Mybatis实现部门表增删改查以及排序

废话不说,直接开门见山!

需要在WebContent下的lib下导入两个包

mybatis-3.2.5.jar

ojdbc6.jar

 package com.xdl.entity;

 import java.io.Serializable;

 public class Dept implements Serializable{
     private Integer deptno;//类型和名称与表保持一致
     private String dname;
     private String loc;

     public Integer getDeptno() {
         return deptno;
     }
     public void setDeptno(Integer deptno) {
         this.deptno = deptno;
     }
     public String getDname() {
         return dname;
     }
     public void setDname(String dname) {
         this.dname = dname;
     }
     public String getLoc() {
         return loc;
     }
     public void setLoc(String loc) {
         this.loc = loc;
     }

 }

Dept

 package com.xdl.Mapper;

 import java.util.List;

 import org.apache.ibatis.annotations.Param;

 import com.xdl.entity.Dept;

 public interface DeptMapper {
     /**
      * 查询所有
      *
      */
     public List<Dept> findAll();

     /**
      * 通过id查询
      *
      */
     public Dept findById(int no);

     /**
      * 插入
      *
      */
     public int save(Dept dept);

     /**
      * 修改
      *
      */
     public int update(Dept dept);

     /**
      * 通过id删除
      *
      */
     public int delete(int no);

     /**
      * 排序
      *
      */
     public List<Dept> findAllOrder(@Param("n") String no);
 }

DeptMapper

 <?xml version="1.0" encoding="UTF-8" ?>
 <!DOCTYPE mapper PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN"
 "http://mybatis.org/dtd/mybatis-3-mapper.dtd">
 <mapper namespace="com.xdl.Mapper.DeptMapper">
     <select id="findAll" resultType="com.xdl.entity.Dept">
         select * from dept
     </select>
     <select id="findById" parameterType="int" resultType="com.xdl.entity.Dept">
         select *
         from dept where deptno = #{no}
     </select>
     <select id="findAllOrder" parameterType="String" resultType="com.xdl.entity.Dept">
         select * from dept order by ${n}
     </select>
     <insert id="save" parameterType="com.xdl.entity.Dept">
         insert into dept
         (deptno,dname,loc) values (dept_seq.nextval,#{dname},#{loc})
     </insert>
     <update id="update">
         update dept set dname = #{dname},loc = #{loc} where
         deptno = #{deptno}
     </update>
     <delete id="delete">
         delete from dept where deptno = #{no}
     </delete>
 </mapper>

deptmapper.xml

 <?xml version="1.0" encoding="UTF-8" ?>
 <!DOCTYPE configuration PUBLIC "-//mybatis.org//DTD Config 3.0//EN"
 "http://mybatis.org/dtd/mybatis-3-config.dtd">
 <configuration>
     <!-- 将底层日志打印 -->
     <settings>
         <setting name="logImpl" value="STDOUT_LOGGING" />
     </settings>
     <environments default="environment">
         <environment id="environment">
             <transactionManager type="JDBC" />
             <!-- 指定数据库连 -->
             <dataSource type="POOLED">
                 <property name="driver" value="oracle.jdbc.OracleDriver" />
                 <property name="url" value="jdbc:oracle:thin:@localhost:1521:XE" />
                 <property name="username" value="SCOTT" />
                 <property name="password" value="tiger" />
             </dataSource>
         </environment>
     </environments>
     <!-- 指定SQL定义文件 -->
     <mappers>
         <mapper resource="com/xdl/sql/DeptMapper.xml" />
     </mappers>
 </configuration> 

sqlmap-config.xml

 package com.xdl.test;

 import java.io.Reader;

 import org.apache.ibatis.io.Resources;
 import org.apache.ibatis.session.SqlSession;
 import org.apache.ibatis.session.SqlSessionFactory;
 import org.apache.ibatis.session.SqlSessionFactoryBuilder;

 public class MyBatisUtil {
     static SqlSessionFactory factory;
     static {
         try {
             String conf = "sqlmap-config.xml"; // 定义配置文件
             SqlSessionFactoryBuilder builder = new SqlSessionFactoryBuilder();
             Reader reader = Resources.getResourceAsReader(conf);
             factory = builder.build(reader);
         } catch (Exception e) {
             e.printStackTrace();
         }
     }

     public static SqlSession getSession() {
         SqlSession sqlSession = factory.openSession();
         return sqlSession;
     }
 }

MybatisUtli

写一个测试类(实现查询和排序)

 package com.xdl.test;

 import java.util.List;

 import org.apache.ibatis.session.SqlSession;
 import org.junit.Test;

 import com.xdl.Mapper.DeptMapper;
 import com.xdl.entity.Dept;

 public class TestDeptMapper {
     /**
      * 查询所有
      */
     @Test
     public void testFindAll() {
         SqlSession sqlSession = MyBatisUtil.getSession();
         // sqlSession.getMapper(接口.class); 根据DeptMapper映射器接口动态生成实现对象
         DeptMapper deptDao = sqlSession.getMapper(DeptMapper.class);
         System.out.println(deptDao.getClass().getName());
         List<Dept> list = deptDao.findAll();
         for (Dept dept : list) {
             System.out.println(dept.getDeptno() + ":" + dept.getDname() + ":" + dept.getLoc());
         }
         sqlSession.close();
     }

     /**
      * 进行排序
      */
     @Test
     public void testOrderBy() {
         SqlSession sqlSession = MyBatisUtil.getSession();
         // sqlSession.getMapper(接口.class); 根据DeptMapper映射器接口动态生成实现对象
         DeptMapper deptDao = sqlSession.getMapper(DeptMapper.class);
         System.out.println(deptDao.getClass().getName());
         List<Dept> list = deptDao.findAllOrder("deptno");
         for (Dept dept : list) {
             System.out.println(dept.getDeptno() + ":" + dept.getDname() + ":" + dept.getLoc());
         }
         sqlSession.close();
     }
 }

TestDeptMapper

写一个测试类(实现增删改查排序)

 package com.xdl.test;

 import java.util.List;

 import org.apache.ibatis.session.SqlSession;
 import org.junit.Test;

 import com.xdl.entity.Dept;

 public class TestDept {
     private static SqlSession sqlSession = MyBatisUtil.getSession();

     /**
      * 查询所有
      */
     @Test
     public void testFindAll() {
         // 使用sqlSession操作SQL selectList("id",parameterType值)
         List<Dept> list = sqlSession.selectList("com.xdl.Mapper.DeptMapper.findAll");
         for (Dept dept : list) {
             System.out.println(dept.getDeptno() + ":" + dept.getDname() + ":" + dept.getLoc());
         }
         sqlSession.close();
     }

     /**
      * 根据ID查询
      */
     @Test
     public void testFindById() {
         Dept dept = sqlSession.selectOne("com.xdl.Mapper.DeptMapper.findById", 10);
         if (dept != null) {
             System.out.println(dept.getDeptno() + ":" + dept.getDname() + ":" + dept.getLoc());
         } else {
             System.out.println("查询结果为空~~");
         }
         sqlSession.close();
     }

     /**
      * 插入
      */
     @Test
     public void testSave() {
         Dept dept = new Dept();
         dept.setDname("xian");
         dept.setLoc("dayanta");
         int rows = sqlSession.insert("com.xdl.Mapper.DeptMapper.save", dept);
         String str = "条记录插入成功";
         System.out.println(rows + str);
         sqlSession.commit();
         sqlSession.close();
     }

     /**
      * 修改
      */
     @Test
     public void testUpdate() {
         Dept dept = new Dept();
         dept.setDeptno(10);
         dept.setDname("spring");
         dept.setLoc("bj");
         int rows = sqlSession.update("com.xdl.Mapper.DeptMapper.update", dept);
         String str = "条记录修改成功";
         System.out.println(rows + str);
         sqlSession.commit();
         sqlSession.close();
     }

     /**
      * 通过id删除
      */
     @Test
     public void testDelete() {
         Dept dept = new Dept();
         int rows = sqlSession.delete("com.xdl.Mapper.DeptMapper.delete", 1);
         String str = "条记录删除成功";
         System.out.println(rows + str);
         sqlSession.commit();
         sqlSession.close();
     }
 }

TestDept

1.在MyBatis中定义SQL语句时,如果SQL里有?号,就必须写parameterType=””参数是int就写对应的类型并且名字可以自定义

2. 在查询的时候最后会返回一个结果集对象,所以就必须在后面继续追加resultType=”包名.实体类名”

3 在执行DML的时候里面要执行多个参数的时候,可以选择集合或者对象,

parameterType=”包名.实体类名”.参数,类型和实体类要一致,参数不一致,可以通过给sql起别名解决,类型不一致就需要对框架里的部分参数进行转换

4 通过实现增删改查,发现DQL有resultType属性,DML都没有resultType属性              数据访问层(Dao)

5 mapper.xml映射器里的<mapper namespace=”包名.接口名”,才可以 达到Mapper.xml里的数据库代码映射到接口中

总结为:

a. Mapper接口中方法名和sql定义id值保持一致

b. Mapper接口中方法参数类型和sql定义中parameterType类型保持一致

c. Mapper接口中方法返回类型,多行查询返回List,单行查询返回对象类型和resultType保持一致DML返回类型为int或void

Mapper映射器规则

1 Mapper接口中方法名与SQL定义id值保持一致

2 Mapper接口中方法参数类型与SQL定义中parameterType类型保持一致

3 Mapper接口中方法返回类型，多行查询返回List、单行返回对象，类型与resultType保 持一致;增删改操作返回类型为int或void

4 SQL定义文件namespace需要指定为"包名.接口名"

参数映射中${}和#{}的区别

1 #{}参数映射机制采用的是PrepareStatement，将SQL和参数分开发送

2 ${}参数映射机制采用Statement，将SQL和参数拼一起发送执行

3 建议采用#{}方式，更安全

4 ${}适合用在字段名或表名位置；#{}适合用在字段值位置