MyBatis系列之模糊查询(注解方式+映射文件方式)
【摘要】
本博客以一个demo的形式说明模糊查询实现的两种方法：
项目结构如图：
ConditionUser.java:
package com.mybatis.entity; public class ConditionUser { private String name; private int minAge; private int...
本博客以一个demo的形式说明模糊查询实现的两种方法：
项目结构如图：
ConditionUser.java:
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package com.mybatis.entity;
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public class ConditionUser {
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private String name;
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private int minAge;
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private int maxAge;
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public ConditionUser(String name,int minAge,int maxAge){
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this.name= name;
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this.minAge = minAge;
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this.maxAge = maxAge;
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}
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public String getName() {
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return name;
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}
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public void setName(String name) {
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this.name = name;
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}
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public int getMinAge() {
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return minAge;
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}
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public void setMinAge(int minAge) {
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this.minAge = minAge;
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}
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public int getMaxAge() {
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return maxAge;
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}
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public void setMaxAge(int maxAge) {
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this.maxAge = maxAge;
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}
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}
User.java:
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package com.mybatis.entity;
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public class User {
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/*
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* ID
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*/
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private int id;
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/*
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* 用户姓名
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*/
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private String name;
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/*
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* age
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*/
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private int age;
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public int getId() {
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return id;
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}
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public void setId(int id) {
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this.id = id;
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}
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public String getName() {
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return name;
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}
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public void setName(String name) {
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this.name = name;
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}
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public int getAge() {
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return age;
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}
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public void setAge(int age) {
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this.age = age;
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}
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@Override
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public String toString() {
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return "User [id=" + id + ", name=" + name + ", age=" + age + "]";
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}
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}
我们先以注解方式实现：
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<?xml version="1.0" encoding="UTF-8"?>
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<!DOCTYPE configuration PUBLIC "-//mybatis.org//DTD Config 3.0//EN"
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"http://mybatis.org/dtd/mybatis-3-config.dtd">
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<configuration>
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<!-- 数据库配置文件 -->
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<properties resource="db.properties" />
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<!-- 实体类,简称 -设置别名 -->
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<typeAliases>
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<typeAlias alias="User" type="com.mybatis.entity.User" />
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</typeAliases>
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<!-- 读取db.properties里的数据，进行数据库配置 -->
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<environments default="development">
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<environment id="development">
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<transactionManager type="JDBC" />
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<dataSource type="POOLED">
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<property name="driver" value="${driver}"/>
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<property name="url" value="${url}" />
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<property name="username" value="${username}"/>
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<property name="password" value="${password}"/>
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</dataSource>
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</environment>
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</environments>
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<!--
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注册userMapper.xml文件
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<mappers>
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<mapper resource="com/mybatis/mapper/userMapper.xml"/>
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</mappers>
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-->
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<mappers>
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<mapper class="com.mybatis.mapper.UserMapper"/>
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</mappers>
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</configuration>
db.properties:
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driver=com.mysql.jdbc.Driver
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url=jdbc\:mysql\://localhost\:3306/db_mysql?useUnicode\=true&characterEncoding\=utf-8
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username=root
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password=111
UserMapper.java:
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package com.mybatis.mapper;
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import java.util.List;
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import org.apache.ibatis.annotations.Delete;
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import org.apache.ibatis.annotations.Insert;
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import org.apache.ibatis.annotations.Select;
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import org.apache.ibatis.annotations.Update;
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import com.mybatis.entity.ConditionUser;
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import com.mybatis.entity.User;
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public interface UserMapper {
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@Insert("insert into users(name,age) values(#{name},#{age})")
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public void save(User user);
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@Update("update users set name=#{name},age=#{age} where id=#{id}")
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public boolean update(User user);
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@Delete("delete from users where id=#{id}")
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public boolean delete(int id);
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@Select("select * from users where id=#{id}")
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public User findById(int id);
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@Select("select * from users where name like #{name} and age >= #{minAge}")
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public List<User> findAll(ConditionUser u);
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}
测试：
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String resource = "mybatis-config.xml";
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try{
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//加载Mybatis的配置文件
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Reader reader = Resources.getResourceAsReader(resource);
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//构建sqlSession的工厂
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SqlSessionFactory sessionFactory = new SqlSessionFactoryBuilder().build(reader);
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//创建可以执行sql的SqlSession
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SqlSession session = sessionFactory.openSession();
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// List<User> list = session.selectList("com.mybatis.mapper.userMapper.findById",new ConditionUser("%a%",0, 1));
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// System.out.println(list);
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UserMapper mapper = session.getMapper(UserMapper.class);
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List<User> list = mapper.findAll(new ConditionUser("%a%", 0, 1));
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System.out.println(list);
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Classes c = session.selectOne("com.mybatis.mapper.classesMapper.findById4",1);
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System.out.println(c);
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}catch (Exception e) {
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e.printStackTrace();
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}
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}
然后以映射文件的方式实现：
注意注解方式和映射文件方式是会冲突的，所以要先删了注解的接口类
然后，在新建userMapper.xml:
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<?xml version="1.0" encoding="UTF-8" ?>
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<!DOCTYPE mapper PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN"
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"http://mybatis.org/dtd/mybatis-3-mapper.dtd">
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<!--
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为这个mapper指定一个唯一的namespace，namespace的值习惯上设置成包名+sql映射文件名，这样就能够保证namespace的值是唯一的
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-->
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<mapper namespace="com.mybatis.mapper.userMapper">
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<!--
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在select标签中编写查询的SQL语句， 设置select标签的id属性为findById，id属性值必须是唯一的，不能够重复
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parameterType可以在MyBatis的配置文件里设置，也可以直接用包名+类名
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-->
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<insert id="save" parameterType="User">
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insert into users(id,name,age) value(#{name},#{age})
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</insert>
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<update id="update" parameterType="User">
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update users set name=#{name},age=#{age} where id=#{id}
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</update>
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<delete id="delete" parameterType="int">
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delete from users where id=#{id}
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</delete>
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<select id="findById" parameterType="com.mybatis.entity.ConditionUser" resultType="User">
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select * from users where age>=#{minAge}
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<if test='name!="%null%"'>and name like #{name}</if>
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</select>
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<select id="findAll" resultType="User">
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select * from users
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</select>
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</mapper>
修改mybatis配置文件：
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<?xml version="1.0" encoding="UTF-8"?>
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<!DOCTYPE configuration PUBLIC "-//mybatis.org//DTD Config 3.0//EN"
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"http://mybatis.org/dtd/mybatis-3-config.dtd">
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<configuration>
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<!-- 数据库配置文件 -->
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<properties resource="db.properties" />
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<!-- 实体类,简称 -设置别名 -->
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<typeAliases>
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<typeAlias alias="User" type="com.mybatis.entity.User" />
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</typeAliases>
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<!-- 读取db.properties里的数据，进行数据库配置 -->
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<environments default="development">
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<environment id="development">
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<transactionManager type="JDBC" />
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<dataSource type="POOLED">
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<property name="driver" value="${driver}"/>
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<property name="url" value="${url}" />
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<property name="username" value="${username}"/>
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<property name="password" value="${password}"/>
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</dataSource>
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</environment>
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</environments>
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<!--
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注册userMapper.xml文件
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<mappers>
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<mapper resource="com/mybatis/mapper/userMapper.xml"/>
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</mappers>
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-->
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<mappers>
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<mapper resource="com/mybatis/mapper/userMapper.xml"/>
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</mappers>
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</configuration>
测试：
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String resource = "mybatis-config.xml";
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try{
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//加载Mybatis的配置文件
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Reader reader = Resources.getResourceAsReader(resource);
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//构建sqlSession的工厂
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SqlSessionFactory sessionFactory = new SqlSessionFactoryBuilder().build(reader);
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//创建可以执行sql的SqlSession
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SqlSession session = sessionFactory.openSession();
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List<User> list = session.selectList("com.mybatis.mapper.userMapper.findById",new ConditionUser("%a%",0, 1));
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System.out.println(list);
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// UserMapper mapper = session.getMapper(UserMapper.class);
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// List<User> list = mapper.findAll(new ConditionUser("%a%", 0, 1));
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// System.out.println(list);
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Classes c = session.selectOne("com.mybatis.mapper.classesMapper.findById4",1);
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System.out.println(c);
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}catch (Exception e) {
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e.printStackTrace();
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}
文章来源: smilenicky.blog.csdn.net，作者：smileNicky，版权归原作者所有，如需转载，请联系作者。
原文链接：smilenicky.blog.csdn.net/article/details/51292469
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