插件支持

README.md

@@ -8,3 +8,4 @@
 [5.resultType结果集处理](https://github.com/FuriousPws002/mini-mybatis/wiki/5.resultType%E7%BB%93%E6%9E%9C%E9%9B%86%E5%A4%84%E7%90%86 "Markdown") <br>
 [6.resultMap结果集处理](https://github.com/FuriousPws002/mini-mybatis/wiki/6.resultMap%E7%BB%93%E6%9E%9C%E9%9B%86%E5%A4%84%E7%90%86 "Markdown") <br>
 [7.动态sql](https://github.com/FuriousPws002/mini-mybatis/wiki/7.%E5%8A%A8%E6%80%81sql "Markdown") <br>
+[8.插件支持](https://github.com/FuriousPws002/mini-mybatis/wiki/8.%E6%8F%92%E4%BB%B6%E6%94%AF%E6%8C%81 "Markdown") <br>

src/main/java/org/apache/ibatis/executor/statement/PrepareStatementHandler.java

@@ -61,4 +61,9 @@ public <T> List<T> query(Statement statement) throws SQLException {
         ps.execute();
         return resultSetHandler.handleResultSets(ps);
     }
+
+    @Override
+    public BoundSql getBoundSql() {
+        return boundSql;
+    }
 }

src/main/java/org/apache/ibatis/executor/statement/StatementHandler.java

@@ -5,6 +5,8 @@
 import java.sql.Statement;
 import java.util.List;
 
+import org.apache.ibatis.mapping.BoundSql;
+
 /**
  * @author furious 2024/4/8
  */
@@ -17,4 +19,6 @@ public interface StatementHandler {
     void parameterize(Statement statement) throws SQLException;
 
     <T> List<T> query(Statement statement) throws SQLException;
+
+    BoundSql getBoundSql();
 }

src/main/java/org/apache/ibatis/plugin/Interceptor.java

@@ -0,0 +1,17 @@
+package org.apache.ibatis.plugin;
+
+import org.apache.ibatis.session.Configuration;
+
+/**
+ * @author furious 2024/4/19
+ */
+public interface Interceptor {
+
+    String pointcut();
+
+    Object intercept(Invocation invocation) throws Throwable;
+
+    default Object plugin(Object target, Configuration configuration) {
+        return Plugin.wrap(target, configuration, this);
+    }
+}

src/main/java/org/apache/ibatis/plugin/InterceptorChain.java

@@ -0,0 +1,30 @@
+package org.apache.ibatis.plugin;
+
+import java.util.ArrayList;
+import java.util.List;
+
+import org.apache.ibatis.session.Configuration;
+
+/**
+ * @author furious 2024/4/19
+ */
+public class InterceptorChain {
+
+    private final Configuration configuration;
+    private final List<Interceptor> interceptors = new ArrayList<>();
+
+    public InterceptorChain(Configuration configuration) {
+        this.configuration = configuration;
+    }
+
+    public <T> T pluginAll(Object target) {
+        for (Interceptor interceptor : interceptors) {
+            target = interceptor.plugin(target, configuration);
+        }
+        return (T) target;
+    }
+
+    public void addInterceptor(Interceptor interceptor) {
+        interceptors.add(interceptor);
+    }
+}

src/main/java/org/apache/ibatis/plugin/Plugin.java

@@ -0,0 +1,44 @@
+package org.apache.ibatis.plugin;
+
+import java.lang.reflect.InvocationHandler;
+import java.lang.reflect.Method;
+import java.lang.reflect.Proxy;
+import java.util.Objects;
+
+import org.apache.ibatis.session.Configuration;
+
+/**
+ * @author furious 2024/4/19
+ */
+public class Plugin implements InvocationHandler {
+
+    private final Object target;
+    private final Configuration configuration;
+    private final Interceptor interceptor;
+
+    public Plugin(Object target, Configuration configuration, Interceptor interceptor) {
+        this.target = target;
+        this.configuration = configuration;
+        this.interceptor = interceptor;
+    }
+
+    public static Object wrap(Object target, Configuration configuration, Interceptor interceptor) {
+        String pointcut = interceptor.pointcut();
+        PointcutDefinition definition = configuration.getPointcutRegistry().getDefinition(pointcut);
+        //不是当前接口类型不代理
+        if (!definition.getType().isAssignableFrom(target.getClass())) {
+            return target;
+        }
+        return Proxy.newProxyInstance(target.getClass().getClassLoader(), new Class<?>[]{definition.getType()}, new Plugin(target, configuration, interceptor));
+    }
+
+    @Override
+    public Object invoke(Object proxy, Method method, Object[] args) throws Throwable {
+        PointcutDefinition definition = configuration.getPointcutRegistry().getDefinition(interceptor.pointcut());
+        if (!Objects.equals(definition.getId(), PointcutDefinition.id(method))) {
+            //没有代理该方法，直接返回
+            return method.invoke(target, args);
+        }
+        return interceptor.intercept(new Invocation(target, method, args));
+    }
+}

src/main/java/org/apache/ibatis/session/Configuration.java

@@ -18,6 +18,10 @@
 import org.apache.ibatis.mapping.BoundSql;
 import org.apache.ibatis.mapping.MappedStatement;
 import org.apache.ibatis.mapping.ResultMap;
+import org.apache.ibatis.plugin.Interceptor;
+import org.apache.ibatis.plugin.InterceptorChain;
+import org.apache.ibatis.plugin.Plugin;
+import org.apache.ibatis.plugin.PointcutRegistry;
 import org.apache.ibatis.scripting.LanguageDriver;
 import org.apache.ibatis.scripting.xmltags.XMLLanguageDriver;
 import org.apache.ibatis.type.TypeHandlerRegistry;
@@ -37,6 +41,8 @@ public class Configuration {
     private final TypeHandlerRegistry typeHandlerRegistry = new TypeHandlerRegistry();
     private final LanguageDriver languageDriver = new XMLLanguageDriver();
     private final Map<String, ResultMap> resultMaps = new HashMap<>();
+    private final PointcutRegistry pointcutRegistry = new PointcutRegistry();
+    private final InterceptorChain interceptorChain = new InterceptorChain(this);
 
     public Configuration() {
     }
@@ -82,7 +88,9 @@ public void setDataSource(DataSource dataSource) {
     }
 
     public StatementHandler newStatementHandler(Executor executor, MappedStatement mappedStatement, Object parameterObject, BoundSql boundSql) {
-        return new PrepareStatementHandler(executor, mappedStatement, parameterObject, boundSql);
+        StatementHandler statementHandler = new PrepareStatementHandler(executor, mappedStatement, parameterObject, boundSql);
+        statementHandler = interceptorChain.pluginAll(statementHandler);
+        return statementHandler;
     }
 
     public ParameterHandler newParameterHandler(MappedStatement mappedStatement, Object parameterObject, BoundSql boundSql) {
@@ -108,4 +116,12 @@ public void addResultMap(ResultMap resultMap) {
     public ResultMap getResultMap(String id) {
         return resultMaps.get(id);
     }
+
+    public PointcutRegistry getPointcutRegistry() {
+        return pointcutRegistry;
+    }
+
+    public void addInterceptor(Interceptor interceptor) {
+        interceptorChain.addInterceptor(interceptor);
+    }
 }

src/test/java/org/apache/ibatis/plugin/PageInterceptor.java

@@ -0,0 +1,28 @@
+package org.apache.ibatis.plugin;
+
+import java.sql.Connection;
+
+import org.apache.ibatis.executor.statement.StatementHandler;
+import org.apache.ibatis.mapping.BoundSql;
+
+/**
+ * @author furious 2024/4/19
+ */
+public class PageInterceptor implements Interceptor {
+    @Override
+    public String pointcut() {
+        return PointcutRegistry.StatementHandler_prepare_Connection_Integer;
+    }
+
+    @Override
+    public Object intercept(Invocation invocation) throws Throwable {
+        StatementHandler statementHandler = invocation.getTarget();
+        BoundSql original = statementHandler.getBoundSql();
+        Object[] args = invocation.getArgs();
+        Connection connection = (Connection) args[0];
+        //不判读是否为select语句，limit仅为示范参数
+        String sql = original.getSql();
+        sql += " LIMIT 1,1";
+        return connection.prepareStatement(sql);
+    }
+}

src/test/java/org/apache/ibatis/session/SqlSessionTest.java

@@ -7,6 +7,7 @@
 import org.apache.ibatis.dao.UserMapper;
 import org.apache.ibatis.entity.UserDO;
 import org.apache.ibatis.entity.UserDTO;
+import org.apache.ibatis.plugin.PageInterceptor;
 import org.apache.ibatis.session.defaults.DefaultSqlSession;
 import org.junit.Assert;
 import org.junit.Test;
@@ -158,6 +159,23 @@ public void queryForeachTag() {
         Assert.assertNotNull(list);
     }
 
+    @Test
+    public void queryPointcut() {
+        Configuration configuration = new Configuration();
+        configuration.addInterceptor(new PageInterceptor());
+        configuration.setDataSource(DataSourceBuilderTest.build());
+        configuration.addMapper(UserMapper.class);
+        SqlSession sqlSession = new DefaultSqlSession(configuration);
+        UserMapper userMapper = sqlSession.getMapper(UserMapper.class);
+        List<Long> idList = new ArrayList<>();
+        idList.add(1L);
+        idList.add(2L);
+        List<UserDO> list = userMapper.listForeach(idList);
+        Assert.assertNotNull(list);
+        Assert.assertEquals(list.size(), 1);
+    }
+
+
     private UserMapper getUserMapper() {
         Configuration configuration = new Configuration();
         configuration.setDataSource(DataSourceBuilderTest.build());