引言： 在Spring Boot下默認提供了若干種可用的連接池，Druid來自于阿里系的一個開源連接池，在連接池之外，還提供了非常優秀的監控功能，這里講解如何與Spring Boot實現集成。
1.? 環境描述
???? Spring Boot 1.4.0.RELEASE,? JDK 1.8
2.?? Druid介紹
???? Druid是一個JDBC組件，它包括三部分：?
- ?DruidDriver 代理Driver，能夠提供基于Filter－Chain模式的插件體系。
- ?DruidDataSource 高效可管理的數據庫連接池。?
- ?SQLParser?
?? Druid可以做什么？??
- ? 可以監控數據庫訪問性能，Druid內置提供了一個功能強大的StatFilter插件，能夠詳細統計SQL的執行性能，這對于線上分析數據庫訪問性能有幫助。
- ? 替換DBCP和C3P0。Druid提供了一個高效、功能強大、可擴展性好的數據庫連接池。
- ? 數據庫密碼加密。直接把數據庫密碼寫在配置文件中，這是不好的行為，容易導致安全問題。DruidDruiver和DruidDataSource都支持PasswordCallback。??
- ?SQL執行日志，Druid提供了不同的LogFilter，能夠支持Common-Logging、Log4j和JdkLog，你可以按需要選擇相應的LogFilter，監控你應用的數據庫訪問情況。?
- ? 擴展JDBC，如果你要對JDBC層有編程的需求，可以通過Druid提供的Filter-Chain機制，很方便編寫JDBC層的擴展插件。?
???? 項目地址： https://github.com/alibaba/druid
3.?? Spring Boot與Druid的集成
?????? MySQL Driver驅動包：
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?copy <dependency>??????????????<groupId>mysql</groupId>??????????????<artifactId>mysql-connector-java</artifactId>??????????????<scope>runtime</scope>??????????</dependency>?? ??? Spring Boot的JPA依賴包：
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?copy <dependency>??????????????<groupId>org.springframework.boot</groupId>??????????????<artifactId>spring-boot-starter-data-jpa</artifactId>??????????</dependency>?? ?? 阿里系的Druid依賴包：
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?copy <dependency>??????????????<groupId>com.alibaba</groupId>??????????????<artifactId>druid</artifactId>??????????????<version>1.0.25</version>??????????</dependency>?? ??? Spring Boot中的application.properties配置信息：
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?copy #?驅動配置信息??spring.datasource.type=com.alibaba.druid.pool.DruidDataSource??spring.datasource.url?=?jdbc:mysql://127.0.0.1:3306/mealsystem?useUnicode=true&characterEncoding=utf-8??spring.datasource.username?=?root??spring.datasource.password?=?123456??spring.datasource.driverClassName?=?com.mysql.jdbc.Driver?????#連接池的配置信息??spring.datasource.initialSize=5??spring.datasource.minIdle=5??spring.datasource.maxActive=20??spring.datasource.maxWait=60000??spring.datasource.timeBetweenEvictionRunsMillis=60000??spring.datasource.minEvictableIdleTimeMillis=300000??spring.datasource.validationQuery=SELECT?1?FROM?DUAL??spring.datasource.testWhileIdle=true??spring.datasource.testOnBorrow=false??spring.datasource.testOnReturn=false??spring.datasource.poolPreparedStatements=true??spring.datasource.maxPoolPreparedStatementPerConnectionSize=20??spring.datasource.filters=stat,wall,log4j??spring.datasource.connectionProperties=druid.stat.mergeSql=true;druid.stat.slowSqlMillis=5000?? ?在Spring Boot1.4.0中驅動配置信息沒有問題，但是連接池的配置信息不再支持這里的配置項，即無法通過配置項直接支持相應的連接池；這里列出的這些配置項可以通過定制化DataSource來實現。
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? 目前Spring Boot中默認支持的連接池有dbcp,dbcp2, tomcat, hikari三種連接池。?
由于Druid暫時不在Spring Bootz中的直接支持，故需要進行配置信息的定制：
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?copy @Configuration??public?class?DruidDBConfig?{??????private?Logger?logger?=?LoggerFactory.getLogger(DruidDBConfig.class);????????????@Value("${spring.datasource.url}")??????private?String?dbUrl;????????????@Value("${spring.datasource.username}")??????private?String?username;????????????@Value("${spring.datasource.password}")??????private?String?password;????????????@Value("${spring.datasource.driverClassName}")??????private?String?driverClassName;????????????@Value("${spring.datasource.initialSize}")??????private?int?initialSize;????????????@Value("${spring.datasource.minIdle}")??????private?int?minIdle;????????????@Value("${spring.datasource.maxActive}")??????private?int?maxActive;????????????@Value("${spring.datasource.maxWait}")??????private?int?maxWait;????????????@Value("${spring.datasource.timeBetweenEvictionRunsMillis}")??????private?int?timeBetweenEvictionRunsMillis;????????????@Value("${spring.datasource.minEvictableIdleTimeMillis}")??????private?int?minEvictableIdleTimeMillis;????????????@Value("${spring.datasource.validationQuery}")??????private?String?validationQuery;????????????@Value("${spring.datasource.testWhileIdle}")??????private?boolean?testWhileIdle;????????????@Value("${spring.datasource.testOnBorrow}")??????private?boolean?testOnBorrow;????????????@Value("${spring.datasource.testOnReturn}")??????private?boolean?testOnReturn;????????????@Value("${spring.datasource.poolPreparedStatements}")??????private?boolean?poolPreparedStatements;????????????@Value("${spring.datasource.maxPoolPreparedStatementPerConnectionSize}")??????private?int?maxPoolPreparedStatementPerConnectionSize;????????????@Value("${spring.datasource.filters}")??????private?String?filters;????????????@Value("{spring.datasource.connectionProperties}")??????private?String?connectionProperties;????????????@Bean?????//聲明其為Bean實例??????@Primary??//在同樣的DataSource中，首先使用被標注的DataSource??????public?DataSource?dataSource(){??????????DruidDataSource?datasource?=?new?DruidDataSource();????????????????????datasource.setUrl(this.dbUrl);??????????datasource.setUsername(username);??????????datasource.setPassword(password);??????????datasource.setDriverClassName(driverClassName);????????????????????//configuration??????????datasource.setInitialSize(initialSize);??????????datasource.setMinIdle(minIdle);??????????datasource.setMaxActive(maxActive);??????????datasource.setMaxWait(maxWait);??????????datasource.setTimeBetweenEvictionRunsMillis(timeBetweenEvictionRunsMillis);??????????datasource.setMinEvictableIdleTimeMillis(minEvictableIdleTimeMillis);??????????datasource.setValidationQuery(validationQuery);??????????datasource.setTestWhileIdle(testWhileIdle);??????????datasource.setTestOnBorrow(testOnBorrow);??????????datasource.setTestOnReturn(testOnReturn);??????????datasource.setPoolPreparedStatements(poolPreparedStatements);??????????datasource.setMaxPoolPreparedStatementPerConnectionSize(maxPoolPreparedStatementPerConnectionSize);??????????try?{??????????????datasource.setFilters(filters);??????????}?catch?(SQLException?e)?{??????????????logger.error("druid?configuration?initialization?filter",?e);??????????}??????????datasource.setConnectionProperties(connectionProperties);????????????????????return?datasource;??????}??}?? ??? DruidDBConfig類被@Configuration標注，用作配置信息； DataSource對象被@Bean聲明，為Spring容器所管理， @Primary表示這里定義的DataSource將覆蓋其他來源的DataSource。
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#?下面為連接池的補充設置，應用到上面所有數據源中
#?初始化大小，最小，最大
spring.datasource.initialSize=5
spring.datasource.minIdle=5
spring.datasource.maxActive=20
#?配置獲取連接等待超時的時間
spring.datasource.maxWait=60000
#?配置間隔多久才進行一次檢測，檢測需要關閉的空閑連接，單位是毫秒
spring.datasource.timeBetweenEvictionRunsMillis=60000
#?配置一個連接在池中最小生存的時間，單位是毫秒
spring.datasource.minEvictableIdleTimeMillis=300000
spring.datasource.validationQuery=SELECT?1?FROM DUAL
spring.datasource.testWhileIdle=true
spring.datasource.testOnBorrow=false
spring.datasource.testOnReturn=false
#?打開PSCache，并且指定每個連接上PSCache的大小
spring.datasource.poolPreparedStatements=true
spring.datasource.maxPoolPreparedStatementPerConnectionSize=20
#?配置監控統計攔截的filters，去掉后監控界面sql無法統計，'wall'用于防火墻
spring.datasource.filters=stat,wall,log4j
#?通過connectProperties屬性來打開mergeSql功能；慢SQL記錄
spring.datasource.connectionProperties=druid.stat.mergeSql=true;druid.stat.slowSqlMillis=5000
#?合并多個DruidDataSource的監控數據
#spring.datasource.useGlobalDataSourceStat=true
需要注意的是：spring.datasource.type舊的spring boot版本是不能識別的。
?配置StatView的Servlet：
?? Filter的實現類：
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?copy import?javax.servlet.annotation.WebFilter;??import?javax.servlet.annotation.WebInitParam;????import?com.alibaba.druid.support.http.WebStatFilter;????@WebFilter(filterName="druidWebStatFilter",urlPatterns="/*",??????initParams={??????????@WebInitParam(name="exclusions",value="*.js,*.gif,*.jpg,*.bmp,*.png,*.css,*.ico,/druid/*")//忽略資源?????}??)??public?class?DruidStatFilter?extends?WebStatFilter?{????}?? ? StatViewServlet:
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?copy import?javax.servlet.annotation.WebInitParam;??import?javax.servlet.annotation.WebServlet;????import?com.alibaba.druid.support.http.StatViewServlet;????@WebServlet(urlPatterns="/druid/*",??????initParams={???????????@WebInitParam(name="allow",value="127.0.0.1,192.168.163.1"),//?IP白名單(沒有配置或者為空，則允許所有訪問)???????????@WebInitParam(name="deny",value="192.168.1.73"),//?IP黑名單?(存在共同時，deny優先于allow)???????????@WebInitParam(name="loginUsername",value="admin"),//?用戶名???????????@WebInitParam(name="loginPassword",value="123456"),//?密碼???????????@WebInitParam(name="resetEnable",value="false")//?禁用HTML頁面上的“Reset?All”功能??})??public?class?DruidStatViewServlet?extends?StatViewServlet?{??????private?static?final?long?serialVersionUID?=?-2688872071445249539L;????}?? 這兩個類相當于在web.xml中聲明了一個servlet， 等價于如下的配置信息（web.xml):
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?copy <servlet>????????????<servlet-name>DruidStatView</servlet-name>????????????<servlet-class>com.alibaba.druid.support.http.StatViewServlet</servlet-class>????????</servlet>????????<servlet-mapping>????????????<servlet-name>DruidStatView</servlet-name>????????????<url-pattern>/druid/*</url-pattern>????????</servlet-mapping>???? ?filter的配置信息：
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?copy <filter>????????????<filter-name>DruidWebStatFilter</filter-name>????????????<filter-class>com.alibaba.druid.support.http.WebStatFilter</filter-class>????????????<init-param>????????????????<param-name>exclusions</param-name>????????????????<param-value>*.js,*.gif,*.jpg,*.png,*.css,*.ico,/druid/*</param-value>????????????</init-param>??????????</filter>??????????<filter-mapping>????????????<filter-name>DruidWebStatFilter</filter-name>????????????<url-pattern>/*</url-pattern>??????????</filter-mapping>???? ?? 然后相應的配置工作就完成了，直接啟動即可看到相應的應用了。
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4.??? 運行界面以及介紹
??? 訪問地址： http://192.168.163.1:8080/druid/index.html
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5.?? 參考資料
- http://blog.csdn.net/xiaoyu411502/article/details/51392237
- ?http://stackoverflow.com/questions/32833641/not-able-to-set-spring-datasource-type
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