Question

我是Spring的新手，我正在尝试创建一个RESTful资源以在我的API上使用。到目前为止，我能够列出元素（GET /people.json），显示特定元素（GET /people/{id}.json），创建新元素（POST /people.json），并删除元素（删除/people/{id}.json）。我的最后一步是处理更新方法（PUT /people/{id}.json，但我不知道该怎么做。

以下是我的控制器代码：

package com.example.controller;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Controller;
import org.springframework.validation.BindingResult;
import org.springframework.web.bind.annotation.ModelAttribute;
import org.springframework.web.bind.annotation.PathVariable;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestMethod;
import org.springframework.web.bind.annotation.ResponseBody;

import com.example.model.Person;
import com.example.service.PersonService;

import java.util.Map;

@Controller
public class PersonController {

    @Autowired
    private PersonService personService;

    @ResponseBody
    @RequestMapping(value = "/people.json", method = RequestMethod.GET)
    public String all(Map<String, Object> map) {
        return "{\"people\": " + personService.all() + "}";
    }

    @ResponseBody
    @RequestMapping(value = "/people/{personId}.json", method = RequestMethod.GET)
    public String show(@PathVariable("personId") Integer personId) {
        Person person = personService.find(personId);
        return "{\"person\": "+person+"}";
    }


    @ResponseBody
    @RequestMapping(value = "/people.json", method = RequestMethod.POST)
    public String create(@ModelAttribute("person") Person person, BindingResult result) {
        personService.create(person);
        return "{\"person\": "+person+"}";
    }

    @ResponseBody
    @RequestMapping(value = "/people/{personId}.json", method = RequestMethod.PUT)
    public String update(@PathVariable("personId") Integer personId, @ModelAttribute("person") Person person, BindingResult result) {
        personService.update(personId, person);
        return "{\"person\": "+person+"}";
    }    

    @ResponseBody
    @RequestMapping(value = "/people/{personId}.json", method = RequestMethod.DELETE)
    public String delete(@PathVariable("personId") Integer personId) {
        personService.delete(personId);
        return "{\"status\": \"ok\", \"message\": \"\"}";
    }
}

以下是我服务的代码：

import org.springframework.stereotype.Service;
import org.springframework.transaction.annotation.Transactional;
import com.example.model.Person;
import javax.persistence.EntityManager;
import javax.persistence.PersistenceContext;
import javax.persistence.criteria.CriteriaQuery;
import javax.persistence.criteria.Root;

import java.util.List;

@Service
public class PersonServiceImpl implements PersonService {

    @PersistenceContext
    EntityManager em;

    @Transactional
    public List<Person> all() {
        CriteriaQuery<Person> c = em.getCriteriaBuilder().createQuery(Person.class);
        c.from(Person.class);
        return em.createQuery(c).getResultList();
    }

    @Transactional
    public Person find(Integer id) {
        Person person = em.find(Person.class, id);
        return person;
    }

    @Transactional
    public void create(Person person) {
        em.persist(person);
    }

    public void update(Integer id, Person person) {
        // TODO: How to implement this?
    }

    @Transactional
    public void delete(Integer id) {
        Person person = em.find(Person.class, id);
        if (null != person) {
            em.remove(person);
        }
    }   
}

所以，对于Spring，那里的hibernate专家，完成我需要的最好的方法是什么？资源更新仅更新实际更改的属性

也很重要

谢谢，

Answer 1

更改PersonService更新方法签名，使其返回Person，同样，您不需要单独的id，只需使用Person对象即可身份证。他们实现这样的方法：

public Person update(Person person) {
    // you might want to validate the person object somehow
    return em.merge(person);
}

同时更新您的网络服务图层。要么更改它以便personId不再存在，要么保留它并使用它设置Person ID：

public String update(@PathVariable("personId") Integer personId, 
        @ModelAttribute("person") Person person, BindingResult result) {
    person.setId(personId);
    Person updated = personService.update(person);
    // You may want to use a JSON library instead of overriding toString.
    return "{\"person\": " + updated + "}";
}

一个小问题，合并也可能会持续存在新实体。因此，如果您想确保update仅更新现有的id，请将其正文更改为：

public Person update(Person person) {
    if(em.find(Person.class, person.getId()) == null) {
        throw new IllegalArgumentException("Person " + person.getId() 
                + " does not exists");
    }
    return em.merge(person);
}

资源更新仅更新实际更改的属性
也很重要

如果希望hibernate只更新JSON对象和数据库之间不同的属性，dynamicUpdate上有selectBeforeUpdate和@org.hibernate.annotations.Entity属性的便捷组合（请查看{ {3}}）。只有在您确实需要行为时才启用此功能（这是非标准行为，可能会降低性能）。

@org.hibernate.annotations.Entity(dynamicUpdate = true, selectBeforeUpdate = true)

在Hibernate 4.0上这些已弃用的属性，您可以使用单独的注释：

@DynamicUpdate
@SelectBeforeUpdate

Spring + Hibernate RESTful资源

1 个答案: