Mybatis Criteria使用and和or进行联合条件查询的操作方法

public List<Contact> searchByExample(Contact contact) { 
        System.out.println("searchByExampleContact"); 
        ContactExample example = new ContactExample(); 
        ContactExample.Criteria cri = example.createCriteria(); 
        if (this.objectAttrNullCheck(contact, "username")) 
            cri.andUsernameEqualTo(contact.getUsername()); 
        if (this.objectAttrNullCheck(contact, "password")) 
            cri.andPasswordEqualTo(contact.getPassword()); 
        ContactMapper vcontactMapper = sqlSession 
                .getMapper(ContactMapper.class); 
        List<Contact> returnList = vcontactMapper.selectByExample(example); 
        return returnList; 
}

andUsernameEqualTo 
andPasswordEqualTo

import java.io.IOException;
import java.io.Reader;
import java.util.ArrayList;
import java.util.List;
import org.apache.ibatis.io.Resources;
import org.apache.ibatis.session.SqlSession;
import org.apache.ibatis.session.SqlSessionFactory;
import org.apache.ibatis.session.SqlSessionFactoryBuilder;
import org.apache.log4j.pattern.ClassNamePatternConverter;
import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;
import cn.itcast.ssm.mapper.ItemsMapper;
import cn.itcast.ssm.po.ItemsExample;
  
public class Student {
  
    public static void main(String[] args) throws IOException {
      
 
        /*方式一  */
        ItemsExample itemsExample1 = new ItemsExample();
        itemsExample1.or().andIdEqualTo(5).andNameIsNotNull();
        itemsExample1.or().andPicEqualTo("xxx").andPicIsNull();
  
        List<Integer> fieldValues = new ArrayList<Integer>();
        fieldValues.add(8);
        fieldValues.add(11);
        fieldValues.add(14);
        fieldValues.add(22);
        itemsExample1.or().andIdIn(fieldValues);
        itemsExample1.or().andIdBetween(5, 9);
  
        /*  方式二 criteria1与criteria2是or的关系 */
        ItemsExample itemsExample2 = new ItemsExample();
        ItemsExample.Criteria criteria1 = itemsExample2.createCriteria();
        criteria1.andIdIsNull();
        criteria1.andPriceEqualTo((float) 3);
  
        ItemsExample.Criteria criteria2 = itemsExample2.createCriteria();
        criteria2.andNameIsNull();
        criteria2.andIdGreaterThanOrEqualTo(5);
        itemsExample2.or(criteria2);
  
        //方式一和方式二是等价的
        // spring获取mapper代理对象
        ApplicationContext applicationContext = new ClassPathXmlApplicationContext("classpath:applicationContext.xml");
        ItemsMapper itemsMapper = (ItemsMapper) applicationContext.getBean("itemsMapper");
        itemsMapper.countByExample(itemsExample2);
  
        // 获取SqlSessionFactory
        String resource = "SqlMapConfig.xml";
        Reader reader = Resources.getResourceAsReader(resource);
        SqlSessionFactory sqlMapper = new SqlSessionFactoryBuilder().build(reader);
        // 获取SqlSession
        SqlSession sqlSession = sqlMapper.openSession();
    }
}

public void getQueryExampleByCondition(Example example, OrderQuery query) {
  
        Criteria criteria1 = example.createCriteria();
  
        // 设置 criteria2 与 criteria1 为 or 方式关联
        Criteria criteria2 = example.or();
        
        if (query != null) {
             
            if (query.getLoadSrc() != null && query.getLoadSrc() != -1) {
                criteria1.andEqualTo("loadSrc", query.getLoadSrc());
            }
                     
            if (!StringUtil.isEmpty(query.getOrderNo())) {
                criteria1.andLike("orderNo", "%" + query.getOrderNo() + "%");
            }
  
            // 以下 3 个会用 OR 方式加上 criteria2 中的条件
            if (query.getStatus() != null && query.getStatus() != -1) {
                criteria1.andEqualTo("status", query.getStatus());
                criteria2.andEqualTo("status", query.getStatus());
            }
  
            if (!StringUtil.isEmpty(query.getRepayDateEnd())) {
                criteria1.andLessThanOrEqualTo("repayDate", query.getRepayDateEnd());
                criteria2.andLessThanOrEqualTo("repayDate", query.getRepayDateEnd());
            }
  
            if (!StringUtil.isEmpty(query.getLoanDay())) {
                criteria1.andEqualTo("loanDay", query.getLoanDay());
                criteria1.andEqualTo("loanDay", query.getLoanDay());
            }
  
        }
    }

SELECT * FROM xxxx WHERE (load_type = 5 AND loan_day = 7) OR (order_No = 5)

DemoExample example=new DemoExample ();
DemoExample.Criteria criteria=example.createCriteria();
criteria.andidEqualTo(id);
criteria.andStatusEqualTo("0");
         
DemoExample.Criteria criteria2=example.createCriteria();
criteria2.andidEqualTo(id);
criteria2.andstatusEqualTo("1");
example.or(criteria2);
dao.countByExample(example);
 

select count(*) from demo WHERE ( ID = ? and STATUS = ? ) or( ID = ? and STATUS = ? )