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();
    }
}