Configuration配置详细解析
Mybatis的一般使用过程
final String resource = "org/apache/ibatis/builder/MapperConfig.xml";
final Reader reader = Resources.getResourceAsReader(resource);
sqlMapper = new SqlSessionFactoryBuilder().build(reader);
SqlSession session = sqlMapper.openSession()
Integer count = session.selectOne("org.apache.ibatis.domain.blog.mappers.BlogMapper.selectCountOfPosts");
如上代码所示，这是Mybatis的一般使用步骤
- 读取配置文件流
- 通过XMLConfigBuilder解析XML文件并生成Configuration对象
- SqlSessionFactoryBuilder根据Configuration生成一个SqlSessionFactory,默认是DefaultSqlSessionFactory
- 通过DefaultSqlSessionFactory生成SqlSession
- SqlSession通过statementId匹配到相应的SQL语句进行增删查改操作
Configuration的生成
Configuration是Mybatis存储所有配置的类。
Configuration是由XMLConfigBuilder类创建并填充的。XMLConfigBuilder类构造函数有多个，可传递配置文件流、环境变量、额外属性配置。创建XMLConfigBuilder的时候就创建了一个Configuration对象，用来储存解析出来的全部配置
public XMLConfigBuilder(Reader reader) {
this(reader, null, null);
}
public XMLConfigBuilder(Reader reader, String environment) {
this(reader, environment, null);
}
public XMLConfigBuilder(Reader reader, String environment, Properties props) {
this(new XPathParser(reader, true, props, new XMLMapperEntityResolver()), environment, props);
}
public XMLConfigBuilder(InputStream inputStream) {
this(inputStream, null, null);
}
public XMLConfigBuilder(InputStream inputStream, String environment) {
this(inputStream, environment, null);
}
public XMLConfigBuilder(InputStream inputStream, String environment, Properties props) {
this(new XPathParser(inputStream, true, props, new XMLMapperEntityResolver()), environment, props);
}
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;
}解析是通过XMLConfigBuilder的parse方法
public Configuration parse() {
if (parsed) {
throw new BuilderException("Each XMLConfigBuilder can only be used once.");
}
parsed = true;
parseConfiguration(parser.evalNode("/configuration"));
return configuration;
}
private void parseConfiguration(XNode root) {
try {
// issue #117 read properties first
// 属性配置
propertiesElement(root.evalNode("properties"));
// setting配置
Properties settings = settingsAsProperties(root.evalNode("settings"));
loadCustomVfs(settings);
loadCustomLogImpl(settings);
// 别名注册
typeAliasesElement(root.evalNode("typeAliases"));
// 插件
pluginElement(root.evalNode("plugins"));
// 对象工厂
objectFactoryElement(root.evalNode("objectFactory"));
// 对象包装工厂
objectWrapperFactoryElement(root.evalNode("objectWrapperFactory"));
// 反射工厂
reflectorFactoryElement(root.evalNode("reflectorFactory"));
settingsElement(settings);
// read it after objectFactory and objectWrapperFactory issue #631
// 环境
environmentsElement(root.evalNode("environments"));
// 数据库提供商
databaseIdProviderElement(root.evalNode("databaseIdProvider"));
// 类型转换器
typeHandlerElement(root.evalNode("typeHandlers"));
// mapper
mapperElement(root.evalNode("mappers"));
} catch (Exception e) {
throw new BuilderException("Error parsing SQL Mapper Configuration. Cause: " + e, e);
}
}这就完全对应了配置文件XML中的configuration标签，一个个标签顺序进行解析。下面是一个包含全部节点的configuration配置文件样例
<!DOCTYPE configuration
PUBLIC "-//mybatis.org//DTD Config 3.0//EN"
"http://mybatis.org/dtd/mybatis-3-config.dtd">
<configuration>
<properties resource="org/apache/ibatis/builder/jdbc.properties">
<property name="prop1" value="aaaa"/>
<property name="jdbcTypeForNull" value="NULL" />
</properties>
<settings>
<setting name="autoMappingBehavior" value="NONE"/>
<setting name="autoMappingUnknownColumnBehavior" value="WARNING"/>
<setting name="cacheEnabled" value="false"/>
<setting name="proxyFactory" value="CGLIB"/>
<setting name="lazyLoadingEnabled" value="true"/>
<setting name="aggressiveLazyLoading" value="true"/>
<setting name="multipleResultSetsEnabled" value="false"/>
<setting name="useColumnLabel" value="false"/>
<setting name="useGeneratedKeys" value="true"/>
<setting name="defaultExecutorType" value="BATCH"/>
<setting name="defaultStatementTimeout" value="10"/>
<setting name="defaultFetchSize" value="100"/>
<setting name="defaultResultSetType" value="SCROLL_INSENSITIVE"/>
<setting name="mapUnderscoreToCamelCase" value="true"/>
<setting name="safeRowBoundsEnabled" value="true"/>
<setting name="localCacheScope" value="STATEMENT"/>
<setting name="jdbcTypeForNull" value="${jdbcTypeForNull}"/>
<setting name="lazyLoadTriggerMethods" value="equals,clone,hashCode,toString,xxx"/>
<setting name="safeResultHandlerEnabled" value="false"/>
<setting name="defaultScriptingLanguage" value="org.apache.ibatis.scripting.defaults.RawLanguageDriver"/>
<setting name="callSettersOnNulls" value="true"/>
<setting name="logPrefix" value="mybatis_"/>
<setting name="logImpl" value="SLF4J"/>
<setting name="vfsImpl" value="org.apache.ibatis.io.JBoss6VFS"/>
<setting name="configurationFactory" value="java.lang.String"/>
<setting name="defaultEnumTypeHandler" value="org.apache.ibatis.type.EnumOrdinalTypeHandler"/>
<setting name="shrinkWhitespacesInSql" value="true"/>
<setting name="defaultSqlProviderType" value="org.apache.ibatis.builder.XmlConfigBuilderTest$MySqlProvider"/>
</settings>
<typeAliases>
<typeAlias alias="BlogAuthor" type="org.apache.ibatis.domain.blog.Author"/>
<typeAlias type="org.apache.ibatis.domain.blog.Blog"/>
<typeAlias type="org.apache.ibatis.domain.blog.Post"/>
<package name="org.apache.ibatis.domain.jpetstore"/>
</typeAliases>
<typeHandlers>
<typeHandler javaType="String" handler="org.apache.ibatis.builder.CustomStringTypeHandler"/>
<typeHandler javaType="String" jdbcType="VARCHAR" handler="org.apache.ibatis.builder.CustomStringTypeHandler"/>
<typeHandler handler="org.apache.ibatis.builder.CustomLongTypeHandler"/>
<package name="org.apache.ibatis.builder.typehandler"/>
</typeHandlers>
<objectFactory type="org.apache.ibatis.builder.ExampleObjectFactory">
<property name="objectFactoryProperty" value="100"/>
</objectFactory>
<objectWrapperFactory type="org.apache.ibatis.builder.CustomObjectWrapperFactory" />
<reflectorFactory type="org.apache.ibatis.builder.CustomReflectorFactory"/>
<plugins>
<plugin interceptor="org.apache.ibatis.builder.ExamplePlugin">
<property name="pluginProperty" value="100"/>
</plugin>
</plugins>
<environments default="development">
<environment id="development">
<transactionManager type="JDBC">
<property name="" value=""/>
</transactionManager>
<dataSource type="UNPOOLED">
<property name="driver" value="${driver}"/>
<property name="url" value="${url}"/>
<property name="username" value="${username}"/>
<property name="password" value="${password}"/>
</dataSource>
</environment>
</environments>
<databaseIdProvider type="DB_VENDOR">
<property name="Apache Derby" value="derby"/>
</databaseIdProvider>
<mappers>
<mapper resource="org/apache/ibatis/builder/BlogMapper.xml"/>
<mapper url="file:./src/test/java/org/apache/ibatis/builder/NestedBlogMapper.xml"/>
<mapper class="org.apache.ibatis.builder.CachedAuthorMapper"/>
<package name="org.apache.ibatis.builder.mapper"/>
</mappers>
</configuration>
节点解析详细说明
properties
<properties resource="xxxxx"></properties>
<properties url="xxxxx"></properties>
<properties resource="org/apache/ibatis/builder/jdbc.properties">
<property name="prop1" value="aaaa"/>
<property name="jdbcTypeForNull" value="NULL" />
</properties>properties支持三种方式配置，称为resource、url、直接配置
private void propertiesElement(XNode context) throws Exception {
if (context != null) {
// 子节点配置
Properties defaults = context.getChildrenAsProperties();
// resource
String resource = context.getStringAttribute("resource");
// url
String url = context.getStringAttribute("url");
// 不支持同时使用resource、url方式配置
if (resource != null && url != null) {
throw new BuilderException("The properties element cannot specify both a URL and a resource based property file reference. Please specify one or the other.");
}
if (resource != null) {
// resource方式读取
defaults.putAll(Resources.getResourceAsProperties(resource));
} else if (url != null) {
// url方式读取
defaults.putAll(Resources.getUrlAsProperties(url));
}
// 已有属性
Properties vars = configuration.getVariables();
if (vars != null) {
// 如果非空则加入已有的属性中
defaults.putAll(vars);
}
parser.setVariables(defaults);
// 保存到configuration的variables属性中
configuration.setVariables(defaults);
}
}从源码可以看出，resource和url不能同时配置，配置优先级由高到低为
Configuration -> resource/url -> 直接配置
settings
<settings>
<setting name="autoMappingBehavior" value="NONE"/>
<setting name="autoMappingUnknownColumnBehavior" value="WARNING"/>
<setting name="cacheEnabled" value="false"/>
<setting name="proxyFactory" value="CGLIB"/>
<setting name="lazyLoadingEnabled" value="true"/>
<setting name="aggressiveLazyLoading" value="true"/>
<setting name="multipleResultSetsEnabled" value="false"/>
<setting name="useColumnLabel" value="false"/>
<setting name="useGeneratedKeys" value="true"/>
<setting name="defaultExecutorType" value="BATCH"/>
<setting name="defaultStatementTimeout" value="10"/>
<setting name="defaultFetchSize" value="100"/>
<setting name="defaultResultSetType" value="SCROLL_INSENSITIVE"/>
<setting name="mapUnderscoreToCamelCase" value="true"/>
<setting name="safeRowBoundsEnabled" value="true"/>
<setting name="localCacheScope" value="STATEMENT"/>
<setting name="jdbcTypeForNull" value="${jdbcTypeForNull}"/>
<setting name="lazyLoadTriggerMethods" value="equals,clone,hashCode,toString,xxx"/>
<setting name="safeResultHandlerEnabled" value="false"/>
<setting name="defaultScriptingLanguage" value="org.apache.ibatis.scripting.defaults.RawLanguageDriver"/>
<setting name="callSettersOnNulls" value="true"/>
<setting name="logPrefix" value="mybatis_"/>
<setting name="logImpl" value="SLF4J"/>
<setting name="vfsImpl" value="org.apache.ibatis.io.JBoss6VFS"/>
<setting name="configurationFactory" value="java.lang.String"/>
<setting name="defaultEnumTypeHandler" value="org.apache.ibatis.type.EnumOrdinalTypeHandler"/>
<setting name="shrinkWhitespacesInSql" value="true"/>
<setting name="defaultSqlProviderType" value="org.apache.ibatis.builder.XmlConfigBuilderTest$MySqlProvider"/>
</settings>setting节点直接对应Configuration里面的成员属性，读取后直接赋值到成员
private void settingsElement(Properties props) {
configuration.setAutoMappingBehavior(AutoMappingBehavior.valueOf(props.getProperty("autoMappingBehavior", "PARTIAL")));
configuration.setAutoMappingUnknownColumnBehavior(AutoMappingUnknownColumnBehavior.valueOf(props.getProperty("autoMappingUnknownColumnBehavior", "NONE")));
configuration.setCacheEnabled(booleanValueOf(props.getProperty("cacheEnabled"), true));
configuration.setProxyFactory((ProxyFactory) createInstance(props.getProperty("proxyFactory")));
configuration.setLazyLoadingEnabled(booleanValueOf(props.getProperty("lazyLoadingEnabled"), false));
configuration.setAggressiveLazyLoading(booleanValueOf(props.getProperty("aggressiveLazyLoading"), false));
configuration.setMultipleResultSetsEnabled(booleanValueOf(props.getProperty("multipleResultSetsEnabled"), true));
configuration.setUseColumnLabel(booleanValueOf(props.getProperty("useColumnLabel"), true));
configuration.setUseGeneratedKeys(booleanValueOf(props.getProperty("useGeneratedKeys"), false));
configuration.setDefaultExecutorType(ExecutorType.valueOf(props.getProperty("defaultExecutorType", "SIMPLE")));
configuration.setDefaultStatementTimeout(integerValueOf(props.getProperty("defaultStatementTimeout"), null));
configuration.setDefaultFetchSize(integerValueOf(props.getProperty("defaultFetchSize"), null));
configuration.setDefaultResultSetType(resolveResultSetType(props.getProperty("defaultResultSetType")));
configuration.setMapUnderscoreToCamelCase(booleanValueOf(props.getProperty("mapUnderscoreToCamelCase"), false));
configuration.setSafeRowBoundsEnabled(booleanValueOf(props.getProperty("safeRowBoundsEnabled"), false));
configuration.setLocalCacheScope(LocalCacheScope.valueOf(props.getProperty("localCacheScope", "SESSION")));
configuration.setJdbcTypeForNull(JdbcType.valueOf(props.getProperty("jdbcTypeForNull", "OTHER")));
configuration.setLazyLoadTriggerMethods(stringSetValueOf(props.getProperty("lazyLoadTriggerMethods"), "equals,clone,hashCode,toString"));
configuration.setSafeResultHandlerEnabled(booleanValueOf(props.getProperty("safeResultHandlerEnabled"), true));
configuration.setDefaultScriptingLanguage(resolveClass(props.getProperty("defaultScriptingLanguage")));
configuration.setDefaultEnumTypeHandler(resolveClass(props.getProperty("defaultEnumTypeHandler")));
configuration.setCallSettersOnNulls(booleanValueOf(props.getProperty("callSettersOnNulls"), false));
configuration.setUseActualParamName(booleanValueOf(props.getProperty("useActualParamName"), true));
configuration.setReturnInstanceForEmptyRow(booleanValueOf(props.getProperty("returnInstanceForEmptyRow"), false));
configuration.setLogPrefix(props.getProperty("logPrefix"));
configuration.setConfigurationFactory(resolveClass(props.getProperty("configurationFactory")));
configuration.setShrinkWhitespacesInSql(booleanValueOf(props.getProperty("shrinkWhitespacesInSql"), false));
configuration.setDefaultSqlProviderType(resolveClass(props.getProperty("defaultSqlProviderType")));
}所有配置以及默认值
typeAliases
typeAliases用来设置别名，有了别名就不用指定完整的全限定名。例如org.apache.ibatis.domain.blog.Author可以用简短的BlogAuthor表示，非常方便。别名的注册，最终是注册到configuration的成员属性上
<typeAliases>
<typeAlias alias="BlogAuthor" type="org.apache.ibatis.domain.blog.Author"/>
<typeAlias type="org.apache.ibatis.domain.blog.Blog"/>
<typeAlias type="org.apache.ibatis.domain.blog.Post"/>
<package name="org.apache.ibatis.domain.jpetstore"/>
</typeAliases>protected final TypeAliasRegistry typeAliasRegistry = new TypeAliasRegistry();TypeAliasRegistry就是用一个HashMap保存别名对应的类对象而已
public class TypeAliasRegistry {
private final Map<String, Class<?>> typeAliases = new HashMap<>();
public TypeAliasRegistry() {
registerAlias("string", String.class);
registerAlias("byte", Byte.class);
registerAlias("long", Long.class);
registerAlias("short", Short.class);
registerAlias("int", Integer.class);
registerAlias("integer", Integer.class);
registerAlias("double", Double.class);
registerAlias("float", Float.class);
registerAlias("boolean", Boolean.class);
registerAlias("byte[]", Byte[].class);
registerAlias("long[]", Long[].class);
registerAlias("short[]", Short[].class);
registerAlias("int[]", Integer[].class);
registerAlias("integer[]", Integer[].class);
registerAlias("double[]", Double[].class);
registerAlias("float[]", Float[].class);
registerAlias("boolean[]", Boolean[].class);
registerAlias("_byte", byte.class);
registerAlias("_long", long.class);
registerAlias("_short", short.class);
registerAlias("_int", int.class);
registerAlias("_integer", int.class);
registerAlias("_double", double.class);
registerAlias("_float", float.class);
registerAlias("_boolean", boolean.class);
registerAlias("_byte[]", byte[].class);
registerAlias("_long[]", long[].class);
registerAlias("_short[]", short[].class);
registerAlias("_int[]", int[].class);
registerAlias("_integer[]", int[].class);
registerAlias("_double[]", double[].class);
registerAlias("_float[]", float[].class);
registerAlias("_boolean[]", boolean[].class);
registerAlias("date", Date.class);
registerAlias("decimal", BigDecimal.class);
registerAlias("bigdecimal", BigDecimal.class);
registerAlias("biginteger", BigInteger.class);
registerAlias("object", Object.class);
registerAlias("date[]", Date[].class);
registerAlias("decimal[]", BigDecimal[].class);
registerAlias("bigdecimal[]", BigDecimal[].class);
registerAlias("biginteger[]", BigInteger[].class);
registerAlias("object[]", Object[].class);
registerAlias("map", Map.class);
registerAlias("hashmap", HashMap.class);
registerAlias("list", List.class);
registerAlias("arraylist", ArrayList.class);
registerAlias("collection", Collection.class);
registerAlias("iterator", Iterator.class);
registerAlias("ResultSet", ResultSet.class);
}
}注册过程
private void typeAliasesElement(XNode parent) {
if (parent != null) {
for (XNode child : parent.getChildren()) {
if ("package".equals(child.getName())) {
// 如果是包名，则把包中的所有类都注册
String typeAliasPackage = child.getStringAttribute("name");
configuration.getTypeAliasRegistry().registerAliases(typeAliasPackage);
} else {
// 如果是类，则单独注册一个
String alias = child.getStringAttribute("alias");
String type = child.getStringAttribute("type");
try {
Class<?> clazz = Resources.classForName(type);
if (alias == null) {
// 如果没有配置别名，则自动生成别名
typeAliasRegistry.registerAlias(clazz);
} else {
// 直接按照别名进行注册
typeAliasRegistry.registerAlias(alias, clazz);
}
} catch (ClassNotFoundException e) {
throw new BuilderException("Error registering typeAlias for '" + alias + "'. Cause: " + e, e);
}
}
}
}
}具体操作就委托给了TypeAliasRegistry的各个registryAlias方法
public void registerAliases(String packageName) {
registerAliases(packageName, Object.class);
}
public void registerAliases(String packageName, Class<?> superType) {
ResolverUtil<Class<?>> resolverUtil = new ResolverUtil<>();
resolverUtil.find(new ResolverUtil.IsA(superType), packageName);
Set<Class<? extends Class<?>>> typeSet = resolverUtil.getClasses();
for (Class<?> type : typeSet) {
// Ignore inner classes and interfaces (including package-info.java)
// Skip also inner classes. See issue #6
if (!type.isAnonymousClass() && !type.isInterface() && !type.isMemberClass()) {
registerAlias(type);
}
}
}
public void registerAlias(Class<?> type) {
// 加单类名当作初始别名
String alias = type.getSimpleName();
// 检查Alias注解
Alias aliasAnnotation = type.getAnnotation(Alias.class);
if (aliasAnnotation != null) {
// 如果有配置Alias注解，则取value值覆盖初始别名
alias = aliasAnnotation.value();
}
// 注册
registerAlias(alias, type);
}
public void registerAlias(String alias, Class<?> value) {
if (alias == null) {
throw new TypeException("The parameter alias cannot be null");
}
// issue #748
String key = alias.toLowerCase(Locale.ENGLISH);
if (typeAliases.containsKey(key) && typeAliases.get(key) != null && !typeAliases.get(key).equals(value)) {
throw new TypeException("The alias '" + alias + "' is already mapped to the value '" + typeAliases.get(key).getName() + "'.");
}
typeAliases.put(key, value);
}
public void registerAlias(String alias, String value) {
try {
registerAlias(alias, Resources.classForName(value));
} catch (ClassNotFoundException e) {
throw new TypeException("Error registering type alias " + alias + " for " + value + ". Cause: " + e, e);
}
}typeHandlers
类型转换器用来处理数据库字段和java属性之间的转换，默认已经注册了常用的类型转换器。最终保存在configuration中
<typeHandlers>
<typeHandler javaType="String" handler="org.apache.ibatis.builder.CustomStringTypeHandler"/>
<typeHandler javaType="String" jdbcType="VARCHAR" handler="org.apache.ibatis.builder.CustomStringTypeHandler"/>
<typeHandler handler="org.apache.ibatis.builder.CustomLongTypeHandler"/>
<package name="org.apache.ibatis.builder.typehandler"/>
</typeHandlers>注册过程
protected final TypeHandlerRegistry typeHandlerRegistry = new TypeHandlerRegistry(this);public final class TypeHandlerRegistry {
// jdbc type 对应的TypeHandler
private final Map<JdbcType, TypeHandler<?>> jdbcTypeHandlerMap = new EnumMap<>(JdbcType.class);
// java type对应的jdbc TypeHandler
private final Map<Type, Map<JdbcType, TypeHandler<?>>> typeHandlerMap = new ConcurrentHashMap<>();
// 未知类型
private final TypeHandler<Object> unknownTypeHandler;
// 全部类型转换器
private final Map<Class<?>, TypeHandler<?>> allTypeHandlersMap = new HashMap<>();
// null对应应的转换器
private static final Map<JdbcType, TypeHandler<?>> NULL_TYPE_HANDLER_MAP = Collections.emptyMap();
// 默认枚举类型转换器
private Class<? extends TypeHandler> defaultEnumTypeHandler = EnumTypeHandler.class;
/**
* The default constructor.
*/
public TypeHandlerRegistry() {
this(new Configuration());
}
/**
* The constructor that pass the MyBatis configuration.
*
* @param configuration a MyBatis configuration
* @since 3.5.4
*/
public TypeHandlerRegistry(Configuration configuration) {
this.unknownTypeHandler = new UnknownTypeHandler(configuration);
register(Boolean.class, new BooleanTypeHandler());
register(boolean.class, new BooleanTypeHandler());
register(JdbcType.BOOLEAN, new BooleanTypeHandler());
register(JdbcType.BIT, new BooleanTypeHandler());
register(Byte.class, new ByteTypeHandler());
register(byte.class, new ByteTypeHandler());
register(JdbcType.TINYINT, new ByteTypeHandler());
register(Short.class, new ShortTypeHandler());
register(short.class, new ShortTypeHandler());
register(JdbcType.SMALLINT, new ShortTypeHandler());
register(Integer.class, new IntegerTypeHandler());
register(int.class, new IntegerTypeHandler());
register(JdbcType.INTEGER, new IntegerTypeHandler());
register(Long.class, new LongTypeHandler());
register(long.class, new LongTypeHandler());
register(Float.class, new FloatTypeHandler());
register(float.class, new FloatTypeHandler());
register(JdbcType.FLOAT, new FloatTypeHandler());
register(Double.class, new DoubleTypeHandler());
register(double.class, new DoubleTypeHandler());
register(JdbcType.DOUBLE, new DoubleTypeHandler());
register(Reader.class, new ClobReaderTypeHandler());
register(String.class, new StringTypeHandler());
register(String.class, JdbcType.CHAR, new StringTypeHandler());
register(String.class, JdbcType.CLOB, new ClobTypeHandler());
register(String.class, JdbcType.VARCHAR, new StringTypeHandler());
register(String.class, JdbcType.LONGVARCHAR, new StringTypeHandler());
register(String.class, JdbcType.NVARCHAR, new NStringTypeHandler());
register(String.class, JdbcType.NCHAR, new NStringTypeHandler());
register(String.class, JdbcType.NCLOB, new NClobTypeHandler());
register(JdbcType.CHAR, new StringTypeHandler());
register(JdbcType.VARCHAR, new StringTypeHandler());
register(JdbcType.CLOB, new ClobTypeHandler());
register(JdbcType.LONGVARCHAR, new StringTypeHandler());
register(JdbcType.NVARCHAR, new NStringTypeHandler());
register(JdbcType.NCHAR, new NStringTypeHandler());
register(JdbcType.NCLOB, new NClobTypeHandler());
register(Object.class, JdbcType.ARRAY, new ArrayTypeHandler());
register(JdbcType.ARRAY, new ArrayTypeHandler());
register(BigInteger.class, new BigIntegerTypeHandler());
register(JdbcType.BIGINT, new LongTypeHandler());
register(BigDecimal.class, new BigDecimalTypeHandler());
register(JdbcType.REAL, new BigDecimalTypeHandler());
register(JdbcType.DECIMAL, new BigDecimalTypeHandler());
register(JdbcType.NUMERIC, new BigDecimalTypeHandler());
register(InputStream.class, new BlobInputStreamTypeHandler());
register(Byte[].class, new ByteObjectArrayTypeHandler());
register(Byte[].class, JdbcType.BLOB, new BlobByteObjectArrayTypeHandler());
register(Byte[].class, JdbcType.LONGVARBINARY, new BlobByteObjectArrayTypeHandler());
register(byte[].class, new ByteArrayTypeHandler());
register(byte[].class, JdbcType.BLOB, new BlobTypeHandler());
register(byte[].class, JdbcType.LONGVARBINARY, new BlobTypeHandler());
register(JdbcType.LONGVARBINARY, new BlobTypeHandler());
register(JdbcType.BLOB, new BlobTypeHandler());
register(Object.class, unknownTypeHandler);
register(Object.class, JdbcType.OTHER, unknownTypeHandler);
register(JdbcType.OTHER, unknownTypeHandler);
register(Date.class, new DateTypeHandler());
register(Date.class, JdbcType.DATE, new DateOnlyTypeHandler());
register(Date.class, JdbcType.TIME, new TimeOnlyTypeHandler());
register(JdbcType.TIMESTAMP, new DateTypeHandler());
register(JdbcType.DATE, new DateOnlyTypeHandler());
register(JdbcType.TIME, new TimeOnlyTypeHandler());
register(java.sql.Date.class, new SqlDateTypeHandler());
register(java.sql.Time.class, new SqlTimeTypeHandler());
register(java.sql.Timestamp.class, new SqlTimestampTypeHandler());
register(String.class, JdbcType.SQLXML, new SqlxmlTypeHandler());
register(Instant.class, new InstantTypeHandler());
register(LocalDateTime.class, new LocalDateTimeTypeHandler());
register(LocalDate.class, new LocalDateTypeHandler());
register(LocalTime.class, new LocalTimeTypeHandler());
register(OffsetDateTime.class, new OffsetDateTimeTypeHandler());
register(OffsetTime.class, new OffsetTimeTypeHandler());
register(ZonedDateTime.class, new ZonedDateTimeTypeHandler());
register(Month.class, new MonthTypeHandler());
register(Year.class, new YearTypeHandler());
register(YearMonth.class, new YearMonthTypeHandler());
register(JapaneseDate.class, new JapaneseDateTypeHandler());
// issue #273
register(Character.class, new CharacterTypeHandler());
register(char.class, new CharacterTypeHandler());
}
}注册过程
private void typeHandlerElement(XNode parent) {
if (parent != null) {
for (XNode child : parent.getChildren()) {
if ("package".equals(child.getName())) {
// 如果配置是包的话，把包下的全部类作为为typeHandler
String typeHandlerPackage = child.getStringAttribute("name");
typeHandlerRegistry.register(typeHandlerPackage);
} else {
// 如果配置的是单个，那就单个注册
String javaTypeName = child.getStringAttribute("javaType");
String jdbcTypeName = child.getStringAttribute("jdbcType");
String handlerTypeName = child.getStringAttribute("handler");
Class<?> javaTypeClass = resolveClass(javaTypeName);
JdbcType jdbcType = resolveJdbcType(jdbcTypeName);
Class<?> typeHandlerClass = resolveClass(handlerTypeName);
if (javaTypeClass != null) {
if (jdbcType == null) {
typeHandlerRegistry.register(javaTypeClass, typeHandlerClass);
} else {
typeHandlerRegistry.register(javaTypeClass, jdbcType, typeHandlerClass);
}
} else {
typeHandlerRegistry.register(typeHandlerClass);
}
}
}
}
}委托给TypeHandlerRegistry的各个register方法完成
public void register(JdbcType jdbcType, TypeHandler<?> handler) {
jdbcTypeHandlerMap.put(jdbcType, handler);
}
//
// REGISTER INSTANCE
//
// Only handler
@SuppressWarnings("unchecked")
public <T> void register(TypeHandler<T> typeHandler) {
boolean mappedTypeFound = false;
MappedTypes mappedTypes = typeHandler.getClass().getAnnotation(MappedTypes.class);
if (mappedTypes != null) {
for (Class<?> handledType : mappedTypes.value()) {
register(handledType, typeHandler);
mappedTypeFound = true;
}
}
// @since 3.1.0 - try to auto-discover the mapped type
if (!mappedTypeFound && typeHandler instanceof TypeReference) {
try {
TypeReference<T> typeReference = (TypeReference<T>) typeHandler;
register(typeReference.getRawType(), typeHandler);
mappedTypeFound = true;
} catch (Throwable t) {
// maybe users define the TypeReference with a different type and are not assignable, so just ignore it
}
}
if (!mappedTypeFound) {
register((Class<T>) null, typeHandler);
}
}
// java type + handler
public <T> void register(Class<T> javaType, TypeHandler<? extends T> typeHandler) {
register((Type) javaType, typeHandler);
}
private <T> void register(Type javaType, TypeHandler<? extends T> typeHandler) {
MappedJdbcTypes mappedJdbcTypes = typeHandler.getClass().getAnnotation(MappedJdbcTypes.class);
if (mappedJdbcTypes != null) {
for (JdbcType handledJdbcType : mappedJdbcTypes.value()) {
register(javaType, handledJdbcType, typeHandler);
}
if (mappedJdbcTypes.includeNullJdbcType()) {
register(javaType, null, typeHandler);
}
} else {
register(javaType, null, typeHandler);
}
}
public <T> void register(TypeReference<T> javaTypeReference, TypeHandler<? extends T> handler) {
register(javaTypeReference.getRawType(), handler);
}
// java type + jdbc type + handler
// Cast is required here
@SuppressWarnings("cast")
public <T> void register(Class<T> type, JdbcType jdbcType, TypeHandler<? extends T> handler) {
register((Type) type, jdbcType, handler);
}
private void register(Type javaType, JdbcType jdbcType, TypeHandler<?> handler) {
if (javaType != null) {
Map<JdbcType, TypeHandler<?>> map = typeHandlerMap.get(javaType);
if (map == null || map == NULL_TYPE_HANDLER_MAP) {
map = new HashMap<>();
}
map.put(jdbcType, handler);
typeHandlerMap.put(javaType, map);
}
allTypeHandlersMap.put(handler.getClass(), handler);
}
//
// REGISTER CLASS
//
// Only handler type
public void register(Class<?> typeHandlerClass) {
boolean mappedTypeFound = false;
MappedTypes mappedTypes = typeHandlerClass.getAnnotation(MappedTypes.class);
if (mappedTypes != null) {
for (Class<?> javaTypeClass : mappedTypes.value()) {
register(javaTypeClass, typeHandlerClass);
mappedTypeFound = true;
}
}
if (!mappedTypeFound) {
register(getInstance(null, typeHandlerClass));
}
}
// java type + handler type
public void register(String javaTypeClassName, String typeHandlerClassName) throws ClassNotFoundException {
register(Resources.classForName(javaTypeClassName), Resources.classForName(typeHandlerClassName));
}
public void register(Class<?> javaTypeClass, Class<?> typeHandlerClass) {
register(javaTypeClass, getInstance(javaTypeClass, typeHandlerClass));
}
// java type + jdbc type + handler type
public void register(Class<?> javaTypeClass, JdbcType jdbcType, Class<?> typeHandlerClass) {
register(javaTypeClass, jdbcType, getInstance(javaTypeClass, typeHandlerClass));
}Mybatis3.4.5默认支持了JSR-310（日期和时间API），全部类型处理器如下
objectFactory
每次创建结果对象的时候，Mybatis都会使用对象工厂来完成实例化工作。默认的对象工厂仅仅实例化目标类，通过无参构造方法或者通过指定参数的构造方法进行实例化。
<objectFactory type="org.apache.ibatis.builder.ExampleObjectFactory">
<property name="objectFactoryProperty" value="100"/>
</objectFactory>解析过程
private void objectFactoryElement(XNode context) throws Exception {
if (context != null) {
// 对象工厂类型
String type = context.getStringAttribute("type");
// 对象工厂属性
Properties properties = context.getChildrenAsProperties();
// 实例化对象工厂
ObjectFactory factory = (ObjectFactory) resolveClass(type).getDeclaredConstructor().newInstance();
// 设置对象工厂属性
factory.setProperties(properties);
// 保存到configuration中
configuration.setObjectFactory(factory);
}
}objectWrapperFactory
objectWrapperFactory是创建包装类工厂
<objectWrapperFactory type="org.apache.ibatis.builder.CustomObjectWrapperFactory" />解析过程
private void objectWrapperFactoryElement(XNode context) throws Exception {
if (context != null) {
// 类型
String type = context.getStringAttribute("type");
// 实例化
ObjectWrapperFactory factory = (ObjectWrapperFactory) resolveClass(type).getDeclaredConstructor().newInstance();
// 保存到configuration中
configuration.setObjectWrapperFactory(factory);
}
}reflectorFactory
ReflectorFactory接口主要是为了实现对Reflector对象的创建和缓存，Mybatis为ReflectorFactory接口提供了一个默认实现类DefaultReflectorFactory，其中findForClass()方法实现会为指定的Class创建Reflector对象，并将Reflector 对象缓存到reflectorMap中
<reflectorFactory type="org.apache.ibatis.builder.CustomReflectorFactory"/>解析过程
private void reflectorFactoryElement(XNode context) throws Exception {
if (context != null) {
// 类型
String type = context.getStringAttribute("type");
// 实例化
ReflectorFactory factory = (ReflectorFactory) resolveClass(type).getDeclaredConstructor().newInstance();
// 保存到configuration中
configuration.setReflectorFactory(factory);
}
}plugins
MyBatis 允许你在映射语句执行过程中的某一点进行拦截调用。默认情况下，MyBatis 允许使用插件来拦截的方法调用包括：
Executor (update, query, flushStatements, commit, rollback, getTransaction, close, isClosed)
ParameterHandler (getParameterObject, setParameters)
ResultSetHandler (handleResultSets, handleOutputParameters)
StatementHandler (prepare, parameterize, batch, update, query)插件保存在configuration的interceptorChain中
protected final InterceptorChain interceptorChain = new InterceptorChain();public class InterceptorChain {
private final List<Interceptor> interceptors = new ArrayList<>();
public Object pluginAll(Object target) {
for (Interceptor interceptor : interceptors) {
target = interceptor.plugin(target);
}
return target;
}
public void addInterceptor(Interceptor interceptor) {
interceptors.add(interceptor);
}
public List<Interceptor> getInterceptors() {
return Collections.unmodifiableList(interceptors);
}
}<plugins>
<plugin interceptor="org.apache.ibatis.builder.ExamplePlugin">
<property name="pluginProperty" value="100"/>
</plugin>
</plugins>注册过程
private void pluginElement(XNode parent) throws Exception {
if (parent != null) {
for (XNode child : parent.getChildren()) {
// 拦截器
String interceptor = child.getStringAttribute("interceptor");
// 拦截器属性
Properties properties = child.getChildrenAsProperties();
// 初始化拦截器
Interceptor interceptorInstance = (Interceptor) resolveClass(interceptor).getDeclaredConstructor().newInstance();
// 设置拦截器属性
interceptorInstance.setProperties(properties);
// 保存到configuration中
configuration.addInterceptor(interceptorInstance);
}
}
}environments
MyBatis 可以配置成适应多种环境，这种机制有助于将 SQL 映射应用于多种数据库之中， 现实情况下有多种理由需要这么做。例如，开发、测试和生产环境需要有不同的配置；或者想在具有相同 Schema 的多个生产数据库中使用相同的 SQL 映射。还有许多类似的使用场景。尽管可以配置多个环境，但每个 SqlSessionFactory 实例只能选择一种环境。
<environments default="development">
<environment id="development">
<transactionManager type="JDBC">
<property name="" value=""/>
</transactionManager>
<dataSource type="UNPOOLED">
<property name="driver" value="${driver}"/>
<property name="url" value="${url}"/>
<property name="username" value="${username}"/>
<property name="password" value="${password}"/>
</dataSource>
</environment>
</environments>解析过程
private void environmentsElement(XNode context) throws Exception {
if (context != null) {
if (environment == null) {
environment = context.getStringAttribute("default");
}
for (XNode child : context.getChildren()) {
String id = child.getStringAttribute("id");
if (isSpecifiedEnvironment(id)) {
// 事务工厂
TransactionFactory txFactory = transactionManagerElement(child.evalNode("transactionManager"));
// 数据源工厂
DataSourceFactory dsFactory = dataSourceElement(child.evalNode("dataSource"));
// 创建数据源
DataSource dataSource = dsFactory.getDataSource();
// 创建环境对象
Environment.Builder environmentBuilder = new Environment.Builder(id)
.transactionFactory(txFactory)
.dataSource(dataSource);
// 保存到configuration中
configuration.setEnvironment(environmentBuilder.build());
}
}
}
}解析事务工厂
private TransactionFactory transactionManagerElement(XNode context) throws Exception {
if (context != null) {
String type = context.getStringAttribute("type");
Properties props = context.getChildrenAsProperties();
TransactionFactory factory = (TransactionFactory) resolveClass(type).getDeclaredConstructor().newInstance();
factory.setProperties(props);
return factory;
}
throw new BuilderException("Environment declaration requires a TransactionFactory.");
}解析数据源工厂
private DataSourceFactory dataSourceElement(XNode context) throws Exception {
if (context != null) {
String type = context.getStringAttribute("type");
Properties props = context.getChildrenAsProperties();
DataSourceFactory factory = (DataSourceFactory) resolveClass(type).getDeclaredConstructor().newInstance();
factory.setProperties(props);
return factory;
}
throw new BuilderException("Environment declaration requires a DataSourceFactory.");
}最终保存再Environment对象中
public final class Environment {
private final String id;
private final TransactionFactory transactionFactory;
private final DataSource dataSource;
}databaseIdProvider
MyBatis 可以根据不同的数据库厂商执行不同的语句，这种多厂商的支持是基于映射语句中的 databaseId 属性。 MyBatis 会加载带有匹配当前数据库 databaseId 属性和所有不带 databaseId 属性的语句。 如果同时找到带有 databaseId 和不带 databaseId 的相同语句，则后者会被舍弃
<databaseIdProvider type="DB_VENDOR">
<property name="Apache Derby" value="derby"/>
</databaseIdProvider>解析过程
private void databaseIdProviderElement(XNode context) throws Exception {
DatabaseIdProvider databaseIdProvider = null;
if (context != null) {
// 类型
String type = context.getStringAttribute("type");
// 保持向下兼容VENDOR
// awful patch to keep backward compatibility
if ("VENDOR".equals(type)) {
type = "DB_VENDOR";
}
// 属性
Properties properties = context.getChildrenAsProperties();
// 实例化DatabaseIdProvider
databaseIdProvider = (DatabaseIdProvider) resolveClass(type).getDeclaredConstructor().newInstance();
// 设置属性
databaseIdProvider.setProperties(properties);
}
Environment environment = configuration.getEnvironment();
if (environment != null && databaseIdProvider != null) {
String databaseId = databaseIdProvider.getDatabaseId(environment.getDataSource());
// 保存到configuration中
configuration.setDatabaseId(databaseId);
}
}mappers
告诉Mybatis去哪里找mapper
<mappers>
<mapper resource="org/apache/ibatis/builder/BlogMapper.xml"/>
<mapper url="file:./src/test/java/org/apache/ibatis/builder/NestedBlogMapper.xml"/>
<mapper class="org.apache.ibatis.builder.CachedAuthorMapper"/>
<package name="org.apache.ibatis.builder.mapper"/>
</mappers>
