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来源:juejin.cn/post/6883081187103866894
Mybatis-Plus(简称MP)是一个 Mybatis 的增强工具,那么它是怎么增强的呢?其实就是它已经封装好了一些crud方法,开发就不需要再写xml了,直接调用这些方法就行,就类似于JPA。那么这篇文章就来阅读以下MP的具体实现,看看是怎样实现这些增强的。入口类:MybatisSqlSessionFactoryBuilder通过在入口类 MybatisSqlSessionFactoryBuilder#build方法中, 在应用启动时, 将mybatis plus(简称MP)自定义的动态配置xml文件注入到Mybatis中。public class MybatisSqlSessionFactoryBuilder extends SqlSessionFactoryBuilder { public SqlSessionFactory build(Configuration configuration) { // ... 省略若干行 if (globalConfig.isEnableSqlRunner()) { new SqlRunnerInjector().inject(configuration); } // ... 省略若干行 return sqlSessionFactory; }}这里涉及到2个MP2个功能类
入口类:MybatisSqlSessionFactoryBuilder
public class MybatisSqlSessionFactoryBuilder extends SqlSessionFactoryBuilder { public SqlSessionFactory build(Configuration configuration) { // ... 省略若干行 if (globalConfig.isEnableSqlRunner()) { new SqlRunnerInjector().inject(configuration); } // ... 省略若干行 return sqlSessionFactory; }}
public class MybatisSqlSessionFactoryBuilder extends SqlSessionFactoryBuilder {
public SqlSessionFactory build(Configuration configuration) {
// ... 省略若干行
if (globalConfig.isEnableSqlRunner()) {
new SqlRunnerInjector().inject(configuration);
}
return sqlSessionFactory;
public class MybatisConfiguration extends Configuration { /** * Mapper 注册 */ protected final MybatisMapperRegistry mybatisMapperRegistry = new MybatisMapperRegistry(this); // .... /** * 初始化调用 */ public MybatisConfiguration() { super(); this.mapUnderscoreToCamelCase = true; languageRegistry.setDefaultDriverClass(MybatisXMLLanguageDriver.class); } /** * MybatisPlus 加载 SQL 顺序: * <p> 1、加载 XML中的 SQL </p> * <p> 2、加载 SqlProvider 中的 SQL </p> * <p> 3、XmlSql 与 SqlProvider不能包含相同的 SQL </p> * <p>调整后的 SQL优先级:XmlSql > sqlProvider > CurdSql </p> */ @Override public void addMappedStatement(MappedStatement ms) { // ... } // ... 省略若干行 /** * 使用自己的 MybatisMapperRegistry */ @Override public <T> void addMapper(Class<T> type) { mybatisMapperRegistry.addMapper(type); } // .... 省略若干行}
public class MybatisConfiguration extends Configuration {
/**
* Mapper 注册
*/
protected final MybatisMapperRegistry mybatisMapperRegistry = new MybatisMapperRegistry(this);
// ....
* 初始化调用
public MybatisConfiguration() {
super();
this.mapUnderscoreToCamelCase = true;
languageRegistry.setDefaultDriverClass(MybatisXMLLanguageDriver.class);
* MybatisPlus 加载 SQL 顺序:
* <p> 1、加载 XML中的 SQL </p>
* <p> 2、加载 SqlProvider 中的 SQL </p>
* <p> 3、XmlSql 与 SqlProvider不能包含相同的 SQL </p>
* <p>调整后的 SQL优先级:XmlSql > sqlProvider > CurdSql </p>
@Override
public void addMappedStatement(MappedStatement ms) {
// ...
* 使用自己的 MybatisMapperRegistry
public <T> void addMapper(Class<T> type) {
mybatisMapperRegistry.addMapper(type);
// .... 省略若干行
在MybatisMapperRegistry中,MP将mybatis的MapperAnnotationBuilder替换为MP自己的MybatisMapperAnnotationBuilder
public class MybatisMapperRegistry extends MapperRegistry { @Override public <T> void addMapper(Class<T> type) { // ... 省略若干行 MybatisMapperAnnotationBuilder parser = new MybatisMapperAnnotationBuilder(config, type); parser.parse(); // ... 省略若干行 }}
public class MybatisMapperRegistry extends MapperRegistry {
MybatisMapperAnnotationBuilder parser = new MybatisMapperAnnotationBuilder(config, type);
parser.parse();
public class MybatisMapperAnnotationBuilder extends MapperAnnotationBuilder { @Overrde public void parse() { //... 省略若干行 for (Method method : type.getMethods()) { /** for循环代码, MP判断method方法是否是@Select @Insert等mybatis注解方法**/ parseStatement(method); InterceptorIgnoreHelper.initSqlParserInfoCache(cache, mapperName, method); SqlParserHelper.initSqlParserInfoCache(mapperName, method); } /** 这2行代码, MP注入默认的方法列表**/ if (GlobalConfigUtils.isSupperMapperChildren(configuration, type)) { GlobalConfigUtils.getSqlInjector(configuration).inspectInject(assistant, type); } //... 省略若干行 } @Override public void inspectInject(MapperBuilderAssistant builderAssistant, Class<?> mapperClass) { Class<?> modelClass = extractModelClass(mapperClass); //... 省略若干行 List<AbstractMethod> methodList = this.getMethodList(mapperClass); TableInfo tableInfo = TableInfoHelper.initTableInfo(builderAssistant, modelClass); // 循环注入自定义方法 methodList.forEach(m -> m.inject(builderAssistant, mapperClass, modelClass, tableInfo)); mapperRegistryCache.add(className); }}public class DefaultSqlInjector extends AbstractSqlInjector { @Override public List<AbstractMethod> getMethodList(Class<?> mapperClass) { return Stream.of( new Insert(), //... 省略若干行 new SelectPage() ).collect(toList()); }}
public class MybatisMapperAnnotationBuilder extends MapperAnnotationBuilder {
@Overrde
public void parse() {
//... 省略若干行
for (Method method : type.getMethods()) {
/** for循环代码, MP判断method方法是否是@Select @Insert等mybatis注解方法**/
parseStatement(method);
InterceptorIgnoreHelper.initSqlParserInfoCache(cache, mapperName, method);
SqlParserHelper.initSqlParserInfoCache(mapperName, method);
/** 这2行代码, MP注入默认的方法列表**/
if (GlobalConfigUtils.isSupperMapperChildren(configuration, type)) {
GlobalConfigUtils.getSqlInjector(configuration).inspectInject(assistant, type);
public void inspectInject(MapperBuilderAssistant builderAssistant, Class<?> mapperClass) {
Class<?> modelClass = extractModelClass(mapperClass);
List<AbstractMethod> methodList = this.getMethodList(mapperClass);
TableInfo tableInfo = TableInfoHelper.initTableInfo(builderAssistant, modelClass);
// 循环注入自定义方法
methodList.forEach(m -> m.inject(builderAssistant, mapperClass, modelClass, tableInfo));
mapperRegistryCache.add(className);
public class DefaultSqlInjector extends AbstractSqlInjector {
public List<AbstractMethod> getMethodList(Class<?> mapperClass) {
return Stream.of(
new Insert(),
new SelectPage()
).collect(toList());
以 SelectById 这个类为例说明下
/** * 根据ID 查询一条数据 */public class SelectById extends AbstractMethod { @Override public MappedStatement injectMappedStatement(Class<?> mapperClass, Class<?> modelClass, TableInfo tableInfo) { /** 定义 mybatis xml method id, 对应 <id="xyz"> **/ SqlMethod sqlMethod = SqlMethod.SELECT_BY_ID; /** 构造id对应的具体xml片段 **/ SqlSource sqlSource = new RawSqlSource(configuration, String.format(sqlMethod.getSql(), sqlSelectColumns(tableInfo, false), tableInfo.getTableName(), tableInfo.getKeyColumn(), tableInfo.getKeyProperty(), tableInfo.getLogicDeleteSql(true, true)), Object.class); /** 将xml method方法添加到mybatis的MappedStatement中 **/ return this.addSelectMappedStatementForTable(mapperClass, getMethod(sqlMethod), sqlSource, tableInfo); }}
* 根据ID 查询一条数据
public class SelectById extends AbstractMethod {
public MappedStatement injectMappedStatement(Class<?> mapperClass, Class<?> modelClass, TableInfo tableInfo) {
/** 定义 mybatis xml method id, 对应 <id="xyz"> **/
SqlMethod sqlMethod = SqlMethod.SELECT_BY_ID;
/** 构造id对应的具体xml片段 **/
SqlSource sqlSource = new RawSqlSource(configuration, String.format(sqlMethod.getSql(),
sqlSelectColumns(tableInfo, false),
tableInfo.getTableName(), tableInfo.getKeyColumn(), tableInfo.getKeyProperty(),
tableInfo.getLogicDeleteSql(true, true)), Object.class);
/** 将xml method方法添加到mybatis的MappedStatement中 **/
return this.addSelectMappedStatementForTable(mapperClass, getMethod(sqlMethod), sqlSource, tableInfo);
public class YourSqlSessionFactoryBean extends SqlSessionFactoryBean implements ApplicationContextAware { private Resource[] mapperLocations; @Override public void setMapperLocations(Resource... mapperLocations) { super.setMapperLocations(mapperLocations); /** 存使用mybatis原生定义的mapper xml文件路径**/ this.mapperLocations = mapperLocations; } /** * {@inheritDoc} */ @Override public void afterPropertiesSet() throws Exception { ConfigurableListableBeanFactory beanFactory = getBeanFactory(); /** 只需要通过将自定义的方法构造成xml resource和原生定义的Resource一起注入到mybatis中即可, 这样就可以实现MP的自定义动态SQL和原生SQL的共生关系**/ this.setMapperLocations(InjectMapper.getMapperResource(this.dbType, beanFactory, this.mapperLocations)); super.afterPropertiesSet(); }}
public class YourSqlSessionFactoryBean extends SqlSessionFactoryBean implements ApplicationContextAware {
private Resource[] mapperLocations;
public void setMapperLocations(Resource... mapperLocations) {
super.setMapperLocations(mapperLocations);
/** 存使用mybatis原生定义的mapper xml文件路径**/
this.mapperLocations = mapperLocations;
* {@inheritDoc}
public void afterPropertiesSet() throws Exception {
ConfigurableListableBeanFactory beanFactory = getBeanFactory();
/** 只需要通过将自定义的方法构造成xml resource和原生定义的Resource一起注入到mybatis中即可, 这样就可以实现MP的自定义动态SQL和原生SQL的共生关系**/
this.setMapperLocations(InjectMapper.getMapperResource(this.dbType, beanFactory, this.mapperLocations));
super.afterPropertiesSet();
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1、985副教授工资曝光
2、心态崩了!税前2万4,到手1万4,年终奖扣税方式1月1日起施行~
3、雷军做程序员时写的博客,很强大!
4、人脸识别的时候,一定要穿上衣服啊!
5、清华大学:2021 元宇宙研究报告!
6、绩效被打3.25B,员工将支付宝告上了法院,判了
`单行代码`