MyBatis 执行动态 SQL语句详解

<select id="executesql" resulttype="map">
${_parameter}
</select>

sqlsession.selectlist("executesql", "select * from sysuser where enabled = 1");

list<map> executesql(string sql);

xxmapper.executesql("select * from sysuser where enabled = 1");

select * from sysuser 
where enabled = #{enabled} 
and username like concat('%',#{username},'%')

<select id="executesql" resulttype="map">
${sql}
</select>

list<map> executesql(map map);

map map = new hashmap();
//这里的 sql 对应 xml 中的 ${sql}
map.put("sql", "select * from sysuser "
+ " where enabled = #{enabled} "
+ " and username like concat('%',#{username},'%')");
//#{enabled}
map.put("enabled", 1);
//#{username}
map.put("username", "admin");
//接口方式调用
list<map> list = xxmapper.executesql(map);
//sqlsession方式调用
sqlsession.selectlist("executesql", map);

@override 
public boundsql getboundsql(object parameterobject) {
dynamiccontext context = new dynamiccontext(configuration, parameterobject);
rootsqlnode.apply(context);
sqlsourcebuilder sqlsourceparser = new sqlsourcebuilder(configuration);
class < ?>parametertype = 
parameterobject == null ? object.class: parameterobject.getclass();
sqlsource sqlsource = sqlsourceparser.parse(context.getsql(), 
parametertype, context.getbindings());
boundsql boundsql = sqlsource.getboundsql(parameterobject);
for (map.entry < string, object > entry: context.getbindings().entryset()) {
boundsql.setadditionalparameter(entry.getkey(), entry.getvalue());
}
return boundsql;
}

sqlsourceparser.parse(context.getsql(), parametertype, context.getbindings());

select * from sysuser 
where 1 = 1
<#if enabled??>
enabled = #{enabled} 
</#if>
<#if username?? && username != ''>
and username like concat('%',#{username},'%')
</#if>

select * from sysuser 
where 1 = 1
<#if enabled??>
enabled = #{enabled} 
</#if>
<#if username?? && username != ''>
and username like '%${username}%'
</#if>

//#{enabled}
map.put("enabled", 1);
//#{username}
map.put("username", "admin");
//这里的 sql 对应 xml 中的 ${sql}
string sql = "上面两个复杂sql中的一个";
//使用freemarker处理sql
sql = processsqlbyfreemarker(sql, map);
//将处理后的sql放到map中
map.put("sql", "select * from sysuser "
+ " where enabled = #{enabled} "
+ " and username like concat('%',#{username},'%')");
//执行方法
list<map> list = xxmapper.executesql(map);

map.put("class", "tk.mybatis.model.sysuser");