Jdbc系列八：批量处理

不念不忘少年蓝@ 2022-01-27 06:49 167阅读 0赞

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；  
![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L2xpemhpcWlhbmcxMjE3_size_16_color_FFFFFF_t_70]  
 一个SQL语句的批量传参；  
![在这里插入图片描述][20190525185801673.png]  
![在这里插入图片描述][20190525185808447.png]  
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);
    	}
    }

[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L2xpemhpcWlhbmcxMjE3_size_16_color_FFFFFF_t_70]: /images/20220127/cae6ed80bc86432fb612e0e1f9f600aa.png
[20190525185801673.png]: /images/20220127/818b96c3483a4a7a9989330914b84b24.png
[20190525185808447.png]: /images/20220127/1e27f039f79e41ff842c303de47b99a0.png