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MyBatis
配置
<?xml version=”1.0″ encoding=”UTF-8″?>
<project xmlns=”http://maven.apache.org/POM/4.0.0″
xmlns:xsi=”http://www.w3.org/2001/XMLSchema-instance”
xsi:schemaLocation=”http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd”>
<modelVersion>4.0.0</modelVersion>
<groupId>com.huifer</groupId>
<artifactId>mybatisBook</artifactId>
<version>1.0-SNAPSHOT</version>
<properties>
<project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
<project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding>
<java.version>1.8</java.version>
</properties>
<dependencies>
<dependency>
<groupId>org.mybatis</groupId>
<artifactId>mybatis</artifactId>
<version>3.5.0</version>
</dependency>
<dependency>
<groupId>mysql</groupId>
<artifactId>mysql-connector-java</artifactId>
<version>8.0.13</version>
</dependency>
<dependency>
<groupId>org.projectlombok</groupId>
<artifactId>lombok</artifactId>
<version>1.18.4</version>
</dependency>
</dependencies>
<build>
<plugins>
<plugin>
<inherited>true</inherited>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-compiler-plugin</artifactId>
<configuration>
<source>1.8</source>
<target>1.8</target>
</configuration>
</plugin>
</plugins>
</build>
</project>
mybatis-config.xml
<?xml version=”1.0″ encoding=”UTF-8″ ?>
<!DOCTYPE configuration
PUBLIC “-//mybatis.org//DTD Config 3.0//EN”
“http://mybatis.org/dtd/mybatis-3-config.dtd”>
<configuration>
<environments default=”development”>
<environment id=”development”>
<transactionManager type=”JDBC”/>
<dataSource type=”POOLED”>
<property name=”driver” value=”com.mysql.cj.jdbc.Driver”/>
<property name=”url” value=”jdbc:mysql://localhost:3306/dy_java?serverTimezone=UTC&rewriteBatchedStatements=true&useUnicode=true&characterEncoding=utf8″/>
<property name=”username” value=”root”/>
<property name=”password” value=”root”/>
</dataSource>
</environment>
</environments>
<mappers>
<mapper resource=”DeptMapper.xml”/>
</mappers>
</configuration>
测试
DeptMapper.xml
<?xml version=”1.0″ encoding=”UTF-8″ ?>
<!DOCTYPE mapper
PUBLIC “-//mybatis.org//DTD Mapper 3.0//EN”
“http://mybatis.org/dtd/mybatis-3-mapper.dtd”>
<mapper namespace=”Dept”>
<insert id=”insertDept” >
INSERT INTO dept (dname, loc)
VALUES (#{dname} , #{loc});
</insert>
</mapper>
Dept.java
package com.huifer.mybatis;
import lombok.AllArgsConstructor;
import lombok.Data;
import lombok.NoArgsConstructor;
/**
* 描述:
*
* @author huifer
* @date 2019-02-21
*/
@Data
@AllArgsConstructor
@NoArgsConstructor
public class Dept {
private Long id;
private String dname;
private String loc;
}
测试类
public class Demo {
public static void main(String[] args) throws Exception {
Dept dept = new Dept();
dept.setDname(“ 技术部 ”);
dept.setLoc(“oc”);
InputStream is = Resources.getResourceAsStream(“mybatis-config.xml”);
SqlSessionFactory factory = new SqlSessionFactoryBuilder().build(is);
SqlSession session = factory.openSession();
session.insert(“insertDept”, dept);
session.commit();
session.close();
}
}
查询表
至此初步配置完成
执行过程
graph TD
start[获取 mybatis.config.xml] –> conditionA[SqlSessionFactory]
conditionA –> |xml 解析成 org.apache.ibatis.session.Configuration | conditionB[接收 SqlSessionFactory]
conditionB –> |org.apache.ibatis.session.defaults.DefaultSqlSessionFactory.openSessionFromDataSource| conditionC[SqlSession]
conditionC –> |org.apache.ibatis.session.defaults.DefaultSqlSession insert 方法 update 方法 | conditionD[insert 方法]
conditionD –> | org.apache.ibatis.mapping.MappedStatement sqlSource 属性 | conditionE[mapper 定位]
conditionE –> | org.apache.ibatis.executor.SimpleExecutor doUpdate 方法 stmt|conditionF[数据绑定到具体 sql]
conditionF –> |org.apache.ibatis.executor.statement.PreparedStatementHandler update 方法 提交 | conditionG[传输 sql]
conditionG –>|commit| stop
session
获取 mybatils-config.xml 配置 解析 xml 标签
org.apache.ibatis.session.defaults.DefaultSqlSessionFactory
private SqlSession openSessionFromDataSource(ExecutorType execType, TransactionIsolationLevel level, boolean autoCommit) {
Transaction tx = null;
DefaultSqlSession var8;
try {
Environment environment = this.configuration.getEnvironment();
TransactionFactory transactionFactory = this.getTransactionFactoryFromEnvironment(environment);
tx = transactionFactory.newTransaction(environment.getDataSource(), level, autoCommit);
Executor executor = this.configuration.newExecutor(tx, execType);
var8 = new DefaultSqlSession(this.configuration, executor, autoCommit);
} catch (Exception var12) {
this.closeTransaction(tx);
throw ExceptionFactory.wrapException(“Error opening session. Cause: ” + var12, var12);
} finally {
ErrorContext.instance().reset();
}
return var8;
}
insert
org.apache.ibatis.session.defaults.DefaultSqlSession
public int insert(String statement, Object parameter) {
return this.update(statement, parameter);
}
public int update(String statement, Object parameter) {
int var4;
try {
this.dirty = true;
MappedStatement ms = this.configuration.getMappedStatement(statement);
var4 = this.executor.update(ms, this.wrapCollection(parameter));
} catch (Exception var8) {
throw ExceptionFactory.wrapException(“Error updating database. Cause: ” + var8, var8);
} finally {
ErrorContext.instance().reset();
}
return var4;
}
ms 对象
doUpdate
org.apache.ibatis.executor.SimpleExecutor
public int doUpdate(MappedStatement ms, Object parameter) throws SQLException {
Statement stmt = null;
int var6;
try {
Configuration configuration = ms.getConfiguration();
StatementHandler handler = configuration.newStatementHandler(this, ms, parameter, RowBounds.DEFAULT, (ResultHandler)null, (BoundSql)null);
stmt = this.prepareStatement(handler, ms.getStatementLog());
var6 = handler.update(stmt);
} finally {
this.closeStatement(stmt);
}
return var6;
}
update
org.apache.ibatis.executor.statement.PreparedStatementHandler
public int update(Statement statement) throws SQLException {
PreparedStatement ps = (PreparedStatement)statement;
ps.execute();
int rows = ps.getUpdateCount();
Object parameterObject = this.boundSql.getParameterObject();
KeyGenerator keyGenerator = this.mappedStatement.getKeyGenerator();
keyGenerator.processAfter(this.executor, this.mappedStatement, ps, parameterObject);
return rows;
}
Mapper
<mappers>
<!–<mapper resource=”DeptMapper.xml”/>–>
<package name=”com.huifer.mybatis.dao”/>
</mappers>
获取过程源码
org.apache.ibatis.builder.xml.XMLConfigBuilder 使用 parseConfiguration 方法将 mybatis-config.xml 中的 mappers 标签内容获取到 mapperElement 具体执行获取内容，作用将 mappers 添加到 configuration 中
private void parseConfiguration(XNode root) {
try {
this.propertiesElement(root.evalNode(“properties”));
Properties settings = this.settingsAsProperties(root.evalNode(“settings”));
this.loadCustomVfs(settings);
this.loadCustomLogImpl(settings);
this.typeAliasesElement(root.evalNode(“typeAliases”));
this.pluginElement(root.evalNode(“plugins”));
this.objectFactoryElement(root.evalNode(“objectFactory”));
this.objectWrapperFactoryElement(root.evalNode(“objectWrapperFactory”));
this.reflectorFactoryElement(root.evalNode(“reflectorFactory”));
this.settingsElement(settings);
this.environmentsElement(root.evalNode(“environments”));
this.databaseIdProviderElement(root.evalNode(“databaseIdProvider”));
this.typeHandlerElement(root.evalNode(“typeHandlers”));
this.mapperElement(root.evalNode(“mappers”));
} catch (Exception var3) {
throw new BuilderException(“Error parsing SQL Mapper Configuration. Cause: ” + var3, var3);
}
}
private void mapperElement(XNode parent) throws Exception {
if (parent != null) {
Iterator var2 = parent.getChildren().iterator();
while(true) {
while(var2.hasNext()) {
XNode child = (XNode)var2.next();
String resource;
if (“package”.equals(child.getName())) {
resource = child.getStringAttribute(“name”);
this.configuration.addMappers(resource);
} else {
resource = child.getStringAttribute(“resource”);
String url = child.getStringAttribute(“url”);
String mapperClass = child.getStringAttribute(“class”);
XMLMapperBuilder mapperParser;
InputStream inputStream;
if (resource != null && url == null && mapperClass == null) {
ErrorContext.instance().resource(resource);
inputStream = Resources.getResourceAsStream(resource);
mapperParser = new XMLMapperBuilder(inputStream, this.configuration, resource, this.configuration.getSqlFragments());
mapperParser.parse();
} else if (resource == null && url != null && mapperClass == null) {
ErrorContext.instance().resource(url);
inputStream = Resources.getUrlAsStream(url);
mapperParser = new XMLMapperBuilder(inputStream, this.configuration, url, this.configuration.getSqlFragments());
mapperParser.parse();
} else {
if (resource != null || url != null || mapperClass == null) {
throw new BuilderException(“A mapper element may only specify a url, resource or class, but not more than one.”);
}
Class<?> mapperInterface = Resources.classForName(mapperClass);
this.configuration.addMapper(mapperInterface);
}
}
}
return;
}
}
}
当前 Configuration 下的 mappedStatements 属性
org.apache.ibatis.binding.MapperRegistry addMapper 方法，作用将解析到的接口对象放到 configuration 中，一个接口只能注册一次
public <T> void addMapper(Class<T> type) {
if (type.isInterface()) {
if (this.hasMapper(type)) {
throw new BindingException(“Type ” + type + ” is already known to the MapperRegistry.”);
}
boolean loadCompleted = false;
try {
this.knownMappers.put(type, new MapperProxyFactory(type));
MapperAnnotationBuilder parser = new MapperAnnotationBuilder(this.config, type);
parser.parse();
loadCompleted = true;
} finally {
if (!loadCompleted) {
this.knownMappers.remove(type);
}
}
}
}
org.apache.ibatis.builder.annotation.MapperAnnotationBuilder parse 方法
loadXmlResource 来确认加载具体的 xml 文件
public void parse() {
String resource = this.type.toString();
if (!this.configuration.isResourceLoaded(resource)) {
this.loadXmlResource();
this.configuration.addLoadedResource(resource);
this.assistant.setCurrentNamespace(this.type.getName());
this.parseCache();
this.parseCacheRef();
Method[] methods = this.type.getMethods();
Method[] var3 = methods;
int var4 = methods.length;
for(int var5 = 0; var5 < var4; ++var5) {
Method method = var3[var5];
try {
if (!method.isBridge()) {
this.parseStatement(method);
}
} catch (IncompleteElementException var8) {
this.configuration.addIncompleteMethod(new MethodResolver(this, method));
}
}
}
this.parsePendingMethods();
}
private void loadXmlResource() {
if (!this.configuration.isResourceLoaded(“namespace:” + this.type.getName())) {
String xmlResource = this.type.getName().replace(‘.’, ‘/’) + “.xml”;
InputStream inputStream = this.type.getResourceAsStream(“/” + xmlResource);
if (inputStream == null) {
try {
inputStream = Resources.getResourceAsStream(this.type.getClassLoader(), xmlResource);
} catch (IOException var4) {
}
}
if (inputStream != null) {
XMLMapperBuilder xmlParser = new XMLMapperBuilder(inputStream, this.assistant.getConfiguration(), xmlResource, this.configuration.getSqlFragments(), this.type.getName());
xmlParser.parse();
}
}
}
根据 loadXmlResource 中下面这行得知，PojoMapper.xml 要和 PojoMapperInterface 放在一个路径下
String xmlResource = this.type.getName().replace(‘.’, ‘/’) + “.xml”;
具体 sql
org.apache.ibatis.builder.xml.XMLStatementBuilder parseStatementNode 方法解析 sql 语句
<select id=”deptFindById” resultType=”com.huifer.mybatis.pojo.Dept” parameterType=”java.lang.Long”>
select * from dept where dept.id=#{deptno};
</select>
public void parseStatementNode() {
String id = this.context.getStringAttribute(“id”);
String databaseId = this.context.getStringAttribute(“databaseId”);
if (this.databaseIdMatchesCurrent(id, databaseId, this.requiredDatabaseId)) {
Integer fetchSize = this.context.getIntAttribute(“fetchSize”);
Integer timeout = this.context.getIntAttribute(“timeout”);
String parameterMap = this.context.getStringAttribute(“parameterMap”);
String parameterType = this.context.getStringAttribute(“parameterType”);
Class<?> parameterTypeClass = this.resolveClass(parameterType);
String resultMap = this.context.getStringAttribute(“resultMap”);
String resultType = this.context.getStringAttribute(“resultType”);
String lang = this.context.getStringAttribute(“lang”);
LanguageDriver langDriver = this.getLanguageDriver(lang);
Class<?> resultTypeClass = this.resolveClass(resultType);
String resultSetType = this.context.getStringAttribute(“resultSetType”);
StatementType statementType = StatementType.valueOf(this.context.getStringAttribute(“statementType”, StatementType.PREPARED.toString()));
ResultSetType resultSetTypeEnum = this.resolveResultSetType(resultSetType);
String nodeName = this.context.getNode().getNodeName();
SqlCommandType sqlCommandType = SqlCommandType.valueOf(nodeName.toUpperCase(Locale.ENGLISH));
boolean isSelect = sqlCommandType == SqlCommandType.SELECT;
boolean flushCache = this.context.getBooleanAttribute(“flushCache”, !isSelect);
boolean useCache = this.context.getBooleanAttribute(“useCache”, isSelect);
boolean resultOrdered = this.context.getBooleanAttribute(“resultOrdered”, false);
XMLIncludeTransformer includeParser = new XMLIncludeTransformer(this.configuration, this.builderAssistant);
includeParser.applyIncludes(this.context.getNode());
this.processSelectKeyNodes(id, parameterTypeClass, langDriver);
SqlSource sqlSource = langDriver.createSqlSource(this.configuration, this.context, parameterTypeClass);
String resultSets = this.context.getStringAttribute(“resultSets”);
String keyProperty = this.context.getStringAttribute(“keyProperty”);
String keyColumn = this.context.getStringAttribute(“keyColumn”);
String keyStatementId = id + “!selectKey”;
keyStatementId = this.builderAssistant.applyCurrentNamespace(keyStatementId, true);
Object keyGenerator;
if (this.configuration.hasKeyGenerator(keyStatementId)) {
keyGenerator = this.configuration.getKeyGenerator(keyStatementId);
} else {
keyGenerator = this.context.getBooleanAttribute(“useGeneratedKeys”, this.configuration.isUseGeneratedKeys() && SqlCommandType.INSERT.equals(sqlCommandType)) ? Jdbc3KeyGenerator.INSTANCE : NoKeyGenerator.INSTANCE;
}
this.builderAssistant.addMappedStatement(id, sqlSource, statementType, sqlCommandType, fetchSize, timeout, parameterMap, parameterTypeClass, resultMap, resultTypeClass, resultSetTypeEnum, flushCache, useCache, resultOrdered, (KeyGenerator)keyGenerator, keyProperty, keyColumn, databaseId, langDriver, resultSets);
}
}
还原 sql 方法
SqlSource sqlSource = langDriver.createSqlSource(this.configuration, this.context, parameterTypeClass);
org.apache.ibatis.scripting.defaults.RawSqlSource RawSqlSource 方法
public RawSqlSource(Configuration configuration, String sql, Class<?> parameterType) {
SqlSourceBuilder sqlSourceParser = new SqlSourceBuilder(configuration);
Class<?> clazz = parameterType == null ? Object.class : parameterType;
this.sqlSource = sqlSourceParser.parse(sql, clazz, new HashMap());
}
org.apache.ibatis.builder.SqlSourceBuilder parse 方法还原成 sql 语句
public SqlSource parse(String originalSql, Class<?> parameterType, Map<String, Object> additionalParameters) {
SqlSourceBuilder.ParameterMappingTokenHandler handler = new SqlSourceBuilder.ParameterMappingTokenHandler(this.configuration, parameterType, additionalParameters);
GenericTokenParser parser = new GenericTokenParser(“#{“, “}”, handler);
String sql = parser.parse(originalSql);
return new StaticSqlSource(this.configuration, sql, handler.getParameterMappings());
}
最后看一下 sqlSource
