Mybatis Generator 自定义插件——指定查询字段

ゞ浴缸里的玫瑰 2023-02-27 05:43 15阅读 0赞

## 引言 ##

最近在使用Mybatis Generator 自动生成的方法中，发现不能指定查询字段，selectByExample将整个表的字段都 返回了，如果想要查询某个表的指定字段，就需要自己手动写sql，这样觉得不方便，所以小编参考了Mybatis Generator 的源代码，自己写了一个插件满足需求。

相关注释在代码中都有，这里就不多说了，直接上代码：

package com.jack.db.plugin;
    
    import org.mybatis.generator.api.IntrospectedTable;
    import org.mybatis.generator.api.PluginAdapter;
    import org.mybatis.generator.api.dom.java.*;
    import org.mybatis.generator.api.dom.xml.Attribute;
    import org.mybatis.generator.api.dom.xml.Document;
    import org.mybatis.generator.api.dom.xml.TextElement;
    import org.mybatis.generator.api.dom.xml.XmlElement;
    
    import java.util.List;
    import java.util.Set;
    import java.util.TreeSet;
    
    /**
     * @Description: 指定查询字段
     * @author: zhenghao
     * @date: 2020/7/15 9:50
     */
    public class SelectConditionPlugin extends PluginAdapter {
    
        /**
         * 修改Mapper类
         */
        @Override
        public boolean clientGenerated(Interface interfaze, TopLevelClass topLevelClass,
                                       IntrospectedTable introspectedTable) {
            addSelectConditionMethod(interfaze, introspectedTable);
    
            return super.clientGenerated(interfaze, topLevelClass, introspectedTable);
        }
    
        /**
         * 修改Mapper.xml
         */
        @Override
        public boolean sqlMapDocumentGenerated(Document document, IntrospectedTable introspectedTable) {
            addSelectConditionXml(document, introspectedTable);
            return super.sqlMapDocumentGenerated(document, introspectedTable);
        }
    
    
        @Override
        public boolean validate(List<String> list) {
            return true;
        }
    
    
        private void addSelectConditionMethod(Interface interfaze, IntrospectedTable introspectedTable) {
            Set<FullyQualifiedJavaType> importedTypes = new TreeSet<FullyQualifiedJavaType>();
            importedTypes.add(FullyQualifiedJavaType.getNewListInstance());
    
    
            Method ibsmethod = new Method();
            // 1.设置方法可见性
            ibsmethod.setVisibility(JavaVisibility.PUBLIC);
    
            // 2.设置返回值类型
            FullyQualifiedJavaType ibsreturnType = FullyQualifiedJavaType.getNewListInstance();
    
            //设置List的类型是实体类的对象
            FullyQualifiedJavaType listType;
            listType = new FullyQualifiedJavaType(
                    introspectedTable.getBaseRecordType());
    
            importedTypes.add(listType);
    
            ibsreturnType.addTypeArgument(listType);
            ibsmethod.setReturnType(ibsreturnType);
    
            // 3.设置方法名
            ibsmethod.setName("selectCondition");
    
    
            // 4.设置参数列表
            FullyQualifiedJavaType paramType = new FullyQualifiedJavaType(introspectedTable.getExampleType());
    
            ibsmethod.addParameter(new Parameter(paramType, "example", "@Param(\"example\")"));
            importedTypes.add(paramType);
    
    
            paramType = FullyQualifiedJavaType.getStringInstance();
            ibsmethod.addParameter(new Parameter(paramType, "fields", "@Param(\"fields\")"));
    
            importedTypes.add(paramType);
    
    
            // 设置需要导入的类
    
            interfaze.addImportedTypes(importedTypes);
    
            interfaze.addMethod(ibsmethod);
        }
    
    
        /**
         * @Description: 生成对应的xml
         * @author: zhenghao
         * @date: 2020/7/16 14:24
         */
        public void addSelectConditionXml(Document document, IntrospectedTable introspectedTable) {
    
            XmlElement trimElement = new XmlElement("trim");
            trimElement.addAttribute(new Attribute("prefix", "("));
            trimElement.addAttribute(new Attribute("suffix", ")"));
            trimElement.addAttribute(new Attribute("suffixOverrides", ","));
    
            XmlElement selectElement = new XmlElement("select");
            selectElement.addAttribute(new Attribute("id", "selectCondition"));
            selectElement.addAttribute(new Attribute("parameterType", "map"));
            selectElement.addAttribute(new Attribute("resultMap", "BaseResultMap"));
            selectElement.addElement(
                    new TextElement("select ${fields} from " + introspectedTable.getAliasedFullyQualifiedTableNameAtRuntime()));
    
            selectElement.addElement(new TextElement("<if test=\"example != null\">"));
            selectElement.addElement(new TextElement("  <include refid=\"" + introspectedTable.getMyBatis3UpdateByExampleWhereClauseId() +
                    "\" />"));
            selectElement.addElement(new TextElement("</if>"));
    
    //        selectElement.addElement(new TextElement("<if test=\"orderByClause != null\">"));
    //        selectElement.addElement(new TextElement("    order by ${orderByClause}"));
    //        selectElement.addElement(new TextElement("</if>"));
    //
    //        selectElement.addElement(new TextElement(" <if test=\"page != null\">"));
    //        selectElement.addElement(new TextElement("        limit #{page.begin} , #{page.size}"));
    //        selectElement.addElement(new TextElement("</if>"));
    
    
            document.getRootElement().addElement(selectElement);
        }
    
    
    }

## 插件使用，直接在xml中引入对应的插件路径即可： ##

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3UwMTMwNDU0Mzc_size_16_color_FFFFFF_t_70][]

## 生成对应方法和实现：  ##

![20200716143204252.png][]

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3UwMTMwNDU0Mzc_size_16_color_FFFFFF_t_70 1][]

## 使用： ##

public List<RobotSysToneDetect> test() {
            //指定数据库字段
            String fields = "result,conditions";
            //指定查询条件
            RobotSysToneDetectExample example = new RobotSysToneDetectExample();
            List<RobotSysToneDetect> robotSysToneDetects = robotSysToneDetectMapper.selectCondition(example, fields);
            return robotSysToneDetects;
    
        }

经过测试， 可以满足我们的业务需求。

[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3UwMTMwNDU0Mzc_size_16_color_FFFFFF_t_70]: /images/20230209/be90f4f91b46415eb3a4c29d119949dd.png
[20200716143204252.png]: /images/20230209/95e6c83f0b2c4eac99eb7cdd786a4b7b.png
[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3UwMTMwNDU0Mzc_size_16_color_FFFFFF_t_70 1]: /images/20230209/bea97e00bacd4f0f87a481b00cdacd4a.png