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AccountMapper

从图中可知，AccountMapper的代理就是1个MapperProxy

主线流程

MapperProxy

public class MapperProxy
   
     implements InvocationHandler, Serializable {  private static final long serialVersionUID = -6424540398559729838L;  private final SqlSession sqlSession;  private final Class
    
      mapperInterface;  private final Map
     
       methodCache;  public MapperProxy(SqlSession sqlSession, Class
      
        mapperInterface, Map
       
         methodCache) {    this.sqlSession = sqlSession;    this.mapperInterface = mapperInterface;    this.methodCache = methodCache;  }  @Override  public Object invoke(Object proxy, Method method, Object[] args) throws Throwable {    try {      if (Object.class.equals(method.getDeclaringClass())) {        return method.invoke(this, args);      } else if (method.isDefault()) { // 如果是默认的方法则执行invokeDefaultMethod        return invokeDefaultMethod(proxy, method, args);      }    } catch (Throwable t) {      throw ExceptionUtil.unwrapThrowable(t);    }    final MapperMethod mapperMethod = cachedMapperMethod(method); // 先从缓存取，缓存不存在，则初始化1个    return mapperMethod.execute(sqlSession, args);  }  private MapperMethod cachedMapperMethod(Method method) {    return methodCache.computeIfAbsent(method, k -> new MapperMethod(mapperInterface, method, sqlSession.getConfiguration()));  }  private Object invokeDefaultMethod(Object proxy, Method method, Object[] args)      throws Throwable {    final Constructor
        
          constructor = MethodHandles.Lookup.class .getDeclaredConstructor(Class.class, int.class); if (!constructor.isAccessible()) { constructor.setAccessible(true); } final Class
          declaringClass = method.getDeclaringClass(); return constructor .newInstance(declaringClass, MethodHandles.Lookup.PRIVATE | MethodHandles.Lookup.PROTECTED | MethodHandles.Lookup.PACKAGE | MethodHandles.Lookup.PUBLIC) .unreflectSpecial(method, declaringClass).bindTo(proxy).invokeWithArguments(args); }}
        
       
      
     
    
   

MapperProxy实现了InvocationHandler接口，是动态代理对象

MapperMethod

public class MapperMethod {  private final SqlCommand command;  private final MethodSignature method;  public MapperMethod(Class
    mapperInterface, Method method, Configuration config) {    this.command = new SqlCommand(config, mapperInterface, method);    this.method = new MethodSignature(config, mapperInterface, method);  }  public Object execute(SqlSession sqlSession, Object[] args) {    Object result;    switch (command.getType()) {      .....................      case SELECT:        if (method.returnsVoid() && method.hasResultHandler()) {          executeWithResultHandler(sqlSession, args);          result = null;        } else if (method.returnsMany()) {          result = executeForMany(sqlSession, args);  //这里        } else if (method.returnsMap()) {          result = executeForMap(sqlSession, args);        } else if (method.returnsCursor()) {          result = executeForCursor(sqlSession, args);        } else {          Object param = method.convertArgsToSqlCommandParam(args);          result = sqlSession.selectOne(command.getName(), param);          if (method.returnsOptional()              && (result == null || !method.getReturnType().equals(result.getClass()))) {            result = Optional.ofNullable(result);          }        }        break;      .....................    }        return result;  }

private 
   
     Object executeForMany(SqlSession sqlSession, Object[] args) {    List
    
      result;    Object param = method.convertArgsToSqlCommandParam(args);    if (method.hasRowBounds()) { // 判断当前方法是不是分页方法      RowBounds rowBounds = method.extractRowBounds(args);      result = sqlSession.selectList(command.getName(), param, rowBounds);    } else { // 不是分页方法      result = sqlSession.selectList(command.getName(), param);    }    // issue #510 Collections & arrays support    if (!method.getReturnType().isAssignableFrom(result.getClass())) {      if (method.getReturnType().isArray()) {        return convertToArray(result);      } else {        return convertToDeclaredCollection(sqlSession.getConfiguration(), result);      }    }    return result;  }
    
   

SqlSessionTemplate

private class SqlSessionInterceptor implements InvocationHandler {    @Override    public Object invoke(Object proxy, Method method, Object[] args) throws Throwable {      SqlSession sqlSession = getSqlSession(SqlSessionTemplate.this.sqlSessionFactory,          SqlSessionTemplate.this.executorType, SqlSessionTemplate.this.exceptionTranslator);      try {        Object result = method.invoke(sqlSession, args);        if (!isSqlSessionTransactional(sqlSession, SqlSessionTemplate.this.sqlSessionFactory)) {          // force commit even on non-dirty sessions because some databases require          // a commit/rollback before calling close()          sqlSession.commit(true);        }        return result;      } catch (Throwable t) {        ............................        throw unwrapped;      } finally {        if (sqlSession != null) {          closeSqlSession(sqlSession, SqlSessionTemplate.this.sqlSessionFactory);        }      }    }  }

BaseExecutor

public abstract class BaseExecutor implements Executor {@Override  public 
   
     List
    
      query(MappedStatement ms, Object parameter, RowBounds rowBounds, ResultHandler resultHandler, CacheKey key, BoundSql boundSql) throws SQLException {    ...........................        List
     
       list;    try {      queryStack++;      list = resultHandler == null ? (List
      
       ) localCache.getObject(key) : null;      if (list != null) { //缓存不为null，从缓存取        handleLocallyCachedOutputParameters(ms, key, parameter, boundSql);      } else { // 查库        list = queryFromDatabase(ms, parameter, rowBounds, resultHandler, key, boundSql);      }    } finally {      queryStack--;    }    ...........................        return list;  }private 
       
         List
        
          queryFromDatabase(MappedStatement ms, Object parameter, RowBounds rowBounds, ResultHandler resultHandler, CacheKey key, BoundSql boundSql) throws SQLException { List
         
           list; localCache.putObject(key, EXECUTION_PLACEHOLDER); try { list = doQuery(ms, parameter, rowBounds, resultHandler, boundSql); } finally { localCache.removeObject(key); } localCache.putObject(key, list); if (ms.getStatementType() == StatementType.CALLABLE) { localOutputParameterCache.putObject(key, parameter); } return list; }}
         
        
       
      
     
    
   

SimpleExecutor

public class SimpleExecutor extends BaseExecutor {@Override  public 
   
     List
    
      doQuery(MappedStatement ms, Object parameter, RowBounds rowBounds, ResultHandler resultHandler, BoundSql boundSql) throws SQLException {    Statement stmt = null;    try {      Configuration configuration = ms.getConfiguration();      StatementHandler handler = configuration.newStatementHandler(wrapper, ms, parameter, rowBounds, resultHandler, boundSql); //创建StatementHandler代理类      stmt = prepareStatement(handler, ms.getStatementLog());      return handler.query(stmt, resultHandler);    } finally {      closeStatement(stmt);    }  }private Statement prepareStatement(StatementHandler handler, Log statementLog) throws SQLException {    Statement stmt;    Connection connection = getConnection(statementLog); //创建动态代理创建出来的是ConnectionLogger    stmt = handler.prepare(connection, transaction.getTimeout());    handler.parameterize(stmt);    return stmt;  }}
    
   

RoutingStatementHandler

public class RoutingStatementHandler implements StatementHandler {  private final StatementHandler delegate;  public RoutingStatementHandler(Executor executor, MappedStatement ms, Object parameter, RowBounds rowBounds, ResultHandler resultHandler, BoundSql boundSql) {    switch (ms.getStatementType()) {      case STATEMENT:        delegate = new SimpleStatementHandler(executor, ms, parameter, rowBounds, resultHandler, boundSql);        break;      case PREPARED:        delegate = new PreparedStatementHandler(executor, ms, parameter, rowBounds, resultHandler, boundSql);        break;      case CALLABLE:        delegate = new CallableStatementHandler(executor, ms, parameter, rowBounds, resultHandler, boundSql);        break;      default:        throw new ExecutorException("Unknown statement type: " + ms.getStatementType());    }  }  @Override  public Statement prepare(Connection connection, Integer transactionTimeout) throws SQLException {    return delegate.prepare(connection, transactionTimeout);  }  @Override  public void parameterize(Statement statement) throws SQLException {    delegate.parameterize(statement);  }  @Override  public void batch(Statement statement) throws SQLException {    delegate.batch(statement);  }  @Override  public int update(Statement statement) throws SQLException {    return delegate.update(statement);  }  @Override  public 
   
     List
    
      query(Statement statement, ResultHandler resultHandler) throws SQLException {    return delegate.query(statement, resultHandler);  }  @Override  public 
     
       Cursor
      
        queryCursor(Statement statement) throws SQLException {    return delegate.queryCursor(statement);  }  @Override  public BoundSql getBoundSql() {    return delegate.getBoundSql();  }  @Override  public ParameterHandler getParameterHandler() {    return delegate.getParameterHandler();  }}
      
     
    
   

PreparedStatementHandler

public class PreparedStatementHandler extends BaseStatementHandler {..........................@Override  public 
   
     List
    
      query(Statement statement, ResultHandler resultHandler) throws SQLException {    PreparedStatement ps = (PreparedStatement) statement;    ps.execute();    return resultSetHandler.handleResultSets(ps);  }..........................}
    
   

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