JdbcUtils-白红宇

JdbcUtils

阅读量：4921 次

发布时间：2019-06-11

本文共 3894 字，大约阅读时间需要 12 分钟。

import java.io.IOException;import java.sql.Connection;import java.sql.DriverManager;import java.sql.PreparedStatement;import java.sql.ResultSet;import java.sql.ResultSetMetaData;import java.sql.SQLException;import java.util.ArrayList;import java.util.HashMap;import java.util.List;import java.util.Map;import java.util.Properties;public class JdbcUtils {    private static volatile JdbcUtils jdbcUtils = null;    private static Connection conn = null;    private static ResultSet rs = null;    private static PreparedStatement ps = null;    static String url = null;    static String user = null;    static String password = null;    static {        Properties p = new Properties();        try {            p.load(JdbcUtils.class.getClassLoader().getResourceAsStream(                    "com/mysql/properties/mysql.properties"));            url = p.getProperty("url");            user = p.getProperty("user");            password = p.getProperty("password");        } catch (IOException e) {            e.printStackTrace();        }    }    private JdbcUtils() {        getConn();    }    private void getConn() {        try {            Class.forName("com.mysql.jdbc.Driver");            conn = DriverManager.getConnection(url, user, password);        } catch (ClassNotFoundException e) {            e.printStackTrace();        } catch (SQLException e) {            e.printStackTrace();        }    }        public static JdbcUtils newInstance() {        if (jdbcUtils == null) {            synchronized (JdbcUtils.class) {                if (jdbcUtils == null) {                    jdbcUtils = new JdbcUtils();                }            }        }        return jdbcUtils;    }    public int insert(String sql, Object... obj) {        int result = 0;        try {            ps = conn.prepareStatement(sql);            int index = 1;            for (Object o : obj) {                ps.setObject(index++, o);            }            result = ps.executeUpdate();        } catch (SQLException e) {            e.printStackTrace();            return -1;        } finally {            close();        }        return result;    }    public int Delete(String sql, Object... obj) {        int result = 0;        try {            ps = conn.prepareStatement(sql);            int index = 1;            for (Object o : obj) {                ps.setObject(index++, o);            }            result = ps.executeUpdate();        } catch (SQLException e) {            e.printStackTrace();            return -1;        } finally {            close();        }        return result;    }    public int update(String sql, Object... obj) {        int result = 0;        try {            ps = conn.prepareStatement(sql);            int index = 1;            for (Object o : obj) {                ps.setObject(index++, o);            }            result = ps.executeUpdate();        } catch (SQLException e) {            e.printStackTrace();            return -1;        } finally {            close();        }        return result;    }    public List
       
        > select(String sql, Object... obj) {        List
        
         
          > list = new ArrayList
          
           
            >(); try { ps = conn.prepareStatement(sql); int index = 1; for (Object o : obj) { ps.setObject(index++, o); } rs = ps.executeQuery(); ResultSetMetaData rsd = rs.getMetaData(); int length = rsd.getColumnCount(); // System.out.println(length); while (rs.next()) { Map
            
              m = new HashMap
             
              (); for (int i = 1; i <= length; i++) { m.put(rsd.getColumnName(i), rs.getObject(i)); } // System.out.println(m.size()); list.add(m); } } catch (SQLException e) { e.printStackTrace(); } finally { } return list; } private void close() { try { if (rs != null) { rs.close(); } if (ps != null) { ps.close(); } } catch (SQLException e) { e.printStackTrace(); } }}