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