如何使用Spring的JdbcTemplate连接到一个简单的MySql数据库？ | 用Spring的JdbcTemplate连接到一个简单的MySq

本文介绍了如何使用Spring的JdbcTemplate连接到一个简单的MySql数据库？的处理方法，对大家解决问题具有一定的参考价值，需要的朋友们下面随着小编来一起学习吧！

问题描述

我正在尝试使用Spring的JdbcTemplate类连接到基于教程。事实上，我使用了他们的项目设置：

pom.xml

 < project xmlns =http://maven.apache.org/POM/4.0.0xmlns：xsi =http://www.w3.org/2001/XMLSchema-instance
 xsi： schemaLocation =http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd\"> 
< modelVersion> 4.0.0< / modelVersion> 
< groupId> test< / groupId> 
< artifactId> jdbc-test< / artifactId> 
< version> 0.0.1-SNAPSHOT< / version> 
 
< parent> 
< groupId> org.springframework.boot< / groupId> 
< artifactId> spring-boot-starter-parent< / artifactId> 
< version> 1.2.2.RELEASE< / version> 
< / parent> 
 
< dependencies> 
< dependency> 
< groupId> org.springframework.boot< / groupId> 
< artifactId> spring-boot-starter< / artifactId> 
< / dependency> 
< dependency> 
< groupId> org.springframework< / groupId> 
< artifactId> spring-jdbc< / artifactId> 
< / dependency> 
< dependency> 
< groupId> mysql< / groupId> 
< artifactId> mysql-connector-java< / artifactId> 
< / dependency> 
< dependency> 
< groupId> org.projectlombok< / groupId> 
< artifactId> lombok< / artifactId> 
< version> 1.14.8< / version> 
< scope>提供< / scope> 
< / dependency> 
< / dependencies> 
< build> 
< plugins> 
< plugin> 
< groupId> org.springframework.boot< / groupId> 
< artifactId> spring-boot-maven-plugin< / artifactId> 
< / plugin> 
< / plugins> 
< / build> 
< / project>

Lombok依赖项适用于getter和setter。

然后是Application类：

  package test; 
 
 import org.springframework.beans.factory.annotation.Autowired; 
 import org.springframework.boot.CommandLineRunner; 
 import org.springframework.boot.SpringApplication; 
 import org.springframework.boot.autoconfigure.SpringBootApplication; 
 import org.springframework.jdbc.core.JdbcTemplate; 
 
 @SpringBootApplication 
公共类应用程序实现CommandLineRunner {
 public static void main（String args []）{
 SpringApplication.run（Application.class，args）; 
} 
 
 @Autowired 
 JdbcTemplate jdbcTemplate; 
 
 @Override 
 public void run（String ... arg0）throws Exception {
 System.out.println（Creating tables）; 
 jdbcTemplate.execute（如果存在则删除表客户）; 
 jdbcTemplate.execute（create table customers（+ 
id serial，first_name varchar（255），last_name varchar（255）））; 
} 
}

最后是客户pojo：

 包裹测试; 
 
 import lombok.AllArgsConstructor; 
 import lombok.Data; 
 
 @Data 
 @AllArgsConstructor 
 public class Customer {
 private long id; 
 private String firstName，lastName; 
}

对于数据源配置，我的资源文件夹中有一个application.properties文件： / p>

  spring.datasource.url = jdbc：mysql：// localhost：3306 / test 
 spring.datasource.username = test 
 spring.datasource.password = test 
 spring.datasource.driver-class-name = com.mysql.jdbc.Driver 
 
 spring.jpa.database = MYSQL 
 
 spring.jpa.show -sql = true 
 
 spring.jpa.hibernate.ddl-auto = update 
 spring.jpa.hibernate.dialect = org.hibernate。 dialect.MySQL5Dialect 
 spring.jpa.hibernate.naming_strategy = org.hibernate.cfg.ImprovedNamingStrategy

数据库已启动并正在运行，但仍然无法使用autowirig。
以下是我尝试运行时遇到的异常：

  org.springframework.beans.factory.BeanCreationException ：创建名为'application'的bean时出错：注入自动连接的依赖项失败;嵌套异常是org.springframework.beans.factory。 
 BeanCreationException：无法自动装配字段：org.springframework.jdbc.core.JdbcTemplate test.Application.jdbcTemplate;嵌套异常是org.springframework.beans.factory.NoSuchBeanDefinitionException：
找不到类型为[org.springframework.jdbc.core.JdbcTemplate]的限定bean依赖：预期至少有1个bean符合此依赖关系的autowire候选资格。依赖注解：
 {@ org.springframework.beans.factory.annotation.Autowired（所需=真）} 
。在org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor.postProcessPropertyValues（AutowiredAnnotationBeanPostProcessor.java:334 ）
 at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.populateBean（AbstractAutowireCapableBeanFactory.java:1202）
 at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean（AbstractAutowireCapableBeanFactory.java:537 ）美元，org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean（AbstractAutowireCapableBeanFactory.java:476 b $ b）
在org.springframework.beans.factory.support.AbstractBeanFactory $ 1.getObject（AbstractBeanFactory.java： 303）
 at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton（DefaultSingletonBeanRegistry.java:230）
 at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean（AbstractBeanFactory.java:299）
 at org.springframework.beans.factory.support.AbstractBeanFactory.getBean（AbstractBeanFactory.java:194）
 at org.springframework.beans.factory.support.DefaultListableBeanFactory.preInstantiateSingletons（DefaultListableBeanFactory.java:755）
 at org.springframework.context.support.AbstractApplicationContext.finishBeanFactoryInitialization（AbstractApplicationContext.java:757）
 at org。 springframework.context.support.AbstractApplicationContext.refresh（AbstractApplicationContext.java:480）
 at org.springframework.boot.SpringApplication.refresh（SpringApplication.java:686）
 at org.springframework.boot.SpringApplication。运行（SpringApplication.java:320）
 at org.springframework.boot.SpringApplication.run（SpringApplication.java:957）
 at org.springframework.boot.SpringApplication.run（SpringApplication.java： 946）
 at test.Application.main（Application.java:12）
 at sun.reflect.NativeMethodAccessorImpl.invoke0（Native Method）
 at sun.reflect.NativeMethodAccessorImpl.invoke（Unknown Source ）
 at sun.reflect.DelegatingMethodAccessorImpl.invoke（Unknown Source）
 at java.lang.reflect.Method.invoke（Unknown Source）
 at org.springframework.boot.loader.MainMethodRunner。 run（MainMethodRunner.java:53）
 at java.lang.Thread.run（Unknown Source）
引起：org.springframework.beans.factory.BeanCreationException：无法自动装配字段：org.springframework。 jdbc.core.JdbcTemplate test.Application.jdbcTemplate;嵌套异常是org.springframework.beans.factory.NoSuchBeanDefinitionException：
找不到类型为[org.springframework.jdbc.core.JdbcTemplate]的限定bean依赖：预期至少有1个bean符合autowire 
这种依赖的候选人。依赖注解：{@ org.springframework.beans.factory.annotation.Autowired（所需=真）} 
。在org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor $ AutowiredFieldElement.inject（AutowiredAnnotationBeanPostProcessor.java:561）$在org.springframework.beans.factory.annotation.InjectionMetadata.inject（InjectionMetadata.java:88）b 
 $ b。在org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor.postProcessPropertyValues（AutowiredAnnotationBeanPostProcessor.java:331）
 ...省略了21个常见帧
引起：org.springframework.beans.factory.NoSuchBeanDefinitionException：找不到类型[org.springframework.jdbc.core.JdbcTemplate]的限定bean用于依赖：预期至少
的1个bean有资格作为此依赖项的autowire候选者。依赖注解：{@ org.springframework.beans.factory.annotation.Autowired（所需=真）} 
。在org.springframework.beans.factory.support.DefaultListableBeanFactory.raiseNoSuchBeanDefinitionException（DefaultListableBeanFactory.java:1301）
。在org.springframework.beans.factory.support.DefaultListableBeanFactory.doResolveDependency（DefaultListableBeanFactory.java:1047）
在org.springframework.beans.factory.support.DefaultListableBeanFactory.resolveDependency（DefaultListableBeanFactory.java:942）
 org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor $ AutowiredFieldElement.inject（AutowiredAnnotationBeanPostProcessor.java:533）
 ...省略了23个常见帧

我觉得奇怪的是，如果我用com.h2数据库替换mysql-connector-java dependeny，它就可以正常工作（如在spring示例中那样）。 / p>

我是否需要配置mysql数据源以一种不同的方式？
有什么建议吗？

解决方案

添加以下依赖项：

 <依赖性> 
< groupId> org.springframework.boot< / groupId> 
< artifactId> spring-boot-starter-jdbc< / artifactId> 
< / dependency>

哪个会自动配置数据源

I am trying to use Spring's JdbcTemplate Class to connect to a simple MySql database based on this tutorial. In fact, I used their project setup:

pom.xml

    <project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>
    <groupId>test</groupId>
    <artifactId>jdbc-test</artifactId>
    <version>0.0.1-SNAPSHOT</version>

    <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>1.2.2.RELEASE</version>
    </parent>

    <dependencies>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-jdbc</artifactId>
        </dependency>
        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
        </dependency>
        <dependency>
            <groupId>org.projectlombok</groupId>
            <artifactId>lombok</artifactId>
            <version>1.14.8</version>
            <scope>provided</scope>
        </dependency>
    </dependencies>
    <build>
        <plugins>
            <plugin>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-maven-plugin</artifactId>
            </plugin>
        </plugins>
    </build>
</project>

The Lombok dependency is for getters and setters.

Then there is the Application class:

package test;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.CommandLineRunner;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.jdbc.core.JdbcTemplate;

@SpringBootApplication
public class Application implements CommandLineRunner {
    public static void main(String args[]) {
        SpringApplication.run(Application.class, args);
    }

    @Autowired
    JdbcTemplate jdbcTemplate;

    @Override
    public void run(String... arg0) throws Exception {
        System.out.println("Creating tables");
        jdbcTemplate.execute("drop table customers if exists");
        jdbcTemplate.execute("create table customers(" +
                "id serial, first_name varchar(255), last_name varchar(255))");
    }
}

And finally a Customer pojo:

package test;

import lombok.AllArgsConstructor;
import lombok.Data;

@Data
@AllArgsConstructor
public class Customer {
    private long id;
    private String firstName, lastName;
}

For datasource configuration I have an application.properties file in my resources folder:

spring.datasource.url=jdbc:mysql://localhost:3306/test
spring.datasource.username=test
spring.datasource.password=test
spring.datasource.driver-class-name=com.mysql.jdbc.Driver

spring.jpa.database = MYSQL

spring.jpa.show-sql = true

spring.jpa.hibernate.ddl-auto = update
spring.jpa.hibernate.dialect = org.hibernate.dialect.MySQL5Dialect
spring.jpa.hibernate.naming_strategy = org.hibernate.cfg.ImprovedNamingStrategy

The database is up and running and still the autowirig dosen't seem to work.Here is the exception I get when I try to run it:

org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'application': Injection of autowired dependencies failed; nested exception is org.springframework.beans.factory.
BeanCreationException: Could not autowire field: org.springframework.jdbc.core.JdbcTemplate test.Application.jdbcTemplate; nested exception is org.springframework.beans.factory.NoSuchBeanDefinitionException:
No qualifying bean of type [org.springframework.jdbc.core.JdbcTemplate] found for dependency: expected at least 1 bean which qualifies as autowire candidate for this dependency. Dependency annotations:
{@org.springframework.beans.factory.annotation.Autowired(required=true)}
        at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor.postProcessPropertyValues(AutowiredAnnotationBeanPostProcessor.java:334)
        at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.populateBean(AbstractAutowireCapableBeanFactory.java:1202)
        at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:537)
        at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:476)
        at org.springframework.beans.factory.support.AbstractBeanFactory$1.getObject(AbstractBeanFactory.java:303)
        at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:230)
        at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:299)
        at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:194)
        at org.springframework.beans.factory.support.DefaultListableBeanFactory.preInstantiateSingletons(DefaultListableBeanFactory.java:755)
        at org.springframework.context.support.AbstractApplicationContext.finishBeanFactoryInitialization(AbstractApplicationContext.java:757)
        at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:480)
        at org.springframework.boot.SpringApplication.refresh(SpringApplication.java:686)
        at org.springframework.boot.SpringApplication.run(SpringApplication.java:320)
        at org.springframework.boot.SpringApplication.run(SpringApplication.java:957)
        at org.springframework.boot.SpringApplication.run(SpringApplication.java:946)
        at test.Application.main(Application.java:12)
        at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
        at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source)
        at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
        at java.lang.reflect.Method.invoke(Unknown Source)
        at org.springframework.boot.loader.MainMethodRunner.run(MainMethodRunner.java:53)
        at java.lang.Thread.run(Unknown Source)
Caused by: org.springframework.beans.factory.BeanCreationException: Could not autowire field: org.springframework.jdbc.core.JdbcTemplate test.Application.jdbcTemplate; nested exception is org.springframework.beans.factory.NoSuchBeanDefinitionException:
No qualifying bean of type [org.springframework.jdbc.core.JdbcTemplate] found for dependency: expected at least 1 bean which qualifies as autowire
candidate for this dependency. Dependency annotations: {@org.springframework.beans.factory.annotation.Autowired(required=true)}
        at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor$AutowiredFieldElement.inject(AutowiredAnnotationBeanPostProcessor.java:561)
        at org.springframework.beans.factory.annotation.InjectionMetadata.inject(InjectionMetadata.java:88)
        at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor.postProcessPropertyValues(AutowiredAnnotationBeanPostProcessor.java:331)
        ... 21 common frames omitted
Caused by: org.springframework.beans.factory.NoSuchBeanDefinitionException: No qualifying bean of type [org.springframework.jdbc.core.JdbcTemplate] found for dependency: expected at least 1 bean which
 qualifies as autowire candidate for this dependency. Dependency annotations: {@org.springframework.beans.factory.annotation.Autowired(required=true)}
        at org.springframework.beans.factory.support.DefaultListableBeanFactory.raiseNoSuchBeanDefinitionException(DefaultListableBeanFactory.java:1301)
        at org.springframework.beans.factory.support.DefaultListableBeanFactory.doResolveDependency(DefaultListableBeanFactory.java:1047)
        at org.springframework.beans.factory.support.DefaultListableBeanFactory.resolveDependency(DefaultListableBeanFactory.java:942)
        at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor$AutowiredFieldElement.inject(AutowiredAnnotationBeanPostProcessor.java:533)
        ... 23 common frames omitted

What I find curious is the fact that if I replace the mysql-connector-java dependeny with a com.h2database, it just works (as in the spring example).

Do I need to configure the mysql datasource in a dirfferent way?Any suggestions?

解决方案

Add the dependency below:

<dependency>
    <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-jdbc</artifactId>
</dependency>

Which will autoconfigure the Datasource

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