2.在src下新建java文件JdbcPool.java,其内容为
import java.io.IOException;
import java.io.InputStream;
import java.io.PrintWriter;
import java.lang.reflect.InvocationHandler;
import java.lang.reflect.Method;
import java.lang.reflect.Proxy;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.SQLException;
import java.sql.SQLFeatureNotSupportedException;
import java.util.LinkedList;
import java.util.Properties;
import java.util.logging.Logger;
import javax.sql.DataSource;
public class JdbcPool implements DataSource {
/**
*
* 使用LinkedList集合来存放数据库链接，
* 由于要频繁读写List集合，所以这里使用LinkedList存储数据库连接比较合适
*/
private static LinkedList<Connection> listConnections = new LinkedList<Connection>();
static{
InputStream in = JdbcPool.class.getClassLoader().getResourceAsStream("db.properties");
Properties prop = new Properties();
try {
prop.load(in);
String driver = prop.getProperty("driver");
String url = prop.getProperty("url");
String username = prop.getProperty("username");
String password = prop.getProperty("password");
//数据库连接池的初始化连接数大小
int jdbcPoolInitSize =Integer.parseInt(prop.getProperty("jdbcPoolInitSize"));
//加载数据库驱动
Class.forName(driver);
for (int i = 0; i < jdbcPoolInitSize; i++){
Connection conn = DriverManager.getConnection(url, username, password);
System.out.println("获取到了链接" + conn);
//将获取到的数据库连接加入到listConnections集合中，listConnections集合此时就是一个存放了数据库连接的连接池
listConnections.add(conn);
}
} catch (Exception e) {
// TODO Auto-generated catch block
throw new ExceptionInInitializerError(e);
}
}
@Override
public PrintWriter getLogWriter() throws SQLException {
// TODO Auto-generated method stub
return null;
}
@Override
public void setLogWriter(PrintWriter out) throws SQLException {
// TODO Auto-generated method stub
}
@Override
public void setLoginTimeout(int seconds) throws SQLException {
// TODO Auto-generated method stub
}
@Override
public int getLoginTimeout() throws SQLException {
// TODO Auto-generated method stub
return 0;
}
@Override
public Logger getParentLogger() throws SQLFeatureNotSupportedException {
// TODO Auto-generated method stub
return null;
}
@Override
public <T> T unwrap(Class<T> iface) throws SQLException {
// TODO Auto-generated method stub
return null;
}
@Override
public boolean isWrapperFor(Class<?> iface) throws SQLException {
// TODO Auto-generated method stub
return false;
}
/* 获取数据库连接
* @see javax.sql.DataSource#getConnection()
*/
@Override
public Connection getConnection() throws SQLException {
//如果数据库连接池中的连接对象的个数大于0
if (listConnections.size()>0){
//从listConnections集合中获取一个数据库连接
final Connection conn = listConnections.removeFirst();
System.out.println("listConnections数据库连接池大小是" + listConnections.size());
//返回Connection对象的代理对象
return (Connection) Proxy.newProxyInstance(JdbcPool.class.getClassLoader(), new Class[]{Connection.class}, new InvocationHandler(){
@Override
public Object invoke(Object proxy, Method method, Object[] args)
throws Throwable {
if(!method.getName().equals("close")){
return method.invoke(conn, args);
}else{
//如果调用的是Connection对象的close方法，就把conn还给数据库连接池
listConnections.add(conn);
System.out.println(conn + "被还给listConnections数据库连接池了！！");
System.out.println("listConnections数据库连接池大小为" + listConnections.size());
}
return null;
}
});
}else{
throw new RuntimeException("对不起，数据库忙");
}
}
@Override
public Connection getConnection(String username, String password)
throws SQLException {
return null;
}
}
