally {
            JdbcUtil.close(conn, prep);
        }
        return false;
    }

    /**
     * 鍚戣〃鎻掑叆鏁版嵁 杩斿洖 鑷娑ㄤ富閿€?     * @param sql   sql鎸囦护
     * @param param 鍙傛暟
     * @return
     */
    public int insert(String sql, Object... param) {
        Connection conn = JdbcUtil.getConn();
        PreparedStatement prep = null;
        ResultSet rs = null;
        try {
            // PreparedStatement.RETURN_GENERATED_KEYS锛氳繑鍥炵敓鎴愮殑key
            prep = conn.prepareStatement(sql, PreparedStatement.RETURN_GENERATED_KEYS);
            for (int i = 0; i < param.length; i++) {
                prep.setObject(i + 1, param[i]);
            }
            prep.executeUpdate();
            // 鐢熸垚鐨勪富閿?            rs = prep.getGeneratedKeys();
            if (rs != null) {
                rs.next();
                return rs.getInt(1);
            }
        } catch (SQLException e) {
            e.printStackTrace();
        } finally {
            JdbcUtil.close(conn, prep);
        }
        return 0;
    }

    /**
     * 閫氱敤鏇存柊
     * @param sql   sql鎸囦护
     * @param param 鍙傛暟
     * @return
     */
    public boolean update(String sql, Object... param) {
        Connection conn = JdbcUtil.getConn();
        PreparedStatement prep = null;
        try {
            prep = conn.prepareStatement(sql);
            for (int i = 0; i < param.length; i++) {
                prep.setObject(i + 1, param[i]);
            }
            int m = prep.executeUpdate();
            return m > 0 ? true : false;
        } catch (SQLException e) {
            e.printStackTrace();
        } finally {
            JdbcUtil.close(conn, prep);
        }
        return false;
    }

    /**
     * 鍒嗛〉鏌ヨ
     * @param <T>   鍏蜂綋鐨勭被
     * @param sql   sql鎸囦护
     * @param page  椤电爜
     * @param limit 姣忛〉鏉℃暟
     * @param cls   鍙嶅皠绫?     * @return
     */
    public <T> PageInfo<T> selectPage(String sql, Integer page, Integer limit, Class<T> cls) {
        // 鎬昏鏁?        int total = this.selectCount(sql);
        // 鏈€澶ч〉鐮?        int maxPage = total % limit == 0 ? total / limit : total / limit + 1;

        // 濡傛灉page姣旀渶澶ч〉鐮佸ぇ  鍒欏€间负鏈€澶ч〉鐮?        if (page > maxPage) {
            page = maxPage;
        }
        // 濡傛灉page鍊煎皬浜?  鍒欎负1
        if (page < 1) {
            page = 1;
        }
        int startIndex = (page - 1) * limit;
        sql = sql + "  limit " + startIndex + "," + limit;
        // 鏌ヨ鏁版嵁
        List<T> data = this.selectList(sql, cls);

        PageInfo<T> pageInfo = new PageInfo<T>(page, limit, total, maxPage, data);
        return pageInfo;
    }

    /**
     * 绗﹀悎鏉′欢鐨勬€昏鏁?     * @param sql sql鎸囦护
     * @return
     */
    private int selectCount(String sql) {
        sql = "select count(1) from (" + sql + ") as rs";
        Connection conn = JdbcUtil.getConn();
        PreparedStatement prep = null;
        ResultSet rs = null;
        try {
            prep = conn.prepareStatement(sql);
            rs = prep.executeQuery();
            rs.next();
            return rs.getInt(1);
        } catch (SQLException e) {
            e.printStackTrace();
        } finally {
            JdbcUtil.close(conn, prep, rs);
        }
        return 0;
    }

}