MyBatis學習筆記之註解式
阿新 • • 發佈：2019-02-20
1. 瞭解什麼是MyBatis：
用百度的話來說，MyBatis 是一款優秀的持久層框架，它支援定製化 SQL、儲存過程以及高階對映。MyBatis 避免了幾乎所有的 JDBC 程式碼和手動設定引數以及獲取結果集。MyBatis 可以使用簡單的 XML 或註解來配置和對映原生資訊，將介面和 Java 的 POJOs(Plain Ordinary Java Object,普通的 Java物件)對映成資料庫中的記錄。
簡而言之，MyBatis是支援普通SQL查詢，儲存過程和高階對映的優秀持久層框架，MyBatis提供的是一種“半自動化”的ORM實現
2.簡單例子：
在這裡我們用的是 IDEA開發工具，首先我們新建一個Maven專案
然後在pom.xml匯入jar包：
mybatis需要jar包：mybatis-3.3.0.jar
mysql驅動jar包：mysql-connector-java-5.1.44.-bin.jar
日誌記錄jar包：log4j-1.2.17.jar
配置MyBatis對映檔案mybatis.cfg.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> <!--配置LOG4J--> <settings> <setting name="logImpl" value="LOG4J"/> </settings> <!--批量別名定義--> <typeAliases> <package name="com.zking.pojo"></package> </typeAliases> <!--jdbc資料庫連線池--> <environments default="development"> <environment id="development"> <transactionManager type="JDBC"/> <dataSource type="POOLED"> <property name="driver" value="com.mysql.jdbc.Driver"/> <property name="url" value="jdbc:mysql://localhost:3306/test"/> <property name="username" value="root"/> <property name="password" value="sasa"/> </dataSource> </environment> </environments> <!--配置對映檔案--> <mappers> <mapper class="com.zking.mapper.IProvinceMapper"/> <mapper class="com.zking.mapper.ICityMapper"/> </mappers> </configuration>
實體類：
City：
package com.zking.pojo; import java.io.Serializable; public class City extends Province implements Serializable{ private String cid; private String cname; private String pid; //設定1對M關係 private Province province; public City() { } public City(String cid, String cname, String pid) { this.cid = cid; this.cname = cname; this.pid = pid; } public String getCid() { return cid; } public void setCid(String cid) { this.cid = cid; } public String getCname() { return cname; } public void setCname(String cname) { this.cname = cname; } public String getPid() { return pid; } public void setPid(String pid) { this.pid = pid; } public Province getProvince() { return province; } public void setProvince(Province province) { this.province = province; } }
Province：
package com.zking.pojo;
import java.io.Serializable;
import java.util.Set;
public class Province implements Serializable{
private String pid;
private String pname;
//設定關係 1V1
private City city;
//1VM
private Set<City> sc;
public Province() {
}
public Province(String pid, String pname) {
this.pid = pid;
this.pname = pname;
}
public String getPid() {
return pid;
}
public void setPid(String pid) {
this.pid = pid;
}
public String getPname() {
return pname;
}
public void setPname(String pname) {
this.pname = pname;
}
public City getCity() {
return city;
}
public void setCity(City city) {
this.city = city;
}
public Set<City> getSc() {
return sc;
}
public void setSc(Set<City> sc) {
this.sc = sc;
}
}
建立方法介面：
package com.zking.mapper;
import com.zking.pojo.City;
import org.apache.ibatis.annotations.Delete;
import org.apache.ibatis.annotations.Insert;
import org.apache.ibatis.annotations.Select;
import org.apache.ibatis.annotations.Update;
import java.util.List;
public interface ICityMapper {
@Insert("insert into City values(#{cid},#{cname},#{pid})")
public int addCity(City city);
@Update("UPDATE City SET cname=#{cname},pid=#{pid} where cid=#{cid}")
public int editCity(City city);
@Delete("delete from City where cid=#{cid}")
public int removeCity(City city);
@Select("select * from City where pid=#{pid}")
public List<City> finfCityAll();
}
package com.zking.mapper;
import com.zking.pojo.City;
import com.zking.pojo.Province;
import org.apache.ibatis.annotations.*;
import java.util.List;
public interface IProvinceMapper {
@Insert("INSERT INTO Province VALUES(#{pid},#{pname})")
public int addProvince(Province province);
@Update("UPDATE Province SET pname=#{pname} where pid=#{pid}")
public int editProvince(Province province);
//1V1關係註解
@Select("select * from Province")
@Results({
@Result(id = true,column = "pid",property = "pid"),
@Result(column = "pname",property = "pname"),
@Result(property = "city",column = "pid",
one=@One(select = "com.zking.mapper.ICityMapper.finfCityAll"))
})
public List<Province> findProvinceAll();
//多對多關係註解
@Select("select * from Province")
@Results({
@Result(id = true,column = "pid",property = "pid"),
@Result(column = "pname",property = "pname"),
@Result(property = "sc",column = "pid",
many=@Many(select = "com.zking.mapper.ICityMapper.finfCityAll"))
})
public List<Province> findProvinceAll2();
//動態SQL註解 作用在介面的方法上
@SelectProvider(type = ProvinceSqlBuilder.class,method = "findProvinceSql")
public List<Province> findProvinceAll3();
@SelectProvider(type = ProvinceSqlBuilder.class,method = "findProvinceByQuery")
public List<Province> findProvinceAll4(Province province);
@SelectProvider(type = ProvinceSqlBuilder.class,method = "findProvinceAll")
public List<City> findProvinceAll5();
}
在MyBatis的對映配置檔案中寫sql語句有時候很方便，但是對於有大量欄位的表結構卻不太簡單，幸好MyBatis提供的有SqlBuilder工具類，可以生成相應的SQL語句，如下：
package com.zking.mapper;
import com.zking.pojo.Province;
import org.apache.ibatis.jdbc.SQL;
public class ProvinceSqlBuilder {
public String findProvinceSql(){
return new SQL()
.SELECT("*")
.FROM("Province")
.toString();
}
public String findProvinceByQuery(final Province province){
return new SQL(){{
SELECT("*");
FROM("Province");
if(province.getPname()!=null){
AND();
WHERE("pname like #{pname}");
}
}}.toString();
}
public String findProvinceAll(){
return new SQL(){{
SELECT("*");
FROM("Province p");
LEFT_OUTER_JOIN(" City c on p.pid=c.pid");
}}.toString();
}
}
測試類：
package com.zking.test;
import com.zking.mapper.ICityMapper;
import com.zking.mapper.IProvinceMapper;
import com.zking.pojo.City;
import com.zking.pojo.Province;
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.junit.Test;
import java.util.List;
import java.util.UUID;
public class MyBatis04Test {
@Test
public void addProvince() throws Exception{
SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(Resources.getResourceAsStream("mybatis-config.xml"));
SqlSession sqlSession = sqlSessionFactory.openSession();
IProvinceMapper ipm = sqlSession.getMapper(IProvinceMapper.class);
Province p=new Province();
p.setPid(String.valueOf(UUID.randomUUID()));
p.setPname("湖北");
ipm.addProvince(p);
sqlSession.commit();
sqlSession.close();
}
@Test
public void editProvince() throws Exception{
SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(Resources.getResourceAsStream("mybatis-config.xml"));
SqlSession sqlSession = sqlSessionFactory.openSession();
IProvinceMapper ipm = sqlSession.getMapper(IProvinceMapper.class);
Province p=new Province();
p.setPid("044ff20a-9da1-4205-a75a-991b6bfb413f");
p.setPname("湖北");
ipm.editProvince(p);
sqlSession.commit();
sqlSession.close();
}
@Test
public void addCity() throws Exception{
SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(Resources.getResourceAsStream("mybatis-config.xml"));
SqlSession sqlSession = sqlSessionFactory.openSession();
ICityMapper icm = sqlSession.getMapper(ICityMapper.class);
City c=new City();
c.setCid(String.valueOf(UUID.randomUUID()));
c.setCname("株洲");
c.setPid("5894c3bf-f89c-4dca-810c-64c5c25da742");
icm.addCity(c);
sqlSession.commit();
sqlSession.close();
}
@Test
public void editCity() throws Exception{
SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(Resources.getResourceAsStream("mybatis-config.xml"));
SqlSession sqlSession = sqlSessionFactory.openSession();
ICityMapper icm = sqlSession.getMapper(ICityMapper.class);
City c=new City();
c.setCid("441c77ef-80aa-4327-9fd7-e1f08c92292b");
c.setCname("長沙");
c.setPid("5894c3bf-f89c-4dca-810c-64c5c25da742");
icm.editCity(c);
sqlSession.commit();
sqlSession.close();
}
@Test
public void removeCity() throws Exception{
SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(Resources.getResourceAsStream("mybatis-config.xml"));
SqlSession sqlSession = sqlSessionFactory.openSession();
ICityMapper icm = sqlSession.getMapper(ICityMapper.class);
City c=new City();
c.setCid("521b672e-0109-432b-ae92-cc75323ea3fc");
icm.removeCity(c);
sqlSession.commit();
sqlSession.close();
}
@Test
public void findProvinceAll() throws Exception{
SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(Resources.getResourceAsStream("mybatis-config.xml"));
SqlSession sqlSession = sqlSessionFactory.openSession();
IProvinceMapper ipm = sqlSession.getMapper(IProvinceMapper.class);
ipm.findProvinceAll();
sqlSession.commit();
sqlSession.close();
}
@Test
public void findProvinceAll2() throws Exception{
SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(Resources.getResourceAsStream("mybatis-config.xml"));
SqlSession sqlSession = sqlSessionFactory.openSession();
IProvinceMapper ipm = sqlSession.getMapper(IProvinceMapper.class);
ipm.findProvinceAll2();
sqlSession.commit();
sqlSession.close();
}
@Test
public void findProvinceAll3() throws Exception{
SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(Resources.getResourceAsStream("mybatis-config.xml"));
SqlSession sqlSession = sqlSessionFactory.openSession();
IProvinceMapper ipm = sqlSession.getMapper(IProvinceMapper.class);
ipm.findProvinceAll3();
sqlSession.commit();
sqlSession.close();
}
@Test
public void findProvinceAll4() throws Exception{
SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(Resources.getResourceAsStream("mybatis-config.xml"));
SqlSession sqlSession = sqlSessionFactory.openSession();
IProvinceMapper ipm = sqlSession.getMapper(IProvinceMapper.class);
Province province=new Province();
province.setPname("%南%");
ipm.findProvinceAll4(province);
sqlSession.commit();
sqlSession.close();
}
@Test
public void findProvinceAll5() throws Exception{
SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(Resources.getResourceAsStream("mybatis-config.xml"));
SqlSession sqlSession = sqlSessionFactory.openSession();
IProvinceMapper ipm = sqlSession.getMapper(IProvinceMapper.class);
List<City> list = ipm.findProvinceAll5();
for (City c : list) {
System.out.println(c.getPname()+"---"+c.getCname());
}
sqlSession.commit();
sqlSession.close();
}
}
其實MyBatis的註解式如果說是單一的Crud可能比較簡便，但是在動態SQL部分就比較麻煩，所以更建議使用配置式。