SpringBoot之内容协商器

作者: 3c69b7c624d9 | 来源:发表于2017-11-28 22:26 被阅读47次

SpringBoot之内容协商器
SpringMVC-ContentNegotiatingView
Websocket在JavaScript中操作字节序之客户端
Content negotiation - Django RES
3.6 内容协商
防盗链之基于springboot过滤器实现
SpringBoot 响应数据
SpringBoot中的内容协商，颠覆你的认知
SpringBoot中的内容协商，颠覆你的认知
SpringBoot系列之JDBC数据访问

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

    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

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。
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
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

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

        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, */*

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 114415_WSkT_871390.png

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

    @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

    private HttpMessageConverter<Object> createExcelHttpMessageConverter() {
        ExcelHttpMessageConverter excelHttpMessageConverter = new ExcelHttpMessageConverter();
        return excelHttpMessageConverter;
    }

直接使用easy-poi导出数据

    /*
     * 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

    @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

http://127.0.0.1:8079/zeus/user

114555_jUQu_871390.png


    {
    "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

114746_7ue1_871390.png

114800_fAcF_871390.png

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！

114823_Pbgq_871390.png

114833_ArRc_871390.png

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