笔记51 Mybatis快速入门（二）

Mybatis的CRUD

1.修改配置文件Category.xml，提供CRUD对应的sql语句。

 <?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="mybatis.pojo">
     <insert id="addCategory" parameterType="Category">
         insert into category ( name ) values (#{name})
     </insert>

     <delete id="deleteCategory" parameterType="Category">
         delete from category where id= #{id}
     </delete>

     <select id="getCategory" parameterType="_int" resultType="Category">
         select * from category where id= #{id}
     </select>

     <update id="updateCategory" parameterType="Category">
         update category set name=#{name} where id=#{id}
     </update>
     <select id="listCategory" resultType="Category">
         select * from category
     </select>
 </mapper>

2.增加（C）

向数据库中插入10条数据

     private void Myinset() throws IOException {
         create();
         for (int i = 0; i < 10; i++) {
             Category category = new Category();
             category.setName("xiaomi" + i);
             session.insert("addCategory", category);
         }
         listAll(session);
         close();
     }

通过session.insert调用addCategory对应的SQL语句，addCategory对应的插入sql语句，#{name}会自动获取category对象的name属性值

 <insert id="addCategory" parameterType="Category">
         insert into category ( name ) values (#{name})
 </insert>

3.删除（D）

删除id=6的对象

     private void Mydelete() throws IOException {
         create();
         Category category = new Category();
         category.setId(6);
         session.delete("deleteCategory", category);
         listAll(session);
         close();
     }

通过session.delete调用deleteCategory对应的SQL语句，deleteCategory对应删除sql语句，#{id}会获取category对象的id。

 <delete id="deleteCategory" parameterType="Category">
         delete from category where id= #{id}
 </delete>

4.更新（U）

通过session.update进行修改。updateCategory对应的sql语句，#{name}和#{id}获取category对象的name和id。

     <update id="updateCategory" parameterType="Category">
         update category set name=#{name} where id=#{id}
     </update>

     private void Myupdate() throws IOException {
         create();
         Category category = session.selectOne("getCategory", 3);
         category.setName("修改了的Category名字");
         session.update("updateCategory", category);
         listAll(session);

     }

5.查询（R）

<1>查询所有

     private void Allquery() throws IOException {
         create();
         listAll(session);
         close();
     }

对应的sql查询语句：

     <select id="listCategory" resultType="Category">
         select * from category
     </select>

<2>根据id查询

通过session.selectOne获取id=3的记录，Category category= session.selectOne("getCategory",3)，getCategory对应的sql语句：

     <select id="getCategory" parameterType="_int" resultType="Category">
         select * from category where id= #{id}
     </select>

     private void Myquery() throws IOException {
         create();
         Category category = session.selectOne("getCategory", 3);
         System.out.println(category.getName());
         close();
     }

testCRUD.java

 package mybatis.test;

 import java.io.IOException;
 import java.io.InputStream;
 import java.util.List;

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

 import mybatis.pojo.Category;

 public class testCRUD {

     private SqlSession session;
     private InputStream inputStream;
     private SqlSessionFactory sqlSessionFactory;

     public testCRUD() throws IOException {
         // TODO Auto-generated constructor stub
         String resource = "mybatis-config.xml";
         this.inputStream = org.apache.ibatis.io.Resources.getResourceAsStream(resource);
         this.sqlSessionFactory = new SqlSessionFactoryBuilder().build(this.inputStream);
     }

     public void create() throws IOException {
         session = sqlSessionFactory.openSession();
     }

     public void close() {
         session.commit();
         session.close();
     }

     // 1.增加
     private void Myinset() throws IOException {
         create();
         for (int i = 0; i < 10; i++) {
             Category category = new Category();
             category.setName("xiaomi" + i);
             session.insert("addCategory", category);
         }
         listAll(session);
         close();
     }

     // 2.删除
     private void Mydelete() throws IOException {
         create();
         Category category = new Category();
         category.setId(6);
         session.delete("deleteCategory", category);
         listAll(session);
         close();
     }

     // 3.查询
     private void Myquery() throws IOException {
         create();
         Category category = session.selectOne("getCategory", 3);
         System.out.println(category.getName());
         close();
     }

     // 4.更新
     private void Myupdate() throws IOException {
         create();
         Category category = session.selectOne("getCategory", 3);
         category.setName("修改了的Category名字");
         session.update("updateCategory", category);
         listAll(session);

     }

     // 5.查询所有
     private void Allquery() throws IOException {
         create();
         listAll(session);
         close();
     }

     // 列出所有的对象名字
     private void listAll(SqlSession session) {
         List<Category> cs = session.selectList("listCategory");
         for (Category c : cs) {
             System.out.println(c.getName());
         }
     }

     public static void main(String[] args) throws IOException {
         testCRUD testCRUD = new testCRUD();
         // testCRUD.Myinset();
         // testCRUD.Mydelete();
         // testCRUD.Myquery();
         testCRUD.Myupdate();
         // testCRUD.Allquery();
     }
 }