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在启动一个 Spring Boot 项目时,遇到以下错误信息 
 APPLICATION FAILED TO START 
 Description: Web server failed to start. Port 5566 was already in use. Action: Identify and stop the process that's listening on port 5566 or configure this application to listen on another port. 
问题原因
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Spring Boot 项目使用的的端口 5566 已被占用,错误信息已明确指出 Web server failed to start. Port 5566 was already in use. 
处理策略
- 终止占用端口的进程
            
            
              bash
              
              
            
          
          # 查找占用进程
netstat -ano | findstr 【端口】
            
            
              bash
              
              
            
          
          # 查看进程 ID 对应的程序
tasklist | findstr 【进程 ID】
            
            
              bash
              
              
            
          
          # 终止进程
taskkill /PID 【进程 ID】 /F- 或者,修改 Spring Boot 项目的端口
            
            
              yml
              
              
            
          
          server:
  port: 6677 # 修改为其他未被占用的端口连带问题
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如下,是 Spring Boot 项目在端口被占用后,引发了数据库连接池关闭的连带问题 
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此问题在端口占用问题被处理后也会得到处理 org.mybatis.spring.MyBatisSystemException 
 at org.mybatis.spring.MyBatisExceptionTranslator.translateExceptionIfPossible(MyBatisExceptionTranslator.java:97)
 at org.mybatis.spring.SqlSessionTemplateSqlSessionInterceptor.invoke(SqlSessionTemplate.java:439) at jdk.proxy2/jdk.proxy2.Proxy61.selectOne(Unknown Source)
 at org.mybatis.spring.SqlSessionTemplate.selectOne(SqlSessionTemplate.java:160)
 ...Cause: org.springframework.jdbc.CannotGetJdbcConnectionException: Failed to obtain JDBC Connectionat org.apache.ibatis.exceptions.ExceptionFactory.wrapException(ExceptionFactory.java:30) at org.apache.ibatis.session.defaults.DefaultSqlSession.selectList(DefaultSqlSession.java:153) at org.apache.ibatis.session.defaults.DefaultSqlSession.selectList(DefaultSqlSession.java:145) at org.apache.ibatis.session.defaults.DefaultSqlSession.selectList(DefaultSqlSession.java:140) ...Caused by: org.springframework.jdbc.CannotGetJdbcConnectionException: Failed to obtain JDBC Connection 
 at org.springframework.jdbc.datasource.DataSourceUtils.getConnection(DataSourceUtils.java:83)
 at org.mybatis.spring.transaction.SpringManagedTransaction.openConnection(SpringManagedTransaction.java:80)
 at org.mybatis.spring.transaction.SpringManagedTransaction.getConnection(SpringManagedTransaction.java:67)
 at org.apache.ibatis.executor.BaseExecutor.getConnection(BaseExecutor.java:337)
 ...
 Caused by: java.sql.SQLException: HikariDataSource HikariDataSource (null) has been closed.
 at com.zaxxer.hikari.HikariDataSource.getConnection(HikariDataSource.java:96)
 at org.springframework.jdbc.datasource.DataSourceUtils.fetchConnection(DataSourceUtils.java:159)
 at org.springframework.jdbc.datasource.DataSourceUtils.doGetConnection(DataSourceUtils.java:117)
 at org.springframework.jdbc.datasource.DataSourceUtils.getConnection(DataSourceUtils.java:80)
 ...