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JDBC连接数据库实例

package javacommon.base;

import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.ResultSetMetaData;
import java.sql.SQLException;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;

/**
 * 数据库操作类
 * @author
 *
 */

public class JDBCTemplate {	

	private Connection conn = null;
	
	private Connection getConnection() {
         if(conn == null) {
        	 conn = DBManager.getConn();
         }
         return conn;
	}
	
	public JDBCTemplate(Connection conn) {
		this.conn = conn;
	}
	
	public JDBCTemplate() {
		conn = getConnection();
	}	
	
	public Connection getConn() {
        return conn;
    }

    public void beginTranscation() throws SQLException {
		conn.setAutoCommit(false);
	}
	
	public void commit() throws SQLException {
		conn.commit();
	}
	
	@SuppressWarnings("unchecked")
	public List query(String sql, Object[] params) throws SQLException {
		
		PreparedStatement pStmt = null;
		ResultSet rSet = null;
		List list = new ArrayList();
		
		try {
			pStmt = conn.prepareStatement(sql);
			for (int i = 0; i < params.length; i++) {
				pStmt.setObject(i + 1, params[i]);
			}
			rSet = pStmt.executeQuery();
			ResultSetMetaData rsmd = rSet.getMetaData();
			String[] names = new String[rsmd.getColumnCount()];
			for (int i = 0; i < names.length; i++) {
				names[i] = rsmd.getColumnName(i + 1);
			}
			while (rSet.next()) {
				Map row = new HashMap();
				for (int i = 0; i < names.length; i++) {
					row.put(names[i], rSet.getObject(i + 1));
				}
				list.add(row);
			}
		} catch(SQLException e) {
			e.printStackTrace();
			throw e;
		} finally {
			if (rSet != null) {
				try {
					rSet.close();
				} catch(SQLException e) {}
			}
			if (pStmt != null) {
				try {
					pStmt.close();
				} catch(SQLException e) {}
			}
		}
		return list;
	}
	
	
	public int insert(String sql, Object[] params) throws SQLException {
		return executeUpdate(sql, params);
	}
	
	
	public int executeUpdate(String sql, Object[] params) throws SQLException {
		PreparedStatement pStmt = null;
		ResultSet rSet = null;
		int result = 0;
		
		try {
			pStmt = conn.prepareStatement(sql);
			for (int i = 0; i < params.length; i++) {
				pStmt.setObject(i + 1, params[i]);
			}
			result = pStmt.executeUpdate();
		} catch(SQLException e) {
			e.printStackTrace();
			throw e;
		} finally {
			if (pStmt != null) {
				try {
					pStmt.close();
				} catch(SQLException e) {}
			}
		}
		return result;		
	}
	
	public void close() {
		
		if (conn != null) {
			DBManager.closeConn(conn);
		}
		
	}
}
package javacommon.base;

import java.sql.Connection;
import java.sql.DatabaseMetaData;
import java.sql.SQLException;
import java.util.Properties;

import javax.sql.DataSource;

import org.apache.commons.dbcp.BasicDataSource;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;

/**
 * 数据库连接池管理类
 * @author
 *
 */
public class DBManager {
	private static final Log LOG = LogFactory.getLog(DBManager.class);
	private static DataSource dataSource;
	
	static {
		Properties properties = PropertiesHandler.readPropertiesFile("/opt/hr/hr-info-sync.properites");
		try {
			BasicDataSource basicDataSource = new BasicDataSource();
			if (null != properties
					.getProperty("dataSource.accessToUnderlyingConnectionAllowed")) {
				basicDataSource
						.setAccessToUnderlyingConnectionAllowed(Boolean.valueOf(properties
								.getProperty("dataSource.accessToUnderlyingConnectionAllowed")));
			}
			// if (null !=
			// properties.getProperty("dataSource.connectionInitSqls"))
			// {basicDataSource.setConnectionInitSqls(properties.getProperty("dataSource.connectionInitSqls"));}
			if (null != properties
					.getProperty("dataSource.connectionProperties")) {
				basicDataSource.setConnectionProperties(properties
						.getProperty("dataSource.connectionProperties"));
			}
			if (null != properties.getProperty("dataSource.defaultAutoCommit")) {
				basicDataSource.setDefaultAutoCommit(Boolean.valueOf(properties
						.getProperty("dataSource.defaultAutoCommit")));
			}
			if (null != properties.getProperty("dataSource.defaultCatalog")) {
				basicDataSource.setDefaultCatalog(properties
						.getProperty("dataSource.defaultCatalog"));
			}
			if (null != properties.getProperty("dataSource.defaultReadOnly")) {
				basicDataSource.setDefaultReadOnly(Boolean.valueOf(properties
						.getProperty("dataSource.defaultReadOnly")));
			}
			if (null != properties
					.getProperty("dataSource.defaultTransactionIsolation")) {
				basicDataSource
						.setDefaultTransactionIsolation(Integer.valueOf(properties
								.getProperty("dataSource.defaultTransactionIsolation")));
			}
			// if (null !=
			// properties.getProperty("dataSource.driverClassLoader"))
			// {basicDataSource.setDriverClassLoader(properties.getProperty("dataSource.driverClassLoader"));}
			if (null != properties.getProperty("dataSource.driverClassName")) {
				basicDataSource.setDriverClassName(properties
						.getProperty("dataSource.driverClassName"));
			}
			if (null != properties.getProperty("dataSource.initialSize")) {
				basicDataSource.setInitialSize(Integer.valueOf(properties
						.getProperty("dataSource.initialSize")));
			}
			if (null != properties.getProperty("dataSource.logAbandoned")) {
				basicDataSource.setLogAbandoned(Boolean.valueOf(properties
						.getProperty("dataSource.logAbandoned")));
			}
			if (null != properties.getProperty("dataSource.loginTimeout")) {
				basicDataSource.setLoginTimeout(Integer.valueOf(properties
						.getProperty("dataSource.loginTimeout")));
			}
			// if (null != properties.getProperty("dataSource.logWriter"))
			// {basicDataSource.setLogWriter(properties.getProperty("dataSource.logWriter"));}
			if (null != properties.getProperty("dataSource.maxActive")) {
				basicDataSource.setMaxActive(Integer.valueOf(properties
						.getProperty("dataSource.maxActive")));
			}
			if (null != properties.getProperty("dataSource.maxIdle")) {
				basicDataSource.setMaxIdle(Integer.valueOf(properties
						.getProperty("dataSource.maxIdle")));
			}
			if (null != properties
					.getProperty("dataSource.maxOpenPreparedStatements")) {
				basicDataSource
						.setMaxOpenPreparedStatements(Integer.valueOf(properties
								.getProperty("dataSource.maxOpenPreparedStatements")));
			}
			if (null != properties.getProperty("dataSource.maxWait")) {
				basicDataSource.setMaxWait(Long.valueOf(properties
						.getProperty("dataSource.maxWait")));
			}
			if (null != properties
					.getProperty("dataSource.minEvictableIdleTimeMillis")) {
				basicDataSource
						.setMinEvictableIdleTimeMillis(Long.valueOf(properties
								.getProperty("dataSource.minEvictableIdleTimeMillis")));
			}
			if (null != properties.getProperty("dataSource.minIdle")) {
				basicDataSource.setMinIdle(Integer.valueOf(properties
						.getProperty("dataSource.minIdle")));
			}
			if (null != properties
					.getProperty("dataSource.numTestsPerEvictionRun")) {
				basicDataSource
						.setNumTestsPerEvictionRun(Integer.valueOf(properties
								.getProperty("dataSource.numTestsPerEvictionRun")));
			}
			if (null != properties.getProperty("dataSource.password")) {
				basicDataSource.setPassword(properties
						.getProperty("dataSource.password"));
			}
			if (null != properties
					.getProperty("dataSource.poolPreparedStatements")) {
				basicDataSource
						.setPoolPreparedStatements(Boolean.valueOf(properties
								.getProperty("dataSource.poolPreparedStatements")));
			}
			if (null != properties.getProperty("dataSource.removeAbandoned")) {
				basicDataSource.setRemoveAbandoned(Boolean.valueOf(properties
						.getProperty("dataSource.removeAbandoned")));
			}
			if (null != properties
					.getProperty("dataSource.removeAbandonedTimeout")) {
				basicDataSource
						.setRemoveAbandonedTimeout(Integer.valueOf(properties
								.getProperty("dataSource.removeAbandonedTimeout")));
			}
			if (null != properties.getProperty("dataSource.testOnBorrow")) {
				basicDataSource.setTestOnBorrow(Boolean.valueOf(properties
						.getProperty("dataSource.testOnBorrow")));
			}
			if (null != properties.getProperty("dataSource.testOnReturn")) {
				basicDataSource.setTestOnReturn(Boolean.valueOf(properties
						.getProperty("dataSource.testOnReturn")));
			}
			if (null != properties.getProperty("dataSource.testWhileIdle")) {
				basicDataSource.setTestWhileIdle(Boolean.valueOf(properties
						.getProperty("dataSource.testWhileIdle")));
			}
			if (null != properties
					.getProperty("dataSource.timeBetweenEvictionRunsMillis")) {
				basicDataSource
						.setTimeBetweenEvictionRunsMillis(Long.valueOf(properties
								.getProperty("dataSource.timeBetweenEvictionRunsMillis")));
			}
			if (null != properties.getProperty("dataSource.url")) {
				basicDataSource
						.setUrl(properties.getProperty("dataSource.url"));
			}
			if (null != properties.getProperty("dataSource.username")) {
				basicDataSource.setUsername(properties
						.getProperty("dataSource.username"));
			}
			if (null != properties.getProperty("dataSource.validationQuery")) {
				basicDataSource.setValidationQuery(properties
						.getProperty("dataSource.validationQuery"));
			}
			if (null != properties
					.getProperty("dataSource.validationQueryTimeout")) {
				basicDataSource
						.setValidationQueryTimeout(Integer.valueOf(properties
								.getProperty("dataSource.validationQueryTimeout")));
			}

			dataSource = basicDataSource;
			
			Connection conn = getConn();
			DatabaseMetaData mdm = conn.getMetaData();
			LOG.info("Connected to " + mdm.getDatabaseProductName() + " "
			+ mdm.getDatabaseProductVersion());
			if (conn != null) {
				conn.close();
			}
		} catch (Exception e) {
			LOG.error("初始化连接池失败：" + e);
		}
	}
	
	/**
	  * 获取链接，用完后记得关闭
	  * @see {@link DBManager#closeConn(Connection)}
	  * @return
	  */
	public static final Connection getConn() {
		Connection conn = null;
		try {
			conn = dataSource.getConnection();
		} catch (SQLException e) {
			LOG.error("获取数据库连接失败：" + e);
		}
		return conn;
	}
	
	/**
	 * 关闭连接
	 * 
	 * @param conn
	 *            需要关闭的连接
	 */
	public static void closeConn(Connection conn) {
		try {
			if (conn != null && !conn.isClosed()) {
				conn.setAutoCommit(true);
				conn.close();
			}
		} catch (SQLException e) {
			LOG.error("关闭数据库连接失败：" + e);
		}
	}
}
package javacommon.base;

import java.io.FileInputStream;
import java.io.IOException;
import java.io.InputStream;
import java.util.Properties;

/**
 * Properties处理
 * @author
 *
 */
public class PropertiesHandler {
	
	/**
	 * 读取资源文件
	 * @param filename 文件名
	 * @return Properties
	 */
	public static Properties readPropertiesFile(String filename)  
	{  
	    Properties properties = new Properties();  
	    try  
	    {  
	        InputStream inputStream = new FileInputStream(filename);  
	        properties.load(inputStream);  
	        inputStream.close(); //关闭流  
	    }  
	    catch (IOException e)  
	    {
	        e.printStackTrace();  
	    }
	    
	    return properties;
	}
}

本文题目：JDBC连接数据库实例
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