SpringBoot中的内容协商器图解

时间：2022-06-12 23:43:48

背景

使用了restful的小伙伴对于导出这些需求本能就是拒绝的~破坏了restful的url的一致性【严格矫正 不是http json就是restful 很多小伙伴都会吧暴露出一个json就直接称为restful 】

正如上文的代码生成器 我们会批量生成一堆代码 其中绝大部分都是restcontroller

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public abstract class abstractrestcontroller<v extends vo, s extends so, pk extends serializable> {
  protected class<v> voclazz;
  @autowired
  private service<v, s, pk> service;
  public abstractrestcontroller() {
    typetoken<v> votype = new typetoken<v>(getclass()) {
    };
    voclazz = (class<v>) votype.getrawtype();
  }
  @postmapping()
  @apioperation(value = "新建实体", notes = "")
  public result add(@requestbody v vo) {
    service.saveselective(vo);
    return resultgenerator.gensuccessresult();
  }
  @deletemapping("/{id}")
  @apioperation(value = "删除实体", notes = "")
  public result delete(@pathvariable pk id) {
    service.deletebyid(id);
    return resultgenerator.gensuccessresult();
  }
  @putmapping
  @apioperation(value = "更新实体", notes = "")
  public result update(@requestbody v vo) {
    service.updatebyprimarykeyselective(vo);
    return resultgenerator.gensuccessresult();
  }
  @getmapping
  @apioperation(value = "获取实体列表", notes = "")
  public result list(s so) {
    pagehelper.startpage(so.getcurrentpage(), so.getpagesize());
    list<v> list = service.findall();
    pageinfo pageinfo = new pageinfo(list);
    excelexportparam();
    return resultgenerator.gensuccessresult(pageinfo);
  }
  protected void excelexportparam() {
    exportparams ep = new exportparams(null, "数据");
    excelexportparam<v> param = new excelexportparam<>();
    param.setclazz(voclazz);
    param.setexcelexport(excelexport.normalexcel);
    param.setexportparams(ep);
    param.setfilename("文件.xls");
    f6static.setexcelexportparam(param);
  }
  @getmapping("/{id}")
  @apioperation(value = "获取单个实体", notes = "")
  public result detail(@pathvariable pk id) {
    v vo = service.findbyid(id);
    return resultgenerator.gensuccessresult(vo);
  }
  @deletemapping("/batch")
  @apioperation(value = "批量删除实体", notes = "")
  public result batchdelete(@requestparam string ids) {
    service.deletebyids(ids);
    return resultgenerator.gensuccessresult();
  }
  @getmapping("/batch")
  @apioperation(value = "批量获取实体", notes = "")
  public result batchdetail(@requestparam string ids) {
    list<v> vos = service.findbyids(ids);
    return resultgenerator.gensuccessresult(vos);
  }
  @postmapping("/batch")
  @apioperation(value = "批量新建实体", notes = "")
  public result add(@requestbody list<v> vos) {
    service.save(vos);
    return resultgenerator.gensuccessresult();
  }
  @getmapping("/count")
  @apioperation(value = "获取实体数目", notes = "")
  public result count(@requestbody v v) {
    int count = service.selectcount(v);
    return resultgenerator.gensuccessresult(count);
  }

那么导出如何做呢？【其实可以理解成导出就是数据的展示 不过此时结果不是json而已】

抛出一个问题那么登录登出呢？传统的方案都是login logout 那么换成restful资源的思路是啥呢？

提示： 登录就是session的新建 登出就是session的删除

实现

基于上述思路 我们自然就想到了那么我们只需要对同一个url返回多种结果不就ok了？【pdf一个版本 json一个版本 xml一个版本 xls一个版本】

bingo！这个是内容协商器的由来

内容协商器并不是spring创造出来的 事实上这个从http头里面也能看出

SpringBoot中的内容协商器图解

1.比如给英语客户返回英语页面 过于客户返回汉语页面

http 协议中定义了质量值(简称 q 值)，允许客户端为每种偏好类别列出多种选项，并为每种偏好选项关联一个优先次序。

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accept-language: en;q=0.5, fr;q=0.0, nl;q=1.0, tr;q=0.0

其中 q 值的范围从 0.0 ~ 1.0（0.0 是优先级最低的，而 1.0 是优先级最高的）。

注意，偏好的排列顺序并不重要，只有与偏好相关的 q 值才是重要的

2.那么还有其他的一些参数 比如 accept-header

通常是先内容协商器有如下几种方案

1.使用accept header:

这一种为教科书中通常描述的一种,理想中这种方式也是最好的,但如果你的资源要给用户直接通过浏览器访问(即html展现),那么由于浏览器的差异,发送上来的accept header头将是不一样的. 将导致服务器不知要返回什么格式的数据给你. 下面是浏览器的accept header   

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chrome:
   accept:application/xml,application/xhtml+xml,textml;q=0.9,text/plain;q=0.8,image/png,*/*;q=0.5    
   firefox:
   accept:text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8     
   ie8:
   accept:image/gif, image/jpeg, image/pjpeg, image/pjpeg, application/x-shockwave-flash, application/x-silverlight, application/x-ms-application, application/x-ms-xbap, application/vnd.ms-xpsdocument, application/xaml+xml, */*

2.使用扩展名

丧失了同一url多种展现的方式,但现在这种在实际环境中是使用最多的.因为更加符合程序员的审美观.

比如/user.json /user.xls /user.xml

使用参数 现在很多open api是使用这种方式,比如淘宝

但是对于不同浏览器可能accept-header并不是特别统一 因此许多实现选择了2 3两种方案

我们在spring中采用上述两种方案

首先配置内容协商器

代码

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@bean
  public viewresolver contentnegotiatingviewresolver(
      contentnegotiationmanager manager) {
    // define the view resolvers
    viewresolver beannameviewresolver = new beannameviewresolver();
    list<viewresolver> resolvers = lists.newarraylist(beannameviewresolver);
    contentnegotiatingviewresolver resolver = new contentnegotiatingviewresolver();
    resolver.setviewresolvers(resolvers);
    resolver.setcontentnegotiationmanager(manager);
    return resolver;
  }
  @override
  public void configurecontentnegotiation(contentnegotiationconfigurer configurer) {
    configurer.favorpathextension(true)
        .usejaf(false)
        .favorparameter(true)
        .parametername("format")
        .ignoreacceptheader(true)
        .defaultcontenttype(mediatype.application_json)
        .mediatype("json", mediatype.application_json)
        .mediatype("xls", excel_media_type);
  }

创建对应的转换器

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private httpmessageconverter<object> createexcelhttpmessageconverter() {
  excelhttpmessageconverter excelhttpmessageconverter = new excelhttpmessageconverter();
  return excelhttpmessageconverter;
}

直接使用easy-poi导出数据

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/*
 * copyright (c) 2017. lorem ipsum dolor sit amet, consectetur adipiscing elit.
 * morbi non lorem porttitor neque feugiat blandit. ut vitae ipsum eget quam lacinia accumsan.
 * etiam sed turpis ac ipsum condimentum fringilla. maecenas magna.
 * proin dapibus sapien vel ante. aliquam erat volutpat. pellentesque sagittis ligula eget metus.
 * vestibulum commodo. ut rhoncus gravida arcu.
 */
package com.f6car.base.web.converter;
import cn.afterturn.easypoi.excel.excelexportutil;
import com.f6car.base.common.result;
import com.f6car.base.core.excelexport;
import com.f6car.base.core.excelexportparam;
import com.github.pagehelper.pageinfo;
import com.google.common.collect.lists;
import org.apache.poi.ss.usermodel.workbook;
import org.springframework.http.httpheaders;
import org.springframework.http.httpinputmessage;
import org.springframework.http.httpoutputmessage;
import org.springframework.http.mediatype;
import org.springframework.http.converter.abstracthttpmessageconverter;
import org.springframework.http.converter.generichttpmessageconverter;
import org.springframework.http.converter.httpmessagenotreadableexception;
import org.springframework.http.converter.httpmessagenotwritableexception;
import java.io.ioexception;
import java.lang.reflect.type;
import java.net.urlencoder;
import java.util.collection;
import java.util.collections;
import java.util.map;
import static com.f6car.base.core.f6static.getexcelexportparam;
/**
 * @author qixiaobo
 */
public class excelhttpmessageconverter extends abstracthttpmessageconverter<object>
    implements generichttpmessageconverter<object> {
  public static final mediatype excel_media_type = new mediatype("application", "vnd.ms-excel");
  public excelhttpmessageconverter() {
    super(excel_media_type);
  }
  @override
  protected boolean supports(class<?> clazz) {
    return false;
  }
  @override
  protected object readinternal(class<?> clazz, httpinputmessage inputmessage) throws ioexception, httpmessagenotreadableexception {
    return null;
  }
  @override
  protected void writeinternal(object o, httpoutputmessage outputmessage) throws ioexception, httpmessagenotwritableexception {
    httpheaders headers = outputmessage.getheaders();
    collection data = getactualdata((result) o);
    excelexportparam excelexportparam = getexcelexportparam();
    workbook workbook;
    switch (excelexportparam.getexcelexport()) {
      case normalexcel:
        workbook = excelexportutil.exportexcel(
            excelexportparam.getexportparams(),
            (class<?>) excelexportparam.getclazz(),
            (collection<?>) data);
        break;
      case mapexcel:
        workbook = excelexportutil.exportexcel(
            excelexportparam.getexportparams(),
            excelexportparam.getexcelexportentities(),
            (collection<? extends map<?, ?>>) data);
        break;
      case bigexcel:
      case mapexcelgraph:
      case pdftemplate:
      case templateexcel:
      case templateword:
      default:
        throw new runtimeexception();
    }
    if (workbook != null) {
      if (excelexportparam.getfilename() != null) {
        string codedfilename = urlencoder.encode(excelexportparam.getfilename(), "utf8");
        headers.setcontentdispositionformdata("attachment", codedfilename);
      }
      workbook.write(outputmessage.getbody());
    }
  }
  private collection getactualdata(result r) {
    if (r != null && r.getdata() != null) {
      object data = r.getdata();
      if (data instanceof pageinfo) {
        return ((pageinfo) data).getlist();
      } else if (!(data instanceof collection)) {
        data = lists.newarraylist(data);
      } else {
        return (collection) data;
      }
    }
    return collections.emptylist();
  }
  @override
  public boolean canread(type type, class<?> contextclass, mediatype mediatype) {
    //不支持excel
    return false;
  }
  @override
  public object read(type type, class<?> contextclass, httpinputmessage inputmessage) throws ioexception, httpmessagenotreadableexception {
    return null;
  }
  @override
  public boolean canwrite(type type, class<?> clazz, mediatype mediatype) {
    return super.canwrite(mediatype) && clazz == result.class && support();
  }
  private boolean support() {
    excelexportparam param = getexcelexportparam();
    if (param == null || param.getexcelexport() == null || param.getexportparams() == null) {
      return false;
    }
    if (param.getexcelexport() == excelexport.normalexcel) {
      return true;
    } else {
      logger.warn(param.getexcelexport() + " not supprot now!");
      return false;
    }
  }
  @override
  public void write(object o, type type, mediatype contenttype, httpoutputmessage outputmessage) throws ioexception, httpmessagenotwritableexception {
    super.write(o, contenttype, outputmessage);
  }
}

暂时只是针对导出 因此在使用的时候如下

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@getmapping
 @apioperation(value = "获取实体列表", notes = "")
 public result list(s so) {
   pagehelper.startpage(so.getcurrentpage(), so.getpagesize());
   list<v> list = service.findall();
   pageinfo pageinfo = new pageinfo(list);
   excelexportparam();
   return resultgenerator.gensuccessresult(pageinfo);
 }
 protected void excelexportparam() {
   exportparams ep = new exportparams(null, "数据");
   excelexportparam<v> param = new excelexportparam<>();
   param.setclazz(voclazz);
   param.setexcelexport(excelexport.normalexcel);
   param.setexportparams(ep);
   param.setfilename("文件.xls");
   f6static.setexcelexportparam(param);
 }

当我们访问时如下

 

SpringBoot中的内容协商器图解

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{
 "code": 200,
 "data": {
 "endrow": 10,
 "firstpage": 1,
 "hasnextpage": true,
 "haspreviouspage": false,
 "isfirstpage": true,
 "islastpage": false,
 "lastpage": 8,
 "list": [
 {
 "cellphone": "13857445502",
 "idemployee": 24201883434352650,
 "idownorg": 23993199378825296,
 "idrole": 88,
 "idwxbstation": "332",
 "idwxbuser": "207",
 "isadmin": 1,
 "isdel": 0,
 "isguideopen": 0,
 "limitmac": 0,
 "openid": "",
 "password": "96e79218965eb72c92a549dd5a330112",
 "pkid": 23993199378825296,
 "username": "lingweiqiche"
 },
 {
 "cellphone": "",
 "idemployee": 0,
 "idownorg": 9999,
 "idrole": 4,
 "idwxbstation": "",
 "idwxbuser": "",
 "isadmin": 0,
 "isdel": 0,
 "isguideopen": 0,
 "limitmac": 0,
 "openid": "",
 "password": "96e79218965eb72c92a549dd5a330112",
 "pkid": 24201883434356532,
 "username": "007"
 },
 {
 "cellphone": "15715139000",
 "idemployee": 24351585207523460,
 "idownorg": 24201883434357600,
 "idrole": 89,
 "idwxbstation": "540",
 "idwxbuser": "298",
 "isadmin": 1,
 "isdel": 0,
 "isguideopen": 0,
 "limitmac": 0,
 "openid": "",
 "password": "96e79218965eb72c92a549dd5a330112",
 "pkid": 24201883434357600,
 "username": "15715139000"
 },
 {
 "cellphone": "",
 "idemployee": 0,
 "idownorg": 24201883434357600,
 "idrole": 216,
 "idwxbstation": "",
 "idwxbuser": "",
 "isadmin": 0,
 "isdel": 0,
 "isguideopen": 0,
 "limitmac": 0,
 "openid": "",
 "password": "96e79218965eb72c92a549dd5a330112",
 "pkid": 24201883434357920,
 "username": "sunlingli"
 },
 {
 "cellphone": "",
 "idemployee": 24351585207425676,
 "idownorg": 24201883434359384,
 "idrole": 90,
 "idwxbstation": "348",
 "idwxbuser": "227",
 "isadmin": 1,
 "isdel": 0,
 "isguideopen": 0,
 "limitmac": 0,
 "openid": "opzuds_v13we500kxymj6xg_gfee",
 "password": "96e79218965eb72c92a549dd5a330112",
 "pkid": 24201883434359388,
 "username": "15952920979"
 },
 {
 "cellphone": "",
 "idemployee": 0,
 "idownorg": 24201883434359790,
 "idrole": 91,
 "idwxbstation": "315",
 "idwxbuser": "175",
 "isadmin": 1,
 "isdel": 0,
 "isguideopen": 0,
 "limitmac": 0,
 "openid": "",
 "password": "96e79218965eb72c92a549dd5a330112",
 "pkid": 24201883434359790,
 "username": "13809056211"
 },
 {
 "cellphone": "18903885585",
 "idemployee": 24201883434366164,
 "idownorg": 24201883434359890,
 "idrole": 92,
 "idwxbstation": "317",
 "idwxbuser": "178",
 "isadmin": 1,
 "isdel": 0,
 "isguideopen": 0,
 "limitmac": 0,
 "openid": "",
 "password": "96e79218965eb72c92a549dd5a330112",
 "pkid": 24201883434359892,
 "username": "18903885585"
 },
 {
 "cellphone": "",
 "idemployee": 24351585207425668,
 "idownorg": 24201883434359924,
 "idrole": 93,
 "idwxbstation": "318",
 "idwxbuser": "179",
 "isadmin": 1,
 "isdel": 0,
 "isguideopen": 0,
 "limitmac": 0,
 "openid": "",
 "password": "96e79218965eb72c92a549dd5a330112",
 "pkid": 24201883434359930,
 "username": "13372299595"
 },
 {
 "cellphone": "",
 "idemployee": 0,
 "idownorg": 24201883434360052,
 "idrole": 94,
 "idwxbstation": "321",
 "idwxbuser": "188",
 "isadmin": 1,
 "isdel": 0,
 "isguideopen": 0,
 "limitmac": 0,
 "openid": "",
 "password": "96e79218965eb72c92a549dd5a330112",
 "pkid": 24201883434360052,
 "username": "15221250005"
 },
 {
 "cellphone": "",
 "idemployee": 0,
 "idownorg": 24201883434360070,
 "idrole": 95,
 "idwxbstation": "325",
 "idwxbuser": "198",
 "isadmin": 1,
 "isdel": 0,
 "isguideopen": 0,
 "limitmac": 0,
 "openid": "",
 "password": "96e79218965eb72c92a549dd5a330112",
 "pkid": 24201883434360070,
 "username": "13837251167"
 }
 ],
 "navigatefirstpage": 1,
 "navigatelastpage": 8,
 "navigatepages": 8,
 "navigatepagenums": [
 1,
 2,
 3,
 4,
 5,
 6,
 7,
 8
 ],
 "nextpage": 2,
 "orderby": "",
 "pagenum": 1,
 "pagesize": 10,
 "pages": 102,
 "prepage": 0,
 "size": 10,
 "startrow": 1,
 "total": 1012
 },
 "message": "success"
 }

当访问http://127.0.0.1:8079/zeus/user?format=xls 或者http://127.0.0.1:8079/zeus/user.xls

如下效果

SpringBoot中的内容协商器图解

SpringBoot中的内容协商器图解

由于这边的数据和查询有关 因此我们可以这样操作http://127.0.0.1:8079/zeus/user.xls?pagesize=1000 轻而易举实现了查询结果xls化！

SpringBoot中的内容协商器图解

SpringBoot中的内容协商器图解

总结

以上所述是小编给大家介绍的springboot中的内容协商器图解，希望对大家有所帮助，如果大家有任何疑问请给我留言，小编会及时回复大家的。在此也非常感谢大家对服务器之家网站的支持！

原文链接：http://www.jianshu.com/p/f7b257585d9a

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