Java 将Spring Boot web app连接到postgresql server

我正在使用Spring Boot制作一个web应用程序，我通过使用内存数据库（H2）实现了我想要的功能，但我无法将它连接到我在计算机上设置的postgresql服务器。我做这件事已经有一段时间了，尝试了一堆不起作用的东西，所以我把一切都恢复到原来的状态，只是为了让它重新工作

这是我的UploadController.java，它处理来自服务器的上传并将其放入内存数据库：

import java.io.BufferedOutputStream;
import java.io.File;
import java.io.FileOutputStream;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestMethod;
import org.springframework.web.bind.annotation.RequestParam;
import org.springframework.web.multipart.MultipartFile;
import project.service.MediaFile;
import project.service.MediaFileRepository;

@Controller
public class UploadController {

    @Autowired
    private MediaFileRepository repository;

    @RequestMapping(value = "/uploadmedia", method = RequestMethod.GET)
    public String uploadForm() {
        return "upload";
    }

    @RequestMapping(value = "/uploadmedia", method = RequestMethod.POST)
    public String uploadSubmit(@RequestParam(value="files[]") MultipartFile[] files,
                               @RequestParam("tags") String tags, @RequestParam("type") String type)
    {
        String[] tagsArray = tags.split("\\s+");
        MultipartFile file;
        String name;
        String tag;
        String path;

        for (int i = 0; i < files.length; i++) {
            file = files[i];
            name = file.getOriginalFilename();
            path = "/Users/johannesthorkell/Developer/spring_prufa/images/" + name;
            System.out.println(name);

            if (!file.isEmpty()) {
                try {
                    byte[] bytes = file.getBytes();
                    BufferedOutputStream stream =
                            new BufferedOutputStream(new FileOutputStream(new File(path)));
                    stream.write(bytes);
                    stream.close();
                    for (int j = 0; j < tagsArray.length; j++) {
                        tag = tagsArray[j].toLowerCase();
                        repository.save(new MediaFile(name, tag, path, type));
                    }
                    System.out.println("Success!");
                } catch (Exception e) {
                    System.out.println("Failure... " + e.getMessage());
                }
            } else {
                System.out.println("No file");
            }
        }
        return "upload";
    }
}

…这是我的pom.xml：

<?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>HBV501G</groupId>
    <artifactId>Spring_Web_MVC</artifactId>
    <version>0.1</version>

    <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>1.2.5.RELEASE</version>
    </parent>

    <dependencies>

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

        <dependency>
            <groupId>org.apache.tomcat.embed</groupId>
            <artifactId>tomcat-embed-jasper</artifactId>
        </dependency>

        <dependency>
            <groupId>javax.servlet</groupId>
            <artifactId>jstl</artifactId>
        </dependency>

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

        <dependency>
            <groupId>com.h2database</groupId>
            <artifactId>h2</artifactId>
        </dependency>

    </dependencies>

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

</project>

在这种设置下，一切正常。我尝试在application.properties中添加以下内容：

spring.view.prefix=/WEB-INF/jsp/
spring.view.suffix=.jsp
multipart.maxFileSize=-1 

spring.datasource.url=jdbc:postgresql://localhost/test
spring.datasource.username=myusername
spring.datasource.password=mypassword
spring.datasource.driver-class-name=org.postgresql.jdbc.Driver

logging.level. = INFO

myapp.dataSource.driver = 
myapp.dataSource.url = 
myapp.dataSource.username = 
myapp.dataSource.password = 

…同时将以下依赖项添加到pom.xml：

<dependency>
    <groupId>org.postgresql</groupId>
    <artifactId>postgresql</artifactId>
    <version>9.4-1200-jdbc41</version>
</dependency>

…我的pom.xml如下所示：

spring.view.prefix=/WEB-INF/jsp/
spring.view.suffix=.jsp
multipart.maxFileSize=-1
debug=true

spring.datasource.url=jdbc:postgresql://localhost:5432/mydb
spring.datasource.username=username
spring.datasource.password=password

<?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>HBV501G</groupId>
    <artifactId>Spring_Web_MVC</artifactId>
    <version>0.1</version>

    <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>1.2.5.RELEASE</version>
    </parent>

    <dependencies>

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

        <dependency>
            <groupId>org.apache.tomcat.embed</groupId>
            <artifactId>tomcat-embed-jasper</artifactId>
        </dependency>

        <dependency>
            <groupId>javax.servlet</groupId>
            <artifactId>jstl</artifactId>
        </dependency>

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

        <dependency>
            <groupId>org.postgresql</groupId>
            <artifactId>postgresql</artifactId>
            <version>9.4-1200-jdbc41</version>
        </dependency>

        <!--<dependency>-->
            <!--<groupId>com.h2database</groupId>-->
            <!--<artifactId>h2</artifactId>-->
        <!--</dependency>-->

    </dependencies>

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

</project>

我将GenerationType更改为IDENTITY，并出现以下错误：

2015-10-06 12:56:32.496 DEBUG 22746 --- [nio-8080-exec-7] org.hibernate.SQL                        : insert into media_file (name, resource, tag, type) values (?, ?, ?, ?)
2015-10-06 12:56:32.505 DEBUG 22746 --- [nio-8080-exec-7] org.hibernate.SQL                        : insert into media_file (name, resource, tag, type) values (?, ?, ?, ?)
Failure... A different object with the same identifier value was already associated with the session : [project.service.MediaFile#0]; nested exception is javax.persistence.EntityExistsException: A different object with the same identifier value was already associated with the session : [project.service.MediaFile#0]

---

如果我是你，我会创建自己的数据源bean，比如：

@Configuration
public class MyConfig{

    @Autowired
    Environment env;

    @Bean
    public DataSource dataSource() {
        DriverManagerDataSource dataSource = new DriverManagerDataSource();
        dataSource.setDriverClassName(env.getProperty("myapp.dataSource.driver"));
        dataSource.setUrl(env.getProperty("myapp.dataSource.url"));
        dataSource.setUsername(env.getProperty("myapp.dataSource.username"));
        dataSource.setPassword(env.getProperty("myapp.dataSource.password"));
        return dataSource;
    }
}

application.properties：

spring.view.prefix=/WEB-INF/jsp/
spring.view.suffix=.jsp
multipart.maxFileSize=-1 

spring.datasource.url=jdbc:postgresql://localhost/test
spring.datasource.username=myusername
spring.datasource.password=mypassword
spring.datasource.driver-class-name=org.postgresql.jdbc.Driver

logging.level. = INFO

myapp.dataSource.driver = 
myapp.dataSource.url = 
myapp.dataSource.username = 
myapp.dataSource.password = 

如果不想尝试，可以尝试将驱动程序org.postgresql.jdbc.driver更改为org.postgresql.driver

---

没有任何日志很难提供帮助。

错误的关键部分是：

2015-10-06 11:32:49.760 ERROR 22287 --- [nio-8080-exec-3] o.h.engine.jdbc.spi.SqlExceptionHelper   : ERROR: relation "hibernate_sequence" does not exist

Hibernate正在寻找一个名为

Hibernate\u sequence

的表，以支持

MediaFile

上的

@GeneratedValue

。您目前已将其配置为

AUTO

。然后，实际行为会因您使用的数据库而异

我认为你有几个选择：

在Postgres中创建一个序列（

Create sequence

），名为

hibernate\u sequence

更改为使用不同的生成类型，例如

GenerationType.IDENTITY

---

当你尝试使用Postgres时，你看到了什么失败？你不需要指定驱动程序，它是自动检测的。您还应该在启动应用程序时添加“-debug”（或将debug放入

application.properties

）以显示自动配置报告。它将准确地告诉您什么被启用/禁用以及为什么。@StépaneNicoll我做了您建议的更改，现在我的应用程序实际运行，但当我尝试将数据放入数据库时，它仍然失败。我添加了application.properties和pom.xml作为“现在看”以及我在主要帖子中遇到的错误，并且我发布了一个问题的答案，其中包含自动配置报告，因为它不适合我的主要帖子。@AndyWilkinson我用我得到的错误消息更新了我的帖子（在底部）.我将生成类型更改为identity，并根据收到的错误消息更改了我的关系，但我遇到了另一个我在OP中输入的错误。我是否生成的id不正确？我认为最好在另一个问题中解决，这与连接Postgres无关。我可以吻你。。。这让我快发疯了，再次感谢你。如果可以，我会给你更多的选票：）