MySQL工具类的封装

女爷i 2022-06-10 05:44 249阅读 0赞

\*\*MySQL工具类的封装

*核心jar包:mysql-connector-java-5.0.4-bin.jar*

package com.lg.mysql.tools;
    
    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 DbUtils { 
        private Connection conn=null; //连接
        private Statement stmt = null;//状态
        private ResultSet rs = null;//结果集
    
        //获取连接
        public void  getConnection(){
            try {
                //加载驱动
                Class.forName("com.mysql.jabc.Driver");
                //获取连接 url user password
                conn = DriverManager.getConnection("jdbc:mysql://localhost:3308/tf_26","root","mysql");
                //
                stmt = conn.createStatement();
    
            } catch (Exception e) {
                e.printStackTrace();
            }
        }
    
        //添加、修改、删除
        public int updatae(String sql){
            int reslut = -1;
    
            try {
                getConnection();
                reslut= stmt.executeUpdate(sql);
            } catch (Exception e) {
                e.printStackTrace();
            }finally{
                close();
            }
    
            return reslut;
        }
    
        //查询
        public List<Map<String, String>> query(String sql){
            List<Map<String, String>> rsList = new ArrayList<Map<String, String>>();
            try {
                getConnection();
                rs= stmt.executeQuery(sql);
                //获取字段名
                ResultSetMetaData rsmd = rs.getMetaData();
                while(rs.next()){
                    Map<String,String> rsMap = new HashMap<String, String>();
                    for(int i=0;i<rsmd.getColumnCount();i++){
                        //获取字段名
                        String columnName = rsmd.getCatalogName(i);
                        //获取字段值
                        String columnValue = rs.getString(columnName);
                        rsMap.put(columnName, columnValue);
                    }
                    rsList.add(rsMap);
                }
            } catch (Exception e) {
                e.printStackTrace();
            }finally{
                close();
            }
            return rsList;
        }
    
        //分页
        public List<Map<String,String>> paging(String sql,int nowPage,int size){
    
            sql = sql + "limit " + (nowPage+1)*size + "," + size;
    
            return query(sql);
        }
    
        //关闭
        public void close(){
            try {
                if(rs!=null){
                    rs.close();
                }
                if(stmt!=null){
                    stmt.close();
                }
                if(conn!=null){
                    conn.close();
                }
    
            } catch (Exception e) {
                e.printStackTrace();
            }
        }
    }