MyBatis mapper.xml文件DOCTYPE 是干啥用的

青旅半醒 2022-02-02 00:27 350阅读 0赞

案例：

<!DOCTYPE mapper PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN" "http://mybatis.org/dtd/mybatis-3-mapper.dtd" >

很多人好奇这行代码在 mapper.xml文件起到了什么作用；反正我是蛮好奇的

把[http://mybatis.org/dtd/mybatis-3-mapper.dtd][http_mybatis.org_dtd_mybatis-3-mapper.dtd] 放在浏览器中；得到一个文件；

粗略看了一眼，脑子中冒出一句话：  so tm what ???

再细看了一眼：基本理解了什么意思

[mybatis-3-mapper.dtd][http_mybatis.org_dtd_mybatis-3-mapper.dtd] 文件后缀名为dtd, 英文为Document Type Definition，中文翻译为文档类型定义；

mapper表示根节点，[mybatis-3-mapper.dtd][http_mybatis.org_dtd_mybatis-3-mapper.dtd]被定义出来的意义，用来验证<mapper>\*\*\*\*\*</mapper>中使用的节点的是不是符合规范用的。

## **切记：此知识点了解就好，不必深究.** ##

**[mybatis-3-mapper.dtd][http_mybatis.org_dtd_mybatis-3-mapper.dtd] 内容如下：**

<?xml version="1.0" encoding="UTF-8" ?>
    
    <!ELEMENT mapper (cache-ref | cache | resultMap* | parameterMap* | sql* | insert* | update* | delete* | select* )+>
    <!ATTLIST mapper
    namespace CDATA #IMPLIED
    >
    
    <!ELEMENT cache-ref EMPTY>
    <!ATTLIST cache-ref
    namespace CDATA #REQUIRED
    >
    
    <!ELEMENT cache (property*)>
    <!ATTLIST cache
    type CDATA #IMPLIED
    eviction CDATA #IMPLIED
    flushInterval CDATA #IMPLIED
    size CDATA #IMPLIED
    readOnly CDATA #IMPLIED
    blocking CDATA #IMPLIED
    >
    
    <!ELEMENT parameterMap (parameter+)?>
    <!ATTLIST parameterMap
    id CDATA #REQUIRED
    type CDATA #REQUIRED
    >
    
    <!ELEMENT parameter EMPTY>
    <!ATTLIST parameter
    property CDATA #REQUIRED
    javaType CDATA #IMPLIED
    jdbcType CDATA #IMPLIED
    mode (IN | OUT | INOUT) #IMPLIED
    resultMap CDATA #IMPLIED
    scale CDATA #IMPLIED
    typeHandler CDATA #IMPLIED
    >
    
    <!ELEMENT resultMap (constructor?,id*,result*,association*,collection*, discriminator?)>
    <!ATTLIST resultMap
    id CDATA #REQUIRED
    type CDATA #REQUIRED
    extends CDATA #IMPLIED
    autoMapping (true|false) #IMPLIED
    >
    
    <!ELEMENT constructor (idArg*,arg*)>
    
    <!ELEMENT id EMPTY>
    <!ATTLIST id
    property CDATA #IMPLIED
    javaType CDATA #IMPLIED
    column CDATA #IMPLIED
    jdbcType CDATA #IMPLIED
    typeHandler CDATA #IMPLIED
    >
    
    <!ELEMENT result EMPTY>
    <!ATTLIST result
    property CDATA #IMPLIED
    javaType CDATA #IMPLIED
    column CDATA #IMPLIED
    jdbcType CDATA #IMPLIED
    typeHandler CDATA #IMPLIED
    >
    
    <!ELEMENT idArg EMPTY>
    <!ATTLIST idArg
    javaType CDATA #IMPLIED
    column CDATA #IMPLIED
    jdbcType CDATA #IMPLIED
    typeHandler CDATA #IMPLIED
    select CDATA #IMPLIED
    resultMap CDATA #IMPLIED
    name CDATA #IMPLIED
    columnPrefix CDATA #IMPLIED
    >
    
    <!ELEMENT arg EMPTY>
    <!ATTLIST arg
    javaType CDATA #IMPLIED
    column CDATA #IMPLIED
    jdbcType CDATA #IMPLIED
    typeHandler CDATA #IMPLIED
    select CDATA #IMPLIED
    resultMap CDATA #IMPLIED
    name CDATA #IMPLIED
    columnPrefix CDATA #IMPLIED
    >
    
    <!ELEMENT collection (constructor?,id*,result*,association*,collection*, discriminator?)>
    <!ATTLIST collection
    property CDATA #REQUIRED
    column CDATA #IMPLIED
    javaType CDATA #IMPLIED
    ofType CDATA #IMPLIED
    jdbcType CDATA #IMPLIED
    select CDATA #IMPLIED
    resultMap CDATA #IMPLIED
    typeHandler CDATA #IMPLIED
    notNullColumn CDATA #IMPLIED
    columnPrefix CDATA #IMPLIED
    resultSet CDATA #IMPLIED
    foreignColumn CDATA #IMPLIED
    autoMapping (true|false) #IMPLIED
    fetchType (lazy|eager) #IMPLIED
    >
    
    <!ELEMENT association (constructor?,id*,result*,association*,collection*, discriminator?)>
    <!ATTLIST association
    property CDATA #REQUIRED
    column CDATA #IMPLIED
    javaType CDATA #IMPLIED
    jdbcType CDATA #IMPLIED
    select CDATA #IMPLIED
    resultMap CDATA #IMPLIED
    typeHandler CDATA #IMPLIED
    notNullColumn CDATA #IMPLIED
    columnPrefix CDATA #IMPLIED
    resultSet CDATA #IMPLIED
    foreignColumn CDATA #IMPLIED
    autoMapping (true|false) #IMPLIED
    fetchType (lazy|eager) #IMPLIED
    >
    
    <!ELEMENT discriminator (case+)>
    <!ATTLIST discriminator
    column CDATA #IMPLIED
    javaType CDATA #REQUIRED
    jdbcType CDATA #IMPLIED
    typeHandler CDATA #IMPLIED
    >
    
    <!ELEMENT case (constructor?,id*,result*,association*,collection*, discriminator?)>
    <!ATTLIST case
    value CDATA #REQUIRED
    resultMap CDATA #IMPLIED
    resultType CDATA #IMPLIED
    >
    
    <!ELEMENT property EMPTY>
    <!ATTLIST property
    name CDATA #REQUIRED
    value CDATA #REQUIRED
    >
    
    <!ELEMENT typeAlias EMPTY>
    <!ATTLIST typeAlias
    alias CDATA #REQUIRED
    type CDATA #REQUIRED
    >
    
    <!ELEMENT select (#PCDATA | include | trim | where | set | foreach | choose | if | bind)*>
    <!ATTLIST select
    id CDATA #REQUIRED
    parameterMap CDATA #IMPLIED
    parameterType CDATA #IMPLIED
    resultMap CDATA #IMPLIED
    resultType CDATA #IMPLIED
    resultSetType (FORWARD_ONLY | SCROLL_INSENSITIVE | SCROLL_SENSITIVE | DEFAULT) #IMPLIED
    statementType (STATEMENT|PREPARED|CALLABLE) #IMPLIED
    fetchSize CDATA #IMPLIED
    timeout CDATA #IMPLIED
    flushCache (true|false) #IMPLIED
    useCache (true|false) #IMPLIED
    databaseId CDATA #IMPLIED
    lang CDATA #IMPLIED
    resultOrdered (true|false) #IMPLIED
    resultSets CDATA #IMPLIED 
    >
    
    <!ELEMENT insert (#PCDATA | selectKey | include | trim | where | set | foreach | choose | if | bind)*>
    <!ATTLIST insert
    id CDATA #REQUIRED
    parameterMap CDATA #IMPLIED
    parameterType CDATA #IMPLIED
    timeout CDATA #IMPLIED
    flushCache (true|false) #IMPLIED
    statementType (STATEMENT|PREPARED|CALLABLE) #IMPLIED
    keyProperty CDATA #IMPLIED
    useGeneratedKeys (true|false) #IMPLIED
    keyColumn CDATA #IMPLIED
    databaseId CDATA #IMPLIED
    lang CDATA #IMPLIED
    >
    
    <!ELEMENT selectKey (#PCDATA | include | trim | where | set | foreach | choose | if | bind)*>
    <!ATTLIST selectKey
    resultType CDATA #IMPLIED
    statementType (STATEMENT|PREPARED|CALLABLE) #IMPLIED
    keyProperty CDATA #IMPLIED
    keyColumn CDATA #IMPLIED
    order (BEFORE|AFTER) #IMPLIED
    databaseId CDATA #IMPLIED
    >
    
    <!ELEMENT update (#PCDATA | selectKey | include | trim | where | set | foreach | choose | if | bind)*>
    <!ATTLIST update
    id CDATA #REQUIRED
    parameterMap CDATA #IMPLIED
    parameterType CDATA #IMPLIED
    timeout CDATA #IMPLIED
    flushCache (true|false) #IMPLIED
    statementType (STATEMENT|PREPARED|CALLABLE) #IMPLIED
    keyProperty CDATA #IMPLIED
    useGeneratedKeys (true|false) #IMPLIED
    keyColumn CDATA #IMPLIED
    databaseId CDATA #IMPLIED
    lang CDATA #IMPLIED
    >
    
    <!ELEMENT delete (#PCDATA | include | trim | where | set | foreach | choose | if | bind)*>
    <!ATTLIST delete
    id CDATA #REQUIRED
    parameterMap CDATA #IMPLIED
    parameterType CDATA #IMPLIED
    timeout CDATA #IMPLIED
    flushCache (true|false) #IMPLIED
    statementType (STATEMENT|PREPARED|CALLABLE) #IMPLIED
    databaseId CDATA #IMPLIED
    lang CDATA #IMPLIED
    >
    
    
    
    <!ELEMENT include (property+)?>
    <!ATTLIST include
    refid CDATA #REQUIRED
    >
    
    <!ELEMENT bind EMPTY>
    <!ATTLIST bind
     name CDATA #REQUIRED
     value CDATA #REQUIRED
    >
    
    <!ELEMENT sql (#PCDATA | include | trim | where | set | foreach | choose | if | bind)*>
    <!ATTLIST sql
    id CDATA #REQUIRED
    lang CDATA #IMPLIED
    databaseId CDATA #IMPLIED
    >
    
    <!ELEMENT trim (#PCDATA | include | trim | where | set | foreach | choose | if | bind)*>
    <!ATTLIST trim
    prefix CDATA #IMPLIED
    prefixOverrides CDATA #IMPLIED
    suffix CDATA #IMPLIED
    suffixOverrides CDATA #IMPLIED
    >
    <!ELEMENT where (#PCDATA | include | trim | where | set | foreach | choose | if | bind)*>
    <!ELEMENT set (#PCDATA | include | trim | where | set | foreach | choose | if | bind)*>
    
    <!ELEMENT foreach (#PCDATA | include | trim | where | set | foreach | choose | if | bind)*>
    <!ATTLIST foreach
    collection CDATA #REQUIRED
    item CDATA #IMPLIED
    index CDATA #IMPLIED
    open CDATA #IMPLIED
    close CDATA #IMPLIED
    separator CDATA #IMPLIED
    >
    
    <!ELEMENT choose (when* , otherwise?)>
    <!ELEMENT when (#PCDATA | include | trim | where | set | foreach | choose | if | bind)*>
    <!ATTLIST when
    test CDATA #REQUIRED
    >
    <!ELEMENT otherwise (#PCDATA | include | trim | where | set | foreach | choose | if | bind)*>
    
    <!ELEMENT if (#PCDATA | include | trim | where | set | foreach | choose | if | bind)*>
    <!ATTLIST if
    test CDATA #REQUIRED
    >

[http_mybatis.org_dtd_mybatis-3-mapper.dtd]: http://mybatis.org/dtd/mybatis-3-mapper.dtd