需要事务才能执行此操作（使用事务或扩展持久性上下文）

Question

我正在使用Wildfly 10.0.0 Final，Java EE7，Maven和JPA 2.1。当我查询我的数据库中的记录时，它工作正常并列出了员工，但是当我试图坚持新员工时，它给了我以下例外：

javax.servlet.ServletException: WFLYJPA0060: Transaction is required to perform this operation (either use a transaction or extended persistence context)
javax.faces.webapp.FacesServlet.service(FacesServlet.java:671)
io.undertow.servlet.handlers.ServletHandler.handleRequest(ServletHandler.java:85)
io.undertow.servlet.handlers.security.ServletSecurityRoleHandler.handleRequest(ServletSecurityRoleHandler.java:62)
io.undertow.servlet.handlers.ServletDispatchingHandler.handleRequest(ServletDispatchingHandler.java:36)
org.wildfly.extension.undertow.security.SecurityContextAssociationHandler.handleRequest(SecurityContextAssociationHandler.java:78)
io.undertow.server.handlers.PredicateHandler.handleRequest(PredicateHandler.java:43)
io.undertow.servlet.handlers.security.SSLInformationAssociationHandler.handleRequest(SSLInformationAssociationHandler.java:131)
...

我正在尝试使用JSF和CDI bean来实现它。我有一个JTA数据源，我在persistence.xml文件中配置了它：

<?xml version="1.0" encoding="UTF-8"?>
<persistence xmlns="http://xmlns.jcp.org/xml/ns/persistence" version="2.1">
    <persistence-unit name="MyPersistenceUnit">
        <provider>org.hibernate.jpa.HibernatePersistenceProvider</provider>
        <jta-data-source>java:/EmployeesDS</jta-data-source>
        <class>com.home.entity.Employee</class>
        <properties>
            <property name="hibernate.archive.autodetection" value="class"/>
            <property name="hibernate.show_sql" value="true"/>
            <property name="hibernate.format_sql" value="true"/>
            <property name="hbm2ddl.auto" value="update"/>
            <property name="hibernate.dialect" value="org.hibernate.dialect.MySQLDialect"/>
        </properties>
    </persistence-unit>
</persistence>

CDI bean可以在下面看到。它相对简单，有一种方法可以列出25名员工，另一种方法可以保留特定员工：

@Named
@RequestScoped
public class DataFetchBean {
    @PersistenceContext
    EntityManager em;

    public List getEmployees() {
        Query query = em.createNamedQuery("findEmployees");
        query.setMaxResults(25);
        return query.getResultList();
    }

    public String getEmployeeNameById(final int id) {
        addEmployee();

        Query query = em.createNamedQuery("findEmployeeNameById");
        query.setParameter("empno", id);
        Employee employee = (Employee) query.getSingleResult();
        return employee.getFirstName() + " " + employee.getLastName();
    }

    public void addEmployee() {
        em.persist(new Employee(500000, new Date(335077446), "Josh", "Carribean", 'm', new Date(335077446)));
    }
}

员工实体类可以在下面找到：

@NamedQueries({
        @NamedQuery(
                name = "findEmployees",
                query = "select e from Employee e"
        ),           
        @NamedQuery(
                name = "findEmployeeNameById",
                query = "select e from Employee e where e.empNo = :empno"
        )
})
@Table(name = "employees")
public class Employee {
    @Id
    @Column(name = "emp_no")
    private int empNo;
    @Basic
    @Column(name = "birth_date")
    private Date birthDate;
    @Basic
    @Column(name = "first_name")
    private String firstName;
    @Basic
    @Column(name = "last_name")
    private String lastName;
    @Basic
    @Column(name = "gender")
    private char gender;
    @Basic
    @Column(name = "hire_date")
    private Date hireDate;

    public Employee() { }

    public int getEmpNo() {
        return empNo;
    }

    public void setEmpNo(int empNo) {
        this.empNo = empNo;
    }

    public Date getBirthDate() {
        return birthDate;
    }

    public void setBirthDate(Date birthDate) {
        this.birthDate = birthDate;
    }

    public String getFirstName() {
        return firstName;
    }

    public void setFirstName(String firstName) {
        this.firstName = firstName;
    }

    public String getLastName() {
        return lastName;
    }

    public void setLastName(String lastName) {
        this.lastName = lastName;
    }

    public char getGender() {
        return gender;
    }

    public void setGender(char gender) {
        this.gender = gender;
    }

    public Date getHireDate() {
        return hireDate;
    }

    public void setHireDate(Date hireDate) {
        this.hireDate = hireDate;
    }

    public Employee(int empNo, Date birthDate, String firstName, String lastName, char gender, Date hireDate) {
        this.empNo = empNo;
        this.birthDate = birthDate;
        this.firstName = firstName;
        this.lastName = lastName;
        this.gender = gender;
        this.hireDate = hireDate;
    }

    @Override
    public boolean equals(Object o) {
        if (this == o) return true;
        if (o == null || getClass() != o.getClass()) return false;

        Employee employee = (Employee) o;

        if (empNo != employee.empNo) return false;
        if (gender != employee.gender) return false;
        if (birthDate != null ? !birthDate.equals(employee.birthDate) : employee.birthDate != null) return false;
        if (firstName != null ? !firstName.equals(employee.firstName) : employee.firstName != null) return false;
        if (lastName != null ? !lastName.equals(employee.lastName) : employee.lastName != null) return false;
        if (hireDate != null ? !hireDate.equals(employee.hireDate) : employee.hireDate != null) return false;

        return true;
    }

    @Override
    public int hashCode() {
        int result = empNo;
        result = 31 * result + (birthDate != null ? birthDate.hashCode() : 0);
        result = 31 * result + (firstName != null ? firstName.hashCode() : 0);
        result = 31 * result + (lastName != null ? lastName.hashCode() : 0);
        result = 31 * result + (int) gender;
        result = 31 * result + (hireDate != null ? hireDate.hashCode() : 0);
        return result;
    }
}

提前致谢！

Answer 1

基本上存在一个容器管理的JTA感知持久化上下文与bean管理事务（BMT）。

因此，除了EntityManager之外，您还应该在DataFetchBean中注入UserTransaction，以便开始，提交或回滚交易。

@Named
@RequestScoped
public class DataFetchBean {
    @PersistenceContext
    EntityManager em;

    @Resource
    private UserTransaction userTransaction;

    ...
}

然后，在您的addEmployee方法中，您必须开始然后提交您的交易，以便您对员工实体的更改可以传播到数据库。

public void addEmployee() throws Exception {
    Employee employee = new Employee(500000, new Date(335077446), "Josh", "Carribean", 'm', new Date(335077446));

    userTransaction.beginTransaction();
    em.persist(employee);
    userTransaction.commit();
}

尽管如此，您应该考虑将数据库操作迁移到EJB中，将其注入到JSF bean中，因此委托容器管理事务的责任，即使用CMT，而不是手动处理它们

Answer 2

另一种处理方法是在@Transactional方法DataFetchBean上使用注释addEmployee。然后您不需要UserTransaction并且可以使用AOP来管理交易。

这是JTA 1.2中添加的新功能。

Answer 3

您可以在下面看到有关处理交易的文件：
Container-Managed Transactions JEE6

根据您的申请使用Transaction Attributes

Answer 4

在您的方法上添加@Transactional批注，它将使其变为“ transactional”

Answer 5

一种简单的方法，将@Transactional(Transactional.TxType.REQUIRED)添加到方法

Answer 6

我遇到了同样的问题，解决方法是

@Transactional(rollbackOn = Exception.class)

添加到Bean调用的方法

Answer 7

与此示例不完全相关，但我遇到了另一个问题。我的项目已经在使用容器管理事务 (CMT) 并收到此错误。

我的问题是我忘记在 EJB 中包含 @Stateless 注释。添加该注解（或其他注解到类）使其实际上是容器管理的并提供所需的事务。