MyBatis(一)
- 使用myBatis步骤
- 创建maven工程，添加依赖jar包
1 <project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" 2 xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd"> 3 <modelVersion>4.0.0</modelVersion> 4 <groupId>cn.zjr</groupId> 5 <artifactId>MyBatis-day01-config</artifactId> 6 <version>0.0.1-SNAPSHOT</version> 7 <dependencies> 8 <dependency> 9 <groupId>org.mybatis</groupId> 10 <artifactId>mybatis</artifactId> 11 <version>3.4.6</version> 12 </dependency> 13 <!-- https://mvnrepository.com/artifact/mysql/mysql-connector-java --> 14 <dependency> 15 <groupId>mysql</groupId> 16 <artifactId>mysql-connector-java</artifactId> 17 <version>5.1.47</version> 18 </dependency> 19 <!-- https://mvnrepository.com/artifact/org.mybatis/mybatis --> 20 <dependency> 21 <groupId>junit</groupId> 22 <artifactId>junit</artifactId> 23 <version>4.12</version> 24 </dependency> 25 </dependencies> 26 </project>
2.创建全局配置文件
该配置文件包含了对 MyBatis 系统的核心设置，包含获取数据库连接实例的数据源（DataSource）和决定事务作用域和控制方式的事务管理器 TransactionManager）。
<?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="com.mysql.jdbc.Driver" />
<property name="url"
value="jdbc:mysql://localhost:3306/testbatis?characterEncoding=utf-8" />
<property name="username" value="root" />
<property name="password" value="1234" />
</dataSource>
</environment>
</environments>
<mappers>
<!-- 关联映射文件 -->
<mapper resource="cn/zjr/pojo/UserMapper.xml"/>
</mappers>
</configuration>
3.定义User实体类
4.创建映射文件UserMapper.xml
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 <!-- namespace 名称空间:作用是用来区分各个xml映射文件的 -->
6 <mapper namespace="cn.zjr.pojo.User">
7 <select id="query" resultType="cn.zjr.pojo.User">
8 select * from t_user
9 </select>
10 <insert id="addUser" parameterType="cn.zjr.pojo.User">
11 insert into t_user(name,gender) values(#{name},#{gender})
12 </insert>
13 <update id="updateUser" parameterType="cn.zjr.pojo.User">
14 update t_user set name=#{name},gender=#{gender} where id=#{id}
15 </update>
16 <delete id="deleteUserById" parameterType="int">
17 delete from t_user where id=#{id}
18 </delete>
19 </mapper>
5.将映射文件添加到主配置文件中
6. 编写测试类（增删改查）
1 package cn.zjr.test;
2 import java.io.IOException;
3 import java.io.InputStream;
4 import java.util.List;
5
6 import org.apache.ibatis.io.Resources;
7 import org.apache.ibatis.session.SqlSession;
8 import org.apache.ibatis.session.SqlSessionFactory;
9 import org.apache.ibatis.session.SqlSessionFactoryBuilder;
10 import org.junit.Test;
11
12 import cn.zjr.pojo.User;
13
14 public class MyBatisTest {
15 //查询
16 @Test
17 public void query() throws IOException {
18 //加载全局配置文件
19 InputStream in = Resources.getResourceAsStream("MyBatis-config.xml");
20 //获取SqlSessionFactory
21 SqlSessionFactory factory = new SqlSessionFactoryBuilder().build(in);
22 //获取SqlSession对象
23 SqlSession session = factory.openSession();
24
25 //执行数据库操作 namespace+"."+id
26 List<User> list = session.selectList("cn.zjr.pojo.User.query");
27 for (User user : list) {
28 System.out.println(user);
29 }
30 //关闭
31 in.close();
32
33
34 }
35 //添加
36 @Test
37 public void addUser() throws IOException {
38 InputStream in = Resources.getResourceAsStream("MyBatis-config.xml");
39 SqlSessionFactory factory = new SqlSessionFactoryBuilder().build(in);
40 SqlSession session = factory.openSession();
41 //执行数据库操作
42 User user = new User();
43 user.setName("花花");
44 user.setGender("男");
45 int count = session.insert("cn.zjr.pojo.User.addUser", user);
46 session.commit();
47 System.out.println("影响的行数"+count);
48 session.close();
49 }
50 //修改
51 @Test
52 public void updateUser() throws IOException {
53
54 InputStream in = Resources.getResourceAsStream("MyBatis-config.xml");
55 SqlSessionFactory factory = new SqlSessionFactoryBuilder().build(in);
56 SqlSession session = factory.openSession();
57 //执行数据库操作
58 User user = new User();
59 user.setId(3);
60 user.setName("Tony");
61 user.setGender("男");
62 int count = session.update("cn.zjr.pojo.User.updateUser", user);
63 session.commit();
64 System.out.println("影响的行数"+count);
65 session.close();
66 }
67 //删除
68 @Test
69 public void deleteUserById() throws IOException {
70 InputStream in = Resources.getResourceAsStream("MyBatis-config.xml");
71 SqlSessionFactory factory = new SqlSessionFactoryBuilder().build(in);
72 SqlSession session = factory.openSession();
73 int count = session.update("cn.zjr.pojo.User.deleteUserById", 7);
74 session.commit();
75 System.out.println("影响的行数"+count);
76 session.close();
77 }
81 }
7.优化：
封装获取Session和SqlSessionFactory对象的工具类
package cn.zjr.util;
import java.io.IOException;
import java.io.InputStream;
import org.apache.ibatis.io.Resources;
import org.apache.ibatis.session.SqlSessionFactory;
import org.apache.ibatis.session.SqlSessionFactoryBuilder;
public class Dbutils {
private static InputStream in;
private static SqlSessionFactory factory =null;
public static SqlSessionFactory getSqlSessionFactory(){
try {
in=Resources.getResourceAsStream("mybatis-config.xml");
factory = new SqlSessionFactoryBuilder().build(in);
} catch (IOException e) {
e.printStackTrace();
}
return factory;
}
}
通过代理模式实现对象创建
1 package cn.zjr.test;
2
3 import java.lang.reflect.InvocationHandler;
4 import java.lang.reflect.Method;
5 import java.lang.reflect.Proxy;
6 import java.util.List;
7
8 import org.apache.ibatis.session.SqlSession;
9
10 import cn.zjr.dao.IUserDao;
11 import cn.zjr.pojo.User;
12 import cn.zjr.util.Dbutils;
13
14 public class TestProxy {
15 public static void main(String[] args) {
16 IUserDao proxy = (IUserDao) Proxy.newProxyInstance(TestProxy.class.getClassLoader(), new Class[] {IUserDao.class}, new InvocationHandler() {
17
18 public Object invoke(Object proxy, Method method, Object[] args) throws Throwable {
19 SqlSession session = Dbutils.getSqlSessionFactory().openSession(true);
20 String methodName = method.getName();
21 String statement = IUserDao.class.getName()+"."+methodName;
22 if (methodName.contains("query")) {
23
24 return session.selectList(statement,args);
25 }
26 return null;
27 }
28 });
29 List<User> users = proxy.query();
30 for (User user : users) {
31 System.out.println(user);
32 }
33
34
35 }
36
37 }
对代理模式进行优化：使用MyBatis封装好的代理
1 package cn.zjr.test;
2
3 import java.util.List;
4
5 import org.apache.ibatis.session.SqlSession;
6
7 import cn.zjr.dao.IUserDao;
8 import cn.zjr.pojo.User;
9 import cn.zjr.util.Dbutils;
10
11 public class TestMyBatisProxy {
12 public static void main(String[] args) {
13 SqlSession session = Dbutils.getSqlSessionFactory().openSession();
14 IUserDao userDao = session.getMapper(IUserDao.class);
15 List<User> list = userDao.query();
16 for (User user : list) {
17 System.out.println(user);
18 }
19 }
20 }
对映射文件UserMapper.xml进行优化，改写为IUserDao.xml文件，并配置到主配置文件中
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 <mapper namespace="cn.zjr.dao.IUserDao">
6 <select id="query" resultType="cn.zjr.pojo.User">
7 select * from t_user
8 </select>
9 <insert id="addUser" parameterType="cn.zjr.pojo.User">
10
11 insert into t_user(name,gender) values(#{name},#{gender})
12 </insert>
13 <update id="updateUserById" parameterType="cn.zjr.pojo.User">
14 update t_user set name=#{name},gender=#{gender} where id=#{id}
15 </update>
16 <delete id="deleteById" parameterType="int">
17 delete from t_user where id=#{id}
18
19 </delete>
20 <select id="queryById" resultType="cn.zjr.pojo.User">
21 select * from t_user where id=#{uid}
22 </select>
23
24 </mapper>
