重写Spring的PropertyPlaceholderConfigurer，从数据库加载配置数据

小灰灰 2022-09-26 00:28 251阅读 0赞

1，applicationContext.xml

用自定义扩展类DataBasePropertyPlaceholderConfigurer替换Spring的PropertyPlaceholderConfigurer

<bean id="dataBasePropertyConfigurer" class="com.crc.util.DataBasePropertyPlaceholderConfigurer">  
</bean>

2，DataBasePropertyPlaceholderConfigurer.java

package com.crc.util;
    
    import java.util.Properties;
    import org.springframework.beans.factory.config.PropertyPlaceholderConfigurer;
    
    public class DataBasePropertyPlaceholderConfigurer extends PropertyPlaceholderConfigurer
    {
    	@Override
    	public Properties mergeProperties() 
    	{
    		return ConfigPropertiesUtil.getProperties();
    	}
    	
    }

3，ConfigPropertiesUtil.java，从数据库读取配置数据的工具类

package com.crc.util;
    import java.sql.Connection;
    import java.sql.PreparedStatement;
    import java.sql.ResultSet;
    import java.sql.SQLException;
    import java.util.Properties;
    import java.util.concurrent.locks.ReentrantReadWriteLock;
    import javax.naming.Context;
    import javax.naming.InitialContext;
    import javax.naming.NamingException;
    import javax.sql.DataSource;
    import org.slf4j.Logger;
    import org.slf4j.LoggerFactory;
    
    
    public class ConfigPropertiesUtil
    {
    	private static final String JNDI_PREFIX = "java:comp/env/";
    	private static final String JNDI_NAME = "jdbc/reimburse";
    	
    	private static Properties properties = null;
    	
    	private static final ReentrantReadWriteLock readWriteLock = new ReentrantReadWriteLock();
    
    	private static final String queryString = "select t.property_key, t.property_value from appmgr.t_config_properties t";
    
    	private static final Logger logger = LoggerFactory.getLogger(ConfigPropertiesUtil.class);
    	
    	
    	private ConfigPropertiesUtil() {
    		
    	}
    	
    	
    	public static String getValueByKey(String key)
    	{
    		if(key == null || "".equals(key.trim()))
    		{
    			return "";
    		}
    		
    		loadProperties();
    		
    		return properties.get(key) == null ? "" : properties.get(key).toString();
    	}
    	
    	
    	public static Properties getProperties()
    	{
    		loadProperties();
    		return properties;
    	}
    	
    	
    	private static void loadProperties()
    	{
    		readWriteLock.readLock().lock();
    		
    		if(properties == null)
    		{
    			readWriteLock.readLock().unlock();
    			readWriteLock.writeLock().lock();
    			
    			if(properties == null)
    			{
    				properties = new Properties();
    				
    				DataSource dataSource = null;
    				Connection connection = null;
    				PreparedStatement statement = null;
    				ResultSet resultSet = null;
    				
    				Context context = null;
    				try
    				{
    					context = new InitialContext();
    				}
    				catch(NamingException e3)
    				{
    					logger.error("初始化JNDI上下文出错（加载系统配置数据）：", e3);
    					readWriteLock.writeLock().unlock();
    					return;
    				}
    				
    				try
    				{
    					dataSource = (DataSource)(context.lookup(JNDI_NAME));
    				}
    				catch(NamingException e1)
    				{
    					try
    					{
    						dataSource = (DataSource)(context.lookup(JNDI_PREFIX + JNDI_NAME));
    					}
    					catch(NamingException e2)
    					{
    						logger.error("获取JNDI数据源出错（加载系统配置数据）：", e2);
    						readWriteLock.writeLock().unlock();
    						return;
    					}
    				}
    				
    				try
    				{
    					connection = dataSource.getConnection();
    					statement = connection.prepareStatement(queryString);
    					resultSet = statement.executeQuery();
    					
    					while(resultSet.next())
    					{
    						properties.setProperty(resultSet.getString(1), resultSet.getString(2) == null ? "" : resultSet.getString(2).trim());
    					}
    					
    					logger.info("==========================加载配置数据开始============================");
    					logger.info(properties.toString());
    					logger.info("==========================加载配置数据结束============================");
    				}
    				catch(Exception e)
    				{
    					logger.error("加载系统配置数据出错：", e);
    				}
    				finally
    				{
    					if(resultSet != null)
    					{
    						try
    						{
    							resultSet.close();
    						}
    						catch(SQLException e)
    						{
    							e.printStackTrace();
    						}
    					}
    					if(statement != null)
    					{
    						try
    						{
    							statement.close();
    						}
    						catch(SQLException e)
    						{
    							e.printStackTrace();
    						}
    					}
    					if(connection != null)
    					{
    						try
    						{
    							connection.close();
    						}
    						catch(SQLException e)
    						{
    							e.printStackTrace();
    						}
    					}
    				}
    			}
    			
    			readWriteLock.readLock().lock();
    			readWriteLock.writeLock().unlock();
    		}
    		
    		readWriteLock.readLock().unlock();
    	}
    
    }