# yml 配置：
mybatis-plus:
  global-config:
    db-config:
      update-strategy: IGNORED

@TableField(value = "name", updateStrategy=FieldStrategy.IGNORED)
private String name;

baseMapper.update(sysUser, Wrappers.<SysUser>lambdaUpdate()
                        .set(SysUser::getOrgId, null)
                        .set(SysUser::getOrgName, null)
                        .eq(SysUser::getId, sysUser.getId())
                );

import com.baomidou.mybatisplus.core.injector.AbstractMethod;
import com.baomidou.mybatisplus.core.injector.DefaultSqlInjector;
import com.baomidou.mybatisplus.core.metadata.TableInfo;

import java.util.List;

public class MySqlInjector extends DefaultSqlInjector {
    @Override
    public List<AbstractMethod> getMethodList(Class<?> mapperClass, TableInfo tableInfo) {
        List<AbstractMethod> methodList = super.getMethodList(mapperClass, tableInfo);
        // 根據(jù)id更新所有數(shù)據(jù)
        methodList.add(new UpdateWithNullMethod());
        return methodList;
    }

}

import com.baomidou.mybatisplus.annotation.FieldFill;
import com.baomidou.mybatisplus.annotation.FieldStrategy;
import com.baomidou.mybatisplus.core.injector.AbstractMethod;
import com.baomidou.mybatisplus.core.metadata.TableFieldInfo;
import com.baomidou.mybatisplus.core.metadata.TableInfo;
import com.baomidou.mybatisplus.core.toolkit.StringPool;
import com.baomidou.mybatisplus.core.toolkit.StringUtils;
import com.baomidou.mybatisplus.core.toolkit.sql.SqlScriptUtils;
import lombok.extern.slf4j.Slf4j;
import org.apache.ibatis.mapping.MappedStatement;
import org.apache.ibatis.mapping.SqlSource;

import java.lang.reflect.Field;
import java.util.List;

import static java.util.stream.Collectors.joining;

/**
 * @author ：zzt
 */
@Slf4j
public class UpdateWithNullMethod extends AbstractMethod {
    protected UpdateWithNullMethod() {
        super("updateWithNull");
    }

    @Override
    public MappedStatement injectMappedStatement(Class<?> mapperClass, Class<?> modelClass, TableInfo tableInfo) {
        String sql = "<script>\nupdate %s %s where %s=#{%s}\n</script>";

        final List<TableFieldInfo> fieldList = tableInfo.getFieldList();
        for (TableFieldInfo tableFieldInfo : fieldList) {
            final Class<? extends TableFieldInfo> aClass = tableFieldInfo.getClass();
            try {
                final Field fieldFill = aClass.getDeclaredField("fieldFill");
                fieldFill.setAccessible(true);
                fieldFill.set(tableFieldInfo, FieldFill.UPDATE);
            } catch (NoSuchFieldException | IllegalAccessException e) {
                log.error("獲取fieldFill失敗", e);
            }
        }
        String setSql = this.sqlSet(tableInfo);
        String sqlResult = String.format(sql, tableInfo.getTableName(), setSql, tableInfo.getKeyColumn(), tableInfo.getKeyProperty());
        log.debug("sqlResult----->{}", sqlResult);
        SqlSource sqlSource = languageDriver.createSqlSource(configuration, sqlResult, modelClass);
        // 第三個(gè)參數(shù)必須和rootMapper的自定義方法名一致
        return this.addUpdateMappedStatement(mapperClass, modelClass, "updateWithNull", sqlSource);
    }

    protected String sqlSet(TableInfo table) {
        String sqlScript = table.getFieldList()
                .stream().map(i -> this.getSqlSet(i, StringPool.EMPTY)).collect(joining(StringPool.NEWLINE));
        sqlScript = SqlScriptUtils.convertTrim(sqlScript, "SET", null, null, ",");
        return sqlScript;
    }

    public String getSqlSet(TableFieldInfo i, String prefix) {
        String newPrefix = prefix == null ? StringPool.EMPTY : prefix;
        String column = i.getColumn();
        String update = i.getUpdate();
        FieldFill fieldFill = i.getFieldFill();
        String el = i.getEl();

        // 默認(rèn)：column=
        String sqlSet = column + StringPool.EQUALS;
        if (StringUtils.isNotEmpty(update)) {
            sqlSet += String.format(update, column);
        } else {
            sqlSet += SqlScriptUtils.safeParam(newPrefix +el);
        }

        sqlSet += StringPool.COMMA;
        if (fieldFill == FieldFill.UPDATE || fieldFill == FieldFill.INSERT_UPDATE) {
            // 不進(jìn)行if包裹
            return sqlSet;
        }
        return convertIf(sqlSet, convertIfProperty(newPrefix, column), i.getUpdateStrategy(),
                i.getPropertyType().isPrimitive(), StringUtils.isCharSequence(i.getPropertyType()));
    }

    private String convertIfProperty(String prefix, String property) {
        return StringUtils.isNotBlank(prefix)
                ? prefix.substring(0, prefix.length() - 1) + "['" + property + "']" : property;
    }


    private String convertIf(final String sqlScript, final String property, final FieldStrategy fieldStrategy,
                             boolean isPrimitive, boolean isCharSequence) {
        if (fieldStrategy == FieldStrategy.NEVER) {
            return null;
        }
        if (isPrimitive || fieldStrategy == FieldStrategy.IGNORED) {
            return sqlScript;
        }
        if (fieldStrategy == FieldStrategy.NOT_EMPTY && isCharSequence) {
            return SqlScriptUtils.convertIf(sqlScript, String.format("%s != null and %s !=''", property, property), false);
        }
        return SqlScriptUtils.convertIf(sqlScript, String.format("%s != null", property), false);
    }
}

import com.baomidou.mybatisplus.core.mapper.BaseMapper;

/**
 * @description: 自定義mapper借口，mybatisPlus
 * @author: zzt
 */
public interface MyBaseMapper<T> extends BaseMapper<T> {

    /**
     * 全字段更新，更新為null的字段
     * @param obj 待更新對(duì)象
     * @return 是否成功
     */
    boolean updateWithNull(T obj);
}