Git Product home page Git Product logo

cursor-iterator's Introduction

Cursor Iterator

Build Status Coverage Status Total alerts Language grade: Java Maven Central

一个简单的适合移动端无限下拉构建数据的后端支持组件

使用方法

public class UserDAO {

    private static final int MAX_USER_ID = 938;

    // A fake DAO for test
    public static List<User> getUsersAscById(Integer startId, int limit) {
        if (startId == null) {
            startId = 0;
        }
        List<User> result = IntStream.range(startId, Math.min(startId + limit, MAX_USER_ID))
                .mapToObj(User::new)
                .collect(Collectors.toList());
        System.out.println("get users asc by id, startId:" + startId + ", limit:" + limit
                + ", result:" + result);
        return result;
    }
}

// 声明
CursorIterator<Integer, User> users = CursorIterator.newGenericBuilder()
        .start(startId)
        .cursorExtractor(User::getId)
        .bufferSize(countPerFetch)
        .buildEx(UserDAO::getUsersAscById);

// jdk1.8 Stream方式
List<User> collect = users.stream()
		.filter(user -> user.getId() % 11 == 0)
		.limit(5)
        .collect(Collectors.toList());
        
// 传统迭代器模式
List<User> finalResult = new ArrayList<>();
for (User user : users) {
    if (user.getId() % 11 == 0) { // filter
        System.out.println("add to final result:" + user);
        finalResult.add(user);
    } else {
        System.out.println("ignore add user:" + user);
    }
    if (finalResult.size() == 50) {
        break;
    }
}

注意事项

  • GetByCursorDAO返回的元素不能有null,因为如果结尾的元素是null,CursorIterator将无法根据null计算下一次迭代滑动窗口时的起始位置

cursor-iterator's People

Contributors

phantomthief avatar lixian avatar starlight36 avatar

Recommend Projects

  • React photo React

    A declarative, efficient, and flexible JavaScript library for building user interfaces.

  • Vue.js photo Vue.js

    🖖 Vue.js is a progressive, incrementally-adoptable JavaScript framework for building UI on the web.

  • Typescript photo Typescript

    TypeScript is a superset of JavaScript that compiles to clean JavaScript output.

  • TensorFlow photo TensorFlow

    An Open Source Machine Learning Framework for Everyone

  • Django photo Django

    The Web framework for perfectionists with deadlines.

  • D3 photo D3

    Bring data to life with SVG, Canvas and HTML. 📊📈🎉

Recommend Topics

  • javascript

    JavaScript (JS) is a lightweight interpreted programming language with first-class functions.

  • web

    Some thing interesting about web. New door for the world.

  • server

    A server is a program made to process requests and deliver data to clients.

  • Machine learning

    Machine learning is a way of modeling and interpreting data that allows a piece of software to respond intelligently.

  • Game

    Some thing interesting about game, make everyone happy.

Recommend Org

  • Facebook photo Facebook

    We are working to build community through open source technology. NB: members must have two-factor auth.

  • Microsoft photo Microsoft

    Open source projects and samples from Microsoft.

  • Google photo Google

    Google ❤️ Open Source for everyone.

  • D3 photo D3

    Data-Driven Documents codes.