java_jdbc_基本连接池

MyDataSource实现封装连接池，MyConnection实现connection类，通过代理模式相互调用

 

package cn.itcast;

import java.sql.*;

public class ConnectDemo {

public static void main(String[] args) throws Exception {
for(int i=0;i<21;i++){
Connection conn = JdbcUtils.getConnection();
System.out.println(conn);
JdbcUtils.free(null, null, conn);
}
}

}

 

 

 

package cn.itcast;

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;

import cn.itcast.datasource.DataSourceDemo1;

public final class JdbcUtils {

// private static String url = "jdbc:mysql://";
// private static String user = "";
// private static String password = "";

private static MyDataSource mydatasource = null;

public JdbcUtils() {
}

static {
try {
Class.forName("com.mysql.jdbc.Driver");
mydatasource = new MyDataSource();
} catch (ClassNotFoundException e) {
// TODO Auto-generated catch block
throw new ExceptionInInitializerError(e);
}
}

public static Connection getConnection() throws SQLException {
return mydatasource.getConnection();
}

public static void free(ResultSet rs, Statement st, Connection conn) {
try {
if (rs != null)
rs.close();
} catch (SQLException e) {
e.printStackTrace();
} finally {
try {
if (st != null)
st.close();
} catch (SQLException e) {
e.printStackTrace();
} finally {
if (conn != null)
try {
conn.close();
//						mydatasource.free(conn);
} catch (Exception e) {
e.printStackTrace();
}
}
}
}
}

 

 

 

package cn.itcast;

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.SQLException;
import java.util.LinkedList;

public class MyDataSource {

private static String url = "jdbc:mysql://";
private static String user = "";
private static String password = "";

// 初始化连接数
private static int initCount = 5;
//最大创建数
private static int maxCount = 10;
int currentCount = 0;

public LinkedList<Connection> connectionsPool = new LinkedList<Connection>();

public MyDataSource() {
for (int i = 0; i < initCount; i++) {
try {
this.connectionsPool.addLast(this.createConnection());
this.currentCount++;
} catch (SQLException e) {
throw new ExceptionInInitializerError(e);
}
}
}

public Connection getConnection() throws SQLException {

synchronized (connectionsPool) {
if (this.connectionsPool.size() > 0) {
return this.connectionsPool.removeFirst();
} else if (this.currentCount < maxCount) {
this.currentCount++;
return this.createConnection();
} else {
throw new SQLException("超过最大连接数量");
}

}
}

public void free(Connection conn) {
this.connectionsPool.addLast(conn);
}

private Connection createConnection() throws SQLException {
Connection realConn = DriverManager.getConnection(url, user, password);
MyConnection myConnection = new MyConnection(realConn, this);
return myConnection;
}
}

 

 

package cn.itcast;

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.NClob;
import java.sql.PreparedStatement;
import java.sql.SQLClientInfoException;
import java.sql.SQLException;
import java.sql.SQLWarning;
import java.sql.SQLXML;
import java.sql.Savepoint;
import java.sql.Statement;
import java.sql.Struct;
import java.util.Map;
import java.util.Properties;
import java.util.concurrent.Executor;

import cn.itcast.datasource.DataSourceDemo1;

public class MyConnection implements Connection {
private Connection realConnection;
private MyDataSource dataSource;
//连接最大使用次数
private int maxUseCount = 10;
//当前使用次数
private int currentUserCount = 0;

MyConnection(Connection connection, MyDataSource datasource) {
this.realConnection = connection;
this.dataSource = datasource;
}

@Override
public void close() throws SQLException {
// TODO Auto-generated method stub
this.currentUserCount++;
if (this.currentUserCount > this.maxUseCount)
this.dataSource.connectionsPool.addLast(this);
else {

this.realConnection.close();// 真正关掉
this.dataSource.currentCount--;
}
}

@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 Statement createStatement() throws SQLException {
// TODO Auto-generated method stub
return null;
}

@Override
public PreparedStatement prepareStatement(String sql) throws SQLException {
// TODO Auto-generated method stub
return null;
}

@Override
public CallableStatement prepareCall(String sql) throws SQLException {
// TODO Auto-generated method stub
return null;
}

@Override
public String nativeSQL(String sql) throws SQLException {
// TODO Auto-generated method stub
return null;
}

@Override
public void setAutoCommit(boolean autoCommit) throws SQLException {
// TODO Auto-generated method stub

}

@Override
public boolean getAutoCommit() throws SQLException {
// TODO Auto-generated method stub
return false;
}

@Override
public void commit() throws SQLException {
// TODO Auto-generated method stub
this.realConnection.commit();
}

@Override
public void rollback() throws SQLException {
// TODO Auto-generated method stub

}

@Override
public boolean isClosed() throws SQLException {
// TODO Auto-generated method stub
return false;
}

@Override
public DatabaseMetaData getMetaData() throws SQLException {
// TODO Auto-generated method stub
return null;
}

@Override
public void setReadOnly(boolean readOnly) throws SQLException {
// TODO Auto-generated method stub

}

@Override
public boolean isReadOnly() throws SQLException {
// TODO Auto-generated method stub
return false;
}

@Override
public void setCatalog(String catalog) throws SQLException {
// TODO Auto-generated method stub

}

@Override
public String getCatalog() throws SQLException {
// TODO Auto-generated method stub
return null;
}

@Override
public void setTransactionIsolation(int level) throws SQLException {
// TODO Auto-generated method stub

}

@Override
public int getTransactionIsolation() throws SQLException {
// TODO Auto-generated method stub
return 0;
}

@Override
public SQLWarning getWarnings() throws SQLException {
// TODO Auto-generated method stub
return null;
}

@Override
public void clearWarnings() throws SQLException {
// TODO Auto-generated method stub
this.realConnection.clearWarnings();
}

@Override
public Statement createStatement(int resultSetType, int resultSetConcurrency)
throws SQLException {
// TODO Auto-generated method stub
return this.realConnection.createStatement();
}

@Override
public PreparedStatement prepareStatement(String sql, int resultSetType,
int resultSetConcurrency) throws SQLException {
// TODO Auto-generated method stub
return null;
}

@Override
public CallableStatement prepareCall(String sql, int resultSetType,
int resultSetConcurrency) throws SQLException {
// TODO Auto-generated method stub
return null;
}

@Override
public Map<String, Class<?>> getTypeMap() throws SQLException {
// TODO Auto-generated method stub
return null;
}

@Override
public void setTypeMap(Map<String, Class<?>> map) throws SQLException {
// TODO Auto-generated method stub

}

@Override
public void setHoldability(int holdability) throws SQLException {
// TODO Auto-generated method stub

}

@Override
public int getHoldability() throws SQLException {
// TODO Auto-generated method stub
return 0;
}

@Override
public Savepoint setSavepoint() throws SQLException {
// TODO Auto-generated method stub
return null;
}

@Override
public Savepoint setSavepoint(String name) throws SQLException {
// TODO Auto-generated method stub
return null;
}

@Override
public void rollback(Savepoint savepoint) throws SQLException {
// TODO Auto-generated method stub

}

@Override
public void releaseSavepoint(Savepoint savepoint) throws SQLException {
// TODO Auto-generated method stub

}

@Override
public Statement createStatement(int resultSetType,
int resultSetConcurrency, int resultSetHoldability)
throws SQLException {
// TODO Auto-generated method stub
return null;
}

@Override
public PreparedStatement prepareStatement(String sql, int resultSetType,
int resultSetConcurrency, int resultSetHoldability)
throws SQLException {
// TODO Auto-generated method stub
return null;
}

@Override
public CallableStatement prepareCall(String sql, int resultSetType,
int resultSetConcurrency, int resultSetHoldability)
throws SQLException {
// TODO Auto-generated method stub
return null;
}

@Override
public PreparedStatement prepareStatement(String sql, int autoGeneratedKeys)
throws SQLException {
// TODO Auto-generated method stub
return null;
}

@Override
public PreparedStatement prepareStatement(String sql, int[] columnIndexes)
throws SQLException {
// TODO Auto-generated method stub
return null;
}

@Override
public PreparedStatement prepareStatement(String sql, String[] columnNames)
throws SQLException {
// TODO Auto-generated method stub
return null;
}

@Override
public Clob createClob() throws SQLException {
// TODO Auto-generated method stub
return null;
}

@Override
public Blob createBlob() throws SQLException {
// TODO Auto-generated method stub
return null;
}

@Override
public NClob createNClob() throws SQLException {
// TODO Auto-generated method stub
return null;
}

@Override
public SQLXML createSQLXML() throws SQLException {
// TODO Auto-generated method stub
return null;
}

@Override
public boolean isValid(int timeout) throws SQLException {
// TODO Auto-generated method stub
return false;
}

@Override
public void setClientInfo(String name, String v
ae6a
alue)
throws SQLClientInfoException {
// TODO Auto-generated method stub

}

@Override
public void setClientInfo(Properties properties)
throws SQLClientInfoException {
// TODO Auto-generated method stub

}

@Override
public String getClientInfo(String name) throws SQLException {
// TODO Auto-generated method stub
return null;
}

@Override
public Properties getClientInfo() throws SQLException {
// TODO Auto-generated method stub
return null;
}

@Override
public Array createArrayOf(String typeName, Object[] elements)
throws SQLException {
// TODO Auto-generated method stub
return null;
}

@Override
public Struct createStruct(String typeName, Object[] attributes)
throws SQLException {
// TODO Auto-generated method stub
return null;
}

@Override
public void setSchema(String schema) throws SQLException {
// TODO Auto-generated method stub

}

@Override
public String getSchema() throws SQLException {
// TODO Auto-generated method stub
return null;
}

@Override
public void abort(Executor executor) throws SQLException {
// TODO Auto-generated method stub

}

@Override
public void setNetworkTimeout(Executor executor, int milliseconds)
throws SQLException {
// TODO Auto-generated method stub

}

@Override
public int getNetworkTimeout() throws SQLException {
// TODO Auto-generated method stub
return 0;
}

}