JDBC编程学习笔记之数据库连接池的实现
2016-02-03 12:05
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在JDBC编程的时候,获取到一个数据库连接资源是很宝贵的,倘若数据库访问量超大,而数据库连接资源又没能得到及时的释放,就会导致系统的崩溃甚至宕机。造成的损失将会是巨大的。再看有了数据库连接池的JDBC,就会较好的解决资源的创建与连接问题,其主要还是针对于连接资源使用层面的改进。下面我就谈一谈我对数据库连接池的理解。
但是,最为关键的是,开发人员在使用完连接对象后通常会调用conn.close(),方法来释放数据库连接资源,这将会把数据库连接返还给数据库,而不是数据库连接池,因此,数据库连接池的存在就没了意义了。所以我们要增强close方法,来保证数据库连接资源返还给数据库连接池。
不难看出,数据库连接池相对于普通的数据库连接的创建,并没有什么特别难写的部分。
创建子类,覆盖close方法,但是创建子类的时候要实现的部分可能会特别多,因此并不常用
使用包装设计模式
使用动态代理方式
今天我就来实现一下怎么使用包装设计模式来实现close方法的增强。
创建一个类,实现与被增强对象相同的接口
将被增强对象作为一个成员变量加到这个类中
定义一个构造方法,并把被增强对象作为参数传进来
覆盖要增强的方法,这里是close方法
对于不想进行增强的方法,借助于被增强对象实现即可。
下面是基于包装设计模式实现的增强的MyConnection类:
db.properties中内容如下:
下面就是JDBCPool工具类的实现:
数据库连接对象应从数据库连接池中获取,使用完之后再返还给数据库连接池
使用包装设计模式进行方法的增强是较为合理的,但是更为常用的是开源的数据库连接池,即动态代理方式。如DBCP等等
数据库连接池理论基础
对于创建一个数据库连接池,需要做好准备工作。原理就是先实现DataSource接口,覆盖里面的getConnection()方法,这个方法是我们最为关注的。既然是池,就不会是一个连接对象,因此需要使用集合来保存这些个连接对象。
但是,最为关键的是,开发人员在使用完连接对象后通常会调用conn.close(),方法来释放数据库连接资源,这将会把数据库连接返还给数据库,而不是数据库连接池,因此,数据库连接池的存在就没了意义了。所以我们要增强close方法,来保证数据库连接资源返还给数据库连接池。
创建数据库连接池
public class JDCBCPool implements DataSource { /* * 既然是一个数据库连接池,就必须有许多的连接,所以需要使用一个集合类保存这些连接 (non-Javadoc) * * @see javax.sql.CommonDataSource#getLogWriter() */ private static LinkedList<Connection> list = new LinkedList<Connection>(); // 创建一个配置文件,用于读取相应配置文件中保存的数据信息 private static Properties config = new Properties(); /* * 在这里向数据库申请一批数据库连接 为了只加载一次驱动程序,因此在静态代码块中进行声明,这样驱动就只会加载一次 */ static { try { config.load(JDBCUtils.class.getClassLoader().getResourceAsStream("db.properties")); // Class.forName("com.mysql.jdbc.Driver"); Class.forName(config.getProperty("DRIVER")); try { //申请十个数据库连接对象,也就是数据库连接池的容量是10 for(int i=0 ;i<10;i++){ Connection conn = DriverManager.getConnection(config.getProperty("URL"), config.getProperty("USER"),config.getProperty("PASSWORD")); list.add(conn); } } catch (SQLException e) { // TODO Auto-generated catch block e.printStackTrace(); } } catch (ClassNotFoundException | IOException e) { // TODO Auto-generated catch block throw new ExceptionInInitializerError(); } } @Override public Connection getConnection() throws SQLException { if(list.size()<=0){ throw new RuntimeException("数据库忙,请待会再试试吧!"); } //需要注意的是,不能使用get方式(这个方法知识返回一个引用而已), //应该在获取的同时,删除掉这个链接,之后再还回来.现在注意是返还给数据库连接池!!! Connection conn = list.removeFirst(); MyConnection myconn = new MyConnection(conn); //从这里开始返回的就是一个数据库连接池对象的conn return myconn; } /////////////////////////////////////////////////////////////////////////datasource接口的实现方法开始 @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; } @Override public Connection getConnection(String username, String password) throws SQLException { // TODO Auto-generated method stub return null; } }
不难看出,数据库连接池相对于普通的数据库连接的创建,并没有什么特别难写的部分。
增强close方法,保证数据库连接资源用完后返还给连接池
要想增强close方法的功能,一般来说我们有如下几种方式。创建子类,覆盖close方法,但是创建子类的时候要实现的部分可能会特别多,因此并不常用
使用包装设计模式
使用动态代理方式
今天我就来实现一下怎么使用包装设计模式来实现close方法的增强。
包装设计模式实现close方法的增强
要实现包装设计模式,思路很简单。创建一个类,实现与被增强对象相同的接口
将被增强对象作为一个成员变量加到这个类中
定义一个构造方法,并把被增强对象作为参数传进来
覆盖要增强的方法,这里是close方法
对于不想进行增强的方法,借助于被增强对象实现即可。
下面是基于包装设计模式实现的增强的MyConnection类:
class MyConnection implements Connection { private Connection conn ; public MyConnection(Connection conn ){ this.conn = conn; } /** * 自定义的包装设计模式类,增强close方法, * 将数据库链接资源返还给数据库连接池,而不是数据库 */ public void close(){ list.add(conn); } @Override public <T> T unwrap(Class<T> iface) throws SQLException { // TODO Auto-generated method stub return this.conn.unwrap(iface); } @Override public boolean isWrapperFor(Class<?> iface) throws SQLException { // TODO Auto-generated method stub return this.conn.isWrapperFor(iface); } @Override public Statement createStatement() throws SQLException { // TODO Auto-generated method stub return this.conn.createStatement(); } @Override public PreparedStatement prepareStatement(String sql) throws SQLException { // TODO Auto-generated method stub return this.conn.prepareStatement(sql); } @Override public CallableStatement prepareCall(String sql) throws SQLException { // TODO Auto-generated method stub return this.conn.prepareCall(sql); } @Override public String nativeSQL(String sql) throws SQLException { // TODO Auto-generated method stub return this.conn.nativeSQL(sql); } @Override public void setAutoCommit(boolean autoCommit) throws SQLException { // TODO Auto-generated method stub this.conn.setAutoCommit(autoCommit); } @Override public boolean getAutoCommit() throws SQLException { // TODO Auto-generated method stub return this.conn.getAutoCommit(); } @Override public void commit() throws SQLException { // TODO Auto-generated method stub this.conn.commit(); } @Override public void rollback() throws SQLException { // TODO Auto-generated method stub this.conn.rollback(); } @Override public boolean isClosed() throws SQLException { // TODO Auto-generated method stub return this.conn.isClosed(); } @Override public DatabaseMetaData getMetaData() throws SQLException { // TODO Auto-generated method stub return this.conn.getMetaData(); } @Override public void setReadOnly(boolean readOnly) throws SQLException { // TODO Auto-generated method stub this.conn.setReadOnly(readOnly); } @Override public boolean isReadOnly() throws SQLException { // TODO Auto-generated method stub return this.conn.isReadOnly(); } @Override public void setCatalog(String catalog) throws SQLException { // TODO Auto-generated method stub this.conn.setCatalog(catalog); } @Override public String getCatalog() throws SQLException { // TODO Auto-generated method stub return this.conn.getCatalog(); } @Override public void setTransactionIsolation(int level) throws SQLException { // TODO Auto-generated method stub this.conn.setTransactionIsolation(level); } @Override public int getTransactionIsolation() throws SQLException { // TODO Auto-generated method stub return this.conn.getTransactionIsolation(); } @Override public SQLWarning getWarnings() throws SQLException { // TODO Auto-generated method stub return this.conn.getWarnings(); } @Override public void clearWarnings() throws SQLException { // TODO Auto-generated method stub this.conn.clearWarnings(); } @Override public Statement createStatement(int resultSetType, int resultSetConcurrency) throws SQLException { // TODO Auto-generated method stub return this.conn.createStatement(resultSetType, resultSetConcurrency); } @Override public PreparedStatement prepareStatement(String sql, int resultSetType, int resultSetConcurrency) throws SQLException { // TODO Auto-generated method stub return this.conn.prepareStatement(sql, resultSetType, resultSetConcurrency); } @Override public CallableStatement prepareCall(String sql, int resultSetType, int resultSetConcurrency) throws SQLException { // TODO Auto-generated method stub return this.conn.prepareCall(sql, resultSetType, resultSetConcurrency); } @Override public Map<String, Class<?>> getTypeMap() throws SQLException { // TODO Auto-generated method stub return this.conn.getTypeMap(); } @Override public void setTypeMap(Map<String, Class<?>> map) throws SQLException { // TODO Auto-generated method stub this.conn.setTypeMap(map); } @Override public void setHoldability(int holdability) throws SQLException { // TODO Auto-generated method stub this.conn.setHoldability(holdability); } @Override public int getHoldability() throws SQLException { // TODO Auto-generated method stub return this.conn.getHoldability(); } @Override public Savepoint setSavepoint() throws SQLException { // TODO Auto-generated method stub return this.conn.setSavepoint(); } @Override public Savepoint setSavepoint(String name) throws SQLException { // TODO Auto-generated method stub return this.conn.setSavepoint(name); } @Override public void rollback(Savepoint savepoint) throws SQLException { // TODO Auto-generated method stub this.conn.rollback(savepoint); } @Override public void releaseSavepoint(Savepoint savepoint) throws SQLException { // TODO Auto-generated method stub this.conn.releaseSavepoint(savepoint); } @Override public Statement createStatement(int resultSetType, int resultSetConcurrency, int resultSetHoldability) throws SQLException { // TODO Auto-generated method stub return this.conn.createStatement(resultSetType, resultSetConcurrency, resultSetHoldability); } @Override public PreparedStatement prepareStatement(String sql, int resultSetType, int resultSetConcurrency, int resultSetHoldability) throws SQLException { // TODO Auto-generated method stub return this.conn.prepareStatement(sql, resultSetType, resultSetConcurrency, resultSetHoldability); } @Override public CallableStatement prepareCall(String sql, int resultSetType, int resultSetConcurrency, int resultSetHoldability) throws SQLException { // TODO Auto-generated method stub return this.conn.prepareCall(sql, resultSetType, resultSetConcurrency, resultSetHoldability); } @Override public PreparedStatement prepareStatement(String sql, int autoGeneratedKeys) throws SQLException { // TODO Auto-generated method stub return this.conn.prepareStatement(sql, autoGeneratedKeys); } @Override public PreparedStatement prepareStatement(String sql, int[] columnIndexes) throws SQLException { // TODO Auto-generated method stub return this.conn.prepareStatement(sql, columnIndexes); } @Override public PreparedStatement prepareStatement(String sql, String[] columnNames) throws SQLException { // TODO Auto-generated method stub return this.conn.prepareStatement(sql, columnNames); } @Override public Clob createClob() throws SQLException { // TODO Auto-generated method stub return this.conn.createClob(); } @Override public Blob createBlob() throws SQLException { // TODO Auto-generated method stub return this.conn.createBlob(); } @Override public NClob createNClob() throws SQLException { // TODO Auto-generated method stub return this.conn.createNClob(); } @Override public SQLXML createSQLXML() throws SQLException { // TODO Auto-generated method stub return this.conn.createSQLXML(); } @Override public boolean isValid(int timeout) throws SQLException { // TODO Auto-generated method stub return this.conn.isValid(timeout); } @Override public void setClientInfo(String name, String value) throws SQLClientInfoException { // TODO Auto-generated method stub this.conn.setClientInfo(name, value); } @Override public void setClientInfo(Properties properties) throws SQLClientInfoException { // TODO Auto-generated method stub this.conn.setClientInfo(properties); } @Override public String getClientInfo(String name) throws SQLException { // TODO Auto-generated method stub return this.conn.getClientInfo(name); } @Override public Properties getClientInfo() throws SQLException { // TODO Auto-generated method stub return this.conn.getClientInfo(); } @Override public Array createArrayOf(String typeName, Object[] elements) throws SQLException { // TODO Auto-generated method stub return this.conn.createArrayOf(typeName, elements); } @Override public Struct createStruct(String typeName, Object[] attributes) throws SQLException { // TODO Auto-generated method stub return this.conn.createStruct(typeName, attributes); } @Override public void setSchema(String schema) throws SQLException { // TODO Auto-generated method stub this.conn.setSchema(schema); } @Override public String getSchema() throws SQLException { // TODO Auto-generated method stub return this.conn.getSchema(); } @Override public void abort(Executor executor) throws SQLException { // TODO Auto-generated method stub this.conn.abort(executor); } @Override public void setNetworkTimeout(Executor executor, int milliseconds) throws SQLException { // TODO Auto-generated method stub this.conn.setNetworkTimeout(executor, milliseconds); } @Override public int getNetworkTimeout() throws SQLException { // TODO Auto-generated method stub return this.conn.getNetworkTimeout(); } }
一个简单的数据库连接池的实现案例
说是一个案例,其实也可以作为一个工具类作为今后程序开发的使用,这将会大大的提升数据库连接资源的使用。需要注意的是,里面的驱动程序是基于我自己的数据库来书写的,进行使用时记得修改一下配置文件db.properties.文件中的内容即可。db.properties中内容如下:
#when use this db.properties ,need to change the database name DRIVER = com.mysql.jdbc.Driver URL = jdbc:mysql://localhost:3306/test USER = root PASSWORD = mysql
下面就是JDBCPool工具类的实现:
package utils;
import java.io.IOException;
import java.io.PrintWriter;
import java.sql.Array;
import java.sql.Blob;
import java.sql.CallableStatement;
import java.sql.Clob;
import java.sql.Connection;
import java.sql.DatabaseMetaData;
import java.sql.DriverManager;
import java.sql.NClob;
import java.sql.PreparedStatement;
import java.sql.SQLClientInfoException;
import java.sql.SQLException;
import java.sql.SQLFeatureNotSupportedException;
import java.sql.SQLWarning;
import java.sql.SQLXML;
import java.sql.Savepoint;
import java.sql.Statement;
import java.sql.Struct;
import java.util.LinkedList;
import java.util.List;
import java.util.Map;
import java.util.Properties;
import java.util.concurrent.Executor;
import java.util.logging.Logger;
import javax.sql.DataSource;
/**
* 数据库连接池工具类
*
* @author Summer
*
*/
public class JDCBCPool implements DataSource {
/*
* 既然是一个数据库连接池,就必须有许多的连接,所以需要使用一个集合类保存这些连接 (non-Javadoc)
*
* @see javax.sql.CommonDataSource#getLogWriter()
*/
private static LinkedList<Connection> list = new LinkedList<Connection>();
// 创建一个配置文件,用于读取相应配置文件中保存的数据信息
private static Properties config = new Properties();
/*
* 在这里向数据库申请一批数据库连接 为了只加载一次驱动程序,因此在静态代码块中进行声明,这样驱动就只会加载一次
*/
static {
try {
config.load(JDBCUtils.class.getClassLoader().getResourceAsStream("db.properties"));
// Class.forName("com.mysql.jdbc.Driver");
Class.forName(config.getProperty("DRIVER"));
try {
//申请十个数据库连接对象,也就是数据库连接池的容量是10
for(int i=0 ;i<10;i++){
Connection conn = DriverManager.getConnection(config.getProperty("URL"),
config.getProperty("USER"),config.getProperty("PASSWORD"));
list.add(conn);
}
} catch (SQLException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
} catch (ClassNotFoundException | IOException e) {
// TODO Auto-generated catch block
throw new ExceptionInInitializerError();
}
}
@Override
public Connection getConnection() throws SQLException {
if(list.size()<=0){
throw new RuntimeException("数据库忙,请待会再试试吧!");
}
//需要注意的是,不能使用get方式(这个方法知识返回一个引用而已),
//应该在获取的同时,删除掉这个链接,之后再还回来.现在注意是返还给数据库连接池!!!
Connection conn = list.removeFirst();
MyConnection myconn = new MyConnection(conn);
//从这里开始返回的就是一个数据库连接池对象的conn
return myconn;
}
/////////////////////////////////////////////////////////////////////////datasource接口的实现方法开始
@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;
}
@Override
public Connection getConnection(String username, String password) throws SQLException {
// TODO Auto-generated method stub
return null;
}
/////////////////////////////////////////////////////////////////////////datasource接口的实现方法结束
/**
* 包装设计模式实现流程:
* 1.创建一个类,实现与被增强对象相同的接口
* 2.将被增强对象当做自定义类的一个成员变量
* 3.定义一个构造方法,将被增强对象传递进去
* 4.增强想要增强的方法,进行覆盖即可
* 5.对于不像被增强的方法,调用被增强对象的方法进行处理即可
* @author Summer
*
*/
///////////////////////////////////////////////////////////////////////使用包装设计模式,增强close方法的自定义类开始
class MyConnection implements Connection { private Connection conn ; public MyConnection(Connection conn ){ this.conn = conn; } /** * 自定义的包装设计模式类,增强close方法, * 将数据库链接资源返还给数据库连接池,而不是数据库 */ public void close(){ list.add(conn); } @Override public <T> T unwrap(Class<T> iface) throws SQLException { // TODO Auto-generated method stub return this.conn.unwrap(iface); } @Override public boolean isWrapperFor(Class<?> iface) throws SQLException { // TODO Auto-generated method stub return this.conn.isWrapperFor(iface); } @Override public Statement createStatement() throws SQLException { // TODO Auto-generated method stub return this.conn.createStatement(); } @Override public PreparedStatement prepareStatement(String sql) throws SQLException { // TODO Auto-generated method stub return this.conn.prepareStatement(sql); } @Override public CallableStatement prepareCall(String sql) throws SQLException { // TODO Auto-generated method stub return this.conn.prepareCall(sql); } @Override public String nativeSQL(String sql) throws SQLException { // TODO Auto-generated method stub return this.conn.nativeSQL(sql); } @Override public void setAutoCommit(boolean autoCommit) throws SQLException { // TODO Auto-generated method stub this.conn.setAutoCommit(autoCommit); } @Override public boolean getAutoCommit() throws SQLException { // TODO Auto-generated method stub return this.conn.getAutoCommit(); } @Override public void commit() throws SQLException { // TODO Auto-generated method stub this.conn.commit(); } @Override public void rollback() throws SQLException { // TODO Auto-generated method stub this.conn.rollback(); } @Override public boolean isClosed() throws SQLException { // TODO Auto-generated method stub return this.conn.isClosed(); } @Override public DatabaseMetaData getMetaData() throws SQLException { // TODO Auto-generated method stub return this.conn.getMetaData(); } @Override public void setReadOnly(boolean readOnly) throws SQLException { // TODO Auto-generated method stub this.conn.setReadOnly(readOnly); } @Override public boolean isReadOnly() throws SQLException { // TODO Auto-generated method stub return this.conn.isReadOnly(); } @Override public void setCatalog(String catalog) throws SQLException { // TODO Auto-generated method stub this.conn.setCatalog(catalog); } @Override public String getCatalog() throws SQLException { // TODO Auto-generated method stub return this.conn.getCatalog(); } @Override public void setTransactionIsolation(int level) throws SQLException { // TODO Auto-generated method stub this.conn.setTransactionIsolation(level); } @Override public int getTransactionIsolation() throws SQLException { // TODO Auto-generated method stub return this.conn.getTransactionIsolation(); } @Override public SQLWarning getWarnings() throws SQLException { // TODO Auto-generated method stub return this.conn.getWarnings(); } @Override public void clearWarnings() throws SQLException { // TODO Auto-generated method stub this.conn.clearWarnings(); } @Override public Statement createStatement(int resultSetType, int resultSetConcurrency) throws SQLException { // TODO Auto-generated method stub return this.conn.createStatement(resultSetType, resultSetConcurrency); } @Override public PreparedStatement prepareStatement(String sql, int resultSetType, int resultSetConcurrency) throws SQLException { // TODO Auto-generated method stub return this.conn.prepareStatement(sql, resultSetType, resultSetConcurrency); } @Override public CallableStatement prepareCall(String sql, int resultSetType, int resultSetConcurrency) throws SQLException { // TODO Auto-generated method stub return this.conn.prepareCall(sql, resultSetType, resultSetConcurrency); } @Override public Map<String, Class<?>> getTypeMap() throws SQLException { // TODO Auto-generated method stub return this.conn.getTypeMap(); } @Override public void setTypeMap(Map<String, Class<?>> map) throws SQLException { // TODO Auto-generated method stub this.conn.setTypeMap(map); } @Override public void setHoldability(int holdability) throws SQLException { // TODO Auto-generated method stub this.conn.setHoldability(holdability); } @Override public int getHoldability() throws SQLException { // TODO Auto-generated method stub return this.conn.getHoldability(); } @Override public Savepoint setSavepoint() throws SQLException { // TODO Auto-generated method stub return this.conn.setSavepoint(); } @Override public Savepoint setSavepoint(String name) throws SQLException { // TODO Auto-generated method stub return this.conn.setSavepoint(name); } @Override public void rollback(Savepoint savepoint) throws SQLException { // TODO Auto-generated method stub this.conn.rollback(savepoint); } @Override public void releaseSavepoint(Savepoint savepoint) throws SQLException { // TODO Auto-generated method stub this.conn.releaseSavepoint(savepoint); } @Override public Statement createStatement(int resultSetType, int resultSetConcurrency, int resultSetHoldability) throws SQLException { // TODO Auto-generated method stub return this.conn.createStatement(resultSetType, resultSetConcurrency, resultSetHoldability); } @Override public PreparedStatement prepareStatement(String sql, int resultSetType, int resultSetConcurrency, int resultSetHoldability) throws SQLException { // TODO Auto-generated method stub return this.conn.prepareStatement(sql, resultSetType, resultSetConcurrency, resultSetHoldability); } @Override public CallableStatement prepareCall(String sql, int resultSetType, int resultSetConcurrency, int resultSetHoldability) throws SQLException { // TODO Auto-generated method stub return this.conn.prepareCall(sql, resultSetType, resultSetConcurrency, resultSetHoldability); } @Override public PreparedStatement prepareStatement(String sql, int autoGeneratedKeys) throws SQLException { // TODO Auto-generated method stub return this.conn.prepareStatement(sql, autoGeneratedKeys); } @Override public PreparedStatement prepareStatement(String sql, int[] columnIndexes) throws SQLException { // TODO Auto-generated method stub return this.conn.prepareStatement(sql, columnIndexes); } @Override public PreparedStatement prepareStatement(String sql, String[] columnNames) throws SQLException { // TODO Auto-generated method stub return this.conn.prepareStatement(sql, columnNames); } @Override public Clob createClob() throws SQLException { // TODO Auto-generated method stub return this.conn.createClob(); } @Override public Blob createBlob() throws SQLException { // TODO Auto-generated method stub return this.conn.createBlob(); } @Override public NClob createNClob() throws SQLException { // TODO Auto-generated method stub return this.conn.createNClob(); } @Override public SQLXML createSQLXML() throws SQLException { // TODO Auto-generated method stub return this.conn.createSQLXML(); } @Override public boolean isValid(int timeout) throws SQLException { // TODO Auto-generated method stub return this.conn.isValid(timeout); } @Override public void setClientInfo(String name, String value) throws SQLClientInfoException { // TODO Auto-generated method stub this.conn.setClientInfo(name, value); } @Override public void setClientInfo(Properties properties) throws SQLClientInfoException { // TODO Auto-generated method stub this.conn.setClientInfo(properties); } @Override public String getClientInfo(String name) throws SQLException { // TODO Auto-generated method stub return this.conn.getClientInfo(name); } @Override public Properties getClientInfo() throws SQLException { // TODO Auto-generated method stub return this.conn.getClientInfo(); } @Override public Array createArrayOf(String typeName, Object[] elements) throws SQLException { // TODO Auto-generated method stub return this.conn.createArrayOf(typeName, elements); } @Override public Struct createStruct(String typeName, Object[] attributes) throws SQLException { // TODO Auto-generated method stub return this.conn.createStruct(typeName, attributes); } @Override public void setSchema(String schema) throws SQLException { // TODO Auto-generated method stub this.conn.setSchema(schema); } @Override public String getSchema() throws SQLException { // TODO Auto-generated method stub return this.conn.getSchema(); } @Override public void abort(Executor executor) throws SQLException { // TODO Auto-generated method stub this.conn.abort(executor); } @Override public void setNetworkTimeout(Executor executor, int milliseconds) throws SQLException { // TODO Auto-generated method stub this.conn.setNetworkTimeout(executor, milliseconds); } @Override public int getNetworkTimeout() throws SQLException { // TODO Auto-generated method stub return this.conn.getNetworkTimeout(); } }
/////////////////////////////////////////////////////////////////////////////包装设计模式结束
}
总结
在实际的开发过程中,数据库连接池使用的很广泛,我们应该加以掌握。数据库连接对象应从数据库连接池中获取,使用完之后再返还给数据库连接池
使用包装设计模式进行方法的增强是较为合理的,但是更为常用的是开源的数据库连接池,即动态代理方式。如DBCP等等
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