SpringBoot

56.SpringBoot学习笔记

SpringData-整合MyBatis-配置版MyBatis

Posted by Chen Xingxu on June 20, 2020

56.SpringBoot学习笔记–SpringData-整合MyBatis-配置版MyBatis

配置文件版

mybatis\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>
    <settings>
        <setting name="mapUnderscoreToCamelCase" value="true"/>
    </settings>
</configuration>

demo.yangxu.springboot.mapper.EmployeeMapper

package demo.yangxu.springboot.mapper;

import demo.yangxu.springboot.bean.Employee;

//@Mapper或者@MapperScan将接口扫描装配到容器中
public interface EmployeeMapper {
    public Employee getEmpById(Integer id);
    public void insertEmp(Employee employee);
}

mybatis\mapper\EmployeeMapper.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="demo.yangxu.springboot.mapper.EmployeeMapper">

    <select id="getEmpById" resultType="demo.yangxu.springboot.bean.Employee">
        SELECT * FROM employee WHERE id=#{id}
    </select>

    <insert id="insertEmp"  parameterType="demo.yangxu.springboot.bean.Employee" useGeneratedKeys="true" keyProperty="id">
        INSERT INTO employee(lastName,gender,email,d_id) VALUES(#{lastName},#{gender},#{email},#{dId})
    </insert>
</mapper>

application.yml

mybatis:
  # 指定全局配置文件位置
  config-location: classpath:mybatis/mybatis-config.xml
  # 指定sql映射文件位置
  mapper-locations: classpath:mybatis/mapper/*.xml

demo.yangxu.springboot.controller.EmployeeController

package demo.yangxu.springboot.controller;

import demo.yangxu.springboot.bean.Department;
import demo.yangxu.springboot.bean.Employee;
import demo.yangxu.springboot.mapper.EmployeeMapper;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.PathVariable;
import org.springframework.web.bind.annotation.RestController;

@RestController
public class EmployeeController {

    @Autowired
    EmployeeMapper employeeMapper;

    @GetMapping("/emp/{id}")
    public Employee getEmpById(@PathVariable("id") Integer id){
        return employeeMapper.getEmpById(id);
    }

    @GetMapping("/emp")
    public Employee insertEmp(Employee employee){
        employeeMapper.insertEmp(employee);
        return employee;
    }
}

访问以下网址进行测试：

http://localhost:8080/emp?lastName=employ1&gender=1&email=emply1@163.com&dId=1
http://localhost:8080/emp/1

更多使用参照

https://mybatis.org/mybatis-3/getting-started.html

The configuration XML file contains settings for the core of the MyBatis system, including a DataSource for acquiring database Connection instances, as well as a TransactionManager for determining how transactions should be scoped and controlled. The full details of the XML configuration file can be found later in this document, but here is a simple example:

<?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="${driver}"/>
        <property name="url" value="${url}"/>
        <property name="username" value="${username}"/>
        <property name="password" value="${password}"/>
      </dataSource>
    </environment>
  </environments>
  <mappers>
    <mapper resource="org/mybatis/example/BlogMapper.xml"/>
  </mappers>
</configuration>

In either of the examples above, the statements could have been defined by either XML or Annotations. Let’s take a look at XML first. The full set of features provided by MyBatis can be realized by using the XML based mapping language that has made MyBatis popular over the years. If you’ve used MyBatis before, the concept will be familiar to you, but there have been numerous improvements to the XML mapping documents that will become clear later. Here is an example of an XML based mapped statement that would satisfy the above SqlSession calls.

<?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="org.mybatis.example.BlogMapper">
  <select id="selectBlog" resultType="Blog">
    select * from Blog where id = #{id}
  </select>
</mapper>

https://mybatis.org/mybatis-3/configuration.html

settings

These are extremely important tweaks that modify the way that MyBatis behaves at runtime. The following table describes the settings, their meanings and their default values.

Setting Description Valid Values Default
cacheEnabled Globally enables or disables any caches configured in any mapper under this configuration. true | false true
lazyLoadingEnabled Globally enables or disables lazy loading. When enabled, all relations will be lazily loaded. This value can be superseded for a specific relation by using the fetchType attribute on it. true | false false
aggressiveLazyLoading When enabled, any method call will load all the lazy properties of the object. Otherwise, each property is loaded on demand (see also lazyLoadTriggerMethods). true | false false (true in ≤3.4.1)
multipleResultSetsEnabled Allows or disallows multiple ResultSets to be returned from a single statement (compatible driver required). true | false true
useColumnLabel Uses the column label instead of the column name. Different drivers behave differently in this respect. Refer to the driver documentation, or test out both modes to determine how your driver behaves. true | false true
useGeneratedKeys Allows JDBC support for generated keys. A compatible driver is required. This setting forces generated keys to be used if set to true, as some drivers deny compatibility but still work (e.g. Derby). true | false False
autoMappingBehavior Specifies if and how MyBatis should automatically map columns to fields/properties. NONE disables auto-mapping. PARTIAL will only auto-map results with no nested result mappings defined inside. FULL will auto-map result mappings of any complexity (containing nested or otherwise). NONE, PARTIAL, FULL PARTIAL
autoMappingUnknownColumnBehavior Specify the behavior when detects an unknown column (or unknown property type) of automatic mapping target.NONE: Do nothingWARNING: Output warning log (The log level of 'org.apache.ibatis.session.AutoMappingUnknownColumnBehavior' must be set to WARN)FAILING: Fail mapping (Throw SqlSessionException) NONE, WARNING, FAILING NONE
defaultExecutorType Configures the default executor. SIMPLE executor does nothing special. REUSE executor reuses prepared statements. BATCH executor reuses statements and batches updates. SIMPLE REUSE BATCH SIMPLE
defaultStatementTimeout Sets the number of seconds the driver will wait for a response from the database. Any positive integer Not Set (null)
defaultFetchSize Sets the driver a hint as to control fetching size for return results. This parameter value can be override by a query setting. Any positive integer Not Set (null)
defaultResultSetType Specifies a scroll strategy when omit it per statement settings. (Since: 3.5.2) FORWARD_ONLY | SCROLL_SENSITIVE | SCROLL_INSENSITIVE | DEFAULT(same behavior with ‘Not Set’) Not Set (null)
safeRowBoundsEnabled Allows using RowBounds on nested statements. If allow, set the false. true | false False
safeResultHandlerEnabled Allows using ResultHandler on nested statements. If allow, set the false. true | false True
mapUnderscoreToCamelCase Enables automatic mapping from classic database column names A_COLUMN to camel case classic Java property names aColumn. true | false False
localCacheScope MyBatis uses local cache to prevent circular references and speed up repeated nested queries. By default (SESSION) all queries executed during a session are cached. If localCacheScope=STATEMENT local session will be used just for statement execution, no data will be shared between two different calls to the same SqlSession. SESSION | STATEMENT SESSION
jdbcTypeForNull Specifies the JDBC type for null values when no specific JDBC type was provided for the parameter. Some drivers require specifying the column JDBC type but others work with generic values like NULL, VARCHAR or OTHER. JdbcType enumeration. Most common are: NULL, VARCHAR and OTHER OTHER
lazyLoadTriggerMethods Specifies which Object’s methods trigger a lazy load A method name list separated by commas equals,clone,hashCode,toString
defaultScriptingLanguage Specifies the language used by default for dynamic SQL generation. A type alias or fully qualified class name. org.apache.ibatis.scripting.xmltags.XMLLanguageDriver
defaultEnumTypeHandler Specifies the TypeHandler used by default for Enum. (Since: 3.4.5) A type alias or fully qualified class name. org.apache.ibatis.type.EnumTypeHandler
callSettersOnNulls Specifies if setters or map’s put method will be called when a retrieved value is null. It is useful when you rely on Map.keySet() or null value initialization. Note primitives such as (int,boolean,etc.) will not be set to null. true | false false
returnInstanceForEmptyRow MyBatis, by default, returns null when all the columns of a returned row are NULL. When this setting is enabled, MyBatis returns an empty instance instead. Note that it is also applied to nested results (i.e. collectioin and association). Since: 3.4.2 true | false false
logPrefix Specifies the prefix string that MyBatis will add to the logger names. Any String Not set
logImpl Specifies which logging implementation MyBatis should use. If this setting is not present logging implementation will be autodiscovered. SLF4J | LOG4J | LOG4J2 | JDK_LOGGING | COMMONS_LOGGING | STDOUT_LOGGING | NO_LOGGING Not set
proxyFactory Specifies the proxy tool that MyBatis will use for creating lazy loading capable objects. CGLIB | JAVASSIST JAVASSIST (MyBatis 3.3 or above)
vfsImpl Specifies VFS implementations Fully qualified class names of custom VFS implementation separated by commas. Not set
useActualParamName Allow referencing statement parameters by their actual names declared in the method signature. To use this feature, your project must be compiled in Java 8 with -parameters option. (Since: 3.4.1) true | false true
configurationFactory Specifies the class that provides an instance of Configuration. The returned Configuration instance is used to load lazy properties of deserialized objects. This class must have a method with a signature static Configuration getConfiguration(). (Since: 3.2.3) A type alias or fully qualified class name. Not set
shrinkWhitespacesInSql Removes extra whitespace characters from the SQL. Note that this also affects literal strings in SQL. (Since 3.5.5) true | false false

An example of the settings element fully configured is as follows:

<settings>
  <setting name="cacheEnabled" value="true"/>
  <setting name="lazyLoadingEnabled" value="true"/>
  <setting name="multipleResultSetsEnabled" value="true"/>
  <setting name="useColumnLabel" value="true"/>
  <setting name="useGeneratedKeys" value="false"/>
  <setting name="autoMappingBehavior" value="PARTIAL"/>
  <setting name="autoMappingUnknownColumnBehavior" value="WARNING"/>
  <setting name="defaultExecutorType" value="SIMPLE"/>
  <setting name="defaultStatementTimeout" value="25"/>
  <setting name="defaultFetchSize" value="100"/>
  <setting name="safeRowBoundsEnabled" value="false"/>
  <setting name="mapUnderscoreToCamelCase" value="false"/>
  <setting name="localCacheScope" value="SESSION"/>
  <setting name="jdbcTypeForNull" value="OTHER"/>
  <setting name="lazyLoadTriggerMethods"
    value="equals,clone,hashCode,toString"/>
</settings>

https://mybatis.org/spring-boot-starter/mybatis-spring-boot-autoconfigure/

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