public class MapperProxy<T> implements InvocationHandler {
     @Override
     public Object invoke(Object proxy, Method method, Object[] args) throws Throwable {
         // 在這里設(shè)置行斷點(diǎn) - 觀察所有Mapper方法調(diào)用
         final MapperMethod mapperMethod = cachedMapperMethod(method);
         return mapperMethod.execute(sqlSession, args);
     }
 }

 // 只在用戶ID為100時(shí)觸發(fā)斷點(diǎn)
 "user".equals(parameter.getUserType()) && parameter.getUserId() == 100

 // 只在通過特定Service方法調(diào)用時(shí)觸發(fā)
 Thread.currentThread().getStackTrace()[3].getMethodName().equals("findActiveUsers")

 // 只在執(zhí)行時(shí)間超過閾值時(shí)觸發(fā)
 System.currentTimeMillis() - startTime > 1000

 public class SimpleExecutor extends BaseExecutor {
     @Override
     public <E> List<E> doQuery(MappedStatement ms, Object parameter, 
                               RowBounds rowBounds, ResultHandler resultHandler, 
                               BoundSql boundSql) throws SQLException {
         // 在調(diào)試時(shí)評(píng)估表達(dá)式：
         // boundSql.getSql() - 查看生成的SQL
         // parameter.toString() - 查看參數(shù)詳情
         // ms.getSqlSource().getClass().getSimpleName() - 查看SqlSource類型
         Statement stmt = null;
         try {
             Configuration configuration = ms.getConfiguration();
             // ...
         } finally {
             closeStatement(stmt);
         }
     }
 }

 MapperProxy.invoke() 
 → MapperMethod.execute() 
 → SqlSession.selectList() 
 → Executor.query() 
 → CachingExecutor.query() 
 → BaseExecutor.query() 
 → SimpleExecutor.doQuery() 
 → StatementHandler.query() 
 → PreparedStatement.execute()

 public class MapperProxy<T> implements InvocationHandler {
     @Override
     public Object invoke(Object proxy, Method method, Object[] args) throws Throwable {
         // 觀察信息：
         // - method: 被調(diào)用的接口方法
         // - args: 方法參數(shù)數(shù)組
         // - method.getDeclaringClass(): Mapper接口類
         try {
             if (Object.class.equals(method.getDeclaringClass())) {
                 return method.invoke(this, args);
             }
             return cachedMapperMethod(method).execute(sqlSession, args);
         } catch (Throwable t) {
             throw ExceptionUtil.unwrapThrowable(t);
         }
     }
 }

public class CachingExecutor implements Executor {
    @Override
    public <E> List<E> query(MappedStatement ms, Object parameter, 
                            RowBounds rowBounds, ResultHandler resultHandler, 
                            CacheKey key, BoundSql boundSql) throws SQLException {
        // 觀察信息：
        // - ms: 映射語(yǔ)句配置
        // - key: 緩存鍵（決定緩存命中的關(guān)鍵）
        // - boundSql: 最終執(zhí)行的SQL信息
        Cache cache = ms.getCache();
        if (cache != null) {
            flushCacheIfRequired(ms);
            if (ms.isUseCache() && resultHandler == null) {
                ensureNoOutParams(ms, boundSql);
                @SuppressWarnings("unchecked")
                List<E> list = (List<E>) cache.getObject(key);
                if (list == null) {
                    list = delegate.query(ms, parameter, rowBounds, resultHandler, key, boundSql);
                    cache.putObject(key, list);
                }
                return list;
            }
        }
        return delegate.query(ms, parameter, rowBounds, resultHandler, key, boundSql);
    }
}

at com.example.mapper.UserMapper.findById (UserMapper.java)  
at sun.reflect.NativeMethodAccessorImpl.invoke0 (Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke (NativeMethodAccessorImpl.java:62)
at sun.reflect.DelegatingMethodAccessorImpl.invoke (DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke (Method.java:498)
at org.apache.ibatis.binding.MapperProxy.invoke (MapperProxy.java:59)
at com.sun.proxy.$Proxy123.findById (Unknown Source)
at com.example.service.UserService.getUserById (UserService.java:38)

// 條件斷點(diǎn)：只在特定線程中觸發(fā)
Thread.currentThread().getName().equals("http-nio-8080-exec-1")
 
// 觀察ThreadLocal中的資源管理
SqlSessionUtils.getSqlSession(SqlSessionFactory sessionFactory, 
                             ExecutorType executorType, 
                             PersistenceExceptionTranslator exceptionTranslator)

public class DynamicSqlSource implements SqlSource {
    @Override
    public BoundSql getBoundSql(Object parameterObject) {
        DynamicContext context = new DynamicContext(configuration, parameterObject);
        
        // 在這里設(shè)置斷點(diǎn)，觀察SqlNode樹的處理過程
        rootSqlNode.apply(context);
        
        // 評(píng)估表達(dá)式：context.getSql() 查看生成的SQL
        SqlSourceBuilder sqlSourceParser = new SqlSourceBuilder(configuration);
        Class<?> parameterType = parameterObject == null ? Object.class : parameterObject.getClass();
        SqlSource sqlSource = sqlSourceParser.parse(context.getSql(), parameterType, context.getBindings());
        
        return sqlSource.getBoundSql(parameterObject);
    }
}

public class CachingExecutor implements Executor {
    private long lastQueryTime = 0;
    
    @Override
    public <E> List<E> query(MappedStatement ms, Object parameter, 
                            RowBounds rowBounds, ResultHandler resultHandler, 
                            CacheKey key, BoundSql boundSql) throws SQLException {
        long startTime = System.currentTimeMillis();
        
        // 條件斷點(diǎn)：查詢耗時(shí)超過100ms
        // System.currentTimeMillis() - startTime > 100
        try {
            // 執(zhí)行查詢
            return delegate.query(ms, parameter, rowBounds, resultHandler, key, boundSql);
        } finally {
            long cost = System.currentTimeMillis() - startTime;
            lastQueryTime = cost;
        }
    }
}