package com.mms.db;     import java.sql.Connection;  import java.sql.DriverManager;  import java.sql.ResultSet;  import java.sql.ResultSetMetaData;  import java.sql.Statement;  import java.util.ArrayList;  import java.util.HashMap;  import java.util.List;  import java.util.Map;     public  class MySqlDB {      //初始化      private MySqlDB(){}             //参数配置      public static String name= "root";      public static String pass= "root";      public static String driver= "com.mysql.jdbc.Driver";             //主库连接  jdbc:mysql//服务器地址/数据库名 ，后面的2个参数分别是登陆用户名和密码      public static String urlM= "jdbc:mysql://localhost:3306/matoldb?useUnicode=true&characterEncoding=utf-8";       //从库连接  jdbc:mysql//服务器地址/数据库名 ，后面的2个参数分别是登陆用户名和密码      public static String urlS= "jdbc:mysql://localhost:3306/matoldb?useUnicode=true&characterEncoding=utf-8";                     //数据库连接、操作、结果集      public static Connection conM;  //主库连接        public static Connection conS;  //从库连接      public static Statement st;        public static ResultSet rs;        public static int isNewDriver;  //是否注册数据库连接驱动类             public static void main(String[] args) {          //System.out.println("#Log ["+MySqlDB.getConnection()+"]");                     //MySqlDB.insertOrUpdate("delete from mi_socket where id = 1");                     //MySqlDB.getList("SELECT * from mi_socket LIMIT 0,1");          //MySqlDB.getObject("SELECT * from mi_socket where id = 1");      }                    /*       * 根据主从库标识，返回相应的主从库连接。 0主库 1从库       */      private synchronized static Connection getConnection(int ms) {            try {              //数据库驱动只注册一次              if(isNewDriver == 0){                  Class.forName(driver).newInstance();                  isNewDriver = 1;              }                             //从库，进行查询操作              if(ms == 1){                  if(conS == null){                      conS = DriverManager.getConnection(urlS, name, pass);                  }                  return conS;              }              //主库，进行增、删、改、(查)操作              else{                    if(conM == null){                      conM = DriverManager.getConnection(urlM, name, pass);                  }                  return conM;              }          } catch (Exception e) {               System.out.println("#Error log["+e.getMessage()+"]");          }            //默认主库          return conM;      }                     /*       * 执行一条新增、删除、修改操作        */      public synchronized static int insertOrUpdate(String sql) {            getConnection(0);           int count =0;            try {                st = conM.createStatement();                count = st.executeUpdate(sql);            } catch (Exception e) {                System.out.println("#Error log["+e.getMessage()+"]");           } finally{                try {                    if (st != null) {                        st.close();                        st = null;                    }                    if (conM != null) {                        conM.close();                        conM = null;                    }                } catch (Exception e2) {                    System.out.println("#Error log["+e2.getMessage()+"]");               }            }            return count;        }           /*       * 执行一条查询类SQL，返回多条记录集        */      public synchronized static List<Map> getList(String sql) {            getConnection(1);                     List<Map> list = null;              try {                st = conS.createStatement();                rs = st.executeQuery(sql);                if(rs != null){                  ResultSetMetaData md = rs.getMetaData(); //得到结果集(rs)的结构信息，比如字段数、字段名等                       int count = md.getColumnCount(); //返回此 ResultSet 对象中的列数                                      Map map = null;                     list = new ArrayList<Map>();                  while (rs.next()) {                           map = new HashMap();                           for(int i = 1; i <= count; i++) {                              //System.out.println("#Log ["+md.getColumnName(i)+"] ["+rs.getObject(i)+"]");                          map.put(md.getColumnName(i), rs.getObject(i));                           }                           list.add(map);                          }                   }           } catch(Exception e) {                System.out.println("#Error log["+e.getMessage()+"]");            } finally{                try {                    if (st != null) {                        st.close();                        st = null;                    }                    if (rs != null) {                        rs.close();                        rs = null;                    }                } catch (Exception e2) {                    System.out.println("#Error log["+e2.getMessage()+"]");               }            }                      return list;      }               /*       * 执行一条查询类SQL，返回单条记录集        */      public synchronized static Map getObject(String sql) {            getConnection(1);                      Map map = null;          try {                st = conS.createStatement();                rs = st.executeQuery(sql);                if(rs != null){                  ResultSetMetaData md = rs.getMetaData(); //得到结果集(rs)的结构信息，比如字段数、字段名等                       int count = md.getColumnCount(); //返回此 ResultSet 对象中的列数                                      map = new HashMap();                       if(rs.next()) {                              for(int i = 1; i <= count; i++) {                              //System.out.println("#Log ["+md.getColumnName(i)+"] ["+rs.getObject(i)+"]");                          map.put(md.getColumnName(i), rs.getObject(i));                           }                             }                   }           } catch (Exception e) {                System.out.println("#Error log["+e.getMessage()+"]");             } finally{                try {                    if (st != null) {                        st.close();                        st = null;                    }                    if (rs != null) {                        rs.close();                        rs = null;                    }                              } catch (Exception e2) {                    System.out.println("#Error log["+e2.getMessage()+"]");                 }            }                      return map;      }    }