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MybatisGenerator插件开发六【逻辑删除】

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逻辑删除在项目中也是很常见的，比较常见的方式是添加一个deleted的标记位，当然也有其他的实现方式。本章节的插件针对的是添加标记位的方式来实现逻辑删除的。如果说没有和deleted标记位一起的唯一联合索引，那是很容易实现的，标志位只要两个值：0、1，然后通过updateByExampleSelective修改就可以了。但是往往我们表中会有唯一索引在，比如说名字不能重复之类的。这个时候我们采取的简单的处理方式是set deleted = deleted + 1来避免无法删除已经删除过的数据的问题。索性这个插件就提供了两个方法：logicDelete和logicDeleteWithUIndex。

修改Mapper接口和SqlMap文件

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public class LogicDeletePlugin extends PluginAdapter {
    @Override
    public boolean validate(List<String> list) {
        return true;
    }
    /**
     * 修改Mapper类
     */
    @Override
    public boolean clientGenerated(Interface interfaze, TopLevelClass topLevelClass, IntrospectedTable introspectedTable) {
        addLogicDeleteMethod(interfaze);
        return true;
    }
    private void addLogicDeleteMethod(Interface interfaze) {
        // 方法的返回值
        FullyQualifiedJavaType returnTypeInt = FullyQualifiedJavaType.getIntInstance();
        Method logicDeleteMethod = new Method();
        // 1.设置方法可见性
        logicDeleteMethod.setVisibility(JavaVisibility.PUBLIC);
        // 2.设置返回值类型 int类型
        logicDeleteMethod.setReturnType(returnTypeInt);
        // 3.设置方法名
        logicDeleteMethod.setName("logicDelete");
        // 4.设置参数列表
        FullyQualifiedJavaType paramType = PrimitiveTypeWrapper.getLongInstance();
        logicDeleteMethod.addParameter(new Parameter(paramType, "id"));
        interfaze.addMethod(logicDeleteMethod);
        Method logicDeleteWithUIndexMethod = new Method();
        // 1.设置方法可见性
        logicDeleteWithUIndexMethod.setVisibility(JavaVisibility.PUBLIC);
        // 2.设置返回值类型 int类型
        logicDeleteWithUIndexMethod.setReturnType(returnTypeInt);
        // 3.设置方法名
        logicDeleteWithUIndexMethod.setName("logicDeleteWithUIndex");
        // 4.设置参数列表
        FullyQualifiedJavaType paramTypeSelective = PrimitiveTypeWrapper.getLongInstance();
        logicDeleteWithUIndexMethod.addParameter(new Parameter(paramTypeSelective, "id", "@Param(\"id\")"));
        logicDeleteWithUIndexMethod.addParameter(new Parameter(FullyQualifiedJavaType.getStringInstance(), "uIndexes", "@Param(\"uIndexes\")", true));
        interfaze.addMethod(logicDeleteWithUIndexMethod);
    }
    /**
     * 修改Mapper.xml
     */
    @Override
    public boolean sqlMapDocumentGenerated(Document document, IntrospectedTable introspectedTable) {
        addLogicDeleteXml(document, introspectedTable);
        addLogicDeleteWithUIndexXml(document, introspectedTable);
        return true;
    }
    private void addLogicDeleteXml(Document document, IntrospectedTable introspectedTable) {
        XmlElement logicDeleteElement = new XmlElement("update");
        logicDeleteElement.addAttribute(new Attribute("id", "logicDelete"));
        logicDeleteElement.addAttribute(new Attribute("parameterType", "java.lang.Long"));
        logicDeleteElement.addElement(new TextElement("update " + introspectedTable.getAliasedFullyQualifiedTableNameAtRuntime()));
        logicDeleteElement.addElement(new TextElement("set deleted = 1, update_time = REPLACE(unix_timestamp(current_timestamp(3)),'.','') where id = #{id,jdbcType=BIGINT}"));
        document.getRootElement().addElement(logicDeleteElement);
    }
    private void addLogicDeleteWithUIndexXml(Document document, IntrospectedTable introspectedTable) {
        XmlElement logicDeleteWithUIndexElement = new XmlElement("update");
        logicDeleteWithUIndexElement.addAttribute(new Attribute("id", "logicDeleteWithUIndex"));
        logicDeleteWithUIndexElement.addAttribute(new Attribute("parameterType", "map"));
        logicDeleteWithUIndexElement.addElement(new TextElement("update " + introspectedTable.getAliasedFullyQualifiedTableNameAtRuntime() + " A,"));
        logicDeleteWithUIndexElement.addElement(new TextElement("(select C.deleted  from " + introspectedTable.getAliasedFullyQualifiedTableNameAtRuntime() + " C,"));
        logicDeleteWithUIndexElement.addElement(new TextElement("(select"));
        XmlElement foreachElement = new XmlElement("foreach");
        foreachElement.addAttribute(new Attribute("collection", "uIndexes"));
        foreachElement.addAttribute(new Attribute("index", "index"));
        foreachElement.addAttribute(new Attribute("item", "column"));
        foreachElement.addAttribute(new Attribute("separator", ","));
        foreachElement.addElement(new TextElement("${column}"));
        logicDeleteWithUIndexElement.addElement(foreachElement);
        logicDeleteWithUIndexElement.addElement(new TextElement("from " + introspectedTable.getAliasedFullyQualifiedTableNameAtRuntime() + " where id = #{id,jdbcType=BIGINT}) D"));
        XmlElement whereElement = new XmlElement("where");
        XmlElement whereForachElement = new XmlElement("foreach");
        whereForachElement.addAttribute(new Attribute("collection", "uIndexes"));
        whereForachElement.addAttribute(new Attribute("index", "index"));
        whereForachElement.addAttribute(new Attribute("item", "column"));
        whereForachElement.addElement(new TextElement(" and C.${column} = D.${column}"));
        whereElement.addElement(whereForachElement);
        logicDeleteWithUIndexElement.addElement(whereElement);
        logicDeleteWithUIndexElement.addElement(new TextElement("order by C.deleted desc limit 1) B"));
        logicDeleteWithUIndexElement.addElement(new TextElement("set A.deleted = B.deleted + 1, A.update_time = REPLACE(unix_timestamp(current_timestamp(3)),'.','')"));
        logicDeleteWithUIndexElement.addElement(new TextElement("where A.id = #{id,jdbcType=BIGINT}"));
        logicDeleteWithUIndexElement.addElement(new TextElement("and A.deleted = 0"));
        document.getRootElement().addElement(logicDeleteWithUIndexElement);
    }
}

逻辑比较简单，就是在Mapper接口和SqlMap文件中添加方法和对应的sql语句就可以了。

查看生成文件

将插件添加到项目中，并且运行完MybatisGenerator，我们来查看下生成的相关文件：

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public interface AdministratorMapper {
    ...
    int logicDelete(Long id);
    int logicDeleteWithUIndex(@Param("id") Long id, @Param("uIndexes") String ... uIndexes);
}
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<update id="logicDelete" parameterType="java.lang.Long">
   update administrator
   set deleted = 1, update_time = REPLACE(unix_timestamp(current_timestamp(3)),'.','') where id = #{id,jdbcType=BIGINT}
 </update>
 <update id="logicDeleteWithUIndex" parameterType="map">
   update administrator A,
   (select C.deleted  from administrator C,
   (select
   <foreach collection="uIndexes" index="index" item="column" separator=",">
     ${column}
   </foreach>
   from administrator where id = #{id,jdbcType=BIGINT}) D
   <where>
     <foreach collection="uIndexes" index="index" item="column">
        and C.${column} = D.${column}
     </foreach>
   </where>
   order by C.deleted desc limit 1) B
   set A.deleted = B.deleted + 1, A.update_time = REPLACE(unix_timestamp(current_timestamp(3)),'.','')
   where A.id = #{id,jdbcType=BIGINT}
   and A.deleted = 0
 </update>

如何使用

使用方式如下：

这里同样用到了之前添加到Model类中的表字段枚举。

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administratorMapper.logicDeleteWithUIndex(id, Administrator.COLUMNS.MOBILE.getColumn()

本章节就到这里了。以后要用插件来实现一些特殊的Sql，应该可以举一反三了。