package com.battery.device.neware;
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import java.io.PrintWriter;
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import java.sql.Connection;
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import java.sql.DriverManager;
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import java.sql.SQLException;
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import java.sql.SQLFeatureNotSupportedException;
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import java.util.Properties;
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import java.util.logging.Logger;
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import javax.sql.DataSource;
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/**
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* 由 DriverManager 直连厂商库的极简数据源：只被设备适配器使用，不注册进 Spring，
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* 因此不参与任何业务事务，Druid 主数据源的回滚不会波及厂商库。
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*
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* <p>连接复用一条并在查询失败时作废，避免厂商服务端重启后长期持有失效连接；
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* 厂商库实测按固定 60 秒写库，取数频率远低于连接复用带来的收益门槛。
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*
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* <p>{@link DataSource} 接口中与连接获取无关的 JDK 样板方法（日志写出器、登录超时、父日志器、
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* {@code unwrap} / {@code isWrapperFor}）只转发驱动对象，不承载业务语义，因此不单独加方法注释。
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*/
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public final class SingleConnectionVendorDataSource implements DataSource
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{
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private final String url;
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private final Properties credentials;
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private Connection connection;
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public SingleConnectionVendorDataSource(String url, String user, String password)
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{
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if (url == null || url.isBlank()) throw new IllegalArgumentException("vendor jdbc url must not be blank");
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this.url = url;
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this.credentials = new Properties();
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this.credentials.setProperty("user", user == null ? "" : user);
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this.credentials.setProperty("password", password == null ? "" : password);
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}
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/** 返回复用的单条连接，必要时按登记凭据新建；厂商库只读，连接不做写事务。 */
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@Override
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public synchronized Connection getConnection() throws SQLException
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{
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if (connection == null || connection.isClosed())
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{
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connection = DriverManager.getConnection(url, credentials);
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}
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return connection;
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}
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/** 按给定账号临时新建一条连接，不复用也不替换已缓存的那条。 */
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@Override
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public Connection getConnection(String username, String password) throws SQLException
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{
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return DriverManager.getConnection(url, username, password);
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}
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/** 作废当前连接，使下一次取数重新建立；用于查询失败后的自愈。 */
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public synchronized void invalidate()
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{
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if (connection == null) return;
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try
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{
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connection.close();
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}
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catch (SQLException ignored)
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{
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// 连接已失效，无需处理。
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}
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finally
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{
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connection = null;
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}
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}
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@Override
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public PrintWriter getLogWriter() throws SQLException
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{
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return DriverManager.getLogWriter();
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}
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@Override
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public void setLogWriter(PrintWriter out) throws SQLException
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{
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DriverManager.setLogWriter(out);
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}
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@Override
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public void setLoginTimeout(int seconds) throws SQLException
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{
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DriverManager.setLoginTimeout(seconds);
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}
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@Override
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public int getLoginTimeout() throws SQLException
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{
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return DriverManager.getLoginTimeout();
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}
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@Override
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public Logger getParentLogger() throws SQLFeatureNotSupportedException
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{
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return Logger.getLogger("com.battery.device.neware");
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}
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@Override
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public <T> T unwrap(Class<T> iface) throws SQLException
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{
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if (iface.isInstance(this)) return iface.cast(this);
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throw new SQLFeatureNotSupportedException("不支持解包为 " + iface);
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}
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@Override
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public boolean isWrapperFor(Class<?> iface)
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{
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return iface.isInstance(this);
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}
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}
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