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  • 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。

     1 <?xml version="1.0" encoding="UTF-8"?>
     2 <!DOCTYPE mapper
     3     PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN"
     4     "http://mybatis.org/dtd/mybatis-3-mapper.dtd">
     5 
     6 <mapper namespace="mybatis.pojo">
     7     <insert id="addCategory" parameterType="Category">
     8         insert into category ( name ) values (#{name})
     9     </insert>
    10 
    11     <delete id="deleteCategory" parameterType="Category">
    12         delete from category where id= #{id}
    13     </delete>
    14 
    15     <select id="getCategory" parameterType="_int" resultType="Category">
    16         select * from category where id= #{id}
    17     </select>
    18 
    19     <update id="updateCategory" parameterType="Category">
    20         update category set name=#{name} where id=#{id}
    21     </update>
    22     <select id="listCategory" resultType="Category">
    23         select * from category
    24     </select>
    25 </mapper>

    2.增加(C)

    向数据库中插入10条数据

     1     private void Myinset() throws IOException {
     2         create();
     3         for (int i = 0; i < 10; i++) {
     4             Category category = new Category();
     5             category.setName("xiaomi" + i);
     6             session.insert("addCategory", category);
     7         }
     8         listAll(session);
     9         close();
    10     }

    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

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

    3.删除(D)

    删除id=6的对象

    1     private void Mydelete() throws IOException {
    2         create();
    3         Category category = new Category();
    4         category.setId(6);
    5         session.delete("deleteCategory", category);
    6         listAll(session);
    7         close();
    8     }

    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。

    1 <delete id="deleteCategory" parameterType="Category">
    2         delete from category where id= #{id}
    3 </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。

    1     <update id="updateCategory" parameterType="Category">
    2         update category set name=#{name} where id=#{id}
    3     </update>
    1     private void Myupdate() throws IOException {
    2         create();
    3         Category category = session.selectOne("getCategory", 3);
    4         category.setName("修改了的Category名字");
    5         session.update("updateCategory", category);
    6         listAll(session);
    7 
    8     }

    5.查询(R)

    <1>查询所有

    1     private void Allquery() throws IOException {
    2         create();
    3         listAll(session);
    4         close();
    5     }

    对应的sql查询语句:

    1     <select id="listCategory" resultType="Category">
    2         select * from category
    3     </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:

    1     <select id="getCategory" parameterType="_int" resultType="Category">
    2         select * from category where id= #{id}
    3     </select>
    1     private void Myquery() throws IOException {
    2         create();
    3         Category category = session.selectOne("getCategory", 3);
    4         System.out.println(category.getName());
    5         close();
    6     }

    testCRUD.java

     

     1 package mybatis.test;
     2 
     3 import java.io.IOException;
     4 import java.io.InputStream;
     5 import java.util.List;
     6 
     7 import org.apache.ibatis.session.SqlSession;
     8 import org.apache.ibatis.session.SqlSessionFactory;
     9 import org.apache.ibatis.session.SqlSessionFactoryBuilder;
    10 
    11 import mybatis.pojo.Category;
    12 
    13 public class testCRUD {
    14 
    15     private SqlSession session;
    16     private InputStream inputStream;
    17     private SqlSessionFactory sqlSessionFactory;
    18 
    19     public testCRUD() throws IOException {
    20         // TODO Auto-generated constructor stub
    21         String resource = "mybatis-config.xml";
    22         this.inputStream = org.apache.ibatis.io.Resources.getResourceAsStream(resource);
    23         this.sqlSessionFactory = new SqlSessionFactoryBuilder().build(this.inputStream);
    24     }
    25 
    26     public void create() throws IOException {
    27         session = sqlSessionFactory.openSession();
    28     }
    29 
    30     public void close() {
    31         session.commit();
    32         session.close();
    33     }
    34 
    35     // 1.增加
    36     private void Myinset() throws IOException {
    37         create();
    38         for (int i = 0; i < 10; i++) {
    39             Category category = new Category();
    40             category.setName("xiaomi" + i);
    41             session.insert("addCategory", category);
    42         }
    43         listAll(session);
    44         close();
    45     }
    46 
    47     // 2.删除
    48     private void Mydelete() throws IOException {
    49         create();
    50         Category category = new Category();
    51         category.setId(6);
    52         session.delete("deleteCategory", category);
    53         listAll(session);
    54         close();
    55     }
    56 
    57     // 3.查询
    58     private void Myquery() throws IOException {
    59         create();
    60         Category category = session.selectOne("getCategory", 3);
    61         System.out.println(category.getName());
    62         close();
    63     }
    64 
    65     // 4.更新
    66     private void Myupdate() throws IOException {
    67         create();
    68         Category category = session.selectOne("getCategory", 3);
    69         category.setName("修改了的Category名字");
    70         session.update("updateCategory", category);
    71         listAll(session);
    72 
    73     }
    74 
    75     // 5.查询所有
    76     private void Allquery() throws IOException {
    77         create();
    78         listAll(session);
    79         close();
    80     }
    81 
    82     // 列出所有的对象名字
    83     private void listAll(SqlSession session) {
    84         List<Category> cs = session.selectList("listCategory");
    85         for (Category c : cs) {
    86             System.out.println(c.getName());
    87         }
    88     }
    89 
    90     public static void main(String[] args) throws IOException {
    91         testCRUD testCRUD = new testCRUD();
    92         // testCRUD.Myinset();
    93         // testCRUD.Mydelete();
    94         // testCRUD.Myquery();
    95         testCRUD.Myupdate();
    96         // testCRUD.Allquery();
    97     }
    98 }
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  • 原文地址:https://www.cnblogs.com/lyj-gyq/p/9229327.html
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