现象：
接口请求，10秒钟超时，看了一下，是sql查询耗时太长了，数据还没来得及返回，连接就断开了。
连接断开，上层应用直接报错。。

这些问题，都是。。。知道答案后，就觉得，emmm，好简单。知道答案前，…tmd, 这啥玩意儿。。。。

直接说答案吧：
数据库连接超时，那就配置超时时长，准确地说是 druid 的超时时长。。。
要设置 druid 的 connectTimeout 、socketTimeout 这两个配置项，
嗯。单这样说，有点。。。

一份druid 配置

druid:url: jdbc:mysql://10.12.1.9:3306/student?useUnicode=true&characterEncoding=UTF-8&allowMultiQueries=trueusername: usernamepassword: passwordxxxxuseSSL: falseinitial-size: 50min-idle: 50max-active: 200connectTimeout: 600000  #1.2.12版本需要单独配置才生效socketTimeout: 600000   #1.2.12版本需要单独配置才生效

有了配置，不够，需要在代码里面解析配置
于是要写一个：
DruidProperties.java

import org.springframework.boot.context.properties.ConfigurationProperties;/**
* druid
*/
@ConfigurationProperties(prefix = "druid")
public class DruidProperties {private String url;private String username;private String password;private int initialSize;private int minIdle;private int maxActive;private long maxWait;private String validationQuery;private int connectTimeout;private int socketTimeout;private boolean testOnBorrow;public String getUrl() {return url;}public void setUrl(String url) {this.url = url;}public String getUsername() {return username;}public void setUsername(String username) {this.username = username;}public String getPassword() {return password;}public void setPassword(String password) {this.password = password;}public int getInitialSize() {return initialSize;}public void setInitialSize(int initialSize) {this.initialSize = initialSize;}public int getMinIdle() {return minIdle;}public void setMinIdle(int minIdle) {this.minIdle = minIdle;}public int getMaxActive() {return maxActive;}public void setMaxActive(int maxActive) {this.maxActive = maxActive;}public long getMaxWait() {return maxWait;}public void setMaxWait(long maxWait) {this.maxWait = maxWait;}public String getValidationQuery() {return validationQuery;}public void setValidationQuery(String validationQuery) {this.validationQuery = validationQuery;}public int getConnectTimeout() {return connectTimeout;}public void setConnectTimeout(int connectTimeout) {this.connectTimeout = connectTimeout;}public int getSocketTimeout() {return socketTimeout;}public void setSocketTimeout(int socketTimeout) {this.socketTimeout = socketTimeout;}public boolean isTestOnBorrow() {return testOnBorrow;}public void setTestOnBorrow(boolean testOnBorrow) {this.testOnBorrow = testOnBorrow;}
}

还有 DruidAutoConfiguration.java

import com.alibaba.druid.pool.DruidDataSource;
import com.alibaba.druid.support.http.StatViewServlet;import javax.sql.DataSource;
import java.sql.SQLException;/*** Created by chu on 2017/3/2.*/
@Configuration
@EnableConfigurationProperties(DruidProperties.class)
@ConditionalOnClass(DruidDataSource.class)
@ConditionalOnProperty(prefix = "druid", name = "url")
@AutoConfigureBefore(DataSourceAutoConfiguration.class)
public class DruidAutoConfiguration {@Autowiredprivate DruidProperties properties;/*** 获取数据源* @return DataSource*/@Beanpublic DataSource dataSource() {DruidDataSource dataSource = new DruidDataSource();dataSource.setUrl(properties.getUrl());dataSource.setUsername(properties.getUsername());dataSource.setPassword(properties.getPassword());if (properties.getInitialSize() > 0) {dataSource.setInitialSize(properties.getInitialSize());}if (properties.getMaxActive() > 0) {dataSource.setMaxActive(properties.getMaxActive());}if (properties.getMaxWait() > 0) {dataSource.setMaxWait(properties.getMaxWait());}if (properties.getMinIdle() > 0) {dataSource.setMinIdle(properties.getMinIdle());}if (properties.getValidationQuery() != null) {dataSource.setValidationQuery(properties.getValidationQuery());}if (properties.getConnectTimeout() > 0) {dataSource.setConnectTimeout(properties.getConnectTimeout());}if (properties.getSocketTimeout() > 0) {dataSource.setSocketTimeout(properties.getSocketTimeout());}dataSource.setTestOnBorrow(properties.isTestOnBorrow());try {dataSource.init();} catch (SQLException e) {throw new RuntimeException(e);}return dataSource;}/*** 获取ServletRegistrationBean* @return ServletRegistrationBean*/@Beanpublic ServletRegistrationBean druidServlet() {ServletRegistrationBean druidServletRegistration = new ServletRegistrationBean(new DruidStatViewServlet());druidServletRegistration.addInitParameter("allow", "127.0.0.1");druidServletRegistration.addUrlMappings("/druid/*");return druidServletRegistration;}}

一开始，配置文件写到了

spring:datasource:druid:connectTimeout: 600000  #1.2.12版本需要单独配置才生效socketTimeout: 600000   #1.2.12版本需要单独配置才生效

然后配置死活不生效。。。

呃，，，， 所以配置文件，和解析类的前缀一定要匹配才行噢！ 不熟悉的同学，其实很容易踩坑。。。。

我就踩了好多次。。。emmmm
踩坑记录：单独配置：socketTimeout: 600000不生效，需要两项同时配置：

      connectTimeout: 600000  #1.2.12版本需要单独配置才生效socketTimeout: 600000   #1.2.12版本需要单独配置才生效