mybatis之bind模块
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mybatis之bind模块
mybatis通过定义接口mapper,不需要继承或实现接口,Mapper接口中的方法定义select|update|insert|delete方法,通过关联映射文件中定义的sql来执行查询。
.....org.apache.ibats
....................binding
...........................BindingException
...........................MapperMethod
...........................MapperProxy
...........................MapperProxyFactory
...........................MapperRegistry
执行流程
public class MybatisUse
public static void main(String[] args) throws Exception
//加载mybatis的配置文件
String mybatisXml = "mybatis.xml";
InputStream inputStream = Resources.getResourceAsStream(mybatisXml);
SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream);
//获取sqlSession的实现DefaultSqlSession
SqlSession sqlSession = sqlSessionFactory.openSession();
//通过MapperRegistry获取到Mapper的代理
CleanPolicyMapper cleanPolicyMapper = sqlSession.getMapper(CleanPolicyMapper.class);
// 通过MapperMethod执行查询、更新、插入、删除方法逻辑
CleanPolicy cleanPolicy = cleanPolicyMapper.selectById(292L);
System.out.println("name:" + cleanPolicy.getName());
sqlSession.commit();
sqlSession.flushStatements();
sqlSession.close();
来大体看看调用过程
CleanPolicyMapper cleanPolicyMapper = sqlSession.getMapper(CleanPolicyMapper.class);
//DefaultSqlSession
public class DefaultSqlSession implements SqlSession
@Override
public <T> T getMapper(Class<T> type)
return configuration.<T>getMapper(type, this);
public class Configuration
public <T> T getMapper(Class<T> type, SqlSession sqlSession)
return mapperRegistry.getMapper(type, sqlSession);
public class MapperRegistry
public <T> T getMapper(Class<T> type, SqlSession sqlSession)
//查询接口对应的代理工厂(有保存对应的接口)
final MapperProxyFactory<T> mapperProxyFactory = (MapperProxyFactory<T>) knownMappers.get(type);
if (mapperProxyFactory == null)
throw new BindingException("Type " + type + " is not known to the MapperRegistry.");
try
//通过代理工厂实例化代理对象
return mapperProxyFactory.newInstance(sqlSession);
catch (Exception e)
throw new BindingException("Error getting mapper instance. Cause: " + e, e);
//调用接口对应的方法
CleanPolicy cleanPolicy = cleanPolicyMapper.selectById(292L);
//CleanPolicy ---> 对应这里的MapperProxy对象
public class MapperProxy<T> implements InvocationHanlder, Serializable
//代理调用方法
@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 (isDefaultMethod(method))
return invokeDefaultMethod(proxy, method, args);
catch (Throwable t)
throw ExceptionUtil.unwrapThrowable(t);
final MapperMethod mapperMethod = cachedMapperMethod(method);
//调用执行方法
return mapperMethod.execute(sqlSession, args);
public class MapperMethod
//根据执行选择对应的方法
public Object execute(SqlSession sqlSession, Object[] args)
Object result;
switch (command.getType())
case INSERT:
Object param = method.convertArgsToSqlCommandParam(args);
result = rowCountResult(sqlSession.insert(command.getName(), param));
break;
case UPDATE:
Object param = method.convertArgsToSqlCommandParam(args);
result = rowCountResult(sqlSession.update(command.getName(), param));
break;
case DELETE:
Object param = method.convertArgsToSqlCommandParam(args);
result = rowCountResult(sqlSession.delete(command.getName(), param));
break;
case SELECT:
if (method.returnsVoid() && method.hasResultHandler())
executeWithResultHandler(sqlSession, args);
result = null;
else if (method.returnsMany())
result = executeForMany(sqlSession, args);
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);
break;
case FLUSH:
result = sqlSession.flushStatements();
break;
default:
throw new BindingException("Unknown execution method for: " + command.getName());
if (result == null && method.getReturnType().isPrimitive() && !method.returnsVoid())
throw new BindingException("Mapper method '" + command.getName()
+ " attempted to return null from a method with a primitive return type (" + method.getReturnType() + ").");
return result;
classDiagram
MapperRegistry *-- MapperProxyFactory
MapperProxyFactory <.. MapperProxy
MapperProxy *-- MapperMethod
MapperProxyFactory *-- MapperMethod
MapperRegistry
MapperRegistry映射注册器核心两个方法getMapper和addMapper
public class MapperRegistry
private final Configuration config;
private final Map<Class<?>, MapperProxyFactory<?>> knownMappers = new HashMap<Class<?>, MapperProxyFactory<?>>();
// 查询mapper接口的代理对象
public <T> T getMapper(Class<T> type, SqlSession sqlSession)
final MapperProxyFactory<T> mapperProxyFactory = (MapperProxyFactory<T>) knownMappers.get(type);
if (mapperProxyFactory == null)
throw new BindingException("Type " + type + " is not known to the MapperRegistry.");
try
return mapperProxyFactory.newInstance(sqlSession);
catch (Exception e)
throw new BindingException("Error getting mapper instance. Cause: " + e, e);
//插入mapper的代理对象,addMapper调用的时机是解析mybatis.xml时
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