@SelectProvider(type = MySelectProvider.class, method = "dynamicSQL") List<User> selectByRoleAndPage(@Param("role") int role, RowBounds rowBounds);请示例一个springboot项目中的MySelectProvider类
时间: 2024-03-16 07:43:05 浏览: 20
好的,以下是一个示例的`MySelectProvider`类,用于在Spring Boot项目中动态生成SQL语句:
```java
package com.example.demo.mapper.provider;
import org.apache.ibatis.jdbc.SQL;
public class MySelectProvider {
public String dynamicSQL(int role) {
return new SQL() {{
SELECT("id, username, password, role");
FROM("user");
WHERE("role = #{role}");
}}.toString();
}
}
```
在上面的示例中,`MySelectProvider`类位于`mapper.provider`包下,用于为`UserMapper`接口提供动态SQL语句。`dynamicSQL`方法用于生成查询语句,根据传入的`role`参数动态拼接查询条件,返回最终的SQL语句字符串。在`@SelectProvider`注解中,`type`属性指定使用`MySelectProvider`类,`method`属性指定调用`dynamicSQL`方法。
相关问题
public List<User> selectUsers(Integer role, PageSort page) { log.info("批量查询用户信息,查询的角色权限:" + role); List<User> usersList = new ArrayList<User>(); int offset = (page.getPageNum() - 1) * page.getPageSize(); int limit = page.getPageSize(); RowBounds rowBounds = new RowBounds(offset, limit); List<User> userList = userInfoMapper.selectByRoleAndPage(role, rowBounds); return usersList; } @SelectProvider(type = UserSqlProvider.class, method = "selectByRoleAndPage") List<User> selectByRoleAndPage(@Param("role") Integer role, RowBounds rowBounds); public class UserSqlProvider { public String selectByRoleAndPage(Integer role, RowBounds rowBounds) { String sql = "SELECT * FROM user WHERE 1=1"; if (role != -1) { sql += " AND role = #{0}"; } sql += " LIMIT #{1.offset}, #{1.limit}"; return sql; } }方法selectByRoleAndPage没有关联上
selectUsers方法,应该在UserSqlProvider类中添加@Param注解来指定参数名称,如下所示:
```
public String selectByRoleAndPage(@Param("role") Integer role, @Param("rowBounds") RowBounds rowBounds) {
String sql = "SELECT * FROM user WHERE 1=1";
if (role != -1) {
sql += " AND role = #{role}";
}
sql += " LIMIT #{rowBounds.offset}, #{rowBounds.limit}";
return sql;
}
```
同时,在selectUsers方法中,应该将userList赋值给usersList,如下所示:
```
public List<User> selectUsers(Integer role, PageSort page) {
log.info("批量查询用户信息,查询的角色权限:" + role);
List<User> usersList = new ArrayList<User>();
int offset = (page.getPageNum() - 1) * page.getPageSize();
int limit = page.getPageSize();
RowBounds rowBounds = new RowBounds(offset, limit);
List<User> userList = userInfoMapper.selectByRoleAndPage(role, rowBounds);
usersList.addAll(userList);
return usersList;
}
```
public List<User> selectUsers(Integer role, PageSort page) { log.info("批量查询用户信息,查询的角色权限:" + role); List<User> usersList = new ArrayList<User>(); int offset = (page.getPageNum() - 1) * page.getPageSize(); int limit = page.getPageSize(); userInfoMapper.selectByRoleAndPage(role, new RowBounds(offset, limit)); RowBounds rowBounds = new RowBounds(offset, limit); List<User> userList = userInfoMapper.selectByRoleAndPage(role, rowBounds); return usersList; } @SelectProvider(type = UserSqlProvider.class, method = "selectByRoleAndPage") List<User> selectByRoleAndPage(@Param("role") Integer role, RowBounds rowBounds); public class UserSqlProvider { public String selectByRoleAndPage(Integer role, RowBounds rowBounds) { String sql = "SELECT * FROM user WHERE 1=1"; if (role != -1) { sql += " AND role = #{role}"; } sql += " LIMIT #{offset}, #{limit}"; return sql; } } 报错Error invoking SqlProvider method (com.ruifan.taihaolian.biz.mapper.provider.UserSqlProvider.selectByRoleAndPage). Cause: java.lang.IllegalArgumentException: wrong number of arguments
这个错误可能是因为在 `UserSqlProvider` 类中的 `selectByRoleAndPage` 方法声明了两个参数 `role` 和 `RowBounds`,但在 SQL 语句中只传入了一个参数 `role`,没有传入 `RowBounds` 参数。因此,需要将 SQL 语句中的 `LIMIT #{offset}, #{limit}` 替换为 `LIMIT #{1.offset}, #{1.limit}`,表示使用第二个参数 `RowBounds` 的 `offset` 和 `limit` 属性来限制查询结果集。修改后的代码如下所示:
```java
public class UserSqlProvider {
public String selectByRoleAndPage(Integer role, RowBounds rowBounds) {
String sql = "SELECT * FROM user WHERE 1=1";
if (role != -1) {
sql += " AND role = #{0}";
}
sql += " LIMIT #{1.offset}, #{1.limit}";
return sql;
}
}
```
另外,在 `selectUsers` 方法中,代码存在一些问题,`userInfoMapper.selectByRoleAndPage(role, new RowBounds(offset, limit));` 这行代码没有将查询结果保存到 userList 中,应该删除。修改后的代码如下所示:
```java
public List<User> selectUsers(Integer role, PageSort page) {
log.info("批量查询用户信息,查询的角色权限:" + role);
int offset = (page.getPageNum() - 1) * page.getPageSize();
int limit = page.getPageSize();
RowBounds rowBounds = new RowBounds(offset, limit);
List<User> userList = userInfoMapper.selectByRoleAndPage(role, rowBounds);
return userList;
}
```
这样就可以正确地查询出符合条件的用户列表了。