写的Dbutils的代码

import java.sql.Connection;import java.sql.DriverManager;import java.sql.PreparedStatement;import java.sql.ResultSet;import java.sql.SQLException;import java.sql.Statement;import org.apache.commons.dbutils.ResultSetHandler;public class DBUtil {    static String ip = "127.0.0.1";    static String database = "superbook";    static String encoding = "utf8";    static String user = "root";    static String password = "root";    static String port = "3306";    private static final String driverClassName = "com.mysql.jdbc.Driver";        private static boolean TESTMODE = false;//测试模式        public static void enableTestMode() {
   //开启测试模式        TESTMODE = true;    }        private static ThreadLocal
     
       TL = new ThreadLocal
      
       ();//本地线程    static {
   //运用静态代码块初始化加载驱动        try {            Class.forName(driverClassName);        }catch (ClassNotFoundException e) {            e.printStackTrace();        }    }        public static Connection getConnection() throws SQLException {
   //获取连接        Connection conn = null;                //从本地获取        conn = TL.get();                //拼接URL地址        String url = String.format("jdbc:mysql://%s:%s/%s?userUnicode=true&characterEncoding=%s", ip, port, database, encoding)+"&serverTimezone=GMT%2B8&useSSL=false";        //String url = "jdbc:mysql://localhost:3306/superbook?useUnicode=true&characterEncoding=utf-8&useSSL=false";        System.out.println(url);                //如果拿不到，或连接不可用        if(conn==null || conn.isClosed()) {            conn =  DriverManager.getConnection(url, user, password);            //存到ThreadLocal中            TL.set(conn);        }                return conn;    }        public static void startTransaction() {
   //关闭自动提交        try {            Connection conn = getConnection();             if(conn != null) {                conn.setAutoCommit(false);//设置自动提交失效            }        }catch(SQLException e) {            throw new RuntimeException(e);        }    }        public static void commit() {
   //提交事务        try {            Connection conn = getConnection();        if(TESTMODE) {            return;//如果是测试模式，不进行提交        }                if(conn != null) {            conn.commit();//提交        }        }catch (SQLException e) {            e.printStackTrace();        }    }        //关闭资源    public static void close(ResultSet rs) {
   //关闭结果集        try {            if (rs != null)                rs.close();        } catch (SQLException e) {            e.printStackTrace();        }    }    public static void close(Statement stmt) {          try {            if (stmt != null)                stmt.close();        } catch (SQLException e) {            e.printStackTrace();        }    }    public static void close(Connection conn) {
   //关闭连接        try {            if (conn != null)                conn.close();        } catch (SQLException e) {            e.printStackTrace();        }    }        public static void close() {
   //关闭线程连接        try {            close(getConnection());        } catch (SQLException e) {            e.printStackTrace();        }    }        /***     *      * @param sql sql语句     * @param params  插入的参数     */    public static void update(String sql, Object... params) {        Connection conn = null;        PreparedStatement stmt = null;        try {            // 建立连接            conn = getConnection();            // 预编译SQL命令，防止sql注入            stmt = conn.prepareStatement(sql);            // 设置参数            if (params != null) {                for (int i = 0; i < params.length; i++) {                    stmt.setObject(i + 1, params[i]);                }            }            // 执行SQL            stmt.executeUpdate();        } catch (SQLException e) {            throw new RuntimeException(e);        } finally {            // 释放资源            close(stmt);        }    }        /***     *      * @param sql sql语句     * @param h  解析结果集，反射为对象     * @param params sql参数     * @return     */    public static 
       
         T select(String sql, ResultSetHandler
        
          h, Object... params) {        Connection conn = null;        PreparedStatement stmt = null;        ResultSet rs = null;        try {            // 建立连接            conn = getConnection();            // 预编译SQL命令            stmt = conn.prepareStatement(sql);            // 设置参数            if (params != null) {                for (int i = 0; i < params.length; i++) {                    stmt.setObject(i + 1, params[i]);                }            }            // 执行SQL            rs = stmt.executeQuery();            // 解析结果集            T obj = h.handle(rs);            return obj;        } catch (Exception e) {            throw new RuntimeException(e);        } finally {            // 释放资源            close(rs);            close(stmt);        }    }            /**     * 根据信息查新数据     * @param sql     * @param params  查询参数      * @return  返回数据     */    public static String select(String sql,Object... params) {        Connection conn = null;        PreparedStatement stmt = null;        ResultSet rs = null;        try {            // 建立连接            conn = getConnection();            // 预编译SQL命令            stmt = conn.prepareStatement(sql);            // 设置参数            if (params != null) {                for (int i = 0; i < params.length; i++) {                    stmt.setObject(i + 1, params[i]);                }            }            // 执行SQL            rs = stmt.executeQuery();            return rs.toString();        } catch (Exception e) {            throw new RuntimeException(e);        } finally {            // 释放资源            close(rs);            close(stmt);        }    }}