apache commons dbcp 学习与使用

janneyabc

　　类结构
　　org
　　|_demo
　　|_dao
　　|_datasource
　　|_ConnectionTools.java
　　|_DataSourceFactory.java
　　|_PropertyDataSourceFactory.java

package org.demo.dao.datasource;
import javax.sql.DataSource;
/**
* 数据源工厂
* @author  
* @date    2010-6-18
* @file    org.demo.dao.datasource.DataSourceFactory.java
*/
public interface DataSourceFactory {
// 默认数据源名称
String defaultDataSourceName = "default";
/**
* 返回默认数据源
* @return  dataSource or null
*/
DataSource getDataSource();
/**
* 返回指定数据源
* @return  dataSource or null
*/
DataSource getDataSource(String dataSourceName);
}


package org.demo.dao.datasource;
import java.io.IOException;
import java.io.InputStream;
import java.util.HashMap;
import java.util.Iterator;
import java.util.Map;
import java.util.Properties;
import javax.naming.Context;
import javax.naming.InitialContext;
import javax.naming.NamingException;
import javax.sql.DataSource;
import org.apache.commons.dbcp.BasicDataSource;
/**
* 基于属性文件的数据源工厂
* @author  
* @date    2010-6-18
* @file    org.demo.dao.datasource.PropertyDataSourceFactory.java
*/
public class PropertyDataSourceFactory implements DataSourceFactory{
// properties
private static final String defaultFileName = "datasource.properties";
protected Map<String,Properties> datasourceParams = new HashMap<String,Properties>();
protected Map<String,DataSource> datasourceMap = new HashMap<String,DataSource>();
/**
* 构造函数
* @throws  RuntimeException
*          If the datasource.properties could not be found or property key is illegal.
* @throws  IOException
*          If could not load properties from datasource.properties
*/
public PropertyDataSourceFactory()throws IOException{
this(defaultFileName);
}
/**
* 构造函数
* @param fileName
*   The resource name
* @throws  RuntimeException
*          If the resource could not be found or property key is illegal.
* @throws  IOException
*          If could not load properties from resource
*/
public PropertyDataSourceFactory(String fileName)throws IOException{
// getResourceAsStream
InputStream in = PropertyDataSourceFactory.class.getClassLoader()
.getResourceAsStream(fileName);
if(in == null){
throw new RuntimeException("The [" + fileName + "] is not found.");
}
// load properties from stream
Properties props = new Properties();
try {
props.load(in);
} catch (IOException e){
throw new IOException("Could not load [" + fileName + "] config file.",e);
}
// analyze properties
Iterator<Object> it = props.keySet().iterator();
while(it.hasNext()){
String key = (String)it.next();
String value = props.getProperty(key);
int dotIndex = key.indexOf('.');
if(dotIndex < 1){
// dotIndex must > 1 [default.driver=oracle.jdbc.driver.OracleDriver]
throw new RuntimeException("Illegal property key [" + key + "].");
}
String datasourceName = key.substring(0,dotIndex);
key = key.substring(dotIndex + 1);
Properties params = datasourceParams.get(datasourceName);
if(params == null){
params = new Properties();
datasourceParams.put(datasourceName, params);
}
params.put(key,value);
}
}
/**
* 返回默认数据源
* @return  dataSource or null
*/
public DataSource getDataSource(){
return getDataSource(defaultDataSourceName);
}
/**
* 返回指定数据源
* @param  dataSourceName
*         The dataSource name
* @return  dataSource or null
*/
public DataSource getDataSource(String dataSourceName){
DataSource datasource = datasourceMap.get(dataSourceName);
if(datasource != null){
return datasource;
}
datasource = createDataSource(datasourceParams.get(dataSourceName));
if(datasource != null){
datasourceMap.put(dataSourceName, datasource);
}
return datasource;
}
/**
* 创建一个数据源
* @param props
* @return  dataSource or null
* @throws  IllegalArgumentException
*          If props is null
*/
protected DataSource createDataSource(Properties props){
if(props == null){
throw new IllegalArgumentException("props can not be null.");
}
if(props.getProperty("jndiName") != null){
DataSource jndiDataSource = getJndiDataSource(props);
if(jndiDataSource != null){
return jndiDataSource;
}
}
BasicDataSource dataSource = new BasicDataSource();
// required
dataSource.setDriverClassName(props.getProperty("driverClassName"));
dataSource.setUrl(props.getProperty("url"));
dataSource.setUsername(props.getProperty("username",""));
dataSource.setPassword(props.getProperty("password",""));
// options
dataSource.setInitialSize(Integer.parseInt(props.getProperty("initialSize","3")));
dataSource.setMaxActive(Integer.parseInt(props.getProperty("maxActive", "10")));
dataSource.setMaxIdle(Integer.parseInt(props.getProperty("maxIdle","5")));
dataSource.setMaxWait(Long.parseLong(props.getProperty("maxWait","-1")));
dataSource.setValidationQuery(props.getProperty("validationQuery"));
return dataSource;
}
/**
* 返回 jndi 数据源
* @param  props
* @return  dataSource or null
*/
protected DataSource getJndiDataSource(Properties props){
String jndiName = props.getProperty("jndiName");
String inContainer = props.getProperty("inContainer");
String prefix = "java:comp/env/";
if(!jndiName.startsWith(prefix) && "true".equals(inContainer)){
jndiName = prefix + jndiName;
}
//
DataSource jndiDataSource = null;
Context context = null;
try{
context = new InitialContext(props);
jndiDataSource = (DataSource)context.lookup(jndiName);
if(jndiDataSource != null){
return jndiDataSource;
}
} catch (NamingException e){
// ignore
} finally {
try{
if(context != null){
context.close();
}
} catch (NamingException e){
// ignore
}
}
return jndiDataSource;
}
}


package org.demo.dao.datasource;
import java.io.IOException;
import java.sql.Connection;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;
import javax.sql.DataSource;
/**
* 连接工具
* @author  
* @date    2010-6-18
* @file    org.demo.dao.datasource.ConnectionTools.java
*/
public abstract class ConnectionTools {
// 数据源工厂
protected static DataSourceFactory _factory;
static {
try {
_factory = new PropertyDataSourceFactory();
} catch(IOException e){
e.printStackTrace();
}
}
/**
* 返回默认数据源的连接
* @return  connection or null
*/
public static Connection getConnection(){
return getConnection(DataSourceFactory.defaultDataSourceName);
}
/**
* 返回指定数据源的连接
* @param dataSourceName
*        The dataSource name
* @return  connection or null
*/
public static Connection getConnection(String dataSourceName){
DataSource datasource = _factory.getDataSource(dataSourceName);
Connection conn = null;
if(datasource != null){
try{
conn = datasource.getConnection();
} catch (SQLException e){
e.printStackTrace();
}
}
return conn;
}
/**
* 关闭连接对象
* @param rset
*   ResultSet
* @param stmt
*        Statement
* @param conn
*        Connection
*/
public static void close(ResultSet rset,Statement stmt,Connection conn){
try { if (rset != null) rset.close(); } catch (Exception e) {}
try { if (stmt != null) stmt.close(); } catch (Exception e) {}
try { if (conn != null) conn.close(); } catch (Exception e) {}
}
}


# datasource.properties
# oracle
default.driverClassName=oracle.jdbc.driver.OracleDriver
default.url=jdbc:oracle:thin:@localhost:1521:test
default.username=scott
default.password=tiger
#

package org.demo.dao;
import java.sql.Connection;
import java.sql.ResultSet;
import java.sql.Statement;
import org.demo.dao.datasource.ConnectionTools;
//
// library dependencies:
//  * commons-dbcp-1.3.jar   [http://commons.apache.org/dbcp/download_dbcp.cgi]
//  * commons-pool-1.5.4.jar [http://commons.apache.org/pool/download_pool.cgi]
//
/**
* @author  
* @date    2010-6-18
* @file    org.demo.dao.Main.java
*/
public class Main {
/**
* @param args
*/
public static void main(String[] args)throws Exception{
// get connection
Connection conn = ConnectionTools.getConnection();
// execute business operations
Statement stmt = null;
ResultSet rset = null;
stmt = conn.createStatement();
rset = stmt.executeQuery("select 1 from dual");
int cols = rset.getMetaData().getColumnCount();
while(rset.next()){
for(int i=1;i<=cols;i++){
System.out.print("\t" + rset.getObject(i));
}
System.out.println("");
}
// close connection
ConnectionTools.close(rset, stmt, conn);
}
}