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底层基于JDK动态代理技术实现
项目结构 项目代码
pom.xml
?xml version1.0 encodingUTF-8?
project xmlnshttp://maven.apache.org/POM/4.0.0xmlns… 简单手写Mybatis大致原理 大致原理项目结构项目代码代码测试 大致原理
底层基于JDK动态代理技术实现
项目结构 项目代码
pom.xml
?xml version1.0 encodingUTF-8?
project xmlnshttp://maven.apache.org/POM/4.0.0xmlns:xsihttp://www.w3.org/2001/XMLSchema-instancexsi:schemaLocationhttp://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsdmodelVersion4.0.0/modelVersiongroupIdcom/groupIdartifactIdmybatis-jdk-proxy/artifactIdversion1.0-SNAPSHOT/versionbuildpluginsplugingroupIdorg.apache.maven.plugins/groupIdartifactIdmaven-compiler-plugin/artifactIdconfigurationsource8/sourcetarget8/target/configuration/plugin/plugins/builddependenciesdependencygroupIdmysql/groupIdartifactIdmysql-connector-java/artifactIdversion8.0.18/version/dependency/dependencies/projectconfig.properties
driverClasscom.mysql.cj.jdbc.Driver
urljdbc:mysql://127.0.0.1:3306/db_mybatis?serverTimezoneUTC
userroot
passwordadminUserEntity.java
package com.mybatis.entity;/*** author honey* date 2023-07-26 15:29:38*/
public class UserEntity {private Integer id;private String name;Overridepublic String toString() {return UserEntity{ id id , name name \ };}
}UserMapper.java
package com.mybatis.mapper;import com.mybatis.proxy.Insert;/*** author honey* date 2023-07-26 21:04:23*/
public interface UserMapper {/*** 新增用户** return int*/Insert(INSERT INTO tb_user (id, name) VALUES (null, Faker);)int insertUser();
}Insert.java
package com.mybatis.proxy;import java.lang.annotation.*;/*** author honey* date 2023-07-27 20:48:38*/
Documented
Retention(RetentionPolicy.RUNTIME)
Target(ElementType.METHOD)
public interface Insert {String value();
}JdbcUtils.java
package com.mybatis.proxy;import java.io.InputStream;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.Statement;
import java.util.Properties;/*** author honey* date 2023-07-27 20:57:08*/
public class JdbcUtils {private JdbcUtils() {}private static String url;private static String user;private static String password;static {try {InputStream resourceAsStream JdbcUtils.class.getClassLoader().getResourceAsStream(config.properties);Properties properties new Properties();properties.load(resourceAsStream);String driverClass properties.getProperty(driverClass);url properties.getProperty(url);user properties.getProperty(user);password properties.getProperty(password);Class.forName(driverClass);} catch (Exception e) {e.printStackTrace();}}public static Connection getConnection() {try {return DriverManager.getConnection(url, user, password);} catch (Exception e) {e.printStackTrace();return null;}}public static void closeConnection(ResultSet resultSet, Statement statement, Connection connection) {try {if (resultSet ! null) {resultSet.close();}if (statement ! null) {statement.close();}if (connection ! null) {connection.close();}} catch (Exception e) {e.printStackTrace();}}public static void closeConnection(Statement statement, Connection connection) {closeConnection(null, statement, connection);}
}MapperProxy.java
package com.mybatis.proxy;import java.lang.reflect.InvocationHandler;
import java.lang.reflect.Method;
import java.lang.reflect.Proxy;
import java.sql.Connection;
import java.sql.PreparedStatement;/*** author honey* date 2023-07-27 20:17:23*/
public class MapperProxy implements InvocationHandler {private final Class? mapperClass;public MapperProxy(Class? mapperClass) {this.mapperClass mapperClass;}Overridepublic Object invoke(Object proxy, Method method, Object[] args) throws Throwable {// 使用Java反射技术获取该方法上的注解Insert declaredAnnotation method.getDeclaredAnnotation(Insert.class);String insertSql declaredAnnotation.value();// 执行sql语句Connection connection JdbcUtils.getConnection();PreparedStatement preparedStatement connection.prepareStatement(insertSql);return preparedStatement.executeUpdate();}public T T getProxy() {return (T) Proxy.newProxyInstance(mapperClass.getClassLoader(), new Class[]{mapperClass}, this);}
}SqlSession.java
package com.mybatis.proxy;/*** author honey* date 2023-07-27 21:10:30*/
public class SqlSession {public static T T getMapper(ClassT type) {return new MapperProxy(type).getProxy();}
}MybatisTest.java
package com.mybatis.test;import com.mybatis.mapper.UserMapper;
import com.mybatis.proxy.SqlSession;/*** author honey* date 2023-07-26 15:26:48*/
public class MybatisTest {public static void main(String[] args) {System.getProperties().put(sun.misc.ProxyGenerator.saveGeneratedFiles, true);UserMapper userMapper SqlSession.getMapper(UserMapper.class);int result userMapper.insertUser();System.out.println(result);}
}代码测试
运行MybatisTest类
SqlSession.java MapperProxy.java MybatisTest.java MapperProxy.java MybatisTest.java 运行结果
