JDBC浅层封装

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import java.io.IOException;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.SQLException;

/**
 * "org.sqlite.JDBC"
 * "com.mysql.jdbc.driver"
 *
 * @author 41320 ‎
 * @date 2017‎年‎4‎月‎7‎日，‏‎21:28:33
 */
public class SessionFactory {
    final static Logger log = LoggerFactory.getLogger(SessionFactory.class);
    private static String sUrl = null;

    public void build(String driver, String url) throws IOException {
        try{
            Class.forName(driver);
            SessionFactory.sUrl = url;
        } catch(Exception e){
            throw new IOException("无法建立数据库连接:" + url, e);
        }
    }

    public static Connection getConnection(){
        try {
            return DriverManager.getConnection(sUrl);
        } catch (SQLException e) {
            e.printStackTrace();
            throw new RuntimeException(e);
        }
    }

}

import java.sql.*;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;

/**
 * 作为Connection的一个包装类，提取了JDBC中常用的方法，简化数据库的操作难度，
 * 依托于SessionFactory，可以单独作为工具类使用，或者作为EasyDao的基类使用
 *
 * @author 41320
 * @date 2017‎年‎4‎月‎7‎日，‏‎21:28:33
 */
public class Session implements AutoCloseable {
    private Connection conn;

    /**
     * 执行一条Sql语句，包括Insert、Delete、Update
     * @param sql
     * @param params
     * @return
     */
    public int executeUpdate(String sql, Object... params) {
        try (PreparedStatement preparedStatement = conn.prepareStatement(sql)) {
            setParams(preparedStatement, params);
            return preparedStatement.executeUpdate(sql);
        } catch (SQLException e) {
            e.printStackTrace();
            return 0;
        }
    }

    /**
     * 执行一条带参数查询语句，通过回调函数处理结果
     * @param parser
     * @param sql
     * @param params
     * @param <T>
     * @return
     */
    public <T> T queryOne(ResultSetParser<T> parser, String sql, Object... params) {
        try (PreparedStatement preparedStatement = conn.prepareStatement(sql)) {
            setParams(preparedStatement, params);
            try (ResultSet resultSet = preparedStatement.executeQuery()) {
                resultSet.next();
                return parser.parse(resultSet);
            }
        } catch (SQLException e) {
            e.printStackTrace();
            return null;
        }
    }

    /**
     * 执行一条带参数查询语句，通过回调函数处理结果
     *
     * @param sql
     * @param params
     * @return Object
     * @throws SQLException
     */
    public Map<String, Object> queryAsMap(String sql, Object... params) {
        try (PreparedStatement preparedStatement = conn.prepareStatement(sql)) {
            setParams(preparedStatement, params);
            try (ResultSet resultSet = preparedStatement.executeQuery()) {
                ResultSetMetaData metaData = resultSet.getMetaData();
                int cols = metaData.getColumnCount();
                resultSet.next();
                Map<String, Object> map = new HashMap<>(cols);
                for (int i = 0; i < cols; i++) {
                    String key = metaData.getColumnName(i + 1);
                    Object value = resultSet.getObject(i + 1);
                    map.put(key.toUpperCase(), value);
                }
                return map;
            }
        } catch (SQLException e) {
            e.printStackTrace();
            return null;
        }
    }

    /**
     * 执行一条带参数查询语句，通过回调函数处理结果
     *
     * @param parser
     * @param sql
     * @param params
     * @return Object
     */
    public <T> List<T> queryList(ResultSetParser<T> parser, String sql, Object... params) {
        try (PreparedStatement preparedStatement = conn.prepareStatement(sql)) {
            setParams(preparedStatement, params);
            try (ResultSet resultSet = preparedStatement.executeQuery()) {
                List<T> retList = new ArrayList<T>();
                while (resultSet.next()) {
                    retList.add(parser.parse(resultSet));
                }
                return retList;
            }
        } catch (SQLException e) {
            e.printStackTrace();
            return null;
        }
    }


    /**
     * 执行一条带参数查询语句，通过回调函数处理结果
     *
     * @param sql
     * @param params
     * @return Object
     */
    public List<Map<String, Object>> queryAsListMap(String sql, Object... params) {
        try (PreparedStatement preparedStatement = conn.prepareStatement(sql)) {
            setParams(preparedStatement, params);
            try (ResultSet resultSet = preparedStatement.executeQuery()) {
                ResultSetMetaData metaData = resultSet.getMetaData();
                int cols = metaData.getColumnCount();
                List<Map<String, Object>> res = new ArrayList<>();
                while (resultSet.next()) {
                    Map<String, Object> map = new HashMap<>(cols);
                    for (int i = 0; i < cols; i++) {
                        String key = metaData.getColumnName(i + 1);
                        Object value = resultSet.getObject(i + 1);
                        map.put(key.toUpperCase(), value);
                    }
                    res.add(map);
                }
                return res;
            }
        } catch (SQLException e) {
            e.printStackTrace();
            return null;
        }
    }

    public int queryCount(String sql, Object... params) {
        try (PreparedStatement preparedStatement = conn.prepareStatement(sql)) {
            setParams(preparedStatement, params);
            try (ResultSet resultSet = preparedStatement.executeQuery()) {
                resultSet.next();
                return resultSet.getInt(1);
            }
        } catch (SQLException e) {
            e.printStackTrace();
            return 0;
        }
    }

    private int queryCntBySql(String sql, Object... params) {
        int idx = sql.indexOf(" from ");
        if (idx < 0) {
            sql = sql.toLowerCase();
            idx = sql.indexOf(" from ");
        }
        String cntSql = "select count(*) " + sql.substring(idx);
        return queryCount(cntSql, params);
    }

    public <T> Page queryPage(ResultSetParser<T> parser, String sql, Object... params) {
        Page page = new Page();
        page.list = this.queryList(parser, sql, params);
        page.total = queryCntBySql(sql, params);
        return page;
    }

    public Page queryPage(String sql, Object... params) {
        Page page = new Page();
        page.list = this.queryAsListMap(sql, params);
        page.total = queryCntBySql(sql, params);
        return page;
    }

    /**
     * 执行插入操作
     *
     * @param sql   -
     * @param args  -
     * @return 自增的ID
     */
    public Integer insert(String sql, Object... args) {
        try (PreparedStatement ps = conn.prepareStatement(sql)) {
            setParams(ps, args);
            ps.executeUpdate();
            try (ResultSet rs = ps.getGeneratedKeys()) {
                if (rs != null) {
                    return rs.getInt(1);
                }
            }
        } catch (SQLException e) {
            e.printStackTrace();
        }
        return null;
    }

    public void beginTrancation(String methodName) {
        try {
            conn.setAutoCommit(false);
        } catch (SQLException e) {
            e.printStackTrace();
        }
    }

    /**
     * 提交事务，关闭连接，并且清除引用
     */
    public void commit() {
        try {
            conn.commit();
        } catch (SQLException e) {
            e.printStackTrace();
        }
    }

    /**
     * 事务回滚
     */
    public void rollback() {
        try {
            conn.rollback();
        } catch (SQLException e) {
            e.printStackTrace();
        }
    }

    /**
     * 关闭并清除引用
     */
    @Override
    public void close() {
        try {
            if (conn != null){
                conn.close();
            }
        } catch (SQLException e) {
            e.printStackTrace();
        }
    }

    /**
     * PreparedStatement参数注入
     * @param pstmt
     * @param params
     * @throws SQLException
     */
    private void setParams(PreparedStatement pstmt, Object... params) throws SQLException {
        if (params != null) {
            for (int i = 0; i < params.length; i++) {
                pstmt.setObject(i + 1, params[i]);
            }
        }
    }

    /**
     * 结果集处理回调
     */
    @FunctionalInterface
    public interface ResultSetParser<T> {
        T parse(ResultSet rs);
    }

    /**
     * 分页，按需调整
     */
    public class Page {
        public int total;
        public List<?> list;
    }
}