Spring事务03管理事务状态接口2AbstractTransactionStatus

Z时代
2024-01-10
分类：综合
类源码分析如下：
package org.springframework.transaction.support;
import org.springframework.lang.Nullable;
import org.springframework.transaction.NestedTransactionNotSupportedException;
import org.springframework.transaction.SavepointManager;
import org.springframework.transaction.TransactionException;
import org.springframework.transaction.TransactionStatus;
import org.springframework.transaction.TransactionUsageException;
import org.springframework.transaction.support.DefaultTransactionStatus;
import org.springframework.transaction.support.SimpleTransactionStatus;
/**
 * 抽象实现的{@link org.springframework.transaction.TransactionStatus}接口。
 *
 * 预实现本地仅回滚和已完成标志的处理，以及对底层{@link org.springframework.transaction.SavepointManager}的委托。
 * 还提供在事务中保持保存点的选项。
 *
 * 不承担任何特定的内部事务处理，如底层事务对象，也没有事务同步机制。
 *
 * @author Juergen Hoeller
 * @since 1.2.3
 * @see #setRollbackOnly()
 * @see #isRollbackOnly()
 * @see #setCompleted()
 * @see #isCompleted()
 * @see #getSavepointManager()
 * @see SimpleTransactionStatus
 * @see DefaultTransactionStatus
 */
public abstract class AbstractTransactionStatus implements TransactionStatus {
    private boolean rollbackOnly = false;
    private boolean completed = false;
    @Nullable
    private Object savepoint;
    //---------------------------------------------------------------------
    // 处理当前事务状态
    //---------------------------------------------------------------------
    @Override
    public void setRollbackOnly() {
        this.rollbackOnly = true;
    }
    /**
     * 通过检查
     * 这个TransactionStatus的本地rollback-only标志
     * 和
     * 底层事务的全局rollback-only标志(如果有的话)
     * 来确定rollback-only标志。
     *
     * @see #isLocalRollbackOnly()
     * @see #isGlobalRollbackOnly()
     */
    @Override
    public boolean isRollbackOnly() {
        return (isLocalRollbackOnly() || isGlobalRollbackOnly());
    }
    /**
     * 通过检查这个TransactionStatus来确定只回滚标志。
     * 只有当应用程序在这个TransactionStatus对象上调用{@code setRollbackOnly}时，才会返回“true”。
     */
    public boolean isLocalRollbackOnly() {
        return this.rollbackOnly;
    }
    /**
     * 模板方法，用于确定基础事务的全局仅回滚标记(如果有)。
     * 这个实现总是返回{@code false}。
     */
    public boolean isGlobalRollbackOnly() {
        return false;
    }
    /**
     * 这个实现是空的，认为flush是无操作的。
     */
    @Override
    public void flush() {
    }
    /**
     * 将此事务标记为完成，即提交或回滚。
     */
    public void setCompleted() {
        this.completed = true;
    }
    @Override
    public boolean isCompleted() {
        return this.completed;
    }
    //---------------------------------------------------------------------
    // 当前保存点状态的处理
    //---------------------------------------------------------------------
    /**
     * 为该事务设置保存点。对PROPAGATION_NESTED有用
     * @see org.springframework.transaction.TransactionDefinition#PROPAGATION_NESTED
     */
    protected void setSavepoint(@Nullable Object savepoint) {
        this.savepoint = savepoint;
    }
    /**
     * 获取此事务的保存点(如果有)。
     */
    @Nullable
    protected Object getSavepoint() {
        return this.savepoint;
    }
    @Override
    public boolean hasSavepoint() {
        return (this.savepoint != null);
    }
    /**
     * 创建一个保存点，并为事务保存它。
     * 如果基础事务不支持保存点，抛出下面的异常
     * @throws org.springframework.transaction.NestedTransactionNotSupportedException
     */
    public void createAndHoldSavepoint() throws TransactionException {
        setSavepoint(getSavepointManager().createSavepoint());
    }
    /**
     * 回滚到为事务保留的保存点，然后立即释放保存点。
     */
    public void rollbackToHeldSavepoint() throws TransactionException {
        Object savepoint = getSavepoint();
        if (savepoint == null) {
            throw new TransactionUsageException(
                    "Cannot roll back to savepoint - no savepoint associated with current transaction");
        }
        getSavepointManager().rollbackToSavepoint(savepoint);
        getSavepointManager().releaseSavepoint(savepoint);
        setSavepoint(null);
    }
    /**
     * 释放为事务保留的保存点。
     */
    public void releaseHeldSavepoint() throws TransactionException {
        Object savepoint = getSavepoint();
        if (savepoint == null) {
            throw new TransactionUsageException(
                    "Cannot release savepoint - no savepoint associated with current transaction");
        }
        getSavepointManager().releaseSavepoint(savepoint);
        setSavepoint(null);
    }
    //---------------------------------------------------------------------
    // 实现SavepointManager
    //---------------------------------------------------------------------
    /**
     * 如果可能，此实现将底层事务委托给SavepointManager。
     *
     * @see #getSavepointManager()
     * @see SavepointManager#createSavepoint()
     */
    @Override
    public Object createSavepoint() throws TransactionException {
        return getSavepointManager().createSavepoint();
    }
    /**
     * 如果可能，此实现将底层事务委托给SavepointManager。
     *
     * @see #getSavepointManager()
     * @see SavepointManager#rollbackToSavepoint(Object)
     */
    @Override
    public void rollbackToSavepoint(Object savepoint) throws TransactionException {
        getSavepointManager().rollbackToSavepoint(savepoint);
    }
    /**
     * 如果可能，此实现将底层事务委托给SavepointManager。
     *
     * @see #getSavepointManager()
     * @see SavepointManager#releaseSavepoint(Object)
     */
    @Override
    public void releaseSavepoint(Object savepoint) throws TransactionException {
        getSavepointManager().releaseSavepoint(savepoint);
    }
    /**
     * 如果可能，返回底层事务的SavepointManager。
     *
     * 默认实现总是抛出一个NestedTransactionNotSupportedException异常。
     * 如果基础事务不支持保存点，抛出下面的异常
     * @throws org.springframework.transaction.NestedTransactionNotSupportedException
     */
    protected SavepointManager getSavepointManager() {
        throw new NestedTransactionNotSupportedException("This transaction does not support savepoints");
    }
}