Mybatis進階學習筆記——動態代理方式開發Dao介面、Dao層（推薦第二種）
阿新 • • 發佈：2018-12-23
1.原始方法開發Dao
Dao介面
1 package cn.sm1234.dao; 2 3 import java.util.List; 4 5 import cn.sm1234.domain.Customer; 6 7 public interface CustomerDao { 8 9 public void saveCustomer(Customer customer); 10 11 public void updateCustomer(Customer customer); 12 13 publicvoid deleteCustomer(Integer id); 14 15 public List<Customer> queryAllCustomer(); 16 17 public Customer queryCustomerById(Integer id); 18 19 public List<Customer> queryCustomerByName(String name); 20 }
Dao實現：
1 package cn.sm1234.dao.impl; 2 3 importjava.util.List; 4 5 import org.apache.ibatis.session.SqlSession; 6 7 import cn.sm1234.dao.CustomerDao; 8 import cn.sm1234.domain.Customer; 9 import cn.sm1234.utils.SessionUtils; 10 11 public class CustomerDaoImpl implements CustomerDao { 12 13 @Override 14 public void saveCustomer(Customer customer) {15 SqlSession sqlSession = null; 16 try { 17 sqlSession = SessionUtils.getSesion(); 18 sqlSession.insert("insertCustomer", customer); 19 sqlSession.commit(); 20 } catch (Exception e) { 21 e.printStackTrace(); 22 sqlSession.rollback(); 23 } finally { 24 sqlSession.close(); 25 } 26 } 27 28 @Override 29 public void updateCustomer(Customer customer) { 30 SqlSession sqlSession = null; 31 try { 32 sqlSession = SessionUtils.getSesion(); 33 sqlSession.update("updateCustomer", customer); 34 sqlSession.commit(); 35 } catch (Exception e) { 36 e.printStackTrace(); 37 sqlSession.rollback(); 38 } finally { 39 sqlSession.close(); 40 } 41 42 } 43 44 @Override 45 public void deleteCustomer(Integer id) { 46 SqlSession sqlSession = null; 47 try { 48 sqlSession = SessionUtils.getSesion(); 49 sqlSession.delete("deleteCustomer", id); 50 sqlSession.commit(); 51 } catch (Exception e) { 52 e.printStackTrace(); 53 sqlSession.rollback(); 54 } finally { 55 sqlSession.close(); 56 } 57 58 } 59 60 @Override 61 public List<Customer> queryAllCustomer() { 62 SqlSession sqlSession = null; 63 try { 64 sqlSession = SessionUtils.getSesion(); 65 return sqlSession.selectList("queryAllCustomer"); 66 } catch (Exception e) { 67 e.printStackTrace(); 68 } finally { 69 sqlSession.close(); 70 } 71 return null; 72 } 73 74 @Override 75 public Customer queryCustomerById(Integer id) { 76 SqlSession sqlSession = null; 77 try { 78 sqlSession = SessionUtils.getSesion(); 79 return sqlSession.selectOne("queryCustomerById", id); 80 } catch (Exception e) { 81 e.printStackTrace(); 82 } finally { 83 sqlSession.close(); 84 } 85 return null; 86 } 87 88 @Override 89 public List<Customer> queryCustomerByName(String name) { 90 SqlSession sqlSession = null; 91 try { 92 sqlSession = SessionUtils.getSesion(); 93 return sqlSession.selectList("queryCustomerById", name); 94 } catch (Exception e) { 95 e.printStackTrace(); 96 } finally { 97 sqlSession.close(); 98 } 99 return null; 100 } 101 102 }
測試類：
package cn.sm1234.test; import java.util.List; import org.junit.Test; import cn.sm1234.dao.CustomerDao; import cn.sm1234.dao.impl.CustomerDaoImpl; import cn.sm1234.domain.Customer; public class Demo1 { @Test public void test1(){ Customer c = new Customer(); c.setName("陳六222"); c.setGender("男"); c.setTelephone("13244445555"); CustomerDao dao = new CustomerDaoImpl(); dao.saveCustomer(c); } @Test public void test2(){ Customer c = new Customer(); c.setId(1); c.setName("李四"); CustomerDao dao = new CustomerDaoImpl(); dao.updateCustomer(c); } @Test public void test3(){ CustomerDao dao = new CustomerDaoImpl(); dao.deleteCustomer(14); } @Test public void test4(){ CustomerDao dao = new CustomerDaoImpl(); List<Customer> list = dao.queryAllCustomer(); for (Customer customer : list) { System.out.println(customer); } } @Test public void test5(){ CustomerDao dao = new CustomerDaoImpl(); Customer customer = dao.queryCustomerById(1); System.out.println(customer); } @Test public void test6(){ CustomerDao dao = new CustomerDaoImpl(); List<Customer> list = dao.queryCustomerByName("%陳%"); for (Customer customer : list) { System.out.println(customer); } } }
Customer.xml：
1 <?xml version="1.0" encoding="UTF-8" ?> 2 <!DOCTYPE mapper 3 PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN" 4 "http://mybatis.org/dtd/mybatis-3-mapper.dtd"> 5 <!-- 該檔案存放CRUD的sql語句 --> 6 <mapper namespace="test"> 7 <!-- 新增 --> 8 <insert id="insertCustomer" parameterType="customer"> 9 INSERT INTO t_customer(NAME,gender,telephone) VALUES(#{name},#{gender},#{telephone}) 10 </insert> 11 12 <!-- 修改 --> 13 <!-- parameterType傳入物件，包含需要使用的值 --> 14 <update id="updateCustomer" parameterType="customer"> 15 UPDATE t_customer SET NAME = #{name} WHERE id = #{id} 16 </update> 17 18 <!-- 查詢所有資料 --> 19 <!-- 輸出對映 resultType --> 20 <!-- parameterType可以省略，resultType不可以省略 --> 21 <select id="queryAllCustomer" resultType="customer"> 22 SELECT * FROM t_customer 23 </select> 24 25 <!-- 根據id查詢 --> 26 <select id="queryCustomerById" parameterType="_int" resultType="customer"> 27 SELECT * FROM t_customer WHERE id=#{value} 28 </select> 29 30 <!-- 根據name模糊查詢 --> 31 <select id="queryCustomerByName" parameterType="string" resultType="customer"> 32 <!-- 方法一 --> 33 SELECT * FROM t_customer WHERE NAME LIKE #{value} 34 <!-- 方法二 --> 35 <!-- SELECT * FROM t_customer WHERE NAME LIKE '%${value}%' --> 36 </select> 37 38 <!-- 刪除 --> 39 <delete id="deleteCustomer" parameterType="int"> 40 DELETE FROM t_customer WHERE id=#{value} 41 </delete> 42 43 </mapper>
缺點：程式碼繁瑣。
解決方法：利用動態代理方式Dao介面開發。Dao層只需要介面，不需要重複的Dao層實現。
2.動態代理方式開發Dao層（推薦使用）
好處：無需再去編寫Dao層的實現類。
Dao介面：
1 package cn.sm1234.dao; 2 3 import java.util.List; 4 5 import cn.sm1234.domain.Customer; 6 7 public interface CustomerDao { 8 9 public void saveCustomer(Customer customer); 10 11 public void updateCustomer(Customer customer); 12 13 public void deleteCustomer(Integer id); 14 15 public List<Customer> queryAllCustomer(); 16 17 public Customer queryCustomerById(Integer id); 18 19 public List<Customer> queryCustomerByName(String name); 20 }
Customer.xml：
1 <?xml version="1.0" encoding="UTF-8" ?> 2 <!DOCTYPE mapper 3 PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN" 4 "http://mybatis.org/dtd/mybatis-3-mapper.dtd"> 5 <!-- 該檔案存放CRUD的sql語句 --> 6 <!-- 7 如果是動態代理方式 8 1）namespace必須和Dao介面的路徑保持一致 9 2）Dao接口裡面的方法和sql語句的id保持一致 10 3）Dao介面的方法的引數和返回值型別 和 對映檔案的parameterType和resultType要對應 11 --> 12 <mapper namespace="cn.sm1234.dao.CustomerDao"> 13 <!-- 新增 --> 14 <insert id="saveCustomer" parameterType="customer"> 15 INSERT INTO t_customer(NAME,gender,telephone) VALUES(#{name},#{gender},#{telephone}) 16 </insert> 17 18 <!-- 修改 --> 19 <!-- parameterType傳入物件，包含需要使用的值 --> 20 <update id="updateCustomer" parameterType="customer"> 21 UPDATE t_customer SET NAME = #{name} WHERE id = #{id} 22 </update> 23 24 <!-- 查詢所有資料 --> 25 <!-- 輸出對映 resultType --> 26 <!-- parameterType可以省略，resultType不可以省略 --> 27 <select id="queryAllCustomer" resultType="customer"> 28 SELECT * FROM t_customer 29 </select> 30 31 <!-- 根據id查詢 --> 32 <select id="queryCustomerById" parameterType="_int" resultType="customer"> 33 SELECT * FROM t_customer WHERE id=#{value} 34 </select> 35 36 <!-- 根據name模糊查詢 --> 37 <select id="queryCustomerByName" parameterType="string" resultType="customer"> 38 <!-- 方法一 --> 39 SELECT * FROM t_customer WHERE NAME LIKE #{value} 40 <!-- 方法二 --> 41 <!-- SELECT * FROM t_customer WHERE NAME LIKE '%${value}%' --> 42 </select> 43 44 <!-- 刪除 --> 45 <delete id="deleteCustomer" parameterType="int"> 46 DELETE FROM t_customer WHERE id=#{value} 47 </delete> 48 49 </mapper>
測試程式碼：
1 package cn.sm1234.test; 2 3 import java.util.List; 4 5 import org.apache.ibatis.session.SqlSession; 6 import org.junit.Test; 7 8 import cn.sm1234.dao.CustomerDao; 9 import cn.sm1234.domain.Customer; 10 import cn.sm1234.utils.SessionUtils; 11 12 public class Demo2 { 13 14 @Test 15 public void test1(){ 16 Customer c = new Customer(); 17 c.setName("陳六333"); 18 c.setGender("男"); 19 c.setTelephone("13244445555"); 20 21 SqlSession sqlSession = SessionUtils.getSession(); 22 //getMapper(): 返回指定介面的動態代理的實現類物件 23 CustomerDao dao = sqlSession.getMapper(CustomerDao.class); 24 dao.saveCustomer(c); 25 sqlSession.commit(); 26 sqlSession.close(); 27 } 28 29 @Test 30 public void test2(){ 31 Customer c = new Customer(); 32 c.setId(1); 33 c.setName("李四222"); 34 35 SqlSession sqlSession = SessionUtils.getSession(); 36 //getMapper(): 返回指定介面的動態代理的實現類物件 37 CustomerDao dao = sqlSession.getMapper(CustomerDao.class); 38 dao.updateCustomer(c); 39 sqlSession.commit(); 40 sqlSession.close(); 41 } 42 43 @Test 44 public void test3(){ 45 SqlSession sqlSession = SessionUtils.getSession(); 46 CustomerDao dao = sqlSession.getMapper(CustomerDao.class); 47 dao.deleteCustomer(19); 48 sqlSession.commit(); 49 sqlSession.close(); 50 } 51 52 @Test 53 public void test4(){ 54 SqlSession sqlSession = SessionUtils.getSession(); 55 CustomerDao dao = sqlSession.getMapper(CustomerDao.class); 56 List<Customer> list = dao.queryAllCustomer(); 57 for (Customer customer : list) { 58 System.out.println(customer); 59 } 60 } 61 62 @Test 63 public void test5(){ 64 SqlSession sqlSession = SessionUtils.getSession(); 65 CustomerDao dao = sqlSession.getMapper(CustomerDao.class); 66 Customer customer = dao.queryCustomerById(1); 67 System.out.println(customer); 68 } 69 70 @Test 71 public void test6(){ 72 SqlSession sqlSession = SessionUtils.getSession(); 73 CustomerDao dao = sqlSession.getMapper(CustomerDao.class); 74 List<Customer> list = dao.queryCustomerByName("%陳%"); 75 for (Customer customer : list) { 76 System.out.println(customer); 77 } 78 } 79 }
要點總結：
如果是動態代理方式
1）namespace必須和Dao介面的路徑保持一致
2）Dao接口裡面的方法和sql語句的id保持一致
3） Dao介面的方法的引數和返回值型別 和 對映檔案的parameterType和resultType要對應