我使用 EJB 3.0 和 Hibernate 4 以及 PostgreSQL 作为我的数据库服务器来创建一个 Multi-Tenancy 系统，其中每个租户都有独立但相同的模式。我仍处于试用阶段，我有 3 个方案 public、company1、company2 都有一个表人。现在我想做的是根据用户在运行时更改模式，以便他只能查看他/她公司的数据。

这是我的示例代码: 实体对象:

    package com.neebal.domain;

        import java.io.Serializable;
        import java.lang.Long;
        import java.lang.String;

        import javax.persistence.*;
        import org.eclipse.persistence.annotations.Multitenant;
        import org.eclipse.persistence.annotations.MultitenantType;

        @Entity

        //@Table(schema = "company1")
        public class Person implements Serializable {


    @Id
    private Long id;
    private String name;
    private static final long serialVersionUID = 1L;

    public Person() {
        super();
    }   
    public Long getId() {
        return this.id;
    }

    public void setId(Long id) {
        this.id = id;
    }   
    public String getName() {
        return this.name;
    }

    public void setName(String name) {
        this.name = name;
    }  
}

MultiTenantConnectionProvider 类:

import java.sql.Connection;
import java.sql.SQLException;
import java.util.Map;

import org.hibernate.HibernateException;
import org.hibernate.service.config.spi.ConfigurationService;
import org.hibernate.service.jdbc.connections.internal.C3P0ConnectionProvider;
import org.hibernate.service.jdbc.connections.spi.MultiTenantConnectionProvider;
import org.hibernate.service.spi.ServiceRegistryAwareService;
import org.hibernate.service.spi.ServiceRegistryImplementor;

public class MultiTenantProvider implements MultiTenantConnectionProvider, ServiceRegistryAwareService  {

    private static final long serialVersionUID = 4368575201221677384L;

    private C3P0ConnectionProvider connectionProvider = null;

    @Override
    public boolean supportsAggressiveRelease() {
        return false;
    }

    @Override
    public void injectServices(ServiceRegistryImplementor serviceRegistry) {
        Map lSettings = serviceRegistry.getService(ConfigurationService.class).getSettings();

        connectionProvider = new C3P0ConnectionProvider();
        connectionProvider.injectServices(serviceRegistry);
        connectionProvider.configure(lSettings);
    }

    @Override
    public boolean isUnwrappableAs(Class clazz) {
        return false;
    }

    @Override
    public <T> T unwrap(Class<T> clazz) {
        return null;
    }

    @Override
    public Connection getAnyConnection() throws SQLException {
        final Connection connection = connectionProvider.getConnection();
        return connection;
    }

    @Override
    public Connection getConnection(String tenantIdentifier) throws SQLException {
        final Connection connection = getAnyConnection();
        try {
            connection.createStatement().execute("SET SCHEMA '" + tenantIdentifier + "'");
        }
        catch (SQLException e) {
            throw new HibernateException("Could not alter JDBC connection to specified schema [" + tenantIdentifier + "]", e);
        }
        return connection;
    }

    @Override
    public void releaseAnyConnection(Connection connection) throws SQLException {
        try {
            connection.createStatement().execute("SET SCHEMA 'public'");
        }
        catch (SQLException e) {
            throw new HibernateException("Could not alter JDBC connection to specified schema [public]", e);
        }
        connectionProvider.closeConnection(connection);
    }

    @Override
    public void releaseConnection(String tenantIdentifier, Connection connection) throws SQLException {
        releaseAnyConnection(connection);
    }
}

CurrentTenantIdentifierResolver 类:

import org.hibernate.context.spi.CurrentTenantIdentifierResolver;

public class SchemaResolver implements CurrentTenantIdentifierResolver {

    @Override
    public String resolveCurrentTenantIdentifier() {
        System.out.println("company1");
        return "company1"; //TODO: Implement service to identify tenant like: userService.getCurrentlyAuthUser().getTenantId();
    }

    @Override
    public boolean validateExistingCurrentSessions() {
        return false;
    }
}

persistence.xml 文件:

<?xml version="1.0" encoding="UTF-8"?>
<persistence version="2.0"
    xmlns="http://java.sun.com/xml/ns/persistence" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xsi:schemaLocation="http://java.sun.com/xml/ns/persistence http://java.sun.com/xml/ns/persistence/persistence_2_0.xsd">
    <persistence-unit name="testEJB">
        <jta-data-source>jdbc/testpgsql</jta-data-source>
        <properties>
            <property name="javax.persistence.provider" value="org.hibernate.ejb.HibernatePersistence" />

            <property name="hibernate.connection.username" value="postgres" />
            <property name="hibernate.connection.password" value="root" />
            <property name="hibernate.connection.url" value="jdbc:postgresql://localhost:5432/test" />
            <property name="hibernate.connection.driver_class" value="org.postgresql.Driver" />

            <property name="hibernate.multiTenancy" value="SCHEMA" />
            <property name="hibernate.tenant_identifier_resolver" value="com.neebal.util.multitenancy.SchemaResolver" />
            <property name="hibernate.multi_tenant_connection_provider"
                value="com.neebal.util.multitenancy.MultiTenantProvider" />

            <property name="hibernate.hbm2ddl.auto" value="create-drop" />
        </properties>
    </persistence-unit>
</persistence>

最后是 DAO 类:

import java.util.List;

import javax.ejb.Stateless;
import javax.persistence.EntityManager;
import javax.persistence.PersistenceContext;

import com.neebal.domain.Person;

/**
 * Session Bean implementation class PersonDAO
 */
@Stateless
public class PersonDAO implements PersonDAOLocal {

    @PersistenceContext
    EntityManager entityManager;
    /**
     * Default constructor. 
     */
    public PersonDAO() {
        // TODO Auto-generated constructor stub
    }

    @Override
    public void save(Person person) {
        entityManager.persist(person);
    }

    @Override
    public List<Person> getAll() {

        Person person = entityManager.find(Person.class, 2L);
        System.out.println(person.getName());
        return null;
    }

}

在此示例中，我已将架构硬编码为 company1，但它仍然存在或从公共(public)架构中检索数据。那么在这个例子中我哪里错了。

最佳答案

这个问题已经有 1 年历史了，但我认为根据某些运行时条件使用不同模式的问题很常见，所以我还是会回答。如果我对你的理解是正确的并且租户的集合很小，那么我认为最简单的方法来做你想要实现的是在你的 persistence.xml 中为每个租户定义一个单独的持久性单元

<persistence-unit name="public">
.. settings for first schema        
</persistence-unit>
<persistence-unit name="company1">
.. settings for first schema        
</persistence-unit>
<persistence-unit name="company2">
.. settings for first schema        
</persistence-unit>

然后每个人都有一个单独的entityManager:

@PersistenceContext(unitName = "public")
private EntityManager emPublic;

@PersistenceContext(unitName = "company1")
private EntityManager emComp1;

@PersistenceContext(unitName = "company2")
private EntityManager emComp1;

现在您可以在给定当前授权用户的情况下在实体管理器之间切换。

根据您的具体基础设施等，可能还有其他方法。例如，如果您的所有模式都在同一台服务器上，那么您还可以尝试将模式名称直接传递给您的查询。

这是纯 JPA，因此可移植，不依赖于任何持久性提供程序，如 hibernate，也不依赖于您的 DBMS。

关于java - Hibernate 4.0 的 MultiTenancy 和 Separate Schema 方法，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/19348477/