环境与实体映射

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<?xml version="1.0" encoding="UTF-8"?>
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<project xmlns="http://maven.apache.org/POM/4.0.0"
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         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
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         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 https://maven.apache.org/xsd/maven-4.0.0.xsd">
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    <modelVersion>4.0.0</modelVersion>
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    <groupId>com.blog.demo</groupId>
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    <artifactId>hibernate-user-lab</artifactId>
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    <version>1.0.0</version>
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    <properties>
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        <maven.compiler.release>17</maven.compiler.release>
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        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
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        <hibernate.version>6.4.10.Final</hibernate.version>
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        <mysql.version>8.3.0</mysql.version>
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    </properties>
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    <dependencies>
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        <dependency>
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            <groupId>org.hibernate.orm</groupId>
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            <artifactId>hibernate-core</artifactId>
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            <version>${hibernate.version}</version>
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        </dependency>
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        <dependency>
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            <groupId>com.mysql</groupId>
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            <artifactId>mysql-connector-j</artifactId>
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            <version>${mysql.version}</version>
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        </dependency>
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    </dependencies>
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    <build>
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        <plugins>
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            <plugin>
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                <groupId>org.codehaus.mojo</groupId>
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                <artifactId>exec-maven-plugin</artifactId>
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                <version>3.5.0</version>
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            </plugin>
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        </plugins>
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    </build>
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</project>

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<?xml version="1.0" encoding="UTF-8"?>
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<persistence xmlns="https://jakarta.ee/xml/ns/persistence"
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             xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
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             xsi:schemaLocation="https://jakarta.ee/xml/ns/persistence https://jakarta.ee/xml/ns/persistence/persistence_3_0.xsd"
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             version="3.0">
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    <persistence-unit name="jdbc-lab" transaction-type="RESOURCE_LOCAL">
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        <class>demo.hibernate.User</class>
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        <properties>
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            <property name="hibernate.dialect" value="org.hibernate.dialect.MySQLDialect"/>
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            <property name="hibernate.show_sql" value="true"/>
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            <property name="hibernate.format_sql" value="true"/>
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            <property name="hibernate.hbm2ddl.auto" value="validate"/>
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        </properties>
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    </persistence-unit>
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</persistence>

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package demo.hibernate;
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import jakarta.persistence.EntityManagerFactory;
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import jakarta.persistence.Persistence;
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import org.hibernate.cfg.AvailableSettings;
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import java.util.HashMap;
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import java.util.Map;
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public final class Jpa {
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    public static final String PU = "jdbc-lab";
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    private Jpa() {}
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    public static EntityManagerFactory createEntityManagerFactory() {
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        Map<String, Object> overrides = new HashMap<>();
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        overrides.put(AvailableSettings.JAKARTA_JDBC_URL, env("JDBC_URL",
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                "jdbc:mysql://127.0.0.1:3306/jdbc_lab?useSSL=false&allowPublicKeyRetrieval=true&serverTimezone=Asia/Shanghai"));
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        overrides.put(AvailableSettings.JAKARTA_JDBC_USER, env("JDBC_USER", "root"));
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        overrides.put(AvailableSettings.JAKARTA_JDBC_PASSWORD, env("JDBC_PASSWORD", "root"));
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        overrides.put(AvailableSettings.JAKARTA_JDBC_DRIVER, "com.mysql.cj.jdbc.Driver");
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        return Persistence.createEntityManagerFactory(PU, overrides);
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    }
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    private static String env(String key, String fallback) {
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        String value = System.getenv(key);
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        return value == null || value.isBlank() ? fallback : value.trim();
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    }
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}

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package demo.hibernate;
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import jakarta.persistence.*;
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import java.time.LocalDateTime;
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@Entity
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@Table(name = "user")
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public class User {
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    @Id
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    @GeneratedValue(strategy = GenerationType.IDENTITY)
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    private Long id;
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    @Column(name = "user_name", nullable = false, length = 64)
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    private String userName;
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    @Column(length = 128)
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    private String email;
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    @Column(nullable = false)
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    private int status = 1;
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    @Column(name = "created_at", insertable = false, updatable = false)
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    private LocalDateTime createdAt;
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    public User() {}
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    public User(String userName, String email, int status) {
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        this.userName = userName;
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        this.email = email;
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        this.status = status;
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    }
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    public Long getId() { return id; }
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    public void setId(Long id) { this.id = id; }
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    public String getUserName() { return userName; }
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    public void setUserName(String userName) { this.userName = userName; }
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    public String getEmail() { return email; }
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    public void setEmail(String email) { this.email = email; }
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    public int getStatus() { return status; }
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    public void setStatus(int status) { this.status = status; }
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    public LocalDateTime getCreatedAt() { return createdAt; }
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    @Override
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    public String toString() {
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        return "User{id=" + id + ", userName='" + userName + "', email='" + email
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                + "', status=" + status + ", createdAt=" + createdAt + "}";
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    }
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}