微信公众号搜"智元新知"关注
微信扫一扫可直接关注哦！

确保实体中的某些字段不保存到数据库

分类：编程问答

如何解决确保实体中的某些字段不保存到数据库

我正在学习Spring和Hibernate。我准备了图像的实体。这些字段已成功作为列名保存到数据库，但是我需要某些属性存在于实体中但不能保存到数据库。但是实际上正在被保存。我试图删除@Column注释或使用@Column(insertable=false,updatable=false)，但未成功。总是在数据库中使用空值的列。因此，如何防止Spring和Hibernate创建某些字段的列。我正在尝试使用字段size，width和height。

实体代码： 

package tk.trzczy.gallery.domain;

import javax.persistence.*;
import java.awt.*;
import java.util.Date;

import com.fasterxml.jackson.annotation.JsonIgnore;
import com.fasterxml.jackson.annotation.JsonProperty;

@Entity
@Table(name = "images")
public class Image {
    @Id
    @SequenceGenerator(name = "mySeqGen6",sequenceName = "mySeq6",initialValue = 11,allocationSize = 100)
    @GeneratedValue(generator = "mySeqGen6")
    private Integer id;

    @Column(nullable = false,length = 300)
    private String title;

    @Column(nullable = false)
    private String url;

    @Column(insertable=false,updatable=false)
    private Long width;

    @Column(insertable=false,updatable=false)
    private Long height;

    @Column(insertable=false,updatable=false)
    private Dimension size;

    @ManyToOne(cascade=CascadeType.PERSIST,fetch=FetchType.EAGER)
    @JoinColumn(name="image_category_id")
    private ImageCategory imageCategory;

    @Column(name="datecreated",columnDeFinition="TIMESTAMP DEFAULT CURRENT_TIMESTAMP")
    private Date dateCreated;

    @PrePersist
    protected void onCreate() {
        dateCreated = new Date();
    }

    @JsonIgnore
    public Integer getId() {
        return id;
    }

    @JsonProperty
    public void setId(Integer id) {
        this.id = id;
    }
    public String getTitle() {
        return title;
    }
    public void setTitle(String title) {
        this.title = title;
    }
    public String getUrl() {
        return url;
    }
    public void setUrl(String url) {
        this.url = url;
    }

    @JsonIgnore
    public Date getDateCreated() {
        return dateCreated;
    }

    @JsonProperty
    public void setDateCreated(Date dateCreated) {
        this.dateCreated = dateCreated;
    }

    public Image() {}

    public Image(Integer id,String title,String url) {
        this.id = id;
        this.title = title;
        this.url = url;
    }

    @Override
    public String toString() {
        return "Post{" +
                "id=" + id +
                ",title='" + title + '\'' +
                ",url='" + url + '\'' +
                ",date=" + dateCreated +
                '}';
    }

    @JsonIgnore
    public ImageCategory getimageCategory() {
        return imageCategory;
    }

    @JsonProperty
    public void setimageCategory(ImageCategory imageCategory) {
        this.imageCategory = imageCategory;
    }

    public long getWidth() {
        return width;
    }

    public void setWidth(long width) {
        this.width = width;
    }

    public long getHeight() {
        return height;
    }

    public void setHeight(long height) {
        this.height = height;
    }

    public Dimension getSize() {
        return size;
    }

    public void setSize(Dimension size) {
        this.size=size;
    }
}

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>tk.trzczy</groupId>
    <artifactId>spring-webmvc</artifactId>
    <version>0.0.1</version>
    <packaging>war</packaging>


    <properties>
        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
        <aspect.version>1.9.2</aspect.version>
        <jackson.version>2.9.8</jackson.version>
        <hibernate.version>5.4.2.Final</hibernate.version>
        <hibernate.validator.version>5.2.1.Final</hibernate.validator.version>
        <c3p0.version>0.9.5.2</c3p0.version>
    </properties>

    <dependencies>

        <!-- servlets and jps -->
        <dependency>
            <groupId>javax.servlet</groupId>
            <artifactId>jstl</artifactId>
            <version>1.2</version>
        </dependency>
        <dependency>
            <groupId>javax.servlet</groupId>
            <artifactId>javax.servlet-api</artifactId>
            <version>4.0.1</version>
            <scope>provided</scope>
        </dependency>

        <dependency>
            <groupId>org.apache.tiles</groupId>
            <artifactId>tiles-extras</artifactId>
            <version>3.0.8</version>
            <exclusions>
                <exclusion>
                    <groupId>org.slf4j</groupId>
                    <artifactId>jcl-over-slf4j</artifactId>
                </exclusion>
                <exclusion>
                    <groupId>jboss</groupId>
                    <artifactId>javassist</artifactId>
                </exclusion>
            </exclusions>
        </dependency>

        <dependency>
            <groupId>commons-fileupload</groupId>
            <artifactId>commons-fileupload</artifactId>
            <version>1.3.3</version>
        </dependency>
        <dependency>
            <groupId>org.apache.commons</groupId>
            <artifactId>commons-io</artifactId>
            <version>1.3.2</version>
        </dependency>

        <!--hibernate-->
        <dependency>
            <groupId>org.hibernate</groupId>
            <artifactId>hibernate-core</artifactId>
            <version>${hibernate.version}</version>
            <exclusions>
                <exclusion>
                    <groupId>org.javassist</groupId>
                    <artifactId>javassist</artifactId>
                </exclusion>
            </exclusions>
        </dependency>
        <dependency>
            <groupId>org.hibernate</groupId>
            <artifactId>hibernate-entitymanager</artifactId>
            <version>${hibernate.version}</version>
        </dependency>
        <!-- Hibernate-C3P0 Integration -->
        <dependency>
            <groupId>org.hibernate</groupId>
            <artifactId>hibernate-c3p0</artifactId>
            <version>${hibernate.version}</version>
        </dependency>

        <!-- c3p0 -->
        <dependency>
            <groupId>com.mchange</groupId>
            <artifactId>c3p0</artifactId>
            <version>${c3p0.version}</version>
        </dependency>

        <dependency>
            <groupId>org.hibernate</groupId>
            <artifactId>hibernate-validator</artifactId>
            <version>${hibernate.validator.version}</version>
        </dependency>


        <dependency>
            <groupId>MysqL</groupId>
            <artifactId>mysql-connector-java</artifactId>
            <version>5.1.34</version>
        </dependency>

        <!-- for rest services -->
        <dependency>
            <groupId>com.fasterxml.jackson.core</groupId>
            <artifactId>jackson-databind</artifactId>
            <version>${jackson.version}</version>
        </dependency>

        <dependency>
            <groupId>javax.servlet.jsp</groupId>
            <artifactId>javax.servlet.jsp-api</artifactId>
            <version>2.3.3</version>
        </dependency>

        <!-- For Aop -->
        <dependency>
            <groupId>org.aspectj</groupId>
            <artifactId>aspectjrt</artifactId>
            <version>${aspect.version}</version>
        </dependency>
        <dependency>
            <groupId>org.aspectj</groupId>
            <artifactId>aspectjweaver</artifactId>
            <version>${aspect.version}</version>
        </dependency>

        <!-- To Send Email -->
        <dependency>
            <groupId>com.sun.mail</groupId>
            <artifactId>javax.mail</artifactId>
            <version>1.5.4</version>
        </dependency>


        <dependency>
            <groupId>org.springframework.security</groupId>
            <artifactId>spring-security-core</artifactId>
            <version>5.2.0.RELEASE</version>
        </dependency>
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-webmvc</artifactId>
            <version>5.2.0.RELEASE</version>
        </dependency>
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-tx</artifactId>
            <version>5.2.0.RELEASE</version>
        </dependency>
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-orm</artifactId>
            <version>5.2.0.RELEASE</version>
        </dependency>
        <dependency>
            <groupId>org.springframework.security</groupId>
            <artifactId>spring-security-web</artifactId>
            <version>5.2.0.RELEASE</version>
        </dependency>
        <dependency>
            <groupId>org.springframework.security</groupId>
            <artifactId>spring-security-config</artifactId>
            <version>5.2.0.RELEASE</version>
        </dependency>

        <!--logging-->
        <dependency>
            <groupId>org.apache.logging.log4j</groupId>
            <artifactId>log4j-core</artifactId>
            <version>2.8.2</version>
        </dependency>
        <dependency>
            <groupId>org.apache.logging.log4j</groupId>
            <artifactId>log4j-api</artifactId>
            <version>2.8.2</version>
        </dependency>

        <!-- https://mvnrepository.com/artifact/org.apache.logging.log4j/log4j-web -->
        <dependency>
            <groupId>org.apache.logging.log4j</groupId>
            <artifactId>log4j-web</artifactId>
            <version>2.13.3</version>
        </dependency>


        <dependency>
            <groupId>org.slf4j</groupId>
            <artifactId>slf4j-simple</artifactId>
            <version>1.7.30</version>
        </dependency>

        <!-- Postgresql -->
        <dependency>
            <groupId>org.postgresql</groupId>
            <artifactId>postgresql</artifactId>
            <version>42.2.16</version>
        </dependency>
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-context-support</artifactId>
            <version>5.1.3.RELEASE</version>
        </dependency>
        <!-- https://mvnrepository.com/artifact/org.springframework.security/spring-security-taglibs -->
        <dependency>
            <groupId>org.springframework.security</groupId>
            <artifactId>spring-security-taglibs</artifactId>
            <version>5.1.2.RELEASE</version>
        </dependency>
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-context</artifactId>
            <version>5.2.7.RELEASE</version>
        </dependency>
        <!-- https://mvnrepository.com/artifact/org.apache.maven.plugins/maven-war-plugin -->
        <dependency>
            <groupId>org.apache.maven.plugins</groupId>
            <artifactId>maven-war-plugin</artifactId>
            <version>3.2.2</version>
        </dependency>
        <!-- https://mvnrepository.com/artifact/org.apache.maven.plugins/maven-surefire-plugin -->
        <dependency>
            <groupId>org.apache.maven.plugins</groupId>
            <artifactId>maven-surefire-plugin</artifactId>
            <version>2.22.1</version>
        </dependency>
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-web</artifactId>
            <version>5.2.0.RELEASE</version>
        </dependency>
        <!-- https://mvnrepository.com/artifact/org.springframework.data/spring-data-rest-core -->
        <dependency>
            <groupId>org.springframework.data</groupId>
            <artifactId>spring-data-rest-core</artifactId>
            <version>3.3.4.RELEASE</version>
        </dependency>

    </dependencies>

    <build>
        <!-- To define the plugin version in your parent POM -->
        <pluginManagement>
            <plugins>
                <plugin>
                    <groupId>org.apache.maven.plugins</groupId>
                    <artifactId>maven-surefire-plugin</artifactId>
                    <version>2.22.1</version>
                </plugin>
            </plugins>
        </pluginManagement>
        <plugins>
            <!-- To use the plugin goals in your POM or parent POM -->

            <plugin>
                <groupId>org.apache.maven.plugins</groupId>
                <artifactId>maven-compiler-plugin</artifactId>
                <configuration>
                    <source>1.8</source>
                    <target>1.8</target>
                </configuration>
            </plugin>



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

解决方法

transient是一个Java关键字，它标记一个成员变量在持久化到字节流时不要序列化。

JPA或Hibernate中的

@Transient批注用于指示不保留字段或忽略要保存在数据库中的字段。 @Transient存在于javax中。持久性软件包。它用于注释实体类，映射超类或可嵌入类的属性或字段。

因此将字段标记为@Transient。

版权声明：本文内容由互联网用户自发贡献，该文观点与技术仅代表作者本人。本站仅提供信息存储空间服务，不拥有所有权，不承担相关法律责任。如发现本站有涉嫌侵权/违法违规的内容， 请发送邮件至 dio@foxmail.com 举报，一经查实，本站将立刻删除。

苹果市值2025年有望达4万亿美元
pythonJavaScriptjavaHTMLPHPreactjsC#AndroidCSSNode.jssqlrpython-3.xMysqLjQueryc++pandasFlutterangularIOSdjangolinuxswifttypescript路由器JSON路由器设置无线路由器h3c华三华三路由器设置华三路由器电脑软件教程arraysdocker软件图文教程Cvue.jslaravelspring-boot