如何用mybatis写一个拦截器分页

1. 创建一个实现了Interceptor接口的分页拦截器类

public class PageInterceptor implements Interceptor {

    @Override
    public Object intercept(Invocation invocation) throws Throwable {
        // 获取原始sql
        MappedStatement mappedStatement = (MappedStatement) invocation.getArgs()[0];
        Object parameter = invocation.getArgs()[1];
        BoundSql boundSql = mappedStatement.getBoundSql(parameter);
        String originalSql = boundSql.getSql();

        // 获取分页参数
        Pageable pageable = PageableThreadLocal.getPageable();
        if (pageable == null) {
            // 没有分页参数，直接执行原始sql
            return invocation.proceed();
        }
        int pageNum = pageable.getPageNum();
        int pageSize = pageable.getPageSize();

        // 生成分页sql
        String pageSql = generatePageSql(originalSql, pageNum, pageSize);

        // 替换原始sql为分页sql
        Field field = boundSql.getClass().getDeclaredField("sql");
        field.setAccessible(true);
        field.set(boundSql, pageSql);

        // 执行分页sql
        Object result = invocation.proceed();

        // 返回分页结果
        return result;
    }

    @Override
    public Object plugin(Object target) {
        return Plugin.wrap(target, this);
    }

    @Override
    public void setProperties(Properties properties) {
        // do nothing
    }

    private String generatePageSql(String originalSql, int pageNum, int pageSize) {
        StringBuilder builder = new StringBuilder();
        builder.append(originalSql);
        builder.append(" LIMIT ");
        builder.append((pageNum - 1) * pageSize);
        builder.append(",");
        builder.append(pageSize);
        return builder.toString();
    }
}

2. 在Mybatis配置文件中配置拦截器

<plugins>
    <plugin interceptor="com.example.PageInterceptor"/>
</plugins>

3. 在使用分页的Mapper接口方法中设置分页参数

@Select("SELECT * FROM user WHERE name LIKE #{name}")
List<User> findByName(@Param("name") String name, Pageable pageable);

4. 在代码中设置分页参数

Pageable pageable = new Pageable(1, 10);
PageableThreadLocal.setPageable(pageable);
List<User> users = userMapper.findByName("张三");