c3p0数据库连接池实例

c3p0数据库连接池实例

2014-02-22     我来说两句    来源：c3p0数据库连接池实例  

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c3p0下载地址：http://download.csdn.net/detail/huhui_bj/6944595

这篇文章介绍的是，在普通Java Web工程中或者普通Java工程中使用c3p0数据库连接池的实例，c3p0的jar文件包括3个。下面这个实例工程中，主要包括三个重要的文件：
C3P0ConnentionProvider.java 初始化c3p0数据库连接池

SQLHelper.java 通过数据库连接池，提供对数据库的增删改查功能

c3p0.properties c3p0的配置文件

工程文件的截图如下：

c3p0.properties文件内容如下：

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#jdbc基本信息 driverClass=oracle.jdbc.driver.OracleDriver jdbcUrl=jdbc:oracle:thin:@127.0.0.1:1521:orcl user=scott password=tigger #c3p0连接池信息 c3p0.minPoolSize=3 c3p0.maxPoolSize=25 #当连接池中的连接耗尽的时候c3p0一次同时获取的连接数 c3p0.acquireIncrement=3 #定义在从数据库获取新连接失败后重复尝试的次数 c3p0.acquireRetryAttempts=60 #两次连接中间隔时间，单位毫秒 c3p0.acquireRetryDelay=1000 #连接关闭时默认将所有未提交的操作回滚 c3p0.autoCommitOnClose=false #当连接池用完时客户端调用getConnection()后等待获取新连接的时间，超时后将抛出SQLException,如设为0则无限 c3p0.checkoutTimeout=3000 #每120秒检查所有连接池中的空闲连接。Default: 0 c3p0.idleConnectionTestPeriod=120 #最大空闲时间,60秒内未使用则连接被丢弃。若为0则永不丢弃。Default: 0  c3p0.maxIdleTime=600 #如果设为true那么在取得连接的同时将校验连接的有效性。Default: false  c3p0.testConnectionOnCheckin=false #如果maxStatements与maxStatementsPerConnection均为0，则缓存被关闭。Default: 0 c3p0.maxStatements=8 #maxStatementsPerConnection定义了连接池内单个连接所拥有的最大缓存statements数。Default: 0 c3p0.maxStatementsPerConnection=5

C3P0ConnentionProvider.java文件内容如下：

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package com.hh.db; import java.io.FileInputStream; import java.sql.Connection; import java.sql.SQLException; import java.util.Properties; import javax.sql.DataSource; import com.mchange.v2.c3p0.DataSources; /**  * c3p0连接池管理类  */ public class C3P0ConnentionProvider {     private static final String JDBC_DRIVER = "driverClass";     private static final String JDBC_URL = "jdbcUrl";     private static DataSource ds;     /**      * 初始化连接池代码块      */     static {         initDBSource();     }     /**      * 初始化c3p0连接池      */     private static final void initDBSource() {         Properties c3p0Pro = new Properties();         try {             // 加载配置文件             String path = C3P0ConnentionProvider.class.getResource("/").getPath();             String websiteURL = (path.replace("/build/classes", "").replace("%20"," ").replace("classes/", "") + "c3p0.properties").replaceFirst("/", "");             FileInputStream in = new FileInputStream(websiteURL);             c3p0Pro.load(in);         } catch (Exception e) {             e.printStackTrace();         }         String drverClass = c3p0Pro.getProperty(JDBC_DRIVER);         if (drverClass != null) {             try {                 // 加载驱动类                 Class.forName(drverClass);             } catch (ClassNotFoundException e) {                 e.printStackTrace();             }         }         Properties jdbcpropes = new Properties();         Properties c3propes = new Properties();         for (Object key : c3p0Pro.keySet()) {             String skey = (String) key;             if (skey.startsWith("c3p0.")) {                 c3propes.put(skey, c3p0Pro.getProperty(skey));             } else {                 jdbcpropes.put(skey, c3p0Pro.getProperty(skey));             }         }         try {             // 建立连接池             DataSource unPooled = DataSources.unpooledDataSource(c3p0Pro.getProperty(JDBC_URL), jdbcpropes);             ds = DataSources.pooledDataSource(unPooled, c3propes);         } catch (SQLException e) {             e.printStackTrace();         }     }     /**      * 获取数据库连接对象      *      * @return 数据连接对象      * @throws SQLException      */     public static synchronized Connection getConnection() throws SQLException {         final Connection conn = ds.getConnection();         conn.setTransactionIsolation(Connection.TRANSACTION_READ_COMMITTED);         return conn;     } }

SQLHelper.java文件内容如下：

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/**  * 功能：提供统一的查询、修改和插入方法  */ package com.hh.db; import java.sql.Connection; import java.sql.PreparedStatement; import java.sql.ResultSet; import java.sql.ResultSetMetaData; import java.util.ArrayList; import java.util.List; public class SQLHelper {     private Connection conn = null;     private PreparedStatement ps = null;     private ResultSet rs = null;     /**      * 数据查询      * @param sql语句      * @return 返回结果集List<Object>      */     public List<Object> query(String sql) {         if(sql.equals("") || sql == null){             return null;         }         List<Object> list = new ArrayList<Object>();         try {             conn = C3P0ConnentionProvider.getConnection();             ps = conn.prepareStatement(sql);             rs = ps.executeQuery();             ResultSetMetaData rsmd = rs.getMetaData();             // 可以得到有多少列             int columnNum = rsmd.getColumnCount();             // 将数据封装到list中             while (rs.next()) {                 Object[] objects = new Object[columnNum];                 for (int i = 0; i < objects.length; i++) {                     objects[i] = rs.getObject(i + 1);                 }                 list.add(objects);             }         } catch (Exception e) {             // TODO: handle exception             e.printStackTrace();         }         return list;     }     /**      * 插入、修改数据操作      * @param sql语句      * @return boolean 成功返回true，失败返回false      */     public boolean update(String sql) {         boolean b = false;         if(sql.equals("") || sql == null){             return b;         }         try {             conn = C3P0ConnentionProvider.getConnection();             ps = conn.prepareStatement(sql);             int i = ps.executeUpdate();             if (i == 1) {                 b = true;             }         } catch (Exception e) {             // TODO: handle exception             e.printStackTrace();         }         return b;     } }

至于Demo.java文件，可提供参考的内容如下：

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/**  * SQLHelper的测试类  *  */ package com.hh.db; import java.util.ArrayList; import java.util.List; public class Demo {           private SQLHelper sqlHelper = new SQLHelper();           /**      * 测试query      */     /*public void testQuery(){         String sql = "select * from crh2_station where id = 1";         List list = sqlHelper.query(sql);         List<Crh2Station> crh2StationList = new ArrayList<Crh2Station>();         //对查询结果进行封装         for (int i = 0; i < list.size(); i++) {             Object object[] = (Object[]) list.get(i);             Crh2Station crh2Station = new Crh2Station();             crh2Station.setId(Integer.parseInt(object[0].toString()));             crh2Station.setSlopeId(Integer.parseInt(object[1].toString()));             crh2Station.setSlope(Double.parseDouble(object[2].toString()));             crh2Station.setLength(Double.parseDouble(object[3].toString()));             crh2Station.setEnd(Double.parseDouble(object[4].toString()));             crh2Station.setHeight(Double.parseDouble(object[5].toString()));             crh2StationList.add(crh2Station);         }         return crh2StationList;     }*/           /**      * 测试insert、update、delete      */     /*public void testInsertOrUpdate(){         String sql = "delete from crh2_station where id = 1";         boolean b = sqlHelper.update(sql);         if(b){//b为true则操作成功             System.out.println("操作成功");         }else{//b为false则操作失败             System.out.println("操作失败");         }     }*/ }