【Java进阶打卡】JDBC- jdbc连接池

- 概述
- 自定义数据库连接池
- 归还连接-装饰设计模式
- 归还连接-适配器设计模式
- 动态代理
- 动态代理-归还数据库连接

概述

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自定义数据库连接池

DataSource接口概述
- javax.sql.DataSource接口：数据源（数据库连接池） Java官方提供的数据库连接池规范
- 如果像完成数据库连接池技术，就必须实现dataSource接口
- 核心功能：获取数据库连接对象：connection getConnection()

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连接池接口的实现

package com.itheima01;
import com.itheima01.utils.JDBCUtils;
import javax.sql.DataSource;
import java.io.PrintWriter;
import java.sql.Connection;
import java.sql.SQLException;
import java.sql.SQLFeatureNotSupportedException;
import java.util.ArrayList;
import java.util.Collections;
import java.util.List;
import java.util.logging.Logger;public class MyDataSource implements DataSource {// 从连接池中获取一个连接对象// 准备容器 用于保存多个连接对象  将对象设置为线程安全的对象private  static List<Connection> pool = Collections.synchronizedList(new ArrayList<>());// 将arrayList变成线程安全的对象// 定义静态代码块  通过工具类获取10个连接对象 类加载的时候 就执行该静态代码块static {for(int i = 1; i <= 10; i++){try {Connection con = JDBCUtils.getConnection();pool.add(con);// 将连接对象添加到连接池中} catch (SQLException e) {throw new RuntimeException(e);}}}//    重写getConnection 用于获取一个连接对象@Overridepublic Connection getConnection() throws SQLException {// 只要池子中还有对象  返回0索引的对象if(pool.size() > 0){Connection con = pool.remove(0);// 移除一个元素  返回该连接对象return con;}else{throw new RuntimeException("连接数量已经用尽");}}// 定义getSize方法  获取连接池容器的大小public int getSize(){return pool.size();}@Overridepublic Connection getConnection(String username, String password) throws SQLException {return null;}@Overridepublic PrintWriter getLogWriter() throws SQLException {return null;}@Overridepublic void setLogWriter(PrintWriter out) throws SQLException {}@Overridepublic void setLoginTimeout(int seconds) throws SQLException {}@Overridepublic int getLoginTimeout() throws SQLException {return 0;}@Overridepublic Logger getParentLogger() throws SQLFeatureNotSupportedException {return null;}@Overridepublic <T> T unwrap(Class<T> iface) throws SQLException {return null;}@Overridepublic boolean isWrapperFor(Class<?> iface) throws SQLException {return false;}
}

连接池接口的测试

package com.itheima01;import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;public class MyDataSourceTest {public static void main(String[] args) throws SQLException {// 创建连接池对象MyDataSource m = new MyDataSource();// 使用之前的数量System.out.println("使用之前的数量：" + m.getSize());// 通过连接池对象 获取对象Connection con = m.getConnection();// 查询学生表的全部信息String sql = "SELECT * FROM student";// 创建执行者对象 防止SQL攻击PreparedStatement preparedStatement = con.prepareStatement(sql);// 执行sql语句 接收结果集ResultSet resultSet = preparedStatement.executeQuery();// 处理结果集while(resultSet.next()){// 打印学生信息System.out.println(resultSet.getInt("sid") + "\t" + resultSet.getString("name") + "\t" + resultSet.getInt("age") + "\t" + resultSet.getDate("birthday"));}// 释放资源con.close();preparedStatement.close();resultSet.close();// 使用之后的连接池对象数量System.out.println("使用之后的连接池的数量：" + m.getSize());}
}

归还连接-装饰设计模式

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自定义连接对象

package com.itheima01;
import java.sql.*;
import java.util.List;
import java.util.Map;
import java.util.Properties;
import java.util.concurrent.Executor;// 定义一个类 实现Connection接口
// 定义连接对象和连接池容器对象的成员变量
// 通过有参构造方法为成员变量进行赋值
// 重写close方法 完成归还连接
// 剩余方法 还是调用原有的连接对象中的功能即可
public class MyConnection1 implements Connection {// 定义连接对象和连接池容器对象的成员变量private Connection con;// 连接对象private List<Connection> pool;// 连接池对象// 通过有参构造方法为成员变量进行赋值public MyConnection1(Connection con,List<Connection> pool){this.con = con;this.pool = pool;}// 重写close方法  完成归还连接@Overridepublic void close(){pool.add(con);// 将连接对象添加到连接池中}// 剩余方法 还是调用原来的的连接对象中的功能即可@Overridepublic Statement createStatement() throws SQLException {return con.createStatement();}@Overridepublic PreparedStatement prepareStatement(String sql) throws SQLException {return con.prepareStatement(sql);}@Overridepublic CallableStatement prepareCall(String sql) throws SQLException {return con.prepareCall(sql);}@Overridepublic String nativeSQL(String sql) throws SQLException {return con.nativeSQL(sql);}@Overridepublic void setAutoCommit(boolean autoCommit) throws SQLException {con.setAutoCommit(autoCommit);}@Overridepublic boolean getAutoCommit() throws SQLException {return con.getAutoCommit();}@Overridepublic void commit() throws SQLException {con.commit();}@Overridepublic void rollback() throws SQLException {con.rollback();}@Overridepublic boolean isClosed() throws SQLException {return con.isClosed();}@Overridepublic DatabaseMetaData getMetaData() throws SQLException {return con.getMetaData();}@Overridepublic void setReadOnly(boolean readOnly) throws SQLException {con.setReadOnly(readOnly);}@Overridepublic boolean isReadOnly() throws SQLException {return con.isReadOnly();}@Overridepublic void setCatalog(String catalog) throws SQLException {con.setCatalog(catalog);}@Overridepublic String getCatalog() throws SQLException {return con.getCatalog();}@Overridepublic void setTransactionIsolation(int level) throws SQLException {con.setTransactionIsolation(level);}@Overridepublic int getTransactionIsolation() throws SQLException {return con.getTransactionIsolation();}@Overridepublic SQLWarning getWarnings() throws SQLException {return con.getWarnings();}@Overridepublic void clearWarnings() throws SQLException {con.clearWarnings();}@Overridepublic Statement createStatement(int resultSetType, int resultSetConcurrency) throws SQLException {return con.createStatement(resultSetType,resultSetConcurrency);}@Overridepublic PreparedStatement prepareStatement(String sql, int resultSetType, int resultSetConcurrency) throws SQLException {return con.prepareStatement(sql,resultSetType,resultSetConcurrency);}@Overridepublic CallableStatement prepareCall(String sql, int resultSetType, int resultSetConcurrency) throws SQLException {return con.prepareCall(sql,resultSetType,resultSetConcurrency);}@Overridepublic Map<String, Class<?>> getTypeMap() throws SQLException {return con.getTypeMap();}@Overridepublic void setTypeMap(Map<String, Class<?>> map) throws SQLException {con.setTypeMap(map);}@Overridepublic void setHoldability(int holdability) throws SQLException {con.setHoldability(holdability);}@Overridepublic int getHoldability() throws SQLException {return con.getHoldability();}@Overridepublic Savepoint setSavepoint() throws SQLException {return con.setSavepoint();}@Overridepublic Savepoint setSavepoint(String name) throws SQLException {return con.setSavepoint(name);}@Overridepublic void rollback(Savepoint savepoint) throws SQLException {con.rollback(savepoint);}@Overridepublic void releaseSavepoint(Savepoint savepoint) throws SQLException {con.releaseSavepoint(savepoint);}@Overridepublic Statement createStatement(int resultSetType, int resultSetConcurrency, int resultSetHoldability) throws SQLException {return con.createStatement(resultSetType,resultSetConcurrency,resultSetHoldability);}@Overridepublic PreparedStatement prepareStatement(String sql, int resultSetType, int resultSetConcurrency, int resultSetHoldability) throws SQLException {return con.prepareStatement(sql,resultSetType,resultSetConcurrency,resultSetHoldability);}@Overridepublic CallableStatement prepareCall(String sql, int resultSetType, int resultSetConcurrency, int resultSetHoldability) throws SQLException {return con.prepareCall(sql,resultSetType,resultSetConcurrency,resultSetHoldability);}@Overridepublic PreparedStatement prepareStatement(String sql, int autoGeneratedKeys) throws SQLException {return con.prepareStatement(sql,autoGeneratedKeys);}@Overridepublic PreparedStatement prepareStatement(String sql, int[] columnIndexes) throws SQLException {return con.prepareStatement(sql,columnIndexes);}@Overridepublic PreparedStatement prepareStatement(String sql, String[] columnNames) throws SQLException {return con.prepareStatement(sql,columnNames);}@Overridepublic Clob createClob() throws SQLException {return con.createClob();}@Overridepublic Blob createBlob() throws SQLException {return con.createBlob();}@Overridepublic NClob createNClob() throws SQLException {return con.createNClob();}@Overridepublic SQLXML createSQLXML() throws SQLException {return con.createSQLXML();}@Overridepublic boolean isValid(int timeout) throws SQLException {return con.isValid(timeout);}@Overridepublic void setClientInfo(String name, String value) throws SQLClientInfoException {con.setClientInfo(name,value);}@Overridepublic void setClientInfo(Properties properties) throws SQLClientInfoException {con.setClientInfo(properties);}@Overridepublic String getClientInfo(String name) throws SQLException {return con.getClientInfo(name);}@Overridepublic Properties getClientInfo() throws SQLException {return con.getClientInfo();}@Overridepublic Array createArrayOf(String typeName, Object[] elements) throws SQLException {return con.createArrayOf(typeName,elements);}@Overridepublic Struct createStruct(String typeName, Object[] attributes) throws SQLException {return con.createStruct(typeName,attributes);}@Overridepublic void setSchema(String schema) throws SQLException {con.setSchema(schema);}@Overridepublic String getSchema() throws SQLException {return con.getSchema();}@Overridepublic void abort(Executor executor) throws SQLException {con.abort(executor);}@Overridepublic void setNetworkTimeout(Executor executor, int milliseconds) throws SQLException {con.setNetworkTimeout(executor,milliseconds);}@Overridepublic int getNetworkTimeout() throws SQLException {return con.getNetworkTimeout();}@Overridepublic <T> T unwrap(Class<T> iface) throws SQLException {return con.unwrap(iface);}@Overridepublic boolean isWrapperFor(Class<?> iface) throws SQLException {return con.isWrapperFor(iface);}
}

自定义DataSource

package com.itheima01;
import com.itheima01.utils.JDBCUtils;
import javax.sql.DataSource;
import java.io.PrintWriter;
import java.sql.Connection;
import java.sql.SQLException;
import java.sql.SQLFeatureNotSupportedException;
import java.util.ArrayList;
import java.util.Collections;
import java.util.List;
import java.util.logging.Logger;public class MyDataSource implements DataSource {// 从连接池中获取一个连接对象// 准备容器 用于保存多个连接对象  将对象设置为线程安全的对象private  static List<Connection> pool = Collections.synchronizedList(new ArrayList<>());// 将arrayList变成线程安全的对象// 定义静态代码块  通过工具类获取10个连接对象 类加载的时候 就执行该静态代码块static {for(int i = 1; i <= 10; i++){try {Connection con = JDBCUtils.getConnection();pool.add(con);// 将连接对象添加到连接池中} catch (SQLException e) {throw new RuntimeException(e);}}}//    重写getConnection 用于获取一个连接对象@Overridepublic Connection getConnection() throws SQLException {// 只要池子中还有对象  返回0索引的对象if(pool.size() > 0){Connection con = pool.remove(0);// 移除一个元素  返回该连接对象// 创建自定义连接对象  对原有的连接对象进行包装  主要是为了使用归还资源的方法MyConnection1 myCon = new MyConnection1(con,pool);return myCon;}else{throw new RuntimeException("连接数量已经用尽");}}// 定义getSize方法  获取连接池容器的大小public int getSize(){return pool.size();}@Overridepublic Connection getConnection(String username, String password) throws SQLException {return null;}@Overridepublic PrintWriter getLogWriter() throws SQLException {return null;}@Overridepublic void setLogWriter(PrintWriter out) throws SQLException {}@Overridepublic void setLoginTimeout(int seconds) throws SQLException {}@Overridepublic int getLoginTimeout() throws SQLException {return 0;}@Overridepublic Logger getParentLogger() throws SQLFeatureNotSupportedException {return null;}@Overridepublic <T> T unwrap(Class<T> iface) throws SQLException {return null;}@Overridepublic boolean isWrapperFor(Class<?> iface) throws SQLException {return false;}
}

归还连接-适配器设计模式

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MyAdapter

package com.itheima01;import java.sql.*;
import java.util.Map;
import java.util.Properties;
import java.util.concurrent.Executor;// 定义一个适配器类 实现connection接口  没有重写close方法
// 抽象类 既可以有普通方法 抽象方法 也可以有构造方法 私有成员变量
public abstract class MyAdapter implements Connection {// 定义连接对象的成员变量private Connection con;// 通过有参构造为变量进行赋值public MyAdapter(Connection con){this.con = con;}@Overridepublic Statement createStatement() throws SQLException {return con.createStatement();}@Overridepublic PreparedStatement prepareStatement(String sql) throws SQLException {return con.prepareStatement(sql);}@Overridepublic CallableStatement prepareCall(String sql) throws SQLException {return con.prepareCall(sql);}@Overridepublic String nativeSQL(String sql) throws SQLException {return con.nativeSQL(sql);}@Overridepublic void setAutoCommit(boolean autoCommit) throws SQLException {con.setAutoCommit(autoCommit);}@Overridepublic boolean getAutoCommit() throws SQLException {return con.getAutoCommit();}@Overridepublic void commit() throws SQLException {con.commit();}@Overridepublic void rollback() throws SQLException {con.rollback();}@Overridepublic boolean isClosed() throws SQLException {return con.isClosed();}@Overridepublic DatabaseMetaData getMetaData() throws SQLException {return con.getMetaData();}@Overridepublic void setReadOnly(boolean readOnly) throws SQLException {con.setReadOnly(readOnly);}@Overridepublic boolean isReadOnly() throws SQLException {return con.isReadOnly();}@Overridepublic void setCatalog(String catalog) throws SQLException {con.setCatalog(catalog);}@Overridepublic String getCatalog() throws SQLException {return con.getCatalog();}@Overridepublic void setTransactionIsolation(int level) throws SQLException {con.setTransactionIsolation(level);}@Overridepublic int getTransactionIsolation() throws SQLException {return con.getTransactionIsolation();}@Overridepublic SQLWarning getWarnings() throws SQLException {return con.getWarnings();}@Overridepublic void clearWarnings() throws SQLException {con.clearWarnings();}@Overridepublic Statement createStatement(int resultSetType, int resultSetConcurrency) throws SQLException {return con.createStatement(resultSetType,resultSetConcurrency);}@Overridepublic PreparedStatement prepareStatement(String sql, int resultSetType, int resultSetConcurrency) throws SQLException {return con.prepareStatement(sql,resultSetType,resultSetConcurrency);}@Overridepublic CallableStatement prepareCall(String sql, int resultSetType, int resultSetConcurrency) throws SQLException {return con.prepareCall(sql,resultSetType,resultSetConcurrency);}@Overridepublic Map<String, Class<?>> getTypeMap() throws SQLException {return con.getTypeMap();}@Overridepublic void setTypeMap(Map<String, Class<?>> map) throws SQLException {con.setTypeMap(map);}@Overridepublic void setHoldability(int holdability) throws SQLException {con.setHoldability(holdability);}@Overridepublic int getHoldability() throws SQLException {return con.getHoldability();}@Overridepublic Savepoint setSavepoint() throws SQLException {return con.setSavepoint();}@Overridepublic Savepoint setSavepoint(String name) throws SQLException {return con.setSavepoint(name);}@Overridepublic void rollback(Savepoint savepoint) throws SQLException {con.rollback(savepoint);}@Overridepublic void releaseSavepoint(Savepoint savepoint) throws SQLException {con.releaseSavepoint(savepoint);}@Overridepublic Statement createStatement(int resultSetType, int resultSetConcurrency, int resultSetHoldability) throws SQLException {return con.createStatement(resultSetType,resultSetConcurrency,resultSetHoldability);}@Overridepublic PreparedStatement prepareStatement(String sql, int resultSetType, int resultSetConcurrency, int resultSetHoldability) throws SQLException {return con.prepareStatement(sql,resultSetType,resultSetConcurrency,resultSetHoldability);}@Overridepublic CallableStatement prepareCall(String sql, int resultSetType, int resultSetConcurrency, int resultSetHoldability) throws SQLException {return con.prepareCall(sql,resultSetType,resultSetConcurrency,resultSetHoldability);}@Overridepublic PreparedStatement prepareStatement(String sql, int autoGeneratedKeys) throws SQLException {return con.prepareStatement(sql,autoGeneratedKeys);}@Overridepublic PreparedStatement prepareStatement(String sql, int[] columnIndexes) throws SQLException {return con.prepareStatement(sql,columnIndexes);}@Overridepublic PreparedStatement prepareStatement(String sql, String[] columnNames) throws SQLException {return con.prepareStatement(sql,columnNames);}@Overridepublic Clob createClob() throws SQLException {return con.createClob();}@Overridepublic Blob createBlob() throws SQLException {return con.createBlob();}@Overridepublic NClob createNClob() throws SQLException {return con.createNClob();}@Overridepublic SQLXML createSQLXML() throws SQLException {return con.createSQLXML();}@Overridepublic boolean isValid(int timeout) throws SQLException {return con.isValid(timeout);}@Overridepublic void setClientInfo(String name, String value) throws SQLClientInfoException {con.setClientInfo(name,value);}@Overridepublic void setClientInfo(Properties properties) throws SQLClientInfoException {con.setClientInfo(properties);}@Overridepublic String getClientInfo(String name) throws SQLException {return con.getClientInfo(name);}@Overridepublic Properties getClientInfo() throws SQLException {return con.getClientInfo();}@Overridepublic Array createArrayOf(String typeName, Object[] elements) throws SQLException {return con.createArrayOf(typeName,elements);}@Overridepublic Struct createStruct(String typeName, Object[] attributes) throws SQLException {return con.createStruct(typeName,attributes);}@Overridepublic void setSchema(String schema) throws SQLException {con.setSchema(schema);}@Overridepublic String getSchema() throws SQLException {return con.getSchema();}@Overridepublic void abort(Executor executor) throws SQLException {con.abort(executor);}@Overridepublic void setNetworkTimeout(Executor executor, int milliseconds) throws SQLException {con.setNetworkTimeout(executor,milliseconds);}@Overridepublic int getNetworkTimeout() throws SQLException {return con.getNetworkTimeout();}@Overridepublic <T> T unwrap(Class<T> iface) throws SQLException {return con.unwrap(iface);}@Overridepublic boolean isWrapperFor(Class<?> iface) throws SQLException {return con.isWrapperFor(iface);}
}

MyConnection2

package com.itheima01;import java.sql.Connection;
import java.sql.SQLException;
import java.util.List;//定义一个类  继承适配器类
public class MyConnection2 extends MyAdapter{// 定义连接对象和连接池容器对象的成员变量private Connection con;// 连接对象private List<Connection> pool;// 连接池对象// 通过有参构造为变量进行赋值public MyConnection2(Connection con,List<Connection> pool){super(con);this.con = con;this.pool = pool;}@Overridepublic void close() throws SQLException {pool.add(con);// 添加连接对象}
}

MyDataSource

package com.itheima01;
import com.itheima01.utils.JDBCUtils;
import javax.sql.DataSource;
import java.io.PrintWriter;
import java.sql.Connection;
import java.sql.SQLException;
import java.sql.SQLFeatureNotSupportedException;
import java.util.ArrayList;
import java.util.Collections;
import java.util.List;
import java.util.logging.Logger;public class MyDataSource implements DataSource {// 从连接池中获取一个连接对象// 准备容器 用于保存多个连接对象  将对象设置为线程安全的对象private  static List<Connection> pool = Collections.synchronizedList(new ArrayList<>());// 将arrayList变成线程安全的对象// 定义静态代码块  通过工具类获取10个连接对象 类加载的时候 就执行该静态代码块static {for(int i = 1; i <= 10; i++){try {Connection con = JDBCUtils.getConnection();pool.add(con);// 将连接对象添加到连接池中} catch (SQLException e) {throw new RuntimeException(e);}}}//    重写getConnection 用于获取一个连接对象@Overridepublic Connection getConnection() throws SQLException {// 只要池子中还有对象  返回0索引的对象if(pool.size() > 0){Connection con = pool.remove(0);// 移除一个元素  返回该连接对象// 创建自定义连接对象  对原有的连接对象进行包装  主要是为了使用归还资源的方法MyConnection2 myCon = new MyConnection2(con,pool);return myCon;}else{throw new RuntimeException("连接数量已经用尽");}}// 定义getSize方法  获取连接池容器的大小public int getSize(){return pool.size();}@Overridepublic Connection getConnection(String username, String password) throws SQLException {return null;}@Overridepublic PrintWriter getLogWriter() throws SQLException {return null;}@Overridepublic void setLogWriter(PrintWriter out) throws SQLException {}@Overridepublic void setLoginTimeout(int seconds) throws SQLException {}@Overridepublic int getLoginTimeout() throws SQLException {return 0;}@Overridepublic Logger getParentLogger() throws SQLFeatureNotSupportedException {return null;}@Overridepublic <T> T unwrap(Class<T> iface) throws SQLException {return null;}@Overridepublic boolean isWrapperFor(Class<?> iface) throws SQLException {return false;}
}

动态代理

动态代理：在不改变目标对象方法的情况下对方法进行增强
组成：被代理对象：真实的对象代理对象：内存中的一个对象
要求：代理对象必须和被代理对象实现相同的接口
实现:Proxy.newProxyInstance()


package com.itheima02;import java.lang.reflect.InvocationHandler;
import java.lang.reflect.Method;
import java.lang.reflect.Proxy;public class Test {public static void main(String[] args) {Student stu = new Student();
//        stu.eat("米饭");
//        stu.study();//        类加载器：和被代理对象使用相同的类加载器
//        接口类型的数组：和被代理对象使用相同的接口
//        代理的规则：完成代理增强的功能StudentInterface proxyStu = (StudentInterface) Proxy.newProxyInstance(stu.getClass().getClassLoader(), new Class[]{StudentInterface.class}, new InvocationHandler() {@Overridepublic Object invoke(Object proxy, Method method, Object[] args) throws Throwable {if(method.getName().equals("study")){System.out.println("学习");return null;}else {return method.invoke(stu,args);}}});proxyStu.eat("米饭");proxyStu.study();}
}

动态代理-归还数据库连接

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    public Connection getConnection() throws SQLException {// 只要池子中还有对象  返回0索引的对象if(pool.size() > 0){Connection con = pool.remove(0);// 移除一个元素  返回该连接对象Connection proxy = (Connection) Proxy.newProxyInstance(con.getClass().getClassLoader(), new Class[]{Connection.class}, new InvocationHandler() {// 执行Connection实现类连接对象所有的方法都会经过invoke// 如果是close方法 归还链接// 如果不是 直接执行连接对象原有的功能即可@Overridepublic Object invoke(Object proxy, Method method, Object[] args) throws Throwable {if(method.getName().equals("close")){// 归还连接pool.add(con);return null;}else{return method.invoke(con,args);}}});return proxy;}else{throw new RuntimeException("连接数量已经用尽");}}