資訊專欄INFORMATION COLUMN
摘要：提供一個(gè)接口查詢接口如何生成對(duì)象采用的動(dòng)態(tài)代理技術(shù)生成對(duì)象使用動(dòng)態(tài)代理可以實(shí)現(xiàn)在不提供接口的時(shí)候生成對(duì)象構(gòu)建過(guò)程在源代碼中是通過(guò)出一個(gè)對(duì)象然后調(diào)用方法進(jìn)入重寫(xiě)的方法通過(guò)這一句配置文件讀入所有的都將會(huì)調(diào)用該方法這一段中這一句配置讀入進(jìn)入由
提供一個(gè)接口
package com.ming.MyBatis;
import com.ming.MyBatis.POJO.Role;
import com.ming.MyBatis.POJO.Student;
import com.ming.MyBatis.POJO.StudentCard;
import org.apache.ibatis.annotations.Param;
import java.util.List;
import java.util.Map;
public interface RoleMapper {
/**
* @param id
* @return
*/
public Role getRole(int id);
/**
* 查詢Map
* @param params
* @return
*/
public List findRoleByteMap(Map params);
/**
* @param roleName
* @param note
* @return
*/
public List findRoleByteMap1(@Param("roleName") String roleName, @Param("note") String note);
public List findStudentSelfCardByStudentId(@Param("studentId") int studentId);
public List getStudent(@Param("uid")int uid);
}
接口如何生成對(duì)象,采用jdk的動(dòng)態(tài)代理技術(shù),生成對(duì)象
CGLB使用CGLB動(dòng)態(tài)代理可以實(shí)現(xiàn)在不提供接口的時(shí)候,生成對(duì)象
構(gòu)建SqlSessionFactory過(guò)程在源代碼中是
sqlSessionFactory = new SqlSessionFactoryBuilder().build(cfgReader, properties);
通過(guò)new 出一個(gè) SqlSessionFactoryBuilder對(duì)象,然后調(diào)用build方法.
進(jìn)入 SqlSessionFactoryBuilder
/**
* Copyright 2009-2019 the original author or authors.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.apache.ibatis.session;
import java.io.IOException;
import java.io.InputStream;
import java.io.Reader;
import java.util.Properties;
import org.apache.ibatis.builder.xml.XMLConfigBuilder;
import org.apache.ibatis.exceptions.ExceptionFactory;
import org.apache.ibatis.executor.ErrorContext;
import org.apache.ibatis.session.defaults.DefaultSqlSessionFactory;
/**
* Builds {@link SqlSession} instances.
*
* @author Clinton Begin
*/
public class SqlSessionFactoryBuilder {
public SqlSessionFactory build(Reader reader) {
return build(reader, null, null);
}
public SqlSessionFactory build(Reader reader, String environment) {
return build(reader, environment, null);
}
public SqlSessionFactory build(Reader reader, Properties properties) {
return build(reader, null, properties);
}
public SqlSessionFactory build(Reader reader, String environment, Properties properties) {
try {
XMLConfigBuilder parser = new XMLConfigBuilder(reader, environment, properties);
return build(parser.parse());
} catch (Exception e) {
throw ExceptionFactory.wrapException("Error building SqlSession.", e);
} finally {
ErrorContext.instance().reset();
try {
reader.close();
} catch (IOException e) {
// Intentionally ignore. Prefer previous error.
}
}
}
public SqlSessionFactory build(InputStream inputStream) {
return build(inputStream, null, null);
}
public SqlSessionFactory build(InputStream inputStream, String environment) {
return build(inputStream, environment, null);
}
public SqlSessionFactory build(InputStream inputStream, Properties properties) {
return build(inputStream, null, properties);
}
public SqlSessionFactory build(InputStream inputStream, String environment, Properties properties) {
try {
XMLConfigBuilder parser = new XMLConfigBuilder(inputStream, environment, properties);
return build(parser.parse());
} catch (Exception e) {
throw ExceptionFactory.wrapException("Error building SqlSession.", e);
} finally {
ErrorContext.instance().reset();
try {
inputStream.close();
} catch (IOException e) {
// Intentionally ignore. Prefer previous error.
}
}
}
public SqlSessionFactory build(Configuration config) {
return new DefaultSqlSessionFactory(config);
}
}
重寫(xiě)的方法
通過(guò)這一句配置文件讀入
XMLConfigBuilder parser = new XMLConfigBuilder(reader, environment, properties);
所有的都將會(huì)調(diào)用該方法
public SqlSessionFactory build(InputStream inputStream, String environment, Properties properties) {
try {
XMLConfigBuilder parser = new XMLConfigBuilder(inputStream, environment, properties);
return build(parser.parse());
} catch (Exception e) {
throw ExceptionFactory.wrapException("Error building SqlSession.", e);
} finally {
ErrorContext.instance().reset();
try {
inputStream.close();
} catch (IOException e) {
// Intentionally ignore. Prefer previous error.
}
}
}
這一段中
XMLConfigBuilder parser = new XMLConfigBuilder(inputStream, environment, properties);
這一句
XML配置讀入進(jìn)入
由于返回的是XMLConfigBuilder對(duì)象 所以是使用該對(duì)象去創(chuàng)建SqlSessionFactory對(duì)象
其中SqlSessionFactory為接口
/**
* Copyright 2009-2019 the original author or authors.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.apache.ibatis.session;
import java.sql.Connection;
/**
* Creates an {@link SqlSession} out of a connection or a DataSource
*
* @author Clinton Begin
*/
public interface SqlSessionFactory {
SqlSession openSession();
SqlSession openSession(boolean autoCommit);
SqlSession openSession(Connection connection);
SqlSession openSession(TransactionIsolationLevel level);
SqlSession openSession(ExecutorType execType);
SqlSession openSession(ExecutorType execType, boolean autoCommit);
SqlSession openSession(ExecutorType execType, TransactionIsolationLevel level);
SqlSession openSession(ExecutorType execType, Connection connection);
Configuration getConfiguration();
}
其中根據(jù)源碼可以看到XMLConfigBuilder對(duì)象繼承于BaseBuilder, BaseBuilder為抽象類 其中的BaseBuilder 繼承 XMLConfigBuilder
所以,這兩句成立
private volatile static SqlSessionFactory sqlSessionFactory = null; sqlSessionFactory = new SqlSessionFactoryBuilder().build(cfgReader, properties);
最后就有了SqlSessionFactory實(shí)現(xiàn)類
這種創(chuàng)建為Builder創(chuàng)建
進(jìn)入XMLConfigBuilder 可以看到第115行
// read it after objectFactory and objectWrapperFactory issue #631
environmentsElement(root.evalNode("environments"));
可以看到讀入配置文件environments節(jié)點(diǎn)
其中還可以看到
private XMLConfigBuilder(XPathParser parser, String environment, Properties props) {
super(new Configuration());
ErrorContext.instance().resource("SQL Mapper Configuration");
this.configuration.setVariables(props);
this.parsed = false;
this.environment = environment;
this.parser = parser;
}
使用的是super 所以進(jìn)入 Configuration()對(duì)象
可以看到這是所有的配置文件
public Configuration() {
typeAliasRegistry.registerAlias("JDBC", JdbcTransactionFactory.class);
typeAliasRegistry.registerAlias("MANAGED", ManagedTransactionFactory.class);
typeAliasRegistry.registerAlias("JNDI", JndiDataSourceFactory.class);
typeAliasRegistry.registerAlias("POOLED", PooledDataSourceFactory.class);
typeAliasRegistry.registerAlias("UNPOOLED", UnpooledDataSourceFactory.class);
typeAliasRegistry.registerAlias("PERPETUAL", PerpetualCache.class);
typeAliasRegistry.registerAlias("FIFO", FifoCache.class);
typeAliasRegistry.registerAlias("LRU", LruCache.class);
typeAliasRegistry.registerAlias("SOFT", SoftCache.class);
typeAliasRegistry.registerAlias("WEAK", WeakCache.class);
typeAliasRegistry.registerAlias("DB_VENDOR", VendorDatabaseIdProvider.class);
typeAliasRegistry.registerAlias("XML", XMLLanguageDriver.class);
typeAliasRegistry.registerAlias("RAW", RawLanguageDriver.class);
typeAliasRegistry.registerAlias("SLF4J", Slf4jImpl.class);
typeAliasRegistry.registerAlias("COMMONS_LOGGING", JakartaCommonsLoggingImpl.class);
typeAliasRegistry.registerAlias("LOG4J", Log4jImpl.class);
typeAliasRegistry.registerAlias("LOG4J2", Log4j2Impl.class);
typeAliasRegistry.registerAlias("JDK_LOGGING", Jdk14LoggingImpl.class);
typeAliasRegistry.registerAlias("STDOUT_LOGGING", StdOutImpl.class);
typeAliasRegistry.registerAlias("NO_LOGGING", NoLoggingImpl.class);
typeAliasRegistry.registerAlias("CGLIB", CglibProxyFactory.class);
typeAliasRegistry.registerAlias("JAVASSIST", JavassistProxyFactory.class);
languageRegistry.setDefaultDriverClass(XMLLanguageDriver.class);
languageRegistry.register(RawLanguageDriver.class);
}
配置文件信息將會(huì)在這個(gè)類中保存
該類中的方法MappedStatement 為獲取映射器的節(jié)點(diǎn)
public MappedStatement getMappedStatement(String id, boolean validateIncompleteStatements) {
if (validateIncompleteStatements) {
buildAllStatements();
}
return mappedStatements.get(id);
}
public final class MappedStatement {
private String resource;
private Configuration configuration;
private String id;
private Integer fetchSize;
private Integer timeout;
private StatementType statementType;
private ResultSetType resultSetType;
private SqlSource sqlSource;
private Cache cache;
private ParameterMap parameterMap;
private List resultMaps;
private boolean flushCacheRequired;
private boolean useCache;
private boolean resultOrdered;
private SqlCommandType sqlCommandType;
private KeyGenerator keyGenerator;
private String[] keyProperties;
private String[] keyColumns;
private boolean hasNestedResultMaps;
private String databaseId;
private Log statementLog;
private LanguageDriver lang;
private String[] resultSets;
這里進(jìn)入的是映射器的節(jié)點(diǎn)信息
在插件中可以通過(guò)MappedStatement類,來(lái)獲取到映射器的節(jié)點(diǎn),即,獲取到映射器的信息.在Tomcat編譯成為class文件的時(shí)候,會(huì)寫(xiě)死在class文件中..
其中MappedStatement為final類型
在映射類的第43行有一個(gè)重要的屬性
private SqlSource sqlSource;
進(jìn)入該接口
public interface SqlSource {
BoundSql getBoundSql(Object parameterObject);
}
其接口有方法
BoundSql getBoundSql(Object parameterObject);
進(jìn)入該類的查看BoundSql
public class BoundSql {
private final String sql;
private final List parameterMappings;
private final Object parameterObject;
private final Map additionalParameters;
private final MetaObject metaParameters;
public BoundSql(Configuration configuration, String sql, List parameterMappings, Object parameterObject) {
this.sql = sql;
this.parameterMappings = parameterMappings;
this.parameterObject = parameterObject;
this.additionalParameters = new HashMap<>();
this.metaParameters = configuration.newMetaObject(additionalParameters);
}
public String getSql() {
return sql;
}
public List getParameterMappings() {
return parameterMappings;
}
public Object getParameterObject() {
return parameterObject;
}
public boolean hasAdditionalParameter(String name) {
String paramName = new PropertyTokenizer(name).getName();
return additionalParameters.containsKey(paramName);
}
public void setAdditionalParameter(String name, Object value) {
metaParameters.setValue(name, value);
}
public Object getAdditionalParameter(String name) {
return metaParameters.getValue(name);
}
}
BoundSql有三個(gè)屬性,
this.sql = sql;
this.parameterMappings = parameterMappings;
// 傳遞進(jìn)入的參數(shù) 根據(jù)Param注解
this.parameterObject = parameterObject;
this.additionalParameters = new HashMap<>();
this.metaParameters = configuration.newMetaObject(additionalParameters);
SqlSession運(yùn)行
SqlSession通過(guò)動(dòng)態(tài)代理的方式運(yùn)行
首先 SqlSessionFactory sqlSessionFactory 是SqlSessionFactory接口
SqlSession類如下
/**
* Copyright 2009-2019 the original author or authors.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.apache.ibatis.session;
import java.sql.Connection;
/**
* Creates an {@link SqlSession} out of a connection or a DataSource
*
* @author Clinton Begin
*/
public interface SqlSessionFactory {
SqlSession openSession();
SqlSession openSession(boolean autoCommit);
SqlSession openSession(Connection connection);
SqlSession openSession(TransactionIsolationLevel level);
SqlSession openSession(ExecutorType execType);
SqlSession openSession(ExecutorType execType, boolean autoCommit);
SqlSession openSession(ExecutorType execType, TransactionIsolationLevel level);
SqlSession openSession(ExecutorType execType, Connection connection);
Configuration getConfiguration();
}
首先try里面的第四行
sqlSession = SqlSessionFactoryUtil.openSqlSesion();
roleMapper = sqlSession.getMapper(RoleMapper.class);
students = roleMapper.getStudent(1);
students1 = roleMapper.getStudent(1);
sqlSession.commit();
進(jìn)入getMapper
/**
* Copyright 2009-2019 the original author or authors.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.apache.ibatis.session;
import java.io.Closeable;
import java.sql.Connection;
import java.util.List;
import java.util.Map;
import org.apache.ibatis.cursor.Cursor;
import org.apache.ibatis.executor.BatchResult;
/**
* The primary Java interface for working with MyBatis.
* Through this interface you can execute commands, get mappers and manage transactions.
*
* @author Clinton Begin
*/
public interface SqlSession extends Closeable {
/**
* Retrieve a single row mapped from the statement key.
* @param the returned object type
* @param statement
* @return Mapped object
*/
T selectOne(String statement);
/**
* Retrieve a single row mapped from the statement key and parameter.
* @param the returned object type
* @param statement Unique identifier matching the statement to use.
* @param parameter A parameter object to pass to the statement.
* @return Mapped object
*/
T selectOne(String statement, Object parameter);
/**
* Retrieve a list of mapped objects from the statement key and parameter.
* @param the returned list element type
* @param statement Unique identifier matching the statement to use.
* @return List of mapped object
*/
List selectList(String statement);
/**
* Retrieve a list of mapped objects from the statement key and parameter.
* @param the returned list element type
* @param statement Unique identifier matching the statement to use.
* @param parameter A parameter object to pass to the statement.
* @return List of mapped object
*/
List selectList(String statement, Object parameter);
/**
* Retrieve a list of mapped objects from the statement key and parameter,
* within the specified row bounds.
* @param the returned list element type
* @param statement Unique identifier matching the statement to use.
* @param parameter A parameter object to pass to the statement.
* @param rowBounds Bounds to limit object retrieval
* @return List of mapped object
*/
List selectList(String statement, Object parameter, RowBounds rowBounds);
/**
* The selectMap is a special case in that it is designed to convert a list
* of results into a Map based on one of the properties in the resulting
* objects.
* Eg. Return a of Map[Integer,Author] for selectMap("selectAuthors","id")
* @param the returned Map keys type
* @param the returned Map values type
* @param statement Unique identifier matching the statement to use.
* @param mapKey The property to use as key for each value in the list.
* @return Map containing key pair data.
*/
Map selectMap(String statement, String mapKey);
/**
* The selectMap is a special case in that it is designed to convert a list
* of results into a Map based on one of the properties in the resulting
* objects.
* @param the returned Map keys type
* @param the returned Map values type
* @param statement Unique identifier matching the statement to use.
* @param parameter A parameter object to pass to the statement.
* @param mapKey The property to use as key for each value in the list.
* @return Map containing key pair data.
*/
Map selectMap(String statement, Object parameter, String mapKey);
/**
* The selectMap is a special case in that it is designed to convert a list
* of results into a Map based on one of the properties in the resulting
* objects.
* @param the returned Map keys type
* @param the returned Map values type
* @param statement Unique identifier matching the statement to use.
* @param parameter A parameter object to pass to the statement.
* @param mapKey The property to use as key for each value in the list.
* @param rowBounds Bounds to limit object retrieval
* @return Map containing key pair data.
*/
Map selectMap(String statement, Object parameter, String mapKey, RowBounds rowBounds);
/**
* A Cursor offers the same results as a List, except it fetches data lazily using an Iterator.
* @param the returned cursor element type.
* @param statement Unique identifier matching the statement to use.
* @return Cursor of mapped objects
*/
Cursor selectCursor(String statement);
/**
* A Cursor offers the same results as a List, except it fetches data lazily using an Iterator.
* @param the returned cursor element type.
* @param statement Unique identifier matching the statement to use.
* @param parameter A parameter object to pass to the statement.
* @return Cursor of mapped objects
*/
Cursor selectCursor(String statement, Object parameter);
/**
* A Cursor offers the same results as a List, except it fetches data lazily using an Iterator.
* @param the returned cursor element type.
* @param statement Unique identifier matching the statement to use.
* @param parameter A parameter object to pass to the statement.
* @param rowBounds Bounds to limit object retrieval
* @return Cursor of mapped objects
*/
Cursor selectCursor(String statement, Object parameter, RowBounds rowBounds);
/**
* Retrieve a single row mapped from the statement key and parameter
* using a {@code ResultHandler}.
* @param statement Unique identifier matching the statement to use.
* @param parameter A parameter object to pass to the statement.
* @param handler ResultHandler that will handle each retrieved row
*/
void select(String statement, Object parameter, ResultHandler handler);
/**
* Retrieve a single row mapped from the statement
* using a {@code ResultHandler}.
* @param statement Unique identifier matching the statement to use.
* @param handler ResultHandler that will handle each retrieved row
*/
void select(String statement, ResultHandler handler);
/**
* Retrieve a single row mapped from the statement key and parameter
* using a {@code ResultHandler} and {@code RowBounds}.
* @param statement Unique identifier matching the statement to use.
* @param rowBounds RowBound instance to limit the query results
* @param handler ResultHandler that will handle each retrieved row
*/
void select(String statement, Object parameter, RowBounds rowBounds, ResultHandler handler);
/**
* Execute an insert statement.
* @param statement Unique identifier matching the statement to execute.
* @return int The number of rows affected by the insert.
*/
int insert(String statement);
/**
* Execute an insert statement with the given parameter object. Any generated
* autoincrement values or selectKey entries will modify the given parameter
* object properties. Only the number of rows affected will be returned.
* @param statement Unique identifier matching the statement to execute.
* @param parameter A parameter object to pass to the statement.
* @return int The number of rows affected by the insert.
*/
int insert(String statement, Object parameter);
/**
* Execute an update statement. The number of rows affected will be returned.
* @param statement Unique identifier matching the statement to execute.
* @return int The number of rows affected by the update.
*/
int update(String statement);
/**
* Execute an update statement. The number of rows affected will be returned.
* @param statement Unique identifier matching the statement to execute.
* @param parameter A parameter object to pass to the statement.
* @return int The number of rows affected by the update.
*/
int update(String statement, Object parameter);
/**
* Execute a delete statement. The number of rows affected will be returned.
* @param statement Unique identifier matching the statement to execute.
* @return int The number of rows affected by the delete.
*/
int delete(String statement);
/**
* Execute a delete statement. The number of rows affected will be returned.
* @param statement Unique identifier matching the statement to execute.
* @param parameter A parameter object to pass to the statement.
* @return int The number of rows affected by the delete.
*/
int delete(String statement, Object parameter);
/**
* Flushes batch statements and commits database connection.
* Note that database connection will not be committed if no updates/deletes/inserts were called.
* To force the commit call {@link SqlSession#commit(boolean)}
*/
void commit();
/**
* Flushes batch statements and commits database connection.
* @param force forces connection commit
*/
void commit(boolean force);
/**
* Discards pending batch statements and rolls database connection back.
* Note that database connection will not be rolled back if no updates/deletes/inserts were called.
* To force the rollback call {@link SqlSession#rollback(boolean)}
*/
void rollback();
/**
* Discards pending batch statements and rolls database connection back.
* Note that database connection will not be rolled back if no updates/deletes/inserts were called.
* @param force forces connection rollback
*/
void rollback(boolean force);
/**
* Flushes batch statements.
* @return BatchResult list of updated records
* @since 3.0.6
*/
List flushStatements();
/**
* Closes the session.
*/
@Override
void close();
/**
* Clears local session cache.
*/
void clearCache();
/**
* Retrieves current configuration.
* @return Configuration
*/
Configuration getConfiguration();
/**
* Retrieves a mapper.
* @param the mapper type
* @param type Mapper interface class
* @return a mapper bound to this SqlSession
*/
T getMapper(Class type);
/**
* Retrieves inner database connection.
* @return Connection
*/
Connection getConnection();
}
這是一個(gè)接口
其中DefaultSqlSession為舊版本,新版本使用的是SqlSessionManager
進(jìn)入SqlSessionManager
@Override publicT getMapper(Class type) { return getConfiguration().getMapper(type, this); }
可以看到使用getConfiguration().getMapper(type, this);
getConfiguration()為獲取配置信息,mapperRegistry為映射配置類的映射注冊(cè)表,進(jìn)入getMapper
publicT getMapper(Class type, SqlSession sqlSession) { final MapperProxyFactory mapperProxyFactory = (MapperProxyFactory ) 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); } }
如下
@SuppressWarnings("unchecked")
public T getMapper(Class type, SqlSession sqlSession) {
final MapperProxyFactory mapperProxyFactory = (MapperProxyFactory) 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);
}
}
然后進(jìn)入代理工廠類
