小傅哥，feat：第01章：实现一个简单的ORM框架

mybatis-step-01/pom.xml

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+<?xml version="1.0" encoding="UTF-8"?>
+<project xmlns="http://maven.apache.org/POM/4.0.0"
+         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
+    <modelVersion>4.0.0</modelVersion>
+
+    <groupId>cn.bugstack.mybatis</groupId>
+    <artifactId>mybatis-step-01</artifactId>
+    <version>1.0-SNAPSHOT</version>
+
+    <packaging>jar</packaging>
+
+    <parent>
+        <groupId>org.springframework.boot</groupId>
+        <artifactId>spring-boot-starter-parent</artifactId>
+        <version>2.3.5.RELEASE</version>
+        <relativePath/>
+    </parent>
+
+    <dependencies>
+        <dependency>
+            <groupId>org.springframework.boot</groupId>
+            <artifactId>spring-boot-starter</artifactId>
+        </dependency>
+        <dependency>
+            <groupId>org.springframework.boot</groupId>
+            <artifactId>spring-boot-configuration-processor</artifactId>
+            <optional>true</optional>
+        </dependency>
+        <dependency>
+            <groupId>org.springframework.boot</groupId>
+            <artifactId>spring-boot-autoconfigure</artifactId>
+        </dependency>
+        <dependency>
+            <groupId>org.springframework.boot</groupId>
+            <artifactId>spring-boot-starter-aop</artifactId>
+        </dependency>
+        <dependency>
+            <groupId>mysql</groupId>
+            <artifactId>mysql-connector-java</artifactId>
+            <version>5.1.20</version>
+        </dependency>
+        <dependency>
+            <groupId>commons-beanutils</groupId>
+            <artifactId>commons-beanutils</artifactId>
+            <version>1.8.3</version>
+        </dependency>
+        <!-- https://mvnrepository.com/artifact/dom4j/dom4j -->
+        <dependency>
+            <groupId>dom4j</groupId>
+            <artifactId>dom4j</artifactId>
+            <version>1.6.1</version>
+        </dependency>
+        <!-- https://mvnrepository.com/artifact/jaxen/jaxen -->
+        <dependency>
+            <groupId>jaxen</groupId>
+            <artifactId>jaxen</artifactId>
+            <version>1.1.6</version>
+        </dependency>
+        <dependency>
+            <groupId>com.alibaba</groupId>
+            <artifactId>fastjson</artifactId>
+            <version>1.2.75</version>
+        </dependency>
+        <dependency>
+            <groupId>junit</groupId>
+            <artifactId>junit</artifactId>
+            <version>4.12</version>
+            <scope>test</scope>
+        </dependency>
+    </dependencies>
+
+    <build>
+        <finalName>mybatis-step-01</finalName>
+        <resources>
+            <resource>
+                <directory>src/main/resources</directory>
+                <filtering>true</filtering>
+                <includes>
+                    <include>**/**</include>
+                </includes>
+            </resource>
+        </resources>
+        <testResources>
+            <testResource>
+                <directory>src/test/resources</directory>
+                <filtering>true</filtering>
+                <includes>
+                    <include>**/**</include>
+                </includes>
+            </testResource>
+        </testResources>
+        <plugins>
+            <plugin>
+                <groupId>org.apache.maven.plugins</groupId>
+                <artifactId>maven-surefire-plugin</artifactId>
+                <version>2.12.4</version>
+                <configuration>
+                    <skipTests>true</skipTests>
+                </configuration>
+            </plugin>
+            <plugin>
+                <groupId>org.apache.maven.plugins</groupId>
+                <artifactId>maven-resources-plugin</artifactId>
+                <version>2.5</version>
+                <configuration>
+                    <encoding>${project.build.sourceEncoding}</encoding>
+                </configuration>
+            </plugin>
+            <plugin>
+                <groupId>org.apache.maven.plugins</groupId>
+                <artifactId>maven-compiler-plugin</artifactId>
+                <version>2.3.2</version>
+                <configuration>
+                    <source>1.8</source>
+                    <target>1.8</target>
+                    <encoding>${project.build.sourceEncoding}</encoding>
+                </configuration>
+            </plugin>
+            <plugin>
+                <groupId>org.apache.maven.plugins</groupId>
+                <artifactId>maven-source-plugin</artifactId>
+                <version>2.1.2</version>
+                <executions>
+                    <execution>
+                        <id>attach-sources</id>
+                        <goals>
+                            <goal>jar</goal>
+                        </goals>
+                    </execution>
+                </executions>
+            </plugin>
+        </plugins>
+    </build>
+
+</project>

mybatis-step-01/src/main/java/cn/bugstack/mybatis/Configuration.java

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+package cn.bugstack.mybatis;
+
+import java.sql.Connection;
+import java.util.Map;
+
+public class Configuration {
+
+    protected Connection connection;
+    protected Map<String, String> dataSource;
+    protected Map<String, XNode> mapperElement;
+
+    public void setConnection(Connection connection) {
+        this.connection = connection;
+    }
+
+    public void setDataSource(Map<String, String> dataSource) {
+        this.dataSource = dataSource;
+    }
+
+    public void setMapperElement(Map<String, XNode> mapperElement) {
+        this.mapperElement = mapperElement;
+    }
+
+}

mybatis-step-01/src/main/java/cn/bugstack/mybatis/DefaultSqlSession.java

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+package cn.bugstack.mybatis;
+
+import java.lang.reflect.Field;
+import java.lang.reflect.Method;
+import java.sql.*;
+import java.util.Date;
+import java.util.*;
+
+
+public class DefaultSqlSession implements SqlSession {
+
+    private Connection connection;
+    private Map<String, XNode> mapperElement;
+
+    public DefaultSqlSession(Connection connection, Map<String, XNode> mapperElement) {
+        this.connection = connection;
+        this.mapperElement = mapperElement;
+    }
+
+    @Override
+    public <T> T selectOne(String statement) {
+        try {
+            XNode xNode = mapperElement.get(statement);
+            PreparedStatement preparedStatement = connection.prepareStatement(xNode.getSql());
+            ResultSet resultSet = preparedStatement.executeQuery();
+            List<T> objects = resultSet2Obj(resultSet, Class.forName(xNode.getResultType()));
+            return objects.get(0);
+        } catch (Exception e) {
+            e.printStackTrace();
+        }
+        return null;
+    }
+
+    @Override
+    public <T> T selectOne(String statement, Object parameter) {
+        XNode xNode = mapperElement.get(statement);
+        Map<Integer, String> parameterMap = xNode.getParameter();
+        try {
+            PreparedStatement preparedStatement = connection.prepareStatement(xNode.getSql());
+            buildParameter(preparedStatement, parameter, parameterMap);
+            ResultSet resultSet = preparedStatement.executeQuery();
+            List<T> objects = resultSet2Obj(resultSet, Class.forName(xNode.getResultType()));
+            return objects.get(0);
+        } catch (Exception e) {
+            e.printStackTrace();
+        }
+        return null;
+    }
+
+    @Override
+    public <T> List<T> selectList(String statement) {
+        XNode xNode = mapperElement.get(statement);
+        try {
+            PreparedStatement preparedStatement = connection.prepareStatement(xNode.getSql());
+            ResultSet resultSet = preparedStatement.executeQuery();
+            return resultSet2Obj(resultSet, Class.forName(xNode.getResultType()));
+        } catch (Exception e) {
+            e.printStackTrace();
+        }
+        return null;
+    }
+
+    @Override
+    public <T> List<T> selectList(String statement, Object parameter) {
+        XNode xNode = mapperElement.get(statement);
+        Map<Integer, String> parameterMap = xNode.getParameter();
+        try {
+            PreparedStatement preparedStatement = connection.prepareStatement(xNode.getSql());
+            buildParameter(preparedStatement, parameter, parameterMap);
+            ResultSet resultSet = preparedStatement.executeQuery();
+            return resultSet2Obj(resultSet, Class.forName(xNode.getResultType()));
+        } catch (Exception e) {
+            e.printStackTrace();
+        }
+        return null;
+    }
+
+    private void buildParameter(PreparedStatement preparedStatement, Object parameter, Map<Integer, String> parameterMap) throws SQLException, IllegalAccessException {
+
+        int size = parameterMap.size();
+        // 单个参数
+        if (parameter instanceof Long) {
+            for (int i = 1; i <= size; i++) {
+                preparedStatement.setLong(i, Long.parseLong(parameter.toString()));
+            }
+            return;
+        }
+
+        if (parameter instanceof Integer) {
+            for (int i = 1; i <= size; i++) {
+                preparedStatement.setInt(i, Integer.parseInt(parameter.toString()));
+            }
+            return;
+        }
+
+        if (parameter instanceof String) {
+            for (int i = 1; i <= size; i++) {
+                preparedStatement.setString(i, parameter.toString());
+            }
+            return;
+        }
+
+        Map<String, Object> fieldMap = new HashMap<>();
+        // 对象参数
+        Field[] declaredFields = parameter.getClass().getDeclaredFields();
+        for (Field field : declaredFields) {
+            String name = field.getName();
+            field.setAccessible(true);
+            Object obj = field.get(parameter);
+            field.setAccessible(false);
+            fieldMap.put(name, obj);
+        }
+
+        for (int i = 1; i <= size; i++) {
+            String parameterDefine = parameterMap.get(i);
+            Object obj = fieldMap.get(parameterDefine);
+
+            if (obj instanceof Short) {
+                preparedStatement.setShort(i, Short.parseShort(obj.toString()));
+                continue;
+            }
+
+            if (obj instanceof Integer) {
+                preparedStatement.setInt(i, Integer.parseInt(obj.toString()));
+                continue;
+            }
+
+            if (obj instanceof Long) {
+                preparedStatement.setLong(i, Long.parseLong(obj.toString()));
+                continue;
+            }
+
+            if (obj instanceof String) {
+                preparedStatement.setString(i, obj.toString());
+                continue;
+            }
+
+            if (obj instanceof Date) {
+                preparedStatement.setDate(i, (java.sql.Date) obj);
+            }
+
+        }
+
+    }
+
+    private <T> List<T> resultSet2Obj(ResultSet resultSet, Class<?> clazz) {
+        List<T> list = new ArrayList<>();
+        try {
+            ResultSetMetaData metaData = resultSet.getMetaData();
+            int columnCount = metaData.getColumnCount();
+            // 每次遍历行值
+            while (resultSet.next()) {
+                T obj = (T) clazz.newInstance();
+                for (int i = 1; i <= columnCount; i++) {
+                    Object value = resultSet.getObject(i);
+                    String columnName = metaData.getColumnName(i);
+                    String setMethod = "set" + columnName.substring(0, 1).toUpperCase() + columnName.substring(1);
+                    Method method;
+                    if (value instanceof Timestamp) {
+                        method = clazz.getMethod(setMethod, Date.class);
+                    } else {
+                        method = clazz.getMethod(setMethod, value.getClass());
+                    }
+                    method.invoke(obj, value);
+                }
+                list.add(obj);
+            }
+        } catch (Exception e) {
+            e.printStackTrace();
+        }
+        return list;
+    }
+
+    @Override
+    public void close() {
+        if (null == connection) return;
+        try {
+            connection.close();
+        } catch (SQLException e) {
+            e.printStackTrace();
+        }
+    }
+}

mybatis-step-01/src/main/java/cn/bugstack/mybatis/DefaultSqlSessionFactory.java

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+package cn.bugstack.mybatis;
+
+public class DefaultSqlSessionFactory implements SqlSessionFactory {
+
+    private final Configuration configuration;
+
+    public DefaultSqlSessionFactory(Configuration configuration) {
+        this.configuration = configuration;
+    }
+
+    @Override
+    public SqlSession openSession() {
+        return new DefaultSqlSession(configuration.connection, configuration.mapperElement);
+    }
+
+}

mybatis-step-01/src/main/java/cn/bugstack/mybatis/Resources.java

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+package cn.bugstack.mybatis;
+
+import java.io.IOException;
+import java.io.InputStream;
+import java.io.InputStreamReader;
+import java.io.Reader;
+
+public class Resources {
+
+    public static Reader getResourceAsReader(String resource) throws IOException {
+        return new InputStreamReader(getResourceAsStream(resource));
+    }
+
+    private static InputStream getResourceAsStream(String resource) throws IOException {
+        ClassLoader[] classLoaders = getClassLoaders();
+        for (ClassLoader classLoader : classLoaders) {
+            InputStream inputStream = classLoader.getResourceAsStream(resource);
+            if (null != inputStream) {
+                return inputStream;
+            }
+        }
+        throw new IOException("Could not find resource " + resource);
+    }
+
+    private static ClassLoader[] getClassLoaders() {
+        return new ClassLoader[]{
+                ClassLoader.getSystemClassLoader(),
+                Thread.currentThread().getContextClassLoader()};
+    }
+
+}