使用ResultMap生成sql

背景

通常情况下，我们使用工具生成对象和表映射关系，这在mapper对应的xml中以resultMap体现。

获取ResultMap

mybatis将配置全部放在Configuration对象里，故而可以使用Configuration对象获取。

/**
     * 功能描述：表列缓存
     *
     * @author konglcwqy
     * @date 2022/4/26 9:51
     * @param null
     * @return
     */
    private Map<String, ResultMap> FIELD_COLUMN_CACHE = new HashMap<String, ResultMap>();
    @Autowired
    private SqlSessionTemplate sqlSessionTemplate;

    @PostConstruct
    public void init() {
        Collection<ResultMap> resultMaps = this.sqlSessionTemplate.getConfiguration().getResultMaps();
        Iterator<ResultMap> iterator = resultMaps.iterator();
        ResultMap value = null;
        while (iterator.hasNext()) {
            try {
                value = iterator.next();
                FIELD_COLUMN_CACHE.put(value.getType().getName(), value);
            } catch (Exception e) {

            }
        }
    }

一个实例

本实例是根据ResultMap生成增删改的sql。

定义一些属性

 private static final FastDateFormat FORMAT = FastDateFormat.getInstance("yyyy-MM-dd HH:mm:ss");

 private static final ObjectMapper MAPPER = new ObjectMapper();

 private static final String CW_INFO_KEY = "CW_INFO";

定义映射信息

package com.zasd.project.system.cw;

import lombok.AllArgsConstructor;
import lombok.Data;
import lombok.NoArgsConstructor;
import lombok.ToString;

import java.io.Serializable;

/**
 * 
 *
 * @author konglcwqy
 * @description
 * @date 2022/4/26 11:34
 */
@Data
@NoArgsConstructor
@AllArgsConstructor
@ToString
public class CwInfo implements Serializable {
    /**
     * 功能描述：操作：1 新增 2 修改 3 删除
     *
     * @author konglcwqy
     * @date 2022/4/26 11:35
     * @param null
     * @return
     */
    private Integer operator;

    /**
     * 功能描述：类名
     *
     * @author konglcwqy
     * @date 2022/4/26 11:36
     * @param null
     * @return
     */
    private String className;

    /**
     * 功能描述：className对应的对象数据
     *
     * @author konglcwqy
     * @date 2022/4/26 11:36
     * @param null
     * @return
     */
    private String data;

    /**
     * 功能描述：表名
     *
     * @author konglcwqy
     * @date 2022/4/26 14:56
     * @param null
     * @return
     */
    private String tableName;

    /**
     * 功能描述：主键
     *
     * @author konglcwqy
     * @date 2022/4/26 15:19
     * @param null
     * @return
     */
    private String primaryKey;
}

获取属性值

/**
     * 功能描述：获取属性值
     *
     * @param field
     * @param obj
     * @return java.lang.Object
     * @author konglcwqy
     * @date 2022/4/26 11:33
     */
    public Object concat(Field field, Object obj) throws Exception {
        if (field == null) {
            return null;
        }
        field.setAccessible(true);
        Class<?> type = field.getType();
        Object value = field.get(obj);
        if (ObjectUtil.isEmpty(value)) {
            return null;
        }
        if (type == String.class) {
            return "'" + value + "'";
        }
        if (type == Date.class) {
            return "'" + FORMAT.format(value) + "'";
        }
        return value;
    }

获取不为空的列和值

 /**
     * 功能描述：获取不为空的列和值
     *
     * @param info
     * @return java.lang.String
     * @author konglcwqy
     * @date 2022/4/26 11:37
     */
    public Map<String, Object> columnAndValue(String info) throws Exception {
        if (StringUtils.isEmpty(info)) {
            return null;
        }
        CwInfo cwInfo = MAPPER.readValue(info, CwInfo.class);
        String className = cwInfo.getClassName();
        String data = cwInfo.getData();
        Integer operator = cwInfo.getOperator();
        //校验数据正确性
        if (StringUtils.isEmpty(data) || StringUtils.isEmpty(className) || operator == null) {
            return null;
        }
        //获取列
        ResultMap resultMap = FIELD_COLUMN_CACHE.get(className);
        if (resultMap == null) {
            return null;
        }
        //解析列
        List<ResultMapping> resultMappings = resultMap.getResultMappings();
        if (resultMappings == null || resultMappings.size() == 0) {
            return null;
        }
        Class<?> clazz = Class.forName(className);
        Object cwBean = MAPPER.readValue(data, clazz);
        String propertyName = null;
        Field field = null;
        Object value = null;
        Map<String, Object> result = new HashMap<String, Object>();
        for (ResultMapping resultMapping : resultMappings) {
            propertyName = resultMapping.getProperty();
            field = clazz.getDeclaredField(propertyName);
            if (field == null) {
                continue;
            }
            value = this.concat(field, cwBean);
            if (ObjectUtil.isNotEmpty(value)) {
                result.put(resultMapping.getColumn().trim().toLowerCase(), value);
            }
        }
        if (!result.isEmpty()) {
            result.put(CW_INFO_KEY, cwInfo);
        }
        return result.isEmpty() ? null : result;
    }

新增sql

/**
     * 功能描述：获取新增sql
     *
     * @param info
     * @return java.lang.String
     * @author konglcwqy
     * @date 2022/4/26 15:03
     */
    public String getInsertSql(String info) throws Exception {
        Map<String, Object> columnAndValue = this.columnAndValue(info);
        if (columnAndValue == null || columnAndValue.size() == 0) {
            return null;
        }
        CwInfo cwInfo = (CwInfo) columnAndValue.get(CW_INFO_KEY);
        columnAndValue.remove(CW_INFO_KEY);
        StringJoiner columns = new StringJoiner(",");
        StringJoiner values = new StringJoiner(",");
        for (Map.Entry<String, Object> entrySet : columnAndValue.entrySet()) {
            columns.add(entrySet.getKey());
            values.add(entrySet.getValue().toString());
        }
        String tableName = cwInfo.getTableName();
        String sql = "insert into " + tableName + " (" + columns.toString() + ") values " + "(" + values.toString() + ")";
        return sql;
    }

按照主键修改sql

 /**
     * 功能描述：获取按照主键修改sql
     *
     * @param info
     * @return java.lang.String
     * @author konglcwqy
     * @date 2022/4/26 15:14
     */
    public String getUpdateByPrimaryKeySql(String info) throws Exception {
        Map<String, Object> columnAndValue = this.columnAndValue(info);
        if (columnAndValue == null || columnAndValue.size() == 0) {
            return null;
        }
        CwInfo cwInfo = (CwInfo) columnAndValue.get(CW_INFO_KEY);
        columnAndValue.remove(CW_INFO_KEY);
        //主键信息
        String primaryKey = cwInfo.getPrimaryKey();
        if (StringUtils.isEmpty(primaryKey)) {
            return null;
        }
        primaryKey = primaryKey.toLowerCase();
        Object primaryKeyValue = columnAndValue.get(primaryKey);
        if (ObjectUtil.isEmpty(primaryKeyValue)) {
            return null;
        }
        columnAndValue.remove(primaryKeyValue);
        StringJoiner sj = new StringJoiner(",");
        for (Map.Entry<String, Object> entrySet : columnAndValue.entrySet()) {
            sj.add(entrySet.getKey() + " = " + entrySet.getValue());
        }
        String tableName = cwInfo.getTableName();
        String sql = "update " + tableName + " set " + sj.toString() + " where " + primaryKey + " = " + primaryKeyValue;
        return sql;
    }

按照条件删除sql

 /**
     * 功能描述：获取条件删除sql
     *
     * @param info
     * @return java.lang.String
     * @author konglcwqy
     * @date 2022/4/26 15:14
     */
    public String getDeleteSql(String info) throws Exception {
        Map<String, Object> columnAndValue = this.columnAndValue(info);
        if (columnAndValue == null || columnAndValue.size() == 0) {
            return null;
        }
        CwInfo cwInfo = (CwInfo) columnAndValue.get(CW_INFO_KEY);
        columnAndValue.remove(CW_INFO_KEY);
        StringJoiner sj = new StringJoiner(" and ");
        for (Map.Entry<String, Object> entrySet : columnAndValue.entrySet()) {
            sj.add(entrySet.getKey() + " = " + entrySet.getValue());
        }
        String tableName = cwInfo.getTableName();
        String sql = "delete from " + tableName + " where " + sj.toString();
        return sql;
    }

完整代码下载路径

resultMap-sql.zip