MyBatis-数据源模块
约 1825 字大约 6 分钟
MyBatis-数据源模块
模块详情
类DataSourceFactory
public interface DataSourceFactory {
/**
* 设置DataSource相关的属性
* @param props
*/
void setProperties(Properties props);
/**
* 获取 DataSource 相关的设置
* @return
*/
DataSource getDataSource();
}
非池化UnpooledDataSourceFactory
构造方法
public UnpooledDataSourceFactory() {
this.dataSource = new UnpooledDataSource();
}
非池化数据源UnpooledDataSource
- 支持配置几个属性，分别是：
- 用户名：username
- 密码：password
- 链接地址：url
- 驱动：driver
public UnpooledDataSource() {
}
public UnpooledDataSource(String driver, String url, String username, String password) {
this.driver = driver;
this.url = url;
this.username = username;
this.password = password;
}
public UnpooledDataSource(String driver, String url, Properties driverProperties) {
this.driver = driver;
this.url = url;
this.driverProperties = driverProperties;
}
public UnpooledDataSource(ClassLoader driverClassLoader, String driver, String url, String username, String password) {
this.driverClassLoader = driverClassLoader;
this.driver = driver;
this.url = url;
this.username = username;
this.password = password;
}
方法setProperties
@Override
public void setProperties(Properties properties) {
Properties driverProperties = new Properties();
// 创建dataSource对应的MetaObject对象
MetaObject metaDataSource = SystemMetaObject.forObject(dataSource);
for (Object key : properties.keySet()) {
String propertyName = (String) key;
// 如果是 driver 驱动， 初始化到driverProperties当中
if (propertyName.startsWith(DRIVER_PROPERTY_PREFIX)) {
String value = properties.getProperty(propertyName);
driverProperties.setProperty(propertyName.substring(DRIVER_PROPERTY_PREFIX_LENGTH), value);
// 初始化到 MetaObject 当中
} else if (metaDataSource.hasSetter(propertyName)) {
String value = (String) properties.get(propertyName);
Object convertedValue = convertValue(metaDataSource, propertyName, value);
metaDataSource.setValue(propertyName, convertedValue);
} else {
throw new DataSourceException("Unknown DataSource property: " + propertyName);
}
}
// 设置 driverProperties 到 MetaObject 当中
if (driverProperties.size() > 0) {
metaDataSource.setValue("driverProperties", driverProperties);
}
}
转换方法convertValue
private Object convertValue(MetaObject metaDataSource, String propertyName, String value) {
Object convertedValue = value;
// 获取属性名称对应的set方法类
Class<?> targetType = metaDataSource.getSetterType(propertyName);
// 转换对应的类型
if (targetType == Integer.class || targetType == int.class) {
convertedValue = Integer.valueOf(value);
} else if (targetType == Long.class || targetType == long.class) {
convertedValue = Long.valueOf(value);
} else if (targetType == Boolean.class || targetType == boolean.class) {
convertedValue = Boolean.valueOf(value);
}
return convertedValue;
}
池化PooledDataSourceFactory
- 池化数据源工厂继承了非池化数据源工厂类UnpooledDataSourceFactory
构造方法
public PooledDataSourceFactory() {
this.dataSource = new PooledDataSource();
}
自定义参数
// OPTIONAL CONFIGURATION FIELDS
// 在任意时间可以存在的活动（也就是正在使用）连接数量
protected int poolMaximumActiveConnections = 10;
// 任意时间可能存在的空闲连接数。
protected int poolMaximumIdleConnections = 5;
// 在被强制返回之前，池中连接被检出（checked out）时间
protected int poolMaximumCheckoutTime = 20000;
// 这是一个底层设置，如果获取连接花费了相当长的时间，连接池会打印状态日志并重新尝试获取一个连接（避免在误配置的情况下一直安静的失败）
protected int poolTimeToWait = 20000;
// 这是一个关于坏连接容忍度的底层设置， 作用于每一个尝试从缓存池获取连接的线程. 如果这个线程获取到的是一个坏的连接，那么这个数据源允许这个线程尝试重新获取一个新的连接，
// 但是这个重新尝试的次数不应该超过 poolMaximumIdleConnections 与 poolMaximumLocalBadConnectionTolerance 之和
protected int poolMaximumLocalBadConnectionTolerance = 3;
// 发送到数据库的侦测查询，用来检验连接是否正常工作并准备接受请求
protected String poolPingQuery = "NO PING QUERY SET";
// 是否启用侦测查询。若开启，需要设置 poolPingQuery 属性为一个可执行的 SQL 语句（最好是一个速度非常快的 SQL 语句），默认值：false。
protected boolean poolPingEnabled;
protected int poolPingConnectionsNotUsedFor;
类DataSource
- 可以看到PooledDataSource和UnpooledDataSource都实现了DataSource接口，
类UnpooledDataSource
构造方法
- 设置几个主要的参数，包括：驱动名称，链接地址，用户名，密码，事务隔离级别等
private ClassLoader driverClassLoader;
private Properties driverProperties;
private static Map<String, Driver> registeredDrivers = new ConcurrentHashMap<>();
/// 驱动名称
private String driver;
// 链接地址
private String url;
// 用户名
private String username;
// 密码
private String password;
// 是否自动提交sql
private Boolean autoCommit;
// 默认的事务隔离级别
private Integer defaultTransactionIsolationLevel;
// 网络链接超时时间设置
private Integer defaultNetworkTimeout;
static {
Enumeration<Driver> drivers = DriverManager.getDrivers();
while (drivers.hasMoreElements()) {
Driver driver = drivers.nextElement();
registeredDrivers.put(driver.getClass().getName(), driver);
}
}
public UnpooledDataSource() {
}
public UnpooledDataSource(String driver, String url, String username, String password) {
this.driver = driver;
this.url = url;
this.username = username;
this.password = password;
}
public UnpooledDataSource(String driver, String url, Properties driverProperties) {
this.driver = driver;
this.url = url;
this.driverProperties = driverProperties;
}
public UnpooledDataSource(ClassLoader driverClassLoader, String driver, String url, String username, String password) {
this.driverClassLoader = driverClassLoader;
this.driver = driver;
this.url = url;
this.username = username;
this.password = password;
}
public UnpooledDataSource(ClassLoader driverClassLoader, String driver, String url, Properties driverProperties) {
this.driverClassLoader = driverClassLoader;
this.driver = driver;
this.url = url;
this.driverProperties = driverProperties;
}
getConnection
- getConnection主要是调用doGetConnection方法实现
@Override
public Connection getConnection() throws SQLException {
return doGetConnection(username, password);
}
@Override
public Connection getConnection(String username, String password) throws SQLException {
return doGetConnection(username, password);
}
- doGetConnection方法获取链接
private Connection doGetConnection(String username, String password) throws SQLException {
Properties props = new Properties();
if (driverProperties != null) {
props.putAll(driverProperties);
}
if (username != null) {
props.setProperty("user", username);
}
if (password != null) {
props.setProperty("password", password);
}
return doGetConnection(props);
}
private Connection doGetConnection(Properties properties) throws SQLException {
// 初始化驱动
initializeDriver();
// 获取链接
Connection connection = DriverManager.getConnection(url, properties);
// 配置链接参数：比如：是否自动提交，事务隔离级别等
configureConnection(connection);
return connection;
}
initializeDriver
- 初始化驱动到registeredDrivers当中，当缓存当中没有的话，就执行下属逻辑
private synchronized void initializeDriver() throws SQLException {
if (!registeredDrivers.containsKey(driver)) {
// 获取驱动对应的实体类
Class<?> driverType;
try {
if (driverClassLoader != null) {
driverType = Class.forName(driver, true, driverClassLoader);
} else {
driverType = Resources.classForName(driver);
}
// DriverManager requires the driver to be loaded via the system ClassLoader.
// http://www.kfu.com/~nsayer/Java/dyn-jdbc.html
Driver driverInstance = (Driver) driverType.getDeclaredConstructor().newInstance();
DriverManager.registerDriver(new DriverProxy(driverInstance));
// 将本次获取的驱动加入到缓存当中
registeredDrivers.put(driver, driverInstance);
} catch (Exception e) {
throw new SQLException("Error setting driver on UnpooledDataSource. Cause: " + e);
}
}
configureConnection
- 配置链接的参数，比如网络超时时间，是否自动提交，事务的隔离级别
private void configureConnection(Connection conn) throws SQLException {
// 默认的网络超时时间
if (defaultNetworkTimeout != null) {
conn.setNetworkTimeout(Executors.newSingleThreadExecutor(), defaultNetworkTimeout);
}
// 设置是否自动提交
if (autoCommit != null && autoCommit != conn.getAutoCommit()) {
conn.setAutoCommit(autoCommit);
}
// 设置默认的事务隔离级别
if (defaultTransactionIsolationLevel != null) {
conn.setTransactionIsolation(defaultTransactionIsolationLevel);
}
}
类PooledDataSource
构造方法
- 主要设置数据源的各种参数，
- 需要注意的是dataSource是UnpooledDataSource对象，数据源工厂的具体逻辑还是在非池化数据源当中实现的，
private static final Log log = LogFactory.getLog(PooledDataSource.class);
private final PoolState state = new PoolState(this);
private final UnpooledDataSource dataSource;
// OPTIONAL CONFIGURATION FIELDS
// 在任意时间可以存在的活动（也就是正在使用）连接数量
protected int poolMaximumActiveConnections = 10;
// 任意时间可能存在的空闲连接数。
protected int poolMaximumIdleConnections = 5;
// 在被强制返回之前，池中连接被检出（checked out）时间
protected int poolMaximumCheckoutTime = 20000;
// 这是一个底层设置，如果获取连接花费了相当长的时间，连接池会打印状态日志并重新尝试获取一个连接（避免在误配置的情况下一直安静的失败）
protected int poolTimeToWait = 20000;
// 这是一个关于坏连接容忍度的底层设置， 作用于每一个尝试从缓存池获取连接的线程. 如果这个线程获取到的是一个坏的连接，那么这个数据源允许这个线程尝试重新获取一个新的连接，
// 但是这个重新尝试的次数不应该超过 poolMaximumIdleConnections 与 poolMaximumLocalBadConnectionTolerance 之和
protected int poolMaximumLocalBadConnectionTolerance = 3;
// 发送到数据库的侦测查询，用来检验连接是否正常工作并准备接受请求
protected String poolPingQuery = "NO PING QUERY SET";
// 是否启用侦测查询。若开启，需要设置 poolPingQuery 属性为一个可执行的 SQL 语句（最好是一个速度非常快的 SQL 语句），默认值：false。
protected boolean poolPingEnabled;
protected int poolPingConnectionsNotUsedFor;
private int expectedConnectionTypeCode;
public PooledDataSource() {
dataSource = new UnpooledDataSource();
}
public PooledDataSource(UnpooledDataSource dataSource) {
this.dataSource = dataSource;
}
public PooledDataSource(String driver, String url, String username, String password) {
dataSource = new UnpooledDataSource(driver, url, username, password);
expectedConnectionTypeCode = assembleConnectionTypeCode(dataSource.getUrl(), dataSource.getUsername(), dataSource.getPassword());
}
public PooledDataSource(String driver, String url, Properties driverProperties) {
dataSource = new UnpooledDataSource(driver, url, driverProperties);
expectedConnectionTypeCode = assembleConnectionTypeCode(dataSource.getUrl(), dataSource.getUsername(), dataSource.getPassword());
}
public PooledDataSource(ClassLoader driverClassLoader, String driver, String url, String username, String password) {
dataSource = new UnpooledDataSource(driverClassLoader, driver, url, username, password);
expectedConnectionTypeCode = assembleConnectionTypeCode(dataSource.getUrl(), dataSource.getUsername(), dataSource.getPassword());
}
public PooledDataSource(ClassLoader driverClassLoader, String driver, String url, Properties driverProperties) {
dataSource = new UnpooledDataSource(driverClassLoader, driver, url, driverProperties);
expectedConnectionTypeCode = assembleConnectionTypeCode(dataSource.getUrl(), dataSource.getUsername(), dataSource.getPassword());
}
getConnection
@Override
public Connection getConnection() throws SQLException {
return popConnection(dataSource.getUsername(), dataSource.getPassword()).getProxyConnection();
}
- 获取链接方法getConnection实际上是调用的popConnection方法，返回了一个java.sql.Connection对象，
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