事務類本身就是一個攔截器,可以用注解的方式配置。方法內部的所有 DML 操作都將在本次事務之內。
配置代碼如下:
@Before(Tx.class) public void savePost(){ //... }
事務配置就是這麼簡單任性。
上述配置中為 savePost() 配置了事務也就是攔截器 Tx,當調用到 savePost() 的時候,是會進入到 Tx 的 intercept 方法中的:
主要代碼如下:
public void intercept(Invocation inv) { Config config = getConfigWithTxConfig(inv); if (config == null) config = DbKit.getConfig(); Connection conn = config.getThreadLocalConnection(); // 下面這段支持嵌套事務,可以忽略不看 if (conn != null) { try { if (conn.getTransactionIsolation() < getTransactionLevel(config)) conn.setTransactionIsolation(getTransactionLevel(config)); inv.invoke(); return ; } catch (SQLException e) { throw new ActiveRecordException(e); } } Boolean autoCommit = null; try { // 1. 建立數據庫連接 conn = config.getConnection(); autoCommit = conn.getAutoCommit(); config.setThreadLocalConnection(conn); // 2. 設置事務隔離級別 conn.setTransactionIsolation(getTransactionLevel(config)); // conn.setTransactionIsolation(transactionLevel); // 3. 設置事務手動提交 conn.setAutoCommit(false); // 4. 反射機制調用 savePost() inv.invoke(); // 5. 事務提交 conn.commit(); } catch (NestedTransactionHelpException e) { if (conn != null) try {conn.rollback();} catch (Exception e1) {LogKit.error(e1.getMessage(), e1);} LogKit.logNothing(e); } catch (Throwable t) { // 6. 若有異常就回滾 if (conn != null) try {conn.rollback();} catch (Exception e1) {LogKit.error(e1.getMessage(), e1);} throw t instanceof RuntimeException ? (RuntimeException)t : new ActiveRecordException(t); } finally { try { if (conn != null) { if (autoCommit != null) conn.setAutoCommit(autoCommit); conn.close(); } } catch (Throwable t) { LogKit.error(t.getMessage(), t); // can not throw exception here, otherwise the more important exception in previous catch block can not be thrown } finally { config.removeThreadLocalConnection(); // prevent memory leak } } }
Tx.java 使用的是 JFinal 默認配置的事務隔離級別,是在 DbKit.java 中配置的
public static final int DEFAULT_TRANSACTION_LEVEL = Connection.TRANSACTION_REPEATABLE_READ;
JFinal 還有幾個攔截器,可以根據事務隔離級別的需求選用。
它們都繼承與 Tx.java,唯一不同的就是事務隔離級別。
以 TxReadCommitted 為例。
繼承 Tx.java,覆蓋了 getTransactionLevel 方法,返回常量值,這個常量就代表了事務隔離級別。
public class TxReadCommitted extends Tx { /** * A constant indicating that * dirty reads are prevented; non-repeatable reads and phantom * reads can occur. This level only prohibits a transaction * from reading a row with uncommitted changes in it. */ private int TRANSACTION_READ_COMMITTED = 2; @Override protected int getTransactionLevel(com.jfinal.plugin.activerecord.Config config) { return TRANSACTION_READ_COMMITTED; } }
這種實現方式並沒有使用攔截器。
跟蹤代碼最終追到 DbPro.java 如下代碼中:
boolean tx(Config config, int transactionLevel, IAtom atom) { Connection conn = config.getThreadLocalConnection(); if (conn != null) { // Nested transaction support try { if (conn.getTransactionIsolation() < transactionLevel) conn.setTransactionIsolation(transactionLevel); boolean result = atom.run(); if (result) return true; throw new NestedTransactionHelpException("Notice the outer transaction that the nested transaction return false"); // important:can not return false } catch (SQLException e) { throw new ActiveRecordException(e); } } Boolean autoCommit = null; try { // 1. 建立數據庫連接 conn = config.getConnection(); autoCommit = conn.getAutoCommit(); config.setThreadLocalConnection(conn); // 2. 設置事務隔離級別 conn.setTransactionIsolation(transactionLevel); // 3. 設置事務手動提交 conn.setAutoCommit(false); // 4. 所有 DML 操作是否都執行成功? boolean result = atom.run(); // 5. 都成功:提交;不是都成功:回滾 if (result) conn.commit(); else conn.rollback(); return result; } catch (NestedTransactionHelpException e) { if (conn != null) try {conn.rollback();} catch (Exception e1) {LogKit.error(e1.getMessage(), e1);} LogKit.logNothing(e); return false; } catch (Throwable t) { if (conn != null) try {conn.rollback();} catch (Exception e1) {LogKit.error(e1.getMessage(), e1);} throw t instanceof RuntimeException ? (RuntimeException)t : new ActiveRecordException(t); } finally { try { if (conn != null) { if (autoCommit != null) conn.setAutoCommit(autoCommit); conn.close(); } } catch (Throwable t) { LogKit.error(t.getMessage(), t); // can not throw exception here, otherwise the more important exception in previous catch block can not be thrown } finally { config.removeThreadLocalConnection(); // prevent memory leak } } }
主要事務流程:
Jfinal學習之路---Controller使用 http://www.linuxidc.com/Linux/2014-07/104323.htm
JFinal開發8個常見問題 http://www.linuxidc.com/Linux/2015-02/113421.htm
JFinal的詳細介紹:請點這裡
JFinal的下載地址:請點這裡