/**

*

* 拼接Where的指令，较简单的where组装，如果复杂的请在模版直接写where 语句

* @author xianyl

* @since 2018年1月26日-下午8:57:02

*/

public class WhereDirective extends Directive {

//运算符号集合、逻辑符号集合、between条件集合,字段名

public static final String KV_SIGNS = "kv_signs";

public static final String KV_LOGICS = "kv_logics";

public static final String KV_BETWEEN = "kv_between";

public void exec(Env env, Scope scope, Writer writer) {

SqlPara sqlPara = (SqlPara)scope.get("_SQL_PARA_");//SqlKit.SQL_PARA_KEY 需要跟它一致

if (sqlPara == null) {

throw new TemplateException("#where directive invoked by getSqlPara(...) method only", location);

}

//获取参数

Map data = null;

Kv signs = null, logics = null, between = null;

try {

Record record = (Record)exprList.eval(scope);

data = record.getColumns();

signs = (Kv) data.remove(KV_SIGNS);

logics = (Kv) data.remove(KV_LOGICS);

between = (Kv) data.remove(KV_BETWEEN);

} catch (Exception e) {

}

//判断参数不能为null 并且只能是Record

if(MapUtils.isEmpty(data)) return;

StringBuilder sb = new StringBuilder();

//循环拼接参数

Object logic;

Object sign;

for(Entry d : data.entrySet()){

Object _end = null;

//判断逻辑符号

if(logics == null){

logic = LogicsSymbol.And;//没有逻辑符号集合，这是and

}else{

logic = logics.get(d.getKey());

if(logic == null){

logic = LogicsSymbol.And;//没有对应字段的逻辑符号，这是and

}

}

//判断运算符号

if(signs == null){

sign = SignsSymbol.Eq;//没有运算符号集合，这是eq

}else{

sign = signs.get(d.getKey());

if(sign == null){

//没有对应字段的运算符号，这是eq

sign = SignsSymbol.Eq;

}

if(sign == SignsSymbol.Between){

//如果是between运算符号，需要检查between里面的field_end的数据取出

_end = between == null ? null : between.get(d.getKey() + "_end");

}

}

//拼接条件

this.join(sb,sqlPara,d.getKey(),d.getValue(),logic,sign,_end);

}

//写where

write(writer, sb.toString());

}

/**

* 拼接其中一个条件语句

* @param sb

* @param sqlPara

* @param key  字段名

* @param value 字段值

* @param logic 逻辑符号

* @param sign 运算符号

* @param _end between时字段的第二个值

*/

private void join(StringBuilder sb, SqlPara sqlPara, String key, Object value, Object logic, Object sign, Object _end) {

//第一时间判断_end 是否为null, 如果是 SignsSymbol.Between 转成 SignsSymbol.Gte

if(sign == SignsSymbol.Between && _end == null){

sign = SignsSymbol.Gte;

}

//拼接逻辑符号

if(sb.length() == 0){

if(logic == LogicsSymbol.And){

sb.append(" where ");

}else{

sb.append(" where 1=1 ").append(logic);

}

}else{

sb.append(" ").append(logic);

}

//拼接参数

sb.append(" ").append(key).append(" ").append(sign).append(" ").append("?");

sqlPara.addPara(sign == SignsSymbol.Like ? "%"+value+"%" :value);

if(sign == SignsSymbol.Between){

//如果between

sb.append(" and ").append("?");

sqlPara.addPara(_end);

}

}

}模版 ：

#namespace("user")

#sql("list")

select * from user #where(data)

#end

#end

java调用方法：

/**

* 根据模板动态生成 sql 跟参数

* @param key  模板名 namespace.sql

* @param record 查询条件 键值对

* @param signs 运算符号集合  ｛"field":SignsSymbol.Gt｝ , 如果没有，则为Eq

* @param logics 逻辑符号集合 ｛"field":LogicsSymbol.And｝, 如果没有，则为Or

* @param between between条件集合 ｛"field_end":value｝, signs为between时检查这个，如果没有指定的field_end，则转为Gte运算符号

* @return

*/

public SqlPara getSqlPara(String key, Record data, Kv signs, Kv logics, Kv between){

//这几个字段名需要跟WhereDirective里面的对应起来

data.set(WhereDirective.KV_SIGNS, signs);

data.set(WhereDirective.KV_LOGICS, logics);

data.set(WhereDirective.KV_BETWEEN, between);

//data跟sql模版的参数对应起来

return Db.getSqlPara(key, Kv.by("data", data));

}