spring boot(10)-tomcat jdbc连接池

默认连接池

tomcat jdbc是从tomcat7开始推出的一个连接池，相比老的dbcp连接池要优秀很多。spring boot将tomcat jdbc作为默认的连接池，只要在pom.xml中引入了spring boot 的jdbc组件，就会自动引入tomcat jdbc连接池。关于引入jdbc和数据库的连接配置，参考第六篇

默认参数

以下是org.apache.tomcat.jdbc.pool.PoolProperties源码，这是tomcat jdbc连接池的默认初始参数。

这个类实现了一个接口PoolConfiguration，查看这个接口的源码，里面有每一个参数的详细说明。

官方文档： http://tomcat.apache.org/tomcat-8.5-doc/jdbc-pool.html 

public class PoolProperties implements PoolConfiguration, Cloneable, Serializable {    private static final long serialVersionUID = -8519283440854213745L;    private static final Log log = LogFactory.getLog(PoolProperties.class);    public static final int DEFAULT_MAX_ACTIVE = 100;    protected static final AtomicInteger poolCounter = new AtomicInteger(0);    private volatile Properties dbProperties = new Properties();    private volatile String url = null;    private volatile String driverClassName = null;    private volatile Boolean defaultAutoCommit = null;    private volatile Boolean defaultReadOnly = null;    private volatile int defaultTransactionIsolation = DataSourceFactory.UNKNOWN_TRANSACTIONISOLATION;    private volatile String defaultCatalog = null;    private volatile String connectionProperties;    private volatile int initialSize = 10;    private volatile int maxActive = DEFAULT_MAX_ACTIVE;    private volatile int maxIdle = maxActive;    private volatile int minIdle = initialSize;    private volatile int maxWait = 30000;    private volatile String validationQuery;    private volatile int validationQueryTimeout = -1;    private volatile String validatorClassName;    private volatile Validator validator;    private volatile boolean testOnBorrow = false;    private volatile boolean testOnReturn = false;    private volatile boolean testWhileIdle = false;    private volatile int timeBetweenEvictionRunsMillis = 5000;    private volatile int numTestsPerEvictionRun;    private volatile int minEvictableIdleTimeMillis = 60000;    private volatile boolean accessToUnderlyingConnectionAllowed = true;    private volatile boolean removeAbandoned = false;    private volatile int removeAbandonedTimeout = 60;    private volatile boolean logAbandoned = false;    private volatile String name = "Tomcat Connection Pool["+(poolCounter.addAndGet(1))+"-"+System.identityHashCode(PoolProperties.class)+"]";    private volatile String password;    private volatile String username;    private volatile long validationInterval = 3000;    private volatile boolean jmxEnabled = true;    private volatile String initSQL;    private volatile boolean testOnConnect =false;    private volatile String jdbcInterceptors=null;    private volatile boolean fairQueue = true;    private volatile boolean useEquals = true;    private volatile int abandonWhenPercentageFull = 0;    private volatile long maxAge = 0;    private volatile boolean useLock = false;    private volatile InterceptorDefinition[] interceptors = null;    private volatile int suspectTimeout = 0;    private volatile Object dataSource = null;    private volatile String dataSourceJNDI = null;    private volatile boolean alternateUsernameAllowed = false;    private volatile boolean commitOnReturn = false;    private volatile boolean rollbackOnReturn = false;    private volatile boolean useDisposableConnectionFacade = true;    private volatile boolean logValidationErrors = false;    private volatile boolean propagateInterruptState = false;    private volatile boolean ignoreExceptionOnPreLoad = false;    private volatile boolean useStatementFacade = true;

自定义参数

如果要修改某个默认参数值，可以在application.properties中配置，如下

spring.datasource.tomcat是前缀，maxActive是参数名，105是参数值，其他 参数格式也是一样

spring.datasource.tomcat.maxActive=105

在JAVA中自定义参数

在properties中自定义参数有一个问题，如果参数名写错了，是不会有任何错误提示的，会继续使用默认值 。在JAVA中配置可以避免这个问题，以下是设置maxActive参数，set其他参数也是一样

@Beanpublic DataSource dataSource() {PoolProperties poolProperties = new PoolProperties();poolProperties.setMaxActive(105);return new DataSource(poolProperties);}

HikariCP

HikariCP是目前号称最好的连接池，没有之一。不过tomcat连接池有tomcat做为其后盾保障， 文档资料齐全，也更加持久稳妥。这里不讲解 HikariCP，有兴趣可访问https://github.com/brettwooldridge/HikariCP