Question

我是春季启动的新手，并尝试构建一个演示应用程序。我想使用hibernate连接到mysql数据库并从表中获取内容。这就是我的项目结构：

DemoApplication.java类看起来像这样：

    package com.example;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;

@SpringBootApplication
public class DemoApplication {

    public static void main(String[] args) {
        SpringApplication.run(DemoApplication.class, args);
    }
}

HibernateTestController.java如下所示：

    package com.example.controllers;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.servlet.ModelAndView;

import com.example.repositories.PatchRepository;

@Controller
public class HibernateTestController {

    @Autowired
    PatchRepository patchRepository;

    @RequestMapping(value={"/hibernateTest"})
    public ModelAndView home() {
        //List<Patch> patches = patchRepository.findAll();
        return new ModelAndView("hibernateTest");
    }
}

PatchRepository.java如下所示：

    package com.example.repositories;
import java.util.List;

import org.springframework.data.repository.CrudRepository;
import org.springframework.stereotype.Repository;

import com.example.models.Patch;

@Repository
public interface PatchRepository extends CrudRepository<Patch, Long> {
    List<Patch> findAll();
}

现在，每当我启动应用程序时，都会收到错误消息：

***************************申请失败

说明

字段patchRepository中   com.example.controllers.HibernateTestController需要一个bean   键入'com.example.repositories.PatchRepository'，但不能   找到。

动作：

考虑定义类型的bean   您的配置中的“com.example.repositories.PatchRepository”。

我无法弄清楚为什么Autowire for PatchRepository无法正常工作。我认为我的项目结构是正确的，PatchRepository应该被spring自动检测为bean。

这就是POM.xml的样子：

<?xml version="1.0" encoding="UTF-8"?>

http://maven.apache.org/xsd/maven-4.0.0.xsd“＆GT; 4.0.0

<groupId>com.example</groupId>
<artifactId>demo</artifactId>
<version>0.0.1-SNAPSHOT</version>
<packaging>jar</packaging>

<name>demo</name>
<description>Demo project for Spring Boot</description>

<parent>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-parent</artifactId>
    <version>1.4.2.RELEASE</version>
    <relativePath /> 
</parent>

<properties>
    <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
    <project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding>
    <java.version>1.8</java.version>
</properties>

<dependencies>
    <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-cache</artifactId>
    </dependency>
    <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-jersey</artifactId>
    </dependency>
    <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-security</artifactId>
    </dependency>
    <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-thymeleaf</artifactId>
    </dependency>
    <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-web</artifactId>
    </dependency>
    <dependency>
        <groupId>org.projectlombok</groupId>
        <artifactId>lombok</artifactId>
        <optional>true</optional>
    </dependency>
    <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-test</artifactId>
        <scope>test</scope>
    </dependency>
    <dependency>
        <groupId>org.webjars</groupId>
        <artifactId>jquery</artifactId>
        <version>3.1.1-1</version>
    </dependency>
    <dependency>
        <groupId>org.webjars</groupId>
        <artifactId>bootstrap</artifactId>
        <version>3.3.7</version>
    </dependency>
    <dependency>
        <groupId>org.hibernate.javax.persistence</groupId>
        <artifactId>hibernate-jpa-2.1-api</artifactId>
        <version>1.0.0.Final</version>
    </dependency>
    <dependency>
        <groupId>org.springframework.data</groupId>
        <artifactId>spring-data-commons-core</artifactId>
        <version>1.4.1.RELEASE</version>
    </dependency>
    <dependency>
        <groupId>org.springframework.data</groupId>
        <artifactId>spring-data-jpa</artifactId>
        <version>1.10.6.RELEASE</version>
    </dependency>
</dependencies>

<build>
    <plugins>
        <plugin>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-maven-plugin</artifactId>
        </plugin>
    </plugins>
</build>

Answer 1

try using the repository scan in your DemoApplication class

@SpringBootApplication
@EnableJpaRepositories("com.example.repositories")
public class DemoApplication {

    public static void main(String[] args) {
        SpringApplication.run(DemoApplication.class, args);
    }
}

Answer 2

让我们尝试添加“ @ComponentScan”

@SpringBootApplication
@ComponentScan("com.example")
public class DemoApplication {
public static void main(String[] args) {
    SpringApplication.run(DemoApplication.class, args);
}

}

Answer 3

确保你有

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

和

    <dependency>
        <groupId>mysql</groupId>
        <artifactId>mysql-connector-java</artifactId>
    </dependency>

进入你的pom.xml

正确的配置

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

您的Patch类使用@Entity进行注释，并使用@Id注释了Id属性。

一切都应该有用。

Answer 4

我按如下方式重构了我的代码并且工作正常：

package com.example.repositories;
import java.util.List;

import org.springframework.data.repository.CrudRepository;
import org.springframework.stereotype.Repository;

import com.example.models.Patch;
public interface PatchRepository extends CrudRepository<Patch, Long> {
    List<Patch> findAll();
}


    <?xml version="1.0" encoding="UTF-8"?>
<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>com.example</groupId>
    <artifactId>demo</artifactId>
    <version>0.0.1-SNAPSHOT</version>
    <packaging>jar</packaging>

    <name>demo</name>
    <description>Demo project for Spring Boot</description>

    <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>1.4.3.RELEASE</version>
        <relativePath />
    </parent>

    <properties>
        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
        <project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding>
        <java.version>1.8</java.version>
    </properties>

    <dependencies>
        <dependency>
            <groupId>org.webjars</groupId>
            <artifactId>jquery</artifactId>
            <version>3.1.1-1</version>
        </dependency>
        <dependency>
            <groupId>org.webjars</groupId>
            <artifactId>bootstrap</artifactId>
            <version>3.3.7</version>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-data-jpa</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-data-jpa</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-security</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-test</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>
        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-thymeleaf</artifactId>
        </dependency>
    </dependencies>

    <build>
        <plugins>
            <plugin>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-maven-plugin</artifactId>
            </plugin>
        </plugins>
    </build>


</project>


    spring.thymeleaf.cache: false

##DB connections##
spring.datasource.url=jdbc:mysql://localhost/testdb
spring.datasource.username=root
spring.datasource.password=root
spring.datasource.driver-class-name=com.mysql.jdbc.Driver

# Keep the connection alive if idle for a long time (needed in production)
spring.datasource.testWhileIdle = true
spring.datasource.validationQuery = SELECT 1

# Hibernate Configuration
spring.jpa.hibernate.ddl-auto=update
packagesToScan=com.example
hibernate.dialect=org.hibernate.dialect.MySQL5Dialect
hibernate.show_sql=false
hibernate.format_sql=true

# Naming strategy
spring.jpa.hibernate.naming-strategy = org.hibernate.cfg.ImprovedNamingStrategy

entitymanager.packagesToScan=com.example

# Use spring.jpa.properties.* for Hibernate native properties (the prefix is
# stripped before adding them to the entity manager)

#logging.level.org.springframework.web=DEBUG
#logging.level.org.hibernate=DEBUG



 package com.example.controllers;

import java.util.List;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.servlet.ModelAndView;

import com.example.models.Patch;
import com.example.repositories.PatchRepository;

@Controller
public class HibernateTestController {

    @Autowired
    PatchRepository patchRepository;

    @RequestMapping(value={"/hibernateTest"})
    public ModelAndView home() {
        List<Patch> patches = patchRepository.findAll();
        return new ModelAndView("hibernateTest");
    }
}

Application.properties看起来像这样：

spring.thymeleaf.cache: false

##DB connections## spring.datasource.url=jdbc:mysql://localhost/testdb spring.datasource.username=root spring.datasource.password=root
spring.datasource.driver-class-name=com.mysql.jdbc.Driver

# Keep the connection alive if idle for a long time (needed in production) spring.datasource.testWhileIdle = true
spring.datasource.validationQuery = SELECT 1

# Hibernate Configuration spring.jpa.hibernate.ddl-auto=update packagesToScan=com.example
hibernate.dialect=org.hibernate.dialect.MySQL5Dialect
hibernate.show_sql=false hibernate.format_sql=true

# Naming strategy spring.jpa.hibernate.naming-strategy = org.hibernate.cfg.ImprovedNamingStrategy

entitymanager.packagesToScan=com.example

# Use spring.jpa.properties.* for Hibernate native properties (the prefix is
# stripped before adding them to the entity manager)

#logging.level.org.springframework.web=DEBUG
#logging.level.org.hibernate=DEBUG

无法自动加载扩展CRUD存储库的接口

4 个答案: