ICode9
精准搜索请尝试： 精确搜索
首页
编程语言>
数据库
系统相关
互联网
其他分享
Python
Java
JavaScript
android
PHP
首页 > 数据库> 文章详细

java-将Spring Boot Web应用程序连接到Postgresql服务器

2019-10-27 21:00:45  阅读：214  来源： 互联网

标签：spring-boot postgresql jpa java spring-mvc


我正在使用Spring Boot制作Web应用程序,并且可以使用内存数据库(H2)来获得所需的功能,但无法将其连接到在计算机上设置的Postgresql服务器.我已经来过一段时间了,尝试了很多不起作用的东西,所以我将所有内容重新设置为只是使其重新起作用.

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

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MediaFile类,即@Entity对象：

import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.GenerationType;
import javax.persistence.Id;

@Entity
public class MediaFile {

    @Id
    @GeneratedValue(strategy=GenerationType.AUTO)
    private long id;
    private String name;
    private String tag;
    private String resource;
    private String type;

    protected MediaFile() {}

    public MediaFile(String name, String tag, String resource, String type) {
        this.name = name;
        this.tag = tag;
        this.resource = resource;
        this.type = type;
    }

    public String getTag() {
        return tag;
    }

    @Override
    public String toString() {
        return String.format(
                "MediaFile[id=%d, name='%s', tag='%s', resource='%s', type='%s']",
                id, name, tag, resource, type);
    }

}

…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>

…最后是application.properties：

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

通过此设置,一切正常.我尝试将以下内容放入我的application.properties中：

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

…以及向pom.xml添加以下依赖项：

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

…然后我尝试混合并匹配这些内容,并阅读了几个小时的教程,都无济于事.

编辑：

我删除了一行并添加了另一行(在StéphaneNic​​oll的建议下),所以现在我的application.properties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

…而我的pom.xml看起来像这样：

<?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>

随着对application.properties的更改,我的应用程序现在可以运行了！但是,当我将自己的POST表单提交到UploadController.java时,出现以下错误：

2015-10-06 11:32:14.878  INFO 22287 --- [           main] project.Application                      : Started Application in 11.897 seconds (JVM running for 12.971)
2015-10-06 11:32:40.263  INFO 22287 --- [nio-8080-exec-1] o.a.c.c.C.[Tomcat].[localhost].[/]       : Initializing Spring FrameworkServlet 'dispatcherServlet'
2015-10-06 11:32:40.264  INFO 22287 --- [nio-8080-exec-1] o.s.web.servlet.DispatcherServlet        : FrameworkServlet 'dispatcherServlet': initialization started
2015-10-06 11:32:40.295  INFO 22287 --- [nio-8080-exec-1] o.s.web.servlet.DispatcherServlet        : FrameworkServlet 'dispatcherServlet': initialization completed in 31 ms
hopaskipting.pdf
2015-10-06 11:32:49.752 DEBUG 22287 --- [nio-8080-exec-3] org.hibernate.SQL                        : select nextval ('hibernate_sequence')
2015-10-06 11:32:49.760  WARN 22287 --- [nio-8080-exec-3] o.h.engine.jdbc.spi.SqlExceptionHelper   : SQL Error: 0, SQLState: 42P01
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
  Position: 17
Failure... could not extract ResultSet; SQL [n/a]; nested exception is org.hibernate.exception.SQLGrammarException: could not extract ResultSet

我将GenerationType更改为IDENTITY并收到以下错误：

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]

解决方法:

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_sequence的表来支持MediaFile上的@GeneratedValue.您目前已使用AUTO对其进行了配置.然后,实际行为会因所使用的数据库而异.

我认为您有两种选择：

>在Postgres(CREATE SEQUENCE)中创建一个名为hibernate_sequence的序列
>更改为使用其他世代类型,例如GenerationType.IDENTITY

标签：spring-boot,postgresql,jpa,java,spring-mvc
来源： https://codeday.me/bug/20191027/1947441.html

本站声明： 1. iCode9 技术分享网（下文简称本站）提供的所有内容，仅供技术学习、探讨和分享；
2. 关于本站的所有留言、评论、转载及引用，纯属内容发起人的个人观点，与本站观点和立场无关；
3. 关于本站的所有言论和文字，纯属内容发起人的个人观点，与本站观点和立场无关；
4. 本站文章均是网友提供，不完全保证技术分享内容的完整性、准确性、时效性、风险性和版权归属；如您发现该文章侵犯了您的权益，可联系我们第一时间进行删除；
5. 本站为非盈利性的个人网站，所有内容不会用来进行牟利，也不会利用任何形式的广告来间接获益，纯粹是为了广大技术爱好者提供技术内容和技术思想的分享性交流网站。

关于我们 | 联系我们 | 留言反馈

专注分享技术，共同学习，共同进步。侵权联系[81616952@qq.com]

Copyright (C)ICode9.com, All Rights Reserved.

ICode9版权所有