JAVA高级面试进阶训练营视频教程

admin

 环境: mybatis  + oracle11g r2

1.使用"直接路径插入"(以下sql语句中的"/*+append_values */"),而且使用keyword"union all":

<insert id="addUidCodeBatch"  parameterType="java.util.List">  
    insert into /*+append_values */
        T_UID_CODE(C_UID_CODE,
		         C_SERAIL_LEN,
		         C_BATCH_CODE,
		         C_TYPE,
		         C_CREATE_TIME,
		         C_SUPER_CODE,
		         c_security_code,
		         C_SERIAL_CODE
		         )
       <foreach collection="list" item="item" index="index" separator="union all" >  
		  select #{item.uidCode},
		         #{item.kCode},      
		         #{item.batchCode},
		         #{item.type},
		         sysdate,
		         #{item.superCode},
		         #{item.securityCode},
		         #{item.serialCode}
		  from dual
       </foreach>  
    </insert>  

2.dao层实现:   之前是一次性commit,这样做会随着插入数目的增大,运行速度陡然变慢,所以应该分批次进行插入:

	public void save(List<UidCodeBean> uidCodeList) throws Exception {
		SqlSession batchSqlSession = null;
		try {
			batchSqlSession = sqlSessionFactory.openSession(ExecutorType.BATCH, false);//获取批量方式的sqlsession		
			int batchCount = 1000;//每批commit的个数
			int batchLastIndex = batchCount - 1;//每批最后一个的下标
			for(int index = 0; index < uidCodeList.size()-1;){
				if(batchLastIndex > uidCodeList.size()-1){
					batchLastIndex = uidCodeList.size() - 1;
					batchSqlSession.insert(NAMESPACE+".addUidCodeBatch", uidCodeList.subList(index, batchLastIndex));
					batchSqlSession.commit();
					System.out.println("index:"+index+"     batchLastIndex:"+batchLastIndex);
					break;//数据插入完成,退出循环
					
				}else{
					batchSqlSession.insert(NAMESPACE+".addUidCodeBatch", uidCodeList.subList(index, batchLastIndex));					                batchSqlSession.commit();
					System.out.println("index:"+index+"     batchLastIndex:"+batchLastIndex);
					index = batchLastIndex + 1;//设置下一批下标
					batchLastIndex = index + (batchCount - 1);						
				}				
			}						
		}finally{
			batchSqlSession.close();
		}		
	}