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