java连接mysql底层封装

 1 package com.dao.db;

 2 

 3 import java.sql.Connection;

 4 import java.sql.SQLException;

 5 

 6 /**

 7  * 数据库连接层MYSQL

 8  * @author Administrator

 9  *

10  */

11 public class DBConnection {

12     

13     

14     /**

15      * 连接数据库

16      * @return

17      */

18     public static Connection getDBConnection()

19     {

20         // 1. 注册驱动

21         try {

22             Class.forName("com.mysql.jdbc.Driver");

23         } catch (ClassNotFoundException e) {

24             // TODO Auto-generated catch block

25             e.printStackTrace();

26         }

27         // 获取数据库的连接

28         try {

29             Connection conn  = java.sql.DriverManager.getConnection("jdbc:mysql://localhost/mysql?useUnicode=true&characterEncoding=utf-8", "root", "root");

30             return conn;

31         } catch (SQLException e1) {

32             e1.printStackTrace();

33         }

34         return null;

35     }

36     

37 }

连接数据库

  1 package com.dao.db;

  2 

  3 import java.sql.Connection;

  4 import java.sql.PreparedStatement;

  5 import java.sql.ResultSet;

  6 import java.sql.ResultSetMetaData;

  7 import java.sql.SQLException;

  8 import java.sql.Types;

  9 import java.util.ArrayList;

 10 import java.util.HashMap;

 11 

 12 /**

 13  * MYSQL数据库底层封装

 14  * @author Administrator

 15  *

 16  */

 17 public class DBManager {

 18     

 19     private PreparedStatement pstmt;

 20     private Connection conn;

 21     private ResultSet rs;

 22     

 23 

 24     /**

 25      * 打开数据库

 26      */

 27     public DBManager() {

 28         conn = DBConnection.getDBConnection();

 29     }

 30     

 31     /**

 32      * 执行修改添加操作

 33      * @param coulmn

 34      * @param type

 35      * @param sql

 36      * @return

 37      * @throws SQLException

 38      */

 39     public  boolean updateOrAdd(String[] coulmn, int[] type, String sql) throws SQLException

 40     {

 41         if(!setPstmtParam(coulmn, type, sql))

 42             return false;

 43         boolean flag = pstmt.executeUpdate()>0?true:false;

 44         closeDB();

 45         return flag;

 46     }

 47     /**

 48      * 获取查询结果集

 49      * @param coulmn

 50      * @param type

 51      * @param sql

 52      * @throws SQLException

 53      */

 54     public DataTable getResultData(String[] coulmn, int[] type, String sql) throws SQLException

 55     {

 56         DataTable dt = new DataTable();

 57         

 58         ArrayList<HashMap<String, String>>list = new ArrayList<HashMap<String, String>>();

 59         

 60         if(!setPstmtParam(coulmn, type, sql))

 61             return null;

 62         rs = pstmt.executeQuery();

 63         ResultSetMetaData rsmd = rs.getMetaData();//取数据库的列名 

 64         int numberOfColumns = rsmd.getColumnCount();

 65         while(rs.next())

 66         {

 67             HashMap<String, String> rsTree = new HashMap<String, String>(); 

 68             for(int r=1;r<numberOfColumns+1;r++)

 69              {

 70                rsTree.put(rsmd.getColumnName(r),rs.getObject(r).toString());

 71              }

 72             list.add(rsTree);

 73         }

 74         closeDB();

 75         dt.setDataTable(list);

 76         return dt;

 77     }

 78     

 79     /**

 80      * 参数设置

 81      * @param coulmn

 82      * @param type

 83      * @throws SQLException 

 84      * @throws NumberFormatException 

 85      */

 86     private boolean setPstmtParam(String[] coulmn, int[] type, String sql) throws NumberFormatException, SQLException

 87     {

 88         if(sql== null) return false;

 89         pstmt = conn.prepareStatement(sql);

 90         if(coulmn != null && type != null && coulmn.length !=0 && type.length !=0   )

 91         {        

 92             for (int i = 0; i<type.length; i++) {

 93                 switch (type[i]) {

 94                 case Types.INTEGER:

 95                     pstmt.setInt(i+1, Integer.parseInt(coulmn[i]));

 96                     break;

 97                 case Types.BOOLEAN:

 98                     pstmt.setBoolean(i+1, Boolean.parseBoolean(coulmn[i]));

 99                     break;

100                 case Types.CHAR:

101                     pstmt.setString(i+1, coulmn[i]);

102                     break;

103                 case Types.DOUBLE:

104                     pstmt.setDouble(i+1, Double.parseDouble(coulmn[i]));

105                     break;

106                 case Types.FLOAT:

107                     pstmt.setFloat(i+1, Float.parseFloat(coulmn[i]));

108                     break;

109                 default:

110                     break;

111                 }

112             }

113         }

114         return true;

115     }

116     

117     /**

118      * 关闭数据库

119      * @throws SQLException

120      */

121     private void closeDB() throws SQLException

122     {

123         if(rs != null)

124         {

125             rs.close();

126         }

127         if(pstmt != null)

128         {

129             pstmt.close();

130         }

131         if(conn != null)

132         {

133             conn.close();

134         }

135         

136     }

137 }

数据层封装

 1 package com.dao.db;

 2 

 3 import java.util.ArrayList;

 4 import java.util.HashMap;

 5 import java.util.Iterator;

 6 import java.util.Map;

 7 import java.util.Set;

 8 

 9 /**

10  * 数据集封装

11  * @author Administrator

12  *

13  */

14 public class DataTable {

15     

16     public String[] column;//列字段

17     public String[][] row; //行值

18     public int rowCount = 0;//行数

19     public int colCoun = 0;//列数

20     

21     

22     public DataTable() {

23         super();

24     }

25     

26     public DataTable(String[] column, String[][] row, int rowCount, int colCoun) {

27         super();

28         this.column = column;

29         this.row = row;

30         this.rowCount = rowCount;

31         this.colCoun = colCoun;

32     }

33 

34 

35     public void setDataTable(ArrayList<HashMap<String, String>> list) {

36         rowCount = list.size();

37         colCoun = list.get(0).size();

38         column = new String[colCoun];

39         row = new String[rowCount][colCoun];

40         for (int i = 0; i < rowCount; i++) {

41             Set<Map.Entry<String, String>> set = list.get(i).entrySet();

42             int j = 0;

43             for (Iterator<Map.Entry<String, String>> it = set.iterator(); it

44                     .hasNext();) {

45                 Map.Entry<String, String> entry = (Map.Entry<String, String>) it

46                         .next();

47                 row[i][j] = entry.getValue();

48                 if (i == rowCount - 1) {

49                     column[j] = entry.getKey();

50                 }

51                 j++;

52             }

53         }

54     }

55 

56     public String[] getColumn() {

57         return column;

58     }

59 

60     public void setColumn(String[] column) {

61         this.column = column;

62     }

63 

64     public String[][] getRow() {

65         return row;

66     }

67 

68     public void setRow(String[][] row) {

69         this.row = row;

70     }

71 

72     public int getRowCount() {

73         return rowCount;

74     }

75 

76     public void setRowCount(int rowCount) {

77         this.rowCount = rowCount;

78     }

79 

80     public int getColCoun() {

81         return colCoun;

82     }

83 

84     public void setColCoun(int colCoun) {

85         this.colCoun = colCoun;

86     }

87     

88     

89 

90 }

数据集封装

 1 package com.bussiness.test;

 2 

 3 import java.sql.SQLException;

 4 import java.sql.Types;

 5 

 6 import com.dao.db.DBManager;

 7 import com.dao.db.DataTable;

 8 

 9 public class TestBusIness{

10     

11     static String searchSql = "select * from score";

12     static String insertSql = "insert into score(name, age, score)values(?,?,?)";

13     static String deleteSql = "delete from score where id = ?";

14     static String updateSql = "update score set name = ? where id = ?";

15     

16     public static void main(String[] args) {

17         intsertData();

18         searchData();

19     }

20     

21     private static void intsertData()

22     {    

23         DBManager dm = new DBManager();

24         String[] coulmn = new String[]{"wyf2",  "23", "89.5"};

25         int[] type = new int[]{Types.CHAR, Types.INTEGER, Types.DOUBLE};

26         

27         try {

28             boolean flag = dm.updateOrAdd(coulmn, type, insertSql);

29             if(flag)

30                 System.out.println("插入成功");

31         } catch (SQLException e) {

32             e.printStackTrace();

33         }

34     }

35     private static void searchData()

36     {    

37         DBManager dm = new DBManager();

38         String[] coulmn = null;

39         int[] type = null;

40         

41         try {

42             DataTable dt = dm.getResultData(coulmn, type, searchSql);

43             if(dt != null && dt.getRowCount()> 0){            

44                 for(int i = 0; i<dt.getRowCount(); i++)

45                 {

46                     for(int j = 0; j<dt.getColCoun(); j++)

47                     System.out.printf(dt.getRow()[i][j]+"\t");

48                     System.out.println();

49                 }

50             }

51             else

52                 System.out.println("查询失败");

53         } catch (SQLException e) {

54             e.printStackTrace();

55         }

56     }

57 }

测试Demo