1 package it.cast.jdbc;
2
3 import java.sql.Connection;
4 import java.sql.DriverManager;
5 import java.sql.SQLException;
6 import java.util.LinkedList;
7
8 public class MyDataSource {
9
10 private static String url = "jdbc:mysql://localhost:3306/jdbc";
11 private static String username = "root";
12 private static String password = "123";
13
14 private static int initCount = 5;
15 private static int maxCount = 10;
16 private int currentCount = 0;
17
18 private LinkedList<Connection> connectionPool = new LinkedList<Connection>();
19
20 public MyDataSource() {
21 try {
22 for (int i = 0; i < initCount; i++) {
23
24 this.connectionPool.addLast(this.createConnection());
25
26 this.currentCount++;
27 }
28 } catch (SQLException e) {
29 throw new ExceptionInInitializerError(e);
30 }
31
32 }
33
34 public Connection getConnection() throws SQLException {
35 synchronized (connectionPool) {
36 if (this.connectionPool.size() > 0) {
37 return this.connectionPool.removeFirst();
38 }
39 if (this.currentCount < maxCount) {
40 this.currentCount++;
41 return this.createConnection();
42 }
43 throw new SQLException("NO Connection!!");
44 }
45
46 }
47
48 public void free(Connection conn) {
49 this.connectionPool.addLast(conn);
50 }
51
52 private Connection createConnection() throws SQLException {
53 return DriverManager.getConnection(url, username, password);
54 }
55 }
MyDataSource
1 package it.cast.jdbc;
2
3 import java.sql.CallableStatement;
4 import java.sql.Connection;
5 import java.sql.DriverManager;
6 import java.sql.PreparedStatement;
7 import java.sql.ResultSet;
8 import java.sql.SQLException;
9 import java.sql.Statement;
10
11 public class jdbcUtils {
12
13 private static String url = "jdbc:mysql://localhost:3306/jdbc?generateSimpleParameterMetadata=true";
14 private static String user = "root";
15 private static String password = "123";
16
17 private static MyDataSource myDataSource = null;
18
19 private jdbcUtils() {
20
21 }
22
23 static {
24 try {
25 Class.forName("com.mysql.jdbc.Driver");
26 myDataSource =new MyDataSource();
27 } catch (ClassNotFoundException e) {
28 e.printStackTrace();
29 }
30 }
31
32 public static Connection getConnection() throws SQLException {
33 return myDataSource.getConnection();
34 }
35
36 public static void free(ResultSet rs, Statement st, Connection conn) {
37
38 try {
39 if (rs != null)
40 rs.close();
41 } catch (SQLException e) {
42 e.printStackTrace();
43 } finally {
44
45 try {
46 if (st != null)
47 st.close();
48 } catch (SQLException e) {
49 e.printStackTrace();
50 } finally {
51
52 try {
53 if (conn != null)
54 //conn.close();
55 myDataSource.free(conn);
56 } catch (Exception e) {
57 e.printStackTrace();
58 }
59 }
60
61 }
62
63 }
64
65 public static void free(ResultSet rs, PreparedStatement ps, Connection conn) {
66
67 try {
68 if (rs != null)
69 rs.close();
70 } catch (SQLException e) {
71 e.printStackTrace();
72 } finally {
73
74 try {
75 if (ps != null)
76 ps.close();
77 } catch (SQLException e) {
78 e.printStackTrace();
79 } finally {
80
81 try {
82 if (conn != null)
83 //conn.close();
84 myDataSource.free(conn);
85 } catch (Exception e) {
86 e.printStackTrace();
87 }
88 }
89
90 }
91
92 }
93 public static void free(ResultSet rs, CallableStatement cs, Connection conn) {
94
95 try {
96 if (rs != null)
97 rs.close();
98 } catch (SQLException e) {
99 e.printStackTrace();
100 } finally {
101
102 try {
103 if (cs != null)
104 cs.close();
105 } catch (SQLException e) {
106 e.printStackTrace();
107 } finally {
108
109 try {
110 if (conn != null)
111 //conn.close();
112 myDataSource.free(conn);
113 } catch (Exception e) {
114 e.printStackTrace();
115 }
116 }
117
118 }
119
120 }
121 }
jdbcUtils
1 package it.cast.jdbc;
2
3 import java.sql.Connection;
4 import java.sql.ResultSet;
5 import java.sql.SQLException;
6 import java.sql.Statement;
7
8 public class Base {
9
10 static Connection conn = null;
11
12 public static void main(String[] args) throws SQLException, ClassNotFoundException {
13 for (int i = 0; i < 20; i++) {
14 Connection conn = jdbcUtils.getConnection();
15 System.out.println(conn);
16 //jdbcUtils.free(null, null, conn);
17 }
18 }
19
20 static void test() throws SQLException, ClassNotFoundException {
21
22
23 // 2.建立连接
24 conn = jdbcUtils.getConnection();
25
26 // 3.创建语句
27 Statement st = conn.createStatement();
28
29 // 4.执行语句
30 ResultSet rs = st.executeQuery("select * from user");
31
32 // 5.处理结果
33 while (rs.next()) {
34 System.out.println(rs.getObject(1) + "\t" + rs.getObject(2) + "\t"
35 + rs.getObject(3)+"\t" + rs.getObject(4));
36 }
37
38 //6.释放资源
39 jdbcUtils.free(rs, st, conn);
40 }
41
42 }
Base
时间： 2024-10-12 14:21:50