一张图带你看懂原始dao与SQL动态代理开发的区别-Mybatis

 1 public class Factory {
 2     private final static Class<Factory> lock = Factory.class;
 3     private static SqlSessionFactory sqlSessionFactory = null;
 4     private Factory() {}
 5 
 6     public static SqlSessionFactory getSqlSessionFactory() {
 7         synchronized (lock) {
 8             if (sqlSessionFactory != null) {
 9                 return sqlSessionFactory;
10             }
11             //加载核心配置文件
12             String resource = "mybatis-config.xml";
13             InputStream inputStream;
14             try {
15                 inputStream = Resources.getResourceAsStream(resource);
16                 //创建SqlsessionFactory工厂
17                 sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream);
18             } catch (IOException e) {
19                 e.printStackTrace();
20                 return null;
21             }
22             //对外提供一个工厂
23             return sqlSessionFactory;
24         }
25     }
26 
27     //对外提供一个Sqlsession会话
28     public static SqlSession getSession() {
29         if (sqlSessionFactory == null) {
30             getSqlSessionFactory();
31         }
32         return sqlSessionFactory.openSession();
33     }
34 }

 1 <?xml version="1.0" encoding="UTF-8" ?>
 2 <!DOCTYPE configuration
 3         PUBLIC "-//mybatis.org//DTD Config 3.0//EN"
 4         "http://mybatis.org/dtd/mybatis-3-config.dtd">
 5 
 6 <configuration>
 7     <properties resource="jdbc.properties"></properties>
 8 
 9     <!--environments元素：配置Mybatis的运行环境-->
10     <!--可配置多套运行环境，将SQL映射到多个不同的数据库上，但必须通过default属性指定默认运行环境-->
11     <environments default="development"> <!--default属性指定默认运行环境的id-->
12         <environment id="development">   <!-- 第一套运行环境的id-->
13             <transactionManager type="JDBC"></transactionManager> <!--事务管理器配置-->
14             <dataSource type="POOLED">   <!--数据源(连接池)配置-->
15                 <property name="driver" value="${jdbc.driver}"/>
16                 <property name="url" value="${jdbc.url}"/>
17                 <property name="username" value="${jdbc.username}"/>
18                 <property name="password" value="${jdbc.password}"/>
19             </dataSource>
20         </environment>
21     </environments>
22 
23     <!--mappers元素：配置mapper映射器的xml映射文件 以动态代理开发为例，原始dao开发配置方法相同-->
24     <mappers>
25         <!--方式一：使用resource配置映射文件-->
26         <mapper resource="com/nreg/mapper/UserMapper.xml"></mapper>
27         <!--方式二：使用url配置映射文件-->
28         <mapper url="D:\Mybatis-agency-easy\src\main\java\com\nreg\mapper\UserMapper.xml"></mapper>
29         <!--方式三：多个映射器的使用：开启扫描-->
30         <package name="com.nreg.mapper"/>
31     </mappers>
32 </configuration>

1 jdbc.driver=com.mysql.jdbc.Driver
2 jdbc.url=jdbc:mysql://localhost:3306/crud?useSSL=false&serverTimezone=UTC&characterEncoding=utf-8
3 jdbc.username=root
4 jdbc.password=123456

 1 ### 设置Logger输出级别和输出目的地 ### debug更详细,如果把debug改为info，则打印出的表数据遇到字符串就不显示，此外还有log4j.log文件
 2 log4j.rootLogger=debug,stdout
 3         
 4 ### 把日志信息输出到控制台 ###
 5 log4j.appender.stdout=org.apache.log4j.ConsoleAppender 
 6 #log4j.appender.stdout.Target=System.err
 7 log4j.appender.stdout.layout=org.apache.log4j.SimpleLayout 
 8 
 9 ### 把日志信息输出到文件：log4j.log ###
10 log4j.appender.logfile=org.apache.log4j.FileAppender 
11 log4j.appender.logfile.File=log4j.log 
12 log4j.appender.logfile.layout=org.apache.log4j.PatternLayout 
13 log4j.appender.logfile.layout.ConversionPattern=%d{yyyy-MM-dd HH:mm:ss} %F %p %m%n
14 
15 ###显示SQL语句部分 ###
16 #第一行：xml映射文件所在包
17 log4j.logger.com.nreg.sqlMap=DEBUG
18 log4j.logger.java.sql.Connection=DEBUG
19 log4j.logger.java.sql.Statement=DEBUG
20 log4j.logger.java.sql.PreparedStatement=DEBUG
21 log4j.logger.java.sql.ResultSet=DEBUG

 1     //增
 2     boolean addUser(User user);
 3     //删
 4     boolean deleteUserById(int id);
 5     //改
 6     boolean updateUserById(User user);
 7     //查:按id查一个
 8     User getUserById(int id);
 9     //查:查所有
10     List<User> getUser();

    <!--增-->
    <insert id="addUser" parameterType="com.nreg.bean.User" useGeneratedKeys="true" keyProperty="id">
        insert into user values(null,#{username},#{password})
    </insert>

    <!--删-->
    <delete id="deleteUserById" parameterType="int">
        delete from user where id = #{id}
    </delete>

    <!--改-->
    <update id="updateUserById" parameterType="com.nreg.bean.User">
        update user set username = #{username},password = #{password} where id=#{id}
    </update>

    <!--查:按id查-->
    <select id="getUserById" parameterType="int" resultType="com.nreg.bean.User">
        select * from user where 1=1 and id = #{id}<!--注：1=1 and：用于防止后面条件不成立造成SQL语句错误-->
    </select>

    <!--查:查所有-->
    <select id="getUser" resultType="com.nreg.bean.User">
        select * from user
    </select>

  1 public class UserService {
  2     
  3     SqlSession sqlsession=null;
  4     //增
  5     public boolean addUser(User user) {
  6         try {
  7             //1.通过工厂获取会话
  8             sqlsession= Factory.getSession();
  9             //2.从会话中获取接口的代理对象
 10             UserMapper userMapper=sqlsession.getMapper(UserMapper.class);
 11             //3.通过代理对象操作数据库
 12             userMapper.addUser(user);
 13             //提交事务
 14             sqlsession.commit();
 15             return true;
 16         } catch (Exception e) {
 17             //回滚
 18             if(sqlsession !=null){
 19                 sqlsession.rollback();
 20             }
 21             return false;
 22         }finally{
 23             //关闭连接,释放资源
 24             if(sqlsession!=null){
 25                 sqlsession.close();
 26             }
 27         }
 28     }
 29     
 30     //删
 31     public boolean deleteUserById(int id) {
 32         try {
 33             sqlsession= Factory.getSession();
 34             UserMapper userMapper=sqlsession.getMapper(UserMapper.class);
 35             boolean tf=userMapper.deleteUserById(id);
 36             sqlsession.commit();
 37             return tf;
 38         } catch (Exception e) {
 39             if(sqlsession!=null){
 40                 sqlsession.rollback();
 41             }
 42             return false;
 43         }finally{
 44             if(sqlsession!=null){
 45                 sqlsession.close();
 46             }
 47         }
 48     }
 49     
 50     //改
 51     public boolean updateUserById(User user) {
 52 
 53         try {
 54             sqlsession= Factory.getSession();
 55             UserMapper userMapper=sqlsession.getMapper(UserMapper.class);
 56             userMapper.updateUserById(user);
 57             sqlsession.commit();
 58             return true;
 59         } catch (Exception e) {
 60             if(sqlsession !=null){
 61                 sqlsession.rollback();
 62             }
 63             return false;
 64         }finally{
 65             if(sqlsession !=null){
 66                 sqlsession.close();
 67             }
 68         }
 69     }
 70 
 71     //查:按id查一个
 72     public User getUserById(int id) {
 73 
 74         try {
 75             sqlsession= Factory.getSession();
 76             UserMapper userMapper=sqlsession.getMapper(UserMapper.class);
 77             User user = userMapper.getUserById(id);
 78             return user;
 79 
 80         } catch (Exception e) {
 81             if(sqlsession!=null){
 82                 sqlsession.rollback();
 83             }
 84             e.printStackTrace();
 85             return null;
 86         }finally{
 87             if(sqlsession !=null){
 88                 sqlsession.close();
 89             }
 90         }
 91     }
 92 
 93     //查:查所有
 94     public List<User> getUser() {
 95 
 96         try {
 97             sqlsession = Factory.getSession();
 98             List<User> list = null;
 99             UserMapper userMapper=sqlsession.getMapper(UserMapper.class);
100             list = userMapper.getUser();
101             return list;
102         } catch (Exception e) {
103             if(sqlsession!=null){
104                 sqlsession.rollback();
105             }
106             return null;
107         }finally{
108             if(sqlsession !=null){
109                 sqlsession.close();
110             }
111         }
112     }
113 }

  1 public class UserDaoImpl implements UserDao {
  2 
  3     SqlSession sqlsession = null;
  4     //增：
  5     @Override
  6     public boolean addUser(User user) {
  7         try {
  8             //1.通过工厂获取会话
  9             sqlsession = Factory.getSession();
 10             //2.通过会话操作数据库
 11             sqlsession.insert("addUser", user);
 12             //提交事务:增删改都需要提交事务
 13             sqlsession.commit();
 14             return true;
 15         } catch (Exception e) {
 16             //回滚
 17             if (sqlsession != null) {
 18                 sqlsession.rollback();
 19             }
 20             return false;
 21         } finally {
 22             //关闭连接,释放资源
 23             if (sqlsession != null) {
 24                 sqlsession.close();
 25             }
 26         }
 27     }
 28 
 29     //删
 30     @Override
 31     public boolean deleteUserById(int id) {
 32         try {
 33             //1.通过工厂获取会话
 34             sqlsession = Factory.getSession();
 35             //2.通过会话操作数据库
 36             sqlsession.delete("deleteUserById",id);
 37             //3.提交事务
 38             sqlsession.commit();
 39             return true;
 40         } catch (Exception e) {
 41             if (sqlsession != null) {
 42                 //回滚
 43                 sqlsession.rollback();
 44             }
 45             return false;
 46         } finally {
 47             if (sqlsession != null) {
 48                 //关闭连接，释放资源
 49                 sqlsession.close();
 50             }
 51         }
 52     }
 53 
 54 
 55     //改：
 56     @Override
 57     public boolean updateUserById(User user) {
 58         try {
 59             sqlsession = Factory.getSession();
 60             sqlsession.update("updateUserById", user);
 61             sqlsession.commit();
 62             return true;
 63         } catch (Exception e) {
 64             if (sqlsession != null) {
 65                 sqlsession.rollback();
 66             }
 67             return false;
 68         } finally {
 69             if (sqlsession != null) {
 70                 sqlsession.close();
 71             }
 72         }
 73     }
 74     
 75     //查：按id查
 76     @Override
 77     public User getUserById(int id) {
 78         try {
 79             sqlsession = Factory.getSession();
 80             User user = sqlsession.selectOne("getUserById",id);
 81             return user;
 82         } catch (Exception e) {
 83             if (sqlsession != null) {
 84                 sqlsession.rollback();
 85             }
 86             return null;
 87         } finally {
 88             if (sqlsession != null) {
 89                 sqlsession.close();
 90             }
 91         }
 92     }
 93 
 94     //查：查所有
 95     @Override
 96     public List<User> getUser() {
 97         try {
 98             sqlsession = Factory.getSession();
 99             List<User> list = sqlsession.selectList("getUser");
100             return list;
101         } catch (Exception e) {
102             if (sqlsession != null) {
103                 sqlsession.rollback();
104             }
105             return null;
106         } finally {
107             if (sqlsession != null) {
108                 sqlsession.close();
109             }
110         }
111     }
112 }