mybatis拦截器Interceptor

问题：想把整个项目实体包含caseId字段的所有含有Bigdecaml类型的字段动态设置精度。

解决：自己写一个类实现接口org.apache.ibatis.plugin.Interceptor

几个小问题

1.Interceptor接口不能注入业务代码的service（可能是业务service比Interceptor迟加入spring容器，加载Interceptor的时候还是空的），但是可以注入ApplicationContext.

2.MetaObject对象的setValue方法可以对插入之前对象的字段做处理

3.TableFieldInfo对象有我们实体所有的字段信息

有这三个对象，业务代码可以按自己的业务写

代码：

import com.baomidou.mybatisplus.core.metadata.TableFieldInfo;
import com.baomidou.mybatisplus.core.metadata.TableInfo;
import com.baomidou.mybatisplus.core.metadata.TableInfoHelper;
import com.baomidou.mybatisplus.core.toolkit.Constants;
import com.okay.house.bus.service.impl.BusCaseInfoServiceImpl;
import com.okay.house.common.utils.StringUtils;
import org.apache.ibatis.executor.Executor;
import org.apache.ibatis.mapping.BoundSql;
import org.apache.ibatis.mapping.MappedStatement;
import org.apache.ibatis.mapping.SqlCommandType;
import org.apache.ibatis.plugin.Interceptor;
import org.apache.ibatis.plugin.Intercepts;
import org.apache.ibatis.plugin.Invocation;
import org.apache.ibatis.plugin.Plugin;
import org.apache.ibatis.plugin.Signature;
import org.apache.ibatis.reflection.MetaObject;
import org.apache.ibatis.session.Configuration;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.context.ApplicationContext;
import org.springframework.stereotype.Component;
import java.math.BigDecimal;
import java.util.List;
import java.util.Map;
import java.util.Properties;


/**
 * 根据案件统一BigDecimal数值类型小数位数
 */
@Component
@Intercepts(@Signature(type = Executor.class, method = "update", args = {MappedStatement.class,
        Object.class}))
public class MybatisIntercepter implements Interceptor {

    private Integer xsws;

    @Autowired
    private ApplicationContext applicationContext;

    private Configuration configuration;

    private SqlCommandType sqlCommandType;

    @Override
    public Object intercept(Invocation invocation) throws Throwable {
        // mapper映射对象
        MappedStatement mappedStatement = (MappedStatement) invocation.getArgs()[0];
        configuration = mappedStatement.getConfiguration();
        // 执行类型枚举  UNKNOWN, INSERT, UPDATE, DELETE, SELECT, FLUSH
        sqlCommandType = mappedStatement.getSqlCommandType();
        Object parameter = invocation.getArgs()[1];
        BoundSql boundSql = mappedStatement.getBoundSql(parameter);
        String sql = boundSql.getSql();
        Object parameterObject = boundSql.getParameterObject();
        process(parameterObject);
        return invocation.proceed();
    }

    private void process(Object parameter) {
        if (parameter != null) {
            // 表字段对象
            TableInfo tableInfo = null;
            Object entity = parameter;
            if (parameter instanceof Map) {
                Map<?, ?> map = (Map<?, ?>) parameter;
                if (map.containsKey(Constants.ENTITY)) {
                    Object et = map.get(Constants.ENTITY);
                    if (et != null) {
                        entity = et;
                        tableInfo = TableInfoHelper.getTableInfo(entity.getClass());
                    }
                }
            } else {
                tableInfo = TableInfoHelper.getTableInfo(parameter.getClass());
            }
            if (tableInfo != null) {
                //到这里就应该转换到实体参数对象了,因为填充和ID处理都是争对实体对象处理的,不用传递原参数对象下去.
                MetaObject metaObject = this.configuration.newMetaObject(entity);
                List<TableFieldInfo> fieldList = tableInfo.getFieldList();
                // 业务处理
                String property = "";
                for (TableFieldInfo x : fieldList) {
                    if(x.getProperty().equals("caseId")){
                        property = x.getProperty();
                    }
                    if(StringUtils.isNotBlank(property)){
                        break;
                    }
                }
                if(StringUtils.isNotBlank(property)){
                    Object value = metaObject.getValue(property);
                    BusCaseInfoServiceImpl busCaseInfoMapper = applicationContext.getBean(BusCaseInfoServiceImpl.class);
                    xsws = busCaseInfoMapper.getXsws((String) value);
                    for (TableFieldInfo x : fieldList) {
                        Class<?> propertyType = x.getPropertyType();
                        if(propertyType.equals(BigDecimal.class)){
                            String property1 = x.getProperty();
                            if(!property1.equals("ftxs")){
                                BigDecimal decimal = (BigDecimal)metaObject.getValue(property1);
                                // MetaObject对象的setValue方法可以对插入之前对象的字段做处理
                                metaObject.setValue(x.getProperty(),decimal!=null?decimal.setScale(6,6):BigDecimal.ZERO);
                            }
                        }
                    }

                }
            }
        }
    }


    @Override
    public Object plugin(Object target) {
        return Plugin.wrap(target,this);
    }

    @Override
    public void setProperties(Properties properties) {
    }

}