DBUtil

package utils;
import org.apache.log4j.Logger;

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

public class DBUtil4Mysql {
     String JDBC_DRIVER="com.mysql.jdbc.Driver";
     String DB_URL;
     String user;
     String passwd;
    static Logger log=LogUtils.getLogger();

    /**
     * 初始化参数
     * @param dbUrl
     * @param port
     * @param dbName
     * @param user
     * @param passwd
     */
    public void init(String dbUrl, String port, String dbName, String user, String passwd){
        this.DB_URL=String.format("jdbc:mysql://%s:%s/%s",dbUrl,port,dbName);
        this.user=user;
        this.passwd=passwd;
    }

    /**
     * 获取Map<String,Object>的结果
     * @param querySql
     * @return
     */
    public Map<String,Object> queryMapResult(String querySql){
        try {
            Class.forName(JDBC_DRIVER);
        } catch (ClassNotFoundException e) {
            e.printStackTrace();
            log.error("未找到数据库驱动，数据库驱动注册失败");
        }
        Connection connection = null;
        Statement statement=null;
        ResultSet resultSet=null;
        Map<String,Object> map=null;
        try {
            connection = DriverManager.getConnection(DB_URL,user,passwd);
            statement=connection.createStatement();
            resultSet = statement.executeQuery(querySql);
            ResultSetMetaData metaData= resultSet.getMetaData();
            int count=metaData.getColumnCount();
            while (resultSet.next()){
                map=new HashMap<String, Object>();
                for(int i=1;i<=count;i++){
                    map.put(metaData.getColumnName(i),resultSet.getObject(i));
                }
            }
        } catch (SQLException e) {
            e.printStackTrace();
            log.error("获取数据失败");
        }
        close(resultSet,statement,connection);
        return map;




    }

    /**
     * 获取List<Map<String,Object>>的结果
     * @param querySql
     * @return
     */
    public List<Map<String,Object>> queryListMapResult(String querySql){
        try {
            Class.forName(JDBC_DRIVER);
        } catch (ClassNotFoundException e) {
            e.printStackTrace();
            log.error("未找到数据库驱动，数据库驱动注册失败");
        }
        Connection connection = null;
        Statement statement=null;
        ResultSet resultSet=null;
        List<Map<String,Object>> list=null;
        try {
            connection = DriverManager.getConnection(DB_URL,user,passwd);
            statement=connection.createStatement();
            resultSet = statement.executeQuery(querySql);
            ResultSetMetaData metaData= resultSet.getMetaData();
            int count=metaData.getColumnCount();
            list=new ArrayList<Map<String, Object>>();
            while (resultSet.next()){
                Map<String,Object> map=new HashMap<String, Object>();;
                for(int i=1;i<=count;i++){
                    map.put(metaData.getColumnName(i),resultSet.getObject(i));
                }
                list.add(map);
            }
        } catch (SQLException e) {
            e.printStackTrace();
            log.error("获取数据失败");
        }
        
        close(resultSet,statement,connection);
        return list;
    }

    /**
     * 关闭各连接
     * @param resultSet
     * @param statement
     * @param connection
     */
    private void close(ResultSet resultSet,Statement statement,Connection connection){
        try {
            if (resultSet != null) {
                resultSet.close();
            }
        } catch (SQLException e) {
            e.printStackTrace();
            log.error("resultSet 关闭失败");
        } finally {
            try {
                if (statement != null) {
                    statement.close();
                }
            } catch (SQLException e) {
                e.printStackTrace();
                log.error("statement 关闭失败");
            } finally {
                try {
                    if (connection != null) {
                        connection.close();
                    }
                } catch (SQLException e) {
                    e.printStackTrace();
                    log.error("connection 关闭失败");
                }
            }
        }
    }
}