给定一个非空整数数组，除了某个元素只出现一次以外，其余每个元素均出现两次。找出那个只出现了一次的元素。
题解：
- 任何数和
0做异或运算，结果仍然是原来的数- 任何数和其自身做异或运算，结果是
0- 异或运算满足交换律和结合律
0^0 = 0
1^0 = 1
0^1 = 1
1^1 = 0
http://localhost:8080/test?name=管理这样参数存在中文情况，spring boot代码
public RoleResponse selectById(@RequestParam(value = "name", required = false) String name){
return roleService.selectByName(name);
}
可能存在接收到的name是%E7%AE%A1%E7%90%86这样的情况,这是浏览器自动为URL做了UrlEncode;
即使你的application.yml配置了UTF-8编码，也不一定能解决这样的问题:
# application.properties
server:
tomcat:
uri-encoding: UTF-8
spring:
http:
encoding:
charset: UTF-8
enabled: true
force: true
网上查找的方法一：【添加配置类】
@Configuration
public class CustomMVCConfiguration extends WebMvcConfigurerAdapter {
@Bean
public HttpMessageConverter<String> responseBodyConverter() {
StringHttpMessageConverter converter = new StringHttpMessageConverter(
Charset.forName("UTF-8"));
return converter;
}
@Override
public void configureMessageConverters(
List<HttpMessageConverter<?>> converters) {
super.configureMessageConverters(converters);
converters.add(responseBodyConverter());
}
@Override
public void configureContentNegotiation(
ContentNegotiationConfigurer configurer) {
configurer.favorPathExtension(false);
}
}
测试并未解决问题！
方法二：【强制解码】
public RoleResponse selectById(@RequestParam(value = "name", required = false) String name) throws UnsupportedEncodingException {
if (name != null){
name = URLDecoder.decode(name, "UTF-8");
}
return roleService.selectByName(name);
}
测试可以解决问题！
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|---|---|
build |
构建或重建服务 |
help |
命令帮助 |
kill |
杀掉容器 |
logs |
显示容器的输出内容 |
port |
打印绑定的开放端口 |
ps |
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pull |
拉取服务镜像 |
restart |
重启服务,指定服务 |
rm |
删除停止的容器,指定服务 |
run |
运行一个一次性命令 |
scale |
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start |
开启服务,指定服务 |
stop |
停止服务,指定服务 |
up |
创建并启动容器,-d放到后台运行 |
-- 没有用到索引
select * from t_user where user_name like '%test%';
-- 用到索引但是不通用
select * from t_user where user_name like 'test%';
-- LOCATE('substr',str,pos)
-- pos不填:返回substr在str中第一次出现的位置，如果不存在，返回值为0
-- pos存在:返回pos之后第一次出现的位置
select * from t_user where locate('test',user_name)>0;
-- 同locate
select * from t_user where position('test' in user_name);
-- 查找一个字符串在另一个字符串中首次出现的位置
select * from t_user where instr(user_name,'test')>0;
FIND_IN_SET(str,strList)
str 要查询的字符串strList 字段名，参数以 , 分隔，如 (1,2,6,8)-- 测试及结果
mysql> select find_in_set('1','1,2,3,4,5,6');
+--------------------------------+
| find_in_set('1','1,2,3,4,5,6') |
+--------------------------------+
| 1 |
+--------------------------------+
1 row in set
mysql> select find_in_set('2','1,2,3,4,5,6');
+--------------------------------+
| find_in_set('2','1,2,3,4,5,6') |
+--------------------------------+
| 2 |
+--------------------------------+
1 row in set
mysql> select find_in_set('','1,2,3,4,5,6');
+-------------------------------+
| find_in_set('','1,2,3,4,5,6') |
+-------------------------------+
| 0 |
+-------------------------------+
1 row in set
mysql> select find_in_set('2','');
+---------------------+
| find_in_set('2','') |
+---------------------+
| 0 |
+---------------------+
1 row in set
mysql> select find_in_set('7','1,2,3,4,5,6');
+--------------------------------+
| find_in_set('7','1,2,3,4,5,6') |
+--------------------------------+
| 0 |
+--------------------------------+
1 row in set
mysql> select find_in_set(null,'1,2,3,4,5,6');
+---------------------------------+
| find_in_set(null,'1,2,3,4,5,6') |
+---------------------------------+
| NULL |
+---------------------------------+
1 row in set
mysql> select find_in_set('7',null);
+-----------------------+
| find_in_set('7',null) |
+-----------------------+
| NULL |
+-----------------------+
1 row in set