学步园

1 数据库配置

配置项的值来自一个叫mysql_en.properties的文件（该文件应该放到对应的CLASSPATH的目录。

mysql_en.properties

driver=com.mysql.jdbc.Driver<br /> url=jdbc:mysql://localhost:3306/dfs<br /> user=root<br /> password=123456<br /> characterEncoding=utf8<br /> minPoolSize = 3<br /> maxPoolSize = 10 

假设我们用来读取配置文件的class叫ResourceManager，我们使用jdk的ResourceBundle来读取配置文件。

package dbConnectionPool;<br /> import java.util.Locale;<br /> import java.util.ResourceBundle;<br /> public class ResourceManager {<br /> private static ResourceBundle r;<br /> static {<br /> r = ResourceBundle.getBundle("mysql", Locale.ENGLISH);<br /> }<br /> public static String getDriverClass() {<br /> return r.getString("driver");<br /> }<br /> public static String getUrl() {<br /> return r.getString("url");<br /> }<br /> public static String getUsername() {<br /> return r.getString("user");<br /> }<br /> public static String getPassword() {<br /> return r.getString("password");<br /> }<br /> public static String getCharacterEncoding() {<br /> return r.getString("characterEncoding");<br /> }<br /> public static int getMinPoolSize() {<br /> int poolSize = Integer.valueOf(r.getString("minPoolSize"));<br /> return poolSize;<br /> }<br /> public static int getMaxPoolSize() {<br /> int poolSize = Integer.valueOf(r.getString("maxPoolSize"));<br /> return poolSize;<br /> }<br /> public static void refresh() {<br /> r = ResourceBundle.getBundle("resourceBundle");<br /> }<br /> }<br />  

只需要告诉ResourceBundle文件名是"mysql"就足够了。下划线和后面的"en"表示的是本地化信息。这里的en代表"ENGLISH"，后缀properties是默认的。

2  连接池代码

package dbConnectionPool;<br /> import java.sql.Connection;<br /> import java.sql.DriverManager;<br /> import java.sql.SQLException;<br /> import java.util.ArrayList;<br /> import java.util.List;<br /> public class DbConnectionPool {<br /> private List<Connection> pool;<br /> private int minSize = 3;<br /> private int maxSize = 10;<br /> private static DbConnectionPool instance = null;<br /> /**<br /> *得到当前连接池的一个实例<br /> */<br /> public static DbConnectionPool getInstance() {<br /> if (instance == null) {<br /> instance = new DbConnectionPool();<br /> }<br /> return instance;<br /> }<br /> /**<br /> *单例模式私有构造方法，获得本类的对象，通过getIstance方法。<br /> */<br /> private DbConnectionPool() {<br /> pool = new ArrayList<Connection>();<br /> int min_Size = ResourceManager.getMinPoolSize();<br /> int max_Size = ResourceManager.getMaxPoolSize();<br /> if (min_Size > 0 && max_Size > 0 && min_Size < max_Size) {<br /> this.minSize = min_Size;<br /> this.maxSize = max_Size;<br /> }<br /> System.out.println(this.minSize);<br /> System.out.println(this.maxSize);<br /> initPool();<br /> }<br /> /**<br /> *连接池初始化，生成最小数目的连接<br /> */<br /> private void initPool() {<br /> Connection conn = null;<br /> for (int i = 0; i < minSize; i++) {<br /> conn = createConnection();<br /> if (conn != null)<br /> pool.add(conn);<br /> }<br /> }<br /> /**<br /> *创建连接<br /> */<br /> private Connection createConnection() {<br /> Connection conn = null;<br /> try {<br /> Class.forName(ResourceManager.getDriverClass());<br /> conn = DriverManager.getConnection(ResourceManager.getUrl()<br /> + "?characterEncoding="<br /> + ResourceManager.getCharacterEncoding(), ResourceManager<br /> .getUsername(), ResourceManager.getPassword());<br /> } catch (ClassNotFoundException e) {<br /> e.printStackTrace();<br /> } catch (SQLException e) {<br /> e.printStackTrace();<br /> }<br /> return conn;<br /> }<br /> /**<br /> *得到连接池中的一个连接<br /> */<br /> public synchronized Connection getConnection() {<br /> if (pool.size() > 0) {<br /> Connection conn = pool.get(0);<br /> pool.remove(conn);<br /> return conn;<br /> } else {<br /> return createConnection();<br /> }<br /> }<br /> /**<br /> *用完将连接放回到连接池中<br /> */<br /> public synchronized void releaseConnection(Connection conn) {<br /> if (pool.size() < maxSize)<br /> pool.add(conn);<br /> else<br /> try {<br /> conn.close();<br /> conn = null;<br /> } catch (SQLException e) {<br /> e.printStackTrace();<br /> }<br /> }<br /> /**<br /> *关闭连接池中的所有连接<br /> */<br /> public synchronized void closePool() {<br /> Connection conn = null;<br /> for (int i = 0; i < pool.size(); i++) {<br /> try {<br /> conn = (Connection) pool.get(i);<br /> conn.close();<br /> pool.remove(i);<br /> } catch (SQLException e) {<br /> e.printStackTrace();<br /> }<br /> }<br /> }</p> <p> public synchronized int getConnectionNum(){<br /> return pool.size();<br /> }<br /> }<br />