MyBatis增删改查操作Demo

客官°小女子只卖身不卖艺 2022-05-13 12:20 399阅读 0赞
  • 第一步：导包：mybatis及jdbc connector.jar
  • 第二步：编写数据库总配置文件SqlMapConfig.xml（引入如下.dtd约束文件）
    “http://ibatis.apache.org/dtd/ibatis-3-config.dtd“>
  • 第三步：配置表和类的映射文件，实体类名.xml（在里面写sql语句）
  • 第四步：创建数据库会话session，进行增删改查

文件目录
这里写图片描述

SqlMapConfig.xml

  1. <?xml version="1.0" encoding="UTF-8"?>
  2. <!DOCTYPE configuration PUBLIC "-//ibatis.apache.org//DTD SQL Map Config 3.0//EN" "http://ibatis.apache.org/dtd/ibatis-3-config.dtd">
  3. <configuration>
  4. <!-- 可以给实体类取别名，这个放在前面，放在后面会出错 -->
  5.     <typeAliases>
  6.         <typeAlias type="com.test.entity.Student" alias="Student"/>
  7.     </typeAliases>
  8.     <!-- step1:配环境 -->
  9.     <environments default="e1">
  10.         <environment id="e1">
  11.             <!-- 先配事务，事务是必须配的，简单的事务类型JDBC -->
  12.             <transactionManager type="JDBC"></transactionManager>
  13.             <!-- 再配数据源，POOLED 以连接池的方式 -->
  14.             <dataSource type="POOLED">
  15.                 <!-- 在数据源中配置连接属性,注意这里是username不是user -->    
  16.                 <property name="driver" value="com.mysql.jdbc.Driver"/> 
  17.                 <property name="url" value="jdbc:mysql://localhost:3306/test"/> 
  18.                 <property name="username" value="root"/>
  19.                 <property name="password" value="root1205"/>
  20.             </dataSource>
  21.         </environment>  
  22.     </environments>
  23.     <!-- step2:引入实体类的映射配置文件 -->
  24.     <mappers>
  25.         <mapper resource="com/test/entity/Student.xml"/>
  26.     </mappers>      
  27. </configuration>

Student.xml

  1. <?xml version="1.0" encoding="UTF-8"?>
  2. <!DOCTYPE mapper PUBLIC "-//ibatis.apache.org//DTD SQL Map 3.0//EN" "http://ibatis.apache.org/dtd/ibatis-3-mapper.dtd">
  3. <!-- 命名空间必须要加上，解决sql语句id重复 -->
  4. <mapper namespace="ns1">
  5. <!-- 插入数据 -->
  6.     <!-- 写死的 -->
  7.     <insert id="save">
  8.     insert into student(name,age)values('一茶',18)    
  9.     </insert>
  10.     <!-- 使用占位符，不是问号了，其中id，name指的是session的insert方法所传对象参数的属性 -->
  11.     <insert id="save2">
  12.     insert into student(name,age)values(#{name},#{age})
  13.     </insert>
  14.     <insert id="save3">
  15.     insert into student(name,age)values(#{name},#{age});
  16.     </insert>
  17. <!-- 修改数据 -->
  18.     <update id="mod1">
  19.     update student set name='王五',age='10' where id=1
  20.     </update>
  21.     <update id="mod2">
  22.     update student set name=#{name},age=#{age} where id=1
  23.     </update>
  24. <!-- 删除数据 -->
  25.     <delete id="del1">
  26.     delete from student where id=1
  27.     </delete>
  28.     <delete id="del2">
  29.     delete from student where name=#{name} and age=#{age}
  30.     </delete>
  31. <!-- 查询数据 -->
  32.     <!-- ExecutorException:excIt's likely that neither a Result Type nor a Result Map was specified. -->
  33.     <!-- 默认会自动映射，所以resultMap可以不配，如果要自定义映射要配置resultMap -->
  34.     <!-- 可以给com.test.entity.Student配别名，在SqlMapConfig里配typeAliases -->
  35.     <!-- <select id="query1" resultType="com.test.entity.Student"> -->
  36.     <select id="query1" resultType="Student">
  37.     select * from student where id=2    
  38.     </select>
  39.     <select id="query2" resultType="Student">
  40.     select * from student where name=#{name}
  41.     </select>
  42.     <select id="query3" resultType="Student" parameterType="java.lang.String">
  43.     select * from student where name=#{_parameter}
  44.     </select>
  45.     <select id="query4" resultType="Student" parameterType="int">
  46.     select * from student where id=#{_parameter}
  47.     </select>
  48.     <!-- 默认是自动映射，还可以自定义映射，要配置resultMap -->
  49.     <resultMap type="Student" id="myMap">
  50.         <!-- 虽然我只映射了一个表字段，但剩下的字段会按默认情况映射 -->
  51.         <result property="name" column="name2"/>
  52.     </resultMap>
  53.     <select id="query5" resultType="Student" resultMap="myMap">
  54.     select name as name2,age,school from student where id=#{_parameter}
  55.     </select>
  56.     <select id="query6" resultType="Student">
  57.     select * from student where 1=1
  58.     </select>
  59.     <select id="query7" resultType="Student" parameterType="java.lang.String">
  60.     select * from student where name=#{_parameter}
  61.     </select>
  62.     <select id="query8" resultType="Student">
  63.     select * from student where 1=1
  64.     </select>
  65.     <select id="query9" resultType="Student" parameterType="java.lang.String">
  66.     select * from student where name=#{_parameter}
  67.     </select>   
  68. </mapper>

TestDemo.java

  1. package com.test.test;
  3. import java.io.IOException;
  4. import java.io.Reader;
  5. import java.util.HashMap;
  6. import java.util.Iterator;
  7. import java.util.List;
  8. import java.util.Map;
  9. import java.util.Set;
  11. import org.apache.ibatis.io.Resources;
  12. import org.apache.ibatis.session.SqlSession;
  13. import org.apache.ibatis.session.SqlSessionFactory;
  14. import org.apache.ibatis.session.SqlSessionFactoryBuilder;
  16. import com.test.entity.Student;
  18. public class TestDemo {
  20.     /** * @param args * @throws IOException */
  21.     public static void main(String[] args) throws IOException {
  22.         // 测试能否连接数据库，并插入数据
  23.         //第一步：和数据库连接（获取与数据库会话对象）
  24.         SqlSession session = null;
  25.         SqlSessionFactory sessionFactory = null;
  26.         SqlSessionFactoryBuilder factoryBuilder = new SqlSessionFactoryBuilder();
  27.         Reader reader = Resources.getResourceAsReader("SqlMapConfig.xml");
  28.         sessionFactory = factoryBuilder.build(reader);
  29.         session = sessionFactory.openSession();
  30.         //System.out.println(session);//测试是否连接成功
  32.         //第二步：和数据库交互
  33.         //op1:插入数据
  34.         //session.insert("ns1.save");
  35.         //Map map = new HashMap();
  36.         //map.put("name", "zhangsan");
  37.         //map.put("age", "18");//此处的18虽然是字符串，但是也按int插入到age字段里了
  38.         //session.insert("ns1.save2",map);
  39.         //Student stu = new Student();
  40.         //stu.setAge(20);
  41.         //stu.setName("lisi");
  42.         //session.insert("ns1.save3", stu);
  44.         //op2:修改数据
  45.         //session.update("ns1.mod1");
  46.         //Student stu2 = new Student();
  47.         //stu2.setAge(20);
  48.         //stu2.setName("lisi2");
  49.         //session.update("ns1.mod2", stu2);
  51.         //op3:删除数据
  52.         //session.delete("ns1.del1");
  53.         //Student stu3 = new Student();
  54.         //stu3.setAge(20);
  55.         //stu3.setName("lisi");
  56.         //session.delete("ns1.del2",stu3);
  58.         //op4:查询数据
  59.         //selectOne
  60.         Student sd1 = session.selectOne("ns1.query1");
  61.         System.out.println(sd1.getName());
  62.         System.out.println(sd1.getAge());
  63.         Map map2 = new HashMap();
  64.         map2.put("name", "张三");
  65.         //传一个参数这样传太费劲了，name='张三'有两条数据,selectOne返回的结果只能是null或一条，所以此时报异常
  66.         //Expected one result (or null) to be returned by selectOne(), but found: 2
  67.         //System.out.println(session.selectOne("ns1.query2",map2));
  68.         //直接传字符串，需要制定parameterType以及占位符用_parameter
  69.         Student sd3 = session.selectOne("ns1.query3","马冬梅");
  70.         System.out.println(sd3.getAge());
  71.         Student sd4 = session.selectOne("ns1.query4", new Integer(11));
  72.         System.out.println(sd4.getName());
  73.         Student sd5 = session.selectOne("ns1.query5", new Integer(11));
  74.         System.out.println(sd5.getName());
  75.         System.out.println(sd5.getAge());
  76.         System.out.println(sd5.getSchool());
  77.         //selectList
  78.         List<Student> sList = session.selectList("ns1.query6");
  79.         for(Student s:sList){
  80.             System.out.println(s.getName()+","+s.getAge());
  81.         }
  82.         List<Student> sList2 = session.selectList("ns1.query7", "张三");
  83.         for(Student s:sList2){
  84.             System.out.println(s.getName()+","+s.getAge());
  85.         }
  86.         //selectMap
  87.         //selectMap(String s1,String s2)返回的结果是以指定列s2为key，以Bean为value的map
  88.         Map<Integer,Student> map = session.selectMap("ns1.query8","id");
  89.         Set<Integer> k = map.keySet();
  90.         Iterator<Integer> it = k.iterator();
  91.         while(it.hasNext()){
  92.             int key = it.next();
  93.             System.out.print(key+"-----"+map.get(key).getId());
  94.             System.out.print(","+map.get(key).getName());
  95.             System.out.print(","+map.get(key).getAge());
  96.             System.out.println(","+map.get(key).getSchool());
  97.         }
  98.         //selectMap(String s1,Object obj,String s2)返回的结果是以指定列s2为key，以Bean为value的map
  99.         Map<Integer,Student> map3 = session.selectMap("ns1.query9", "张三", "id");
  100.         Set<Integer> k3 = map3.keySet();
  101.         Iterator<Integer> it3 = k3.iterator();
  102.         while(it3.hasNext()){
  103.             int key = it3.next();
  104.             System.out.print(key+"-----"+map3.get(key).getId());
  105.             System.out.print(","+map3.get(key).getName());
  106.             System.out.print(","+map3.get(key).getAge());
  107.             System.out.println(","+map3.get(key).getSchool());
  108.         }
  110.         //必须写提交，不会默认提交的，此处不写，不会提交到数据库
  111.         session.commit();
  113.     }
  115. }

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