mybatis通用mapper源码解析

Posted 2020-12-31 随风逝去,只是凋零

1.javabean的属性值生成sql

  /**
     * 获取所有查询列，如id,name,code...
     *
     * @param entityClass
     * @return
     */
    public static String getAllColumns(Class<?> entityClass) {
        Set<EntityColumn> columnSet = EntityHelper.getColumns(entityClass);
        StringBuilder sql = new StringBuilder();
        for (EntityColumn entityColumn : columnSet) {
            sql.append(entityColumn.getColumn()).append(",");
        }
        return sql.substring(0, sql.length() - 1);
    }

  /**
     * 判断自动==null的条件结构
     *
     * @param entityName
     * @param column
     * @param contents
     * @param empty
     * @return
     */
    public static String getIfIsNull(String entityName, EntityColumn column, String contents, boolean empty) {
        StringBuilder sql = new StringBuilder();
        sql.append("<if test="");
        if (StringUtil.isNotEmpty(entityName)) {
            sql.append(entityName).append(".");
        }
        sql.append(column.getProperty()).append(" == null");
        if (empty && column.getJavaType().equals(String.class)) {
            sql.append(" or ");
            if (StringUtil.isNotEmpty(entityName)) {
                sql.append(entityName).append(".");
            }
            sql.append(column.getProperty()).append(" == ‘‘ ");
        }
        sql.append("">");
        sql.append(contents);
        sql.append("</if>");
        return sql.toString();
    }