微商城网站建设平台合同,wordpress主题制作难吗,自己注册网站要多少钱,大同网页设计前言 ps#xff1a;最近在参与3100保卫战#xff0c;战况很激烈#xff0c;刚刚打完仗#xff0c;来更新一下之前写了一半的博客。 该篇针对日常写查询的时候#xff0c;那些动态条件sql 做个简单的封装#xff0c;自动生成#xff08;抛砖引玉#xff0c;搞个小玩具最近在参与3100保卫战战况很激烈刚刚打完仗来更新一下之前写了一半的博客。 该篇针对日常写查询的时候那些动态条件sql 做个简单的封装自动生成抛砖引玉搞个小玩具不喜勿喷。 正文 来看看我们平时写那些查询基本上都要写的一些动态sql 一个字段写一个if 有没有人觉得烦的。
每张表的查询很多都有这种需求根据什么查询根据什么查询不为空就触发条件。
天天写天天写copy 改copy改 有没有人觉得烦的。 可能有看官看到这就会说 用插件自动生成就好了。 也有看官会说用mybatis-plus就好了。 确实有道理但是我就是想整个小玩具。你管我。 开整 本篇实现的封装小玩具思路 ①制定的规则比如标记自定义注解 JcSqlQuery 或是 函数命名带上JcDynamics。 ② 触发的查询符合规则的 都自动去根据传参对象不为空就自动组装 sql查询条件。
③ 利用mybatis Select 注解把默认表查询sql写好顺便进到自定义的mybatis拦截器里面。
④组装完sql就执行完事。 先写mapper函数
/*** Author JCccc* Description* Date 2023/12/14 16:56*/
Mapper
public interface DistrictMapper {Select(select code,name,parent_code,full_name FROM s_district_info)ListDistrict queryListJcDynamics(District district);Select(select code,name,parent_code,full_name FROM s_district_info)District queryOneJcDynamics(District district);}然后是ParamClassInfo.java 这个用于收集需要参与动态sql组装的类
import lombok.Data;/*** Author JCccc* Description* Date 2021/12/14 16:56*/
Data
public class ParamClassInfo {private String classType;private Object keyValue;private String keyName;} 然后是一个自定义的mybatis拦截器(这里面写了一些小函数实现自主组装下面有图解) MybatisInterceptor.java
import com.example.dotest.entity.ParamClassInfo;
import org.apache.ibatis.executor.Executor;
import org.apache.ibatis.mapping.*;
import org.apache.ibatis.plugin.*;
import org.apache.ibatis.session.ResultHandler;
import org.apache.ibatis.session.RowBounds;
import org.springframework.beans.BeanUtils;
import org.springframework.stereotype.Component;
import org.springframework.util.CollectionUtils;
import org.springframework.util.ReflectionUtils;
import java.beans.PropertyDescriptor;
import java.lang.reflect.Method;
import java.util.*;
import java.util.regex.Matcher;
import java.util.regex.Pattern;import static java.util.regex.Pattern.*;/*** Author JCccc* Description* Date 2021/12/14 16:56*/
Component
Intercepts({Signature(type Executor.class, method update, args {MappedStatement.class, Object.class}),Signature(type Executor.class, method query, args {MappedStatement.class, Object.class, RowBounds.class, ResultHandler.class})
})
public class MybatisInterceptor implements Interceptor {private final static String JC_DYNAMICS JcDynamics;Overridepublic Object intercept(Invocation invocation) throws Throwable {//获取执行参数Object[] objects invocation.getArgs();MappedStatement ms (MappedStatement) objects[0];Object objectParam objects[1];ListParamClassInfo paramClassInfos convertParamList(objectParam);String queryConditionSqlScene getQueryConditionSqlScene(paramClassInfos);//解析执行sql的map方法,开始自定义规则匹配逻辑String mapperMethodAllName ms.getId();int lastIndex mapperMethodAllName.lastIndexOf(.);String mapperClassStr mapperMethodAllName.substring(0, lastIndex);String mapperClassMethodStr mapperMethodAllName.substring((lastIndex 1));Class? mapperClass Class.forName(mapperClassStr);Method[] methods mapperClass.getMethods();for (Method method : methods) {if (method.getName().equals(mapperClassMethodStr) mapperClassMethodStr.contains(JC_DYNAMICS)) {BoundSql boundSql ms.getSqlSource().getBoundSql(objects[1]);String originalSql boundSql.getSql().toLowerCase(Locale.CHINA).replace([\\t\\n\\r], );//进行自动的 条件拼接String newSql originalSql queryConditionSqlScene;BoundSql newBoundSql new BoundSql(ms.getConfiguration(), newSql,boundSql.getParameterMappings(), boundSql.getParameterObject());MappedStatement newMs newMappedStatement(ms, new MyBoundSqlSqlSource(newBoundSql));for (ParameterMapping mapping : boundSql.getParameterMappings()) {String prop mapping.getProperty();if (boundSql.hasAdditionalParameter(prop)) {newBoundSql.setAdditionalParameter(prop, boundSql.getAdditionalParameter(prop));}}Object[] queryArgs invocation.getArgs();queryArgs[0] newMs;System.out.println(打印新SQL语句 newSql);}}//继续执行逻辑return invocation.proceed();}private String getQueryConditionSqlScene(ListParamClassInfo paramClassInfos) {StringBuilder conditionParamBuilder new StringBuilder();if (CollectionUtils.isEmpty(paramClassInfos)) {return ;}conditionParamBuilder.append( WHERE );int size paramClassInfos.size();for (int index 0; index size; index) {ParamClassInfo paramClassInfo paramClassInfos.get(index);String keyName paramClassInfo.getKeyName();//默认驼峰拆成下划线 比如 userName -》 user_name , name - name//如果是需要取别名其实可以加上自定义注解这些但是本篇例子是轻封装思路给到你们i自己玩String underlineKeyName camelToUnderline(keyName);conditionParamBuilder.append(underlineKeyName);Object keyValue paramClassInfo.getKeyValue();String classType paramClassInfo.getClassType();//其他类型怎么处理 可以按照类型区分 比如检测到一组开始时间Date 拼接 between and等
// if (classType.equals(String)){
// conditionParamBuilder .append().append(\).append(keyValue).append(\);
// }conditionParamBuilder.append().append(\).append(keyValue).append(\);if (index ! size - 1) {conditionParamBuilder.append( AND );}}return conditionParamBuilder.toString();}private static ListParamClassInfo convertParamList(Object obj) {ListParamClassInfo paramClassList new ArrayList();for (PropertyDescriptor pd : BeanUtils.getPropertyDescriptors(obj.getClass())) {if (!class.equals(pd.getName())) {if (ReflectionUtils.invokeMethod(pd.getReadMethod(), obj) ! null) {ParamClassInfo paramClassInfo new ParamClassInfo();paramClassInfo.setKeyName(pd.getName());paramClassInfo.setKeyValue(ReflectionUtils.invokeMethod(pd.getReadMethod(), obj));paramClassInfo.setClassType(pd.getPropertyType().getSimpleName());paramClassList.add(paramClassInfo);}}}return paramClassList;}public static String camelToUnderline(String line){if(linenull||.equals(line)){return ;}lineString.valueOf(line.charAt(0)).toUpperCase().concat(line.substring(1));StringBuffer sbnew StringBuffer();Pattern pattern compile([A-Z]([a-z\\d])?);Matcher matcherpattern.matcher(line);while(matcher.find()){String wordmatcher.group();sb.append(word.toUpperCase());sb.append(matcher.end()line.length()?:_);}return sb.toString();}Overridepublic Object plugin(Object o) {//获取代理权if (o instanceof Executor) {//如果是Executor执行增删改查操作则拦截下来return Plugin.wrap(o, this);} else {return o;}}/*** 定义一个内部辅助类作用是包装 SQL*/class MyBoundSqlSqlSource implements SqlSource {private BoundSql boundSql;public MyBoundSqlSqlSource(BoundSql boundSql) {this.boundSql boundSql;}Overridepublic BoundSql getBoundSql(Object parameterObject) {return boundSql;}}private MappedStatement newMappedStatement(MappedStatement ms, SqlSource newSqlSource) {MappedStatement.Builder builder newMappedStatement.Builder(ms.getConfiguration(), ms.getId(), newSqlSource, ms.getSqlCommandType());builder.resource(ms.getResource());builder.fetchSize(ms.getFetchSize());builder.statementType(ms.getStatementType());builder.keyGenerator(ms.getKeyGenerator());if (ms.getKeyProperties() ! null ms.getKeyProperties().length 0) {builder.keyProperty(ms.getKeyProperties()[0]);}builder.timeout(ms.getTimeout());builder.parameterMap(ms.getParameterMap());builder.resultMaps(ms.getResultMaps());builder.resultSetType(ms.getResultSetType());builder.cache(ms.getCache());builder.flushCacheRequired(ms.isFlushCacheRequired());builder.useCache(ms.isUseCache());return builder.build();}Overridepublic void setProperties(Properties properties) {//读取mybatis配置文件中属性}
代码简析 驼峰转换下划线用于转出数据库表的字段 通过反射把 sql入参的对象 不为空的属性名和对应的值拿出来 组件动态查询的sql 语句 写个简单测试用例 AutowiredDistrictMapper districtMapper;Testpublic void test() {District query new District();query.setCode(110000);query.setName(北京市);District district districtMapper.queryOneJcDynamics(query);System.out.println(district.toString());District listQuery new District();listQuery.setParentCode(110100);ListDistrict districts districtMapper.queryListJcDynamics(listQuery);System.out.println(districts.toString());} 看下效果可以看到都自动识别把不为空的字段属性和值拼接成查询条件了 好了该篇就到这。 抛砖引玉领悟分步封装思路最重要都去搞些小玩具娱乐娱乐吧。
