Exception in thread “main“ org.springframework.jdbc.CannotGetJdbcConnectionException: Failed to obta

原创已于 2022-12-12 12:11:14 修改 · 898 阅读

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#数据库 #java #mysql

于 2022-12-12 12:10:31 首次发布

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本文介绍了一种常见的Spring框架中使用JDBC进行数据库操作时出现的连接异常问题及其解决方案。通过修改数据库连接字符串，确保IP地址、端口号、数据库名称、用户名及密码正确无误。

Exception in thread “main”
org.springframework.jdbc.CannotGetJdbcConnectionException: Failed to
obtain JDBC Connection; nested exception is
com.mysql.cj.jdbc.exceptions.CommunicationsException: Communications
link failure

运行时总是报错，看起来像是数据库连接的问题。检查数据库配置文件时，看到数据库连接字符串是我复制过来的，没有修改，修改后就好了。

数据库连接有5个位置需要特别注意：
IP：端口号？数据库名
数据库用户名
数据库密码

applicationContext.xml:

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
       xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
       xmlns:context="http://www.springframework.org/schema/context"
       xsi:schemaLocation="http://www.springframework.org/schema/beans
        https://www.springframework.org/schema/beans/spring-beans.xsd
        http://www.springframework.org/schema/context
        https://www.springframework.org/schema/context/spring-context.xsd">

    <!--   默认 <context:annotation-config/>-->

    <bean id="dataSource" class="org.springframework.jdbc.datasource.DriverManagerDataSource">
        <property name="driverClassName" value="com.mysql.cj.jdbc.Driver"/>
        <property name="url"
                  value="jdbc:mysql://localhost:3306/imooc?useSSL=false&amp;useUnicode=true&amp;characterEncoding=UTF-8&amp;serverTimezone=Asia/Shanghai&amp;allowPublicKeyRetrieval=true"/>
        <property name="username" value="springJDBCtest"/>
        <property name="password" value="Edao6688"/>
    </bean>

    <bean id="jdbdTemplate" class="org.springframework.jdbc.core.JdbcTemplate">
        <property name="dataSource" ref="dataSource"/>
    </bean>

    <bean id="employeeDao" class="com.thdao.spring.jdbc.dao.EmployeeDao">
        <property name="jdbcTemplate" ref="jdbdTemplate"></property>
    </bean>
</beans>

Employee类：

package com.thdao.spring.jdbc.entity;

import java.util.Date;

public class Employee {
    private Integer emo;
    private String ename;
    private Float salary;

    @Override
    public String toString() {
        return "Employee{" +
                "emo=" + emo +
                ", ename='" + ename + '\'' +
                ", salary=" + salary +
                ", dname='" + dname + '\'' +
                ", hiredate=" + hiredate +
                '}';
    }

    public Integer getEmo() {
        return emo;
    }

    public void setEmo(Integer emo) {
        this.emo = emo;
    }

    public String getEname() {
        return ename;
    }

    public void setEname(String ename) {
        this.ename = ename;
    }

    public Float getSalary() {
        return salary;
    }

    public void setSalary(Float salary) {
        this.salary = salary;
    }

    public String getDname() {
        return dname;
    }

    public void setDname(String dname) {
        this.dname = dname;
    }

    public Date getHiredate() {
        return hiredate;
    }

    public void setHiredate(Date hiredate) {
        this.hiredate = hiredate;
    }

    private String dname;
    private Date hiredate;
}

EmployeeDao类：

package com.thdao.spring.jdbc.dao;

import com.thdao.spring.jdbc.entity.Employee;
import org.springframework.jdbc.core.BeanPropertyRowMapper;
import org.springframework.jdbc.core.JdbcTemplate;

public class EmployeeDao {
    private JdbcTemplate jdbcTemplate;

    public Employee findById(Integer eno){
        String sql="select * from employee where eno= ? ";
        Employee employee = jdbcTemplate.queryForObject(sql, new Object[]{eno}, new BeanPropertyRowMapper<Employee>(Employee.class));
        return employee;
    }
    public JdbcTemplate getJdbcTemplate() {
        return jdbcTemplate;
    }

    public void setJdbcTemplate(JdbcTemplate jdbcTemplate) {
        this.jdbcTemplate = jdbcTemplate;
    }
}

SpringApplication类：

package com.thdao.spring.jdbc;

import com.thdao.spring.jdbc.dao.EmployeeDao;
import com.thdao.spring.jdbc.entity.Employee;
import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;

public class SpringApplication {
    public static void main(String[] args) {
        ApplicationContext context = new ClassPathXmlApplicationContext("classpath:applicationContext.xml");
        EmployeeDao employeeDao = context.getBean("employeeDao", EmployeeDao.class);
        Employee employee = employeeDao.findById(3308);
        System.out.println(employee);
    }
}