MyBatis源码分析（三）批量更新
主要是org.apache.ibatis.executor.BatchExecutor这个类，此类继承BaseExecutor(基本增删改查，缓存，懒加载处理)
BatchExecutor这个类有四个属性
//批处理更新最大返回结果 public static final int BATCH_UPDATE_RETURN_VALUE = Integer.MIN_VALUE + 1002;//存放声明(命令)对象集合 private final List<Statement> statementList = new ArrayList<Statement>();// 批处理结果集合 private final List<BatchResult> batchResultList = new ArrayList<BatchResult>();//当前sql语句 private String currentSql;
?一个带参数构造函数,传入配置信息和事务对象
public BatchExecutor(Configuration configuration, Transaction transaction) {super(configuration, transaction);}重写了三个方法， 1.更新方法??2.查询方法 3.刷新方法
我们来看批量更新doUpdate
public int doUpdate(MappedStatement ms, Object parameterObject)throws SQLException {Configuration configuration = ms.getConfiguration();StatementHandler handler = configuration.newStatementHandler(this, ms, parameterObject, RowBounds.DEFAULT, null);BoundSql boundSql = handler.getBoundSql();String sql = boundSql.getSql();Statement stmt;if (currentSql != null && sql.hashCode() == currentSql.hashCode() && sql.length() == currentSql.length()) {int last = statementList.size() - 1;stmt = statementList.get(last);} else {Connection connection = transaction.getConnection();stmt = handler.prepare(connection);currentSql = sql;statementList.add(stmt);batchResultList.add(new BatchResult(ms, sql, parameterObject));}handler.parameterize(stmt);handler.batch(stmt);return BATCH_UPDATE_RETURN_VALUE;}??最重要一句话就是handler.batch(stmt),实际上就是stmt.addBatch();
举个小例子来说明:
//记录1stmt.setInt(1, 1); stmt.setString(2, "Cujo"); stmt.addBatch(); //记录2stmt.setInt(1, 2); stmt.setString(2, "Fred"); stmt.addBatch(); //记录3stmt.setInt(1, 3); stmt.setString(2, "Mark"); stmt.addBatch(); //批量执行上面3条语句int [] counts = statement.executeBatch(); //Commit it connection.commit();
?
如果项目中要用到批量更新如何使用？
下面的映射文件,假设namespace="com.dao.Stuent"
<insert id="insertbatch" parameterType="java.util.List"> <selectKey keyProperty="fetchTime" order="BEFORE" resultType="java.lang.String"> SELECT CURRENT_TIMESTAMP() </selectKey> insert into kangaiduoyaodian ( depart1, depart2, product_name, generic_name, img, product_specification, unit, approval_certificate, manufacturer, marketPrice, vipPrice, website, fetch_time, productdesc ) values <foreach collection="list" item="item" index="index" separator=","> ( #{item.depart1}, #{item.depart2}, #{item.productName}, #{item.genericName}, #{item.img}, #{item.productSpecification}, #{item.unit}, #{item.approvalCertificate}, #{item.manufacturer}, #{item.marketprice}, #{item.vipprice}, #{item.website}, #{fetchTime}, #{item.productdesc} ) </foreach> </insert> ?调用:??SqlSession session = factory.openSession(ExecutorType.BATCH); //关键是这句
原文: http://www.ibatis3.com/thread-111-1-1.html