Jdbc系列八：批量处理

 当需要成批插入或者更新记录时。可以采用Java的批量更新机制，这一机制允许多条语句一次性提交给数据库批量处理。通常情况下比单独提交处理更有效率。  JDBC的批量处理语句包括下面两个方法：   addBatch(String)：添加需要批量处理的SQL语句或是参数；   executeBatch()：执行批量处理语句； 通常我们会遇到两种批量执行SQL语句的情况：  多条SQL语句的批量处理；  一个SQL语句的批量传参； 测试：  向 Oracle 的 customers 数据表中插入 10 万条记录。测试如何插入, 用时最短。 1、使用 Statement，用时 39567ms

@Test public void testBatchWithStatement(){ Connection connection = null; Statement statement = null; String sql = null; try { connection = JDBCTools.getConnection(); JDBCTools.beginTx(connection); statement = connection.createStatement(); long begin = System.currentTimeMillis(); for(int i = 0; i < 100000; i++){ sql = "INSERT INTO customers VALUES(" + (i + 1) + ", 'name_" + i + "', '29-6月 -13')"; statement.addBatch(sql); } long end = System.currentTimeMillis(); System.out.println("Time: " + (end - begin)); //39567 JDBCTools.commit(connection); } catch (Exception e) { e.printStackTrace(); JDBCTools.rollback(connection); } finally{ JDBCTools.releaseDB(null, statement, connection); } }

2、使用 PreparedStatement。用时 9819ms

@Test public void testBatchWithPreparedStatement(){ Connection connection = null; PreparedStatement preparedStatement = null; String sql = null; try { connection = JDBCTools.getConnection(); JDBCTools.beginTx(connection); sql = "INSERT INTO customers VALUES(?,?,?)"; preparedStatement = connection.prepareStatement(sql); Date date = new Date(new java.util.Date().getTime()); long begin = System.currentTimeMillis(); for(int i = 0; i < 100000; i++){ preparedStatement.setInt(1, i + 1); preparedStatement.setString(2, "name_" + i); preparedStatement.setDate(3, date); preparedStatement.executeUpdate(); } long end = System.currentTimeMillis(); System.out.println("Time: " + (end - begin)); //9819 JDBCTools.commit(connection); } catch (Exception e) { e.printStackTrace(); JDBCTools.rollback(connection); } finally{ JDBCTools.releaseDB(null, preparedStatement, connection); } }

3、使用Batch批量操作，用时 569ms

@Test public void testBatch(){ Connection connection = null; PreparedStatement preparedStatement = null; String sql = null; try { connection = JDBCTools.getConnection(); JDBCTools.beginTx(connection); sql = "INSERT INTO customers VALUES(?,?,?)"; preparedStatement = connection.prepareStatement(sql); Date date = new Date(new java.util.Date().getTime()); long begin = System.currentTimeMillis(); for(int i = 0; i < 100000; i++){ preparedStatement.setInt(1, i + 1); preparedStatement.setString(2, "name_" + i); preparedStatement.setDate(3, date); //"积攒" SQL preparedStatement.addBatch(); //当 "积攒" 到一定程度, 就统一的执行一次. 并且清空先前 "积攒" 的 SQL if((i + 1) % 300 == 0){ preparedStatement.executeBatch(); preparedStatement.clearBatch(); } } //若总条数不是批量数值的整数倍, 则还需要再额外的执行一次. if(100000 % 300 != 0){ preparedStatement.executeBatch(); preparedStatement.clearBatch(); } long end = System.currentTimeMillis(); System.out.println("Time: " + (end - begin)); //569 JDBCTools.commit(connection); } catch (Exception e) { e.printStackTrace(); JDBCTools.rollback(connection); } finally{ JDBCTools.releaseDB(null, preparedStatement, connection); } }