Mybatis基本流程实现
一：maven导包（一个连接包、一个mybatis包，一个测试包）
<dependencies> <dependency> <groupId>mysql</groupId> <artifactId>mysql-connector-java</artifactId> <version>5.1.47</version> </dependency> <dependency> <groupId>org.mybatis</groupId> <artifactId>mybatis</artifactId> <version>3.5.2</version> </dependency> <dependency> <groupId>junit</groupId> <artifactId>junit</artifactId> <version>4.12</version> </dependency> </dependencies>
二：配置mybatis-config、do.properties文件，进行数据库连接
<?xml version="1.0" encoding="UTF-8" ?> <!DOCTYPE configuration PUBLIC "-//mybatis.org//DTD Config 3.0//EN" "http://mybatis.org/dtd/mybatis-3-config.dtd"> <configuration> <environments default="development"> <environment id="development"> <transactionManager type="JDBC"/> <dataSource type="POOLED"> <property name="driver" value="${driver}"/> <property name="url" value="${url}"/> <property name="username" value="${username}"/> <property name="password" value="${password}"/> </dataSource> </environment> </environments> <mappers> <mapper resource="com/ma/dao/UserMapper.xml"/> </mappers> </configuration>
driver=com.mysql.jdbc.Driver url=jdbc:mysql://localhost:3306/mybatis?useSSL=false&useUnicode=true&characterEncoding=UTF-8 username=root password=1234
三：要用工具去使用mybatis里面的东西，而这个“工具”写成代码后，是固定的，所以可以封装成一个工具类
package com.ma.utils; import org.apache.ibatis.io.Resources; import org.apache.ibatis.session.SqlSession; import org.apache.ibatis.session.SqlSessionFactory; import org.apache.ibatis.session.SqlSessionFactoryBuilder; import java.io.IOException; import java.io.InputStream; public class MybatisUtil { private static SqlSessionFactory sqlSessionFactory; static{ try { String resource = "mybatis-config.xml"; InputStream inputStream= Resources.getResourceAsStream(resource); sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream); } catch (IOException e) { e.printStackTrace(); } } public static SqlSession getSqlSession(){ return sqlSessionFactory.openSession(); } }
使用方法为：调用这个工具类，去找到相应的mapper类，对对应的数据表进行操作，如下例子：
public void test(){ SqlSession sqlSession = MybatisUtil.getSqlSession(); UserMapper userDao = sqlSession.getMapper(UserMapper.class); List<User> userList = userDao.getUserList(); for(User user:userList){ System.out.println(user); } sqlSession.close(); }
四：（1）数据库情况
（2）编写bean（pojo）类
package com.ma.pojo; public class User { private int id; private String name; private String pwd; public User(int id, String name, String pwd) { this.id = id; this.name = name; this.pwd = pwd; } public User(){ } @Override public String toString() { return "User{" + "id=" + id + ", name='" + name + '\'' + ", pwd='" + pwd + '\'' + '}'; } public String getName() { return name; } public int getId() { return id; } public void setId(int id) { this.id = id; } public void setName(String name) { this.name = name; } public String getPwd() { return pwd; } public void setPwd(String pwd) { this.pwd = pwd; } }
（3）编写dao类，以及实现增删改查的xml文件
package com.ma.dao; import com.ma.pojo.User; import java.util.List; import java.util.Map; public interface UserMapper { List<User> getUserList(); List<User> getUserLike(String value); User getUserById(int id); int addUser(User user); int updateUser(User user); int deleteUser(int id); int addUser2(Map<String, Object> map); }
<?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="com.ma.dao.UserMapper"> <!--映射之后的User--com.ma.pojo.User--> <!-- <select id="getUserList" resultType="hello">--> <select id="getUserList" resultType="User"> select * from mybatis.user </select> <select id="getUserLike" resultType="com.ma.pojo.User"> select * from mybatis.user where name like "%"#{value}"%"; </select> <select id="getUserById" parameterType="int" resultType="com.ma.pojo.User"> select * from mybatis.user where id = #{id}; </select> <insert id="addUser" parameterType="com.ma.pojo.User"> insert into mybatis.user (id, name, pwd) values (#{id},#{name},#{pwd}); </insert> <!-- map用法，可以随意给某赋值，然后其他值不定义--> <!--<insert id="addUser2" parameterType="map"> insert into mybatis.user (id, name, pwd) values (#{userid},#{userName},#{passWord}); </insert>--> <update id="updateUser" parameterType="com.ma.pojo.User"> update mybatis.user set name = #{name}, pwd = #{pwd} where id = #{id}; </update> <delete id="deleteUser" parameterType="int"> delete from mybatis.user where id =#{id}; </delete> </mapper>
其中，除了sql语句之外，<mapper namespace="com.ma.dao.UserMapper">也是需要有对应关系，比如studentmapper对应studentmapper.xml
而这里是Usermapper对应Usermapper.xml
注（对应的xml文件的命名最好与其相同）
五：测试
public void test(){ SqlSession sqlSession = MybatisUtil.getSqlSession(); UserMapper userDao = sqlSession.getMapper(UserMapper.class); List<User> userList = userDao.getUserList(); for(User user:userList){ System.out.println(user); } sqlSession.close(); }
但是，这样子去测试的话，是会报错的，我们需要在mybatis-config中对每一个mapper进行配置
<mappers> <mapper resource="com/ma/dao/UserMapper.xml"/> </mappers>
六：以上操作完毕之后，还是会报错，我们需要在pom中增加一个内容，如下：
<build> <resources> <resource> <directory>src/main/resources</directory> <includes> <include>**/*.properties</include> <include>**/*.xml</include> </includes> <filtering>true</filtering> </resource> <resource> <directory>src/main/java</directory> <includes> <include>**/*.properties</include> <include>**/*.xml</include> </includes> <filtering>true</filtering> </resource> </resources> </build>
