如何生成SQL语句

场景：根据业务逻辑 动态生成 sql语句各部分，比如select部分、where部分等，然后最终生成完整的sql

工具：org.apache.ibatis.jdbc.SqlBuilder（mybatis包内含）

  1. /**
  2.  *    Copyright 2009-2018 the original author or authors.
  3.  *
  4.  *    Licensed under the Apache License, Version 2.0 (the "License");
  5.  *    you may not use this file except in compliance with the License.
  6.  *    You may obtain a copy of the License at
  7.  *
  8.  *       http://www.apache.org/licenses/LICENSE-2.0
  9.  *
  10.  *    Unless required by applicable law or agreed to in writing, software
  11.  *    distributed under the License is distributed on an "AS IS" BASIS,
  12.  *    WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  13.  *    See the License for the specific language governing permissions and
  14.  *    limitations under the License.
  15.  */
  16. package org.apache.ibatis.jdbc;
  18. /**
  19.  * @deprecated Use the {@link SQL} Class
  20.  *
  21.  * @author Jeff Butler
  22.  */
  23. public class SqlBuilder {
  25.   private static final ThreadLocal<SQL> localSQL = new ThreadLocal<>();
  27.   static {
  28.     BEGIN();
  29.   }
  31.   private SqlBuilder() {
  32.     // Prevent Instantiation
  33.   }
  35.   public static void BEGIN() {
  36.     RESET();
  37.   }
  39.   public static void RESET() {
  40.     localSQL.set(new SQL());
  41.   }
  43.   public static void UPDATE(String table) {
  44.     sql().UPDATE(table);
  45.   }
  47.   public static void SET(String sets) {
  48.     sql().SET(sets);
  49.   }
  51.   public static String SQL() {
  52.     try {
  53.       return sql().toString();
  54.     } finally {
  55.         RESET();
  56.     }
  57.   }
  59.   public static void INSERT_INTO(String tableName) {
  60.     sql().INSERT_INTO(tableName);
  61.   }
  63.   public static void VALUES(String columns, String values) {
  64.     sql().VALUES(columns, values);
  65.   }
  67.   public static void SELECT(String columns) {
  68.     sql().SELECT(columns);
  69.   }
  71.   public static void SELECT_DISTINCT(String columns) {
  72.     sql().SELECT_DISTINCT(columns);
  73.   }
  75.   public static void DELETE_FROM(String table) {
  76.     sql().DELETE_FROM(table);
  77.   }
  79.   public static void FROM(String table) {
  80.     sql().FROM(table);
  81.   }
  83.   public static void JOIN(String join) {
  84.     sql().JOIN(join);
  85.   }
  87.   public static void INNER_JOIN(String join) {
  88.     sql().INNER_JOIN(join);
  89.   }
  91.   public static void LEFT_OUTER_JOIN(String join) {
  92.     sql().LEFT_OUTER_JOIN(join);
  93.   }
  95.   public static void RIGHT_OUTER_JOIN(String join) {
  96.     sql().RIGHT_OUTER_JOIN(join);
  97.   }
  99.   public static void OUTER_JOIN(String join) {
  100.     sql().OUTER_JOIN(join);
  101.   }
  103.   public static void WHERE(String conditions) {
  104.     sql().WHERE(conditions);
  105.   }
  107.   public static void OR() {
  108.     sql().OR();
  109.   }
  111.   public static void AND() {
  112.     sql().AND();
  113.   }
  115.   public static void GROUP_BY(String columns) {
  116.     sql().GROUP_BY(columns);
  117.   }
  119.   public static void HAVING(String conditions) {
  120.     sql().HAVING(conditions);
  121.   }
  123.   public static void ORDER_BY(String columns) {
  124.     sql().ORDER_BY(columns);
  125.   }
  127.   private static SQL sql() {
  128.     return localSQL.get();
  129.   }
  131. }