连接池-归还连接详解(上)

目录

归还数据库连接的方式

继承方式归还数据库连接的思想

继承方式归还数据库连接的实现步骤

继承方式归还数据库连接存在的问题

装饰设计模式归还数据库连接的思想

装饰设计模式归还数据库连接的实现步骤

装饰设计模式归还数据库连接存在的问题

装饰设计模式归还实例演示

归还数据库连接的方式

继承方式归还数据库连接的思想

继承方式归还数据库连接的实现步骤

继承方式归还数据库连接存在的问题

装饰设计模式归还数据库连接的思想

装饰设计模式归还数据库连接的实现步骤

装饰设计模式归还数据库连接存在的问题

装饰设计模式归还实例演示

package demo02.myDataSourse;
 
import java.sql.*;
import java.util.List;
import java.util.Map;
import java.util.Properties;
import java.util.concurrent.Executor;
    //1.定义一个类，实现Connection接口
public class demomyConnection implements Connection {
    //2.定义连接对象和连接池容器对象的成员变量
    private Connection con;
    private List pool;
    //3.通过有参构造方法为成员变量赋值
    public demomyConnection(Connection con, List pool) {
        this.con = con;
        this.pool = pool;
    }
    //4.重写close方法，完成归还连接
    @Override
    public void close() throws SQLException {
        pool.add(con);
    }
    //5.剩余方法，还是调用原有的连接对象中的功能即可
    @Override
    public Statement createStatement() throws SQLException {
        return con.createStatement();
    }
 
    @Override
    public PreparedStatement prepareStatement(String sql) throws SQLException {
        return con.prepareStatement(sql);
    }
 
    @Override
    public CallableStatement prepareCall(String sql) throws SQLException {
        return con.prepareCall(sql);
    }
 
    @Override
    public String nativeSQL(String sql) throws SQLException {
        return con.nativeSQL(sql);
    }
 
    @Override
    public void setAutoCommit(boolean autoCommit) throws SQLException {
        con.setAutoCommit(autoCommit);
    }
 
    @Override
    public boolean getAutoCommit() throws SQLException {
        return con.getAutoCommit();
    }
 
    @Override
    public void commit() throws SQLException {
        con.commit();
    }
 
    @Override
    public void rollback() throws SQLException {
        con.rollback();
    }
 
    @Override
    public boolean isClosed() throws SQLException {
        return con.isClosed();
    }
 
    @Override
    public DatabaseMetaData getMetaData() throws SQLException {
        return con.getMetaData();
    }
 
    @Override
    public void setReadOnly(boolean readOnly) throws SQLException {
        con.setReadOnly(readOnly);
    }
 
    @Override
    public boolean isReadOnly() throws SQLException {
        return con.isReadOnly();
    }
 
    @Override
    public void setCatalog(String catalog) throws SQLException {
        con.setCatalog(catalog);
    }
 
    @Override
    public String getCatalog() throws SQLException {
        return con.getCatalog();
    }
 
    @Override
    public void setTransactionIsolation(int level) throws SQLException {
        con.setTransactionIsolation(level);
    }
 
    @Override
    public int getTransactionIsolation() throws SQLException {
        return con.getTransactionIsolation();
    }
 
    @Override
    public SQLWarning getWarnings() throws SQLException {
        return con.getWarnings();
    }
 
    @Override
    public void clearWarnings() throws SQLException {
        con.clearWarnings();
    }
 
    @Override
    public Statement createStatement(int resultSetType, int resultSetConcurrency) throws SQLException {
        return con.createStatement(resultSetType,resultSetConcurrency);
    }
 
    @Override
    public PreparedStatement prepareStatement(String sql, int resultSetType, int resultSetConcurrency) throws SQLException {
        return con.prepareStatement(sql,resultSetType,resultSetConcurrency);
    }
 
    @Override
    public CallableStatement prepareCall(String sql, int resultSetType, int resultSetConcurrency) throws SQLException {
        return con.prepareCall(sql,resultSetType,resultSetConcurrency);
    }
 
    @Override
    public Map> getTypeMap() throws SQLException {
        return con.getTypeMap();
    }
 
    @Override
    public void setTypeMap(Map> map) throws SQLException {
        con.setTypeMap(map);
    }
 
    @Override
    public void setHoldability(int holdability) throws SQLException {
        con.setHoldability(holdability);
    }
 
    @Override
    public int getHoldability() throws SQLException {
        return con.getHoldability();
    }
 
    @Override
    public Savepoint setSavepoint() throws SQLException {
        return con.setSavepoint();
    }
 
    @Override
    public Savepoint setSavepoint(String name) throws SQLException {
        return con.setSavepoint(name);
    }
 
    @Override
    public void rollback(Savepoint savepoint) throws SQLException {
        con.rollback(savepoint);
    }
 
    @Override
    public void releaseSavepoint(Savepoint savepoint) throws SQLException {
        con.releaseSavepoint(savepoint);
    }
 
    @Override
    public Statement createStatement(int resultSetType, int resultSetConcurrency, int resultSetHoldability) throws SQLException {
        return con.createStatement(resultSetType,resultSetConcurrency,resultSetHoldability);
    }
 
    @Override
    public PreparedStatement prepareStatement(String sql, int resultSetType, int resultSetConcurrency, int resultSetHoldability) throws SQLException {
        return con.prepareStatement(sql,resultSetType,resultSetConcurrency,resultSetHoldability);
    }
 
    @Override
    public CallableStatement prepareCall(String sql, int resultSetType, int resultSetConcurrency, int resultSetHoldability) throws SQLException {
        return con.prepareCall(sql,resultSetType,resultSetConcurrency,resultSetHoldability);
    }
 
    @Override
    public PreparedStatement prepareStatement(String sql, int autoGeneratedKeys) throws SQLException {
        return con.prepareStatement(sql,autoGeneratedKeys);
    }
 
    @Override
    public PreparedStatement prepareStatement(String sql, int[] columnIndexes) throws SQLException {
        return con.prepareStatement(sql,columnIndexes);
    }
 
    @Override
    public PreparedStatement prepareStatement(String sql, String[] columnNames) throws SQLException {
        return con.prepareStatement(sql,columnNames);
    }
 
    @Override
    public Clob createClob() throws SQLException {
        return con.createClob();
    }
 
    @Override
    public Blob createBlob() throws SQLException {
        return con.createBlob();
    }
 
    @Override
    public NClob createNClob() throws SQLException {
        return con.createNClob();
    }
 
    @Override
    public SQLXML createSQLXML() throws SQLException {
        return con.createSQLXML();
    }
 
    @Override
    public boolean isValid(int timeout) throws SQLException {
        return con.isValid(timeout);
    }
 
    @Override
    public void setClientInfo(String name, String value) throws SQLClientInfoException {
        con.setClientInfo(name,value);
    }
 
    @Override
    public void setClientInfo(Properties properties) throws SQLClientInfoException {
        con.setClientInfo(properties);
    }
 
    @Override
    public String getClientInfo(String name) throws SQLException {
        return con.getClientInfo(name);
    }
 
    @Override
    public Properties getClientInfo() throws SQLException {
        return con.getClientInfo();
    }
 
    @Override
    public Array createArrayOf(String typeName, Object[] elements) throws SQLException {
        return con.createArrayOf(typeName,elements);
    }
 
    @Override
    public Struct createStruct(String typeName, Object[] attributes) throws SQLException {
        return con.createStruct(typeName,attributes);
    }
 
    @Override
    public void setSchema(String schema) throws SQLException {
        con.setSchema(schema);
    }
 
    @Override
    public String getSchema() throws SQLException {
        return con.getSchema();
    }
 
    @Override
    public void abort(Executor executor) throws SQLException {
        con.abort(executor);
    }
 
    @Override
    public void setNetworkTimeout(Executor executor, int milliseconds) throws SQLException {
        con.setNetworkTimeout(executor,milliseconds);
    }
 
    @Override
    public int getNetworkTimeout() throws SQLException {
        return con.getNetworkTimeout();
    }
 
    @Override
    public  T unwrap(Class iface) throws SQLException {
        return con.unwrap(iface);
    }
 
    @Override
    public boolean isWrapperFor(Class iface) throws SQLException {
        return con.isWrapperFor(iface);
    }
}

package demo02.myDataSourse;
import demo02.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;
 
//自定义数据库连接池
public class demoDataSourse implements DataSource{
    //1.准备容器，用于保存多个连接对象
    private static List pool = Collections.synchronizedList(new ArrayList<>());
    //2.定义静态代码块，通过工具类获取10个连接对象
    static{
        for(int i=1;i<=10;i++){
            Connection con = JDBCUtils.getConnection();
            pool.add(con);
        }
    }
    //3.重写getConnection(),用于获取一个连接对象
    @Override
    public Connection getConnection() throws SQLException {
        if(pool.size()>0){
            Connection con = pool.remove(0);
            //通过自定义的连接对象，对原有的连接对象进行包装
            demomyConnection mycon = new demomyConnection(con,pool);
            return mycon;
        }else{
            throw new RuntimeException("连接数量已用尽");
        }
    }
    //4.定义getSize方法，获取连接池容器的大小
    public int getSize(){
        return pool.size();
    }
    @Override
    public Connection getConnection(String username, String password) throws SQLException {
        return null;
    }
 
    @Override
    public  T unwrap(Class iface) throws SQLException {
        return null;
    }
 
    @Override
    public boolean isWrapperFor(Class iface) throws SQLException {
        return false;
    }
 
    @Override
    public PrintWriter getLogWriter() throws SQLException {
        return null;
    }
 
    @Override
    public void setLogWriter(PrintWriter out) throws SQLException {
 
    }
 
    @Override
    public void setLoginTimeout(int seconds) throws SQLException {
 
    }
 
    @Override
    public int getLoginTimeout() throws SQLException {
        return 0;
    }
 
    @Override
    public Logger getParentLogger() throws SQLFeatureNotSupportedException {
        return null;
    }
}

package demo02.myDataSourse;
 
import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
 
public class demoDataSourseTest {
    public static void main(String[] args) throws Exception {
        //1.创建连接池对象
        demoDataSourse dataSourse = new demoDataSourse();
 
        System.out.println("使用之前的数量" + dataSourse.getSize());
 
        //2.通过连接池对象获取连接对象
        Connection con = dataSourse.getConnection();
        //3.查询学生表的全部信息
        String sql = "SELECT * FROM student";
        PreparedStatement pst = con.prepareStatement(sql);
        //4.执行sql语句,接收结果集
        ResultSet rs = pst.executeQuery();
        //5.处理结果集
        while(rs.next()){
            System.out.println(rs.getInt("sid")+"\t"+rs.getString("name")+"\t"+rs.getInt("age")+"\t"+rs.getDate("birthday"));
        }
        //6.释放资源
        rs.close();
        pst.close();
        con.close();//用完以后，进行归还
 
        System.out.println("使用之后的数量" + dataSourse.getSize());
    }
}