前段時間在一個項目里面發現，針對Excel的處理沒有一個公用的視圖，來個下載的需求就要自己去寫一堆POI的東西，終於有一天給我也來了幾個，還是按照以前的方式來寫，寫多了真心想吐，后面想想還是有必要整個解析Excel的視圖了。花了一天時間，總結出來共有三種方式可以處理Excel視圖。
由於spring已經提供了excel的抽象視圖，所以我們直接繼承過來就可以了。由於POI對excel2007和2003處理方式有些不同，所以spring4.2以上版本提供了兩個excel抽象視圖AbstractXlsxView（2007）、AbstractXlsView（2003）。現在又想到曾經公司的報表系統了，下載一年的銷售數據，有上百萬的數據在一個excel里面，打開直接卡死，后面還得分批次查詢去搞，針對這種情況，程序里面其實可以一次性搞定的，分頁查詢、切割結果集到多個列表、多線程處理等等，所以處理的結果集最后還是放到Map里面的，以防數據量大的時候分成多個列表下載。這里還是只分析3中視圖如何處理的，關於性能方面的東西，在實際項目中還是要充分考慮，這里就不分析了。下面的代碼都是以excel2003進行分析。
這三種解析方式都要用到具體的Excel實現類，代碼如下：
public class ExcelView extends AbstractXlsView {
@Override
protected void buildExcelDocument(Map<String, Object> model, Workbook workbook, HttpServletRequest request, HttpServletResponse response) throws Exception { response.setHeader("Content-Disposition", "attachment;filename="+ new String((DateFormatUtils.format(new Date(), "yyyyMMddHHmmss") + ".xls").getBytes(), "iso-8859-1")); //分割list for (Entry<String, Object> e : model.entrySet()) { HSSFSheet sheet = (HSSFSheet) workbook.createSheet("測試"); if (e.getValue() instanceof List) { List<?> dataList = (List<?>) e.getValue(); HSSFRow rowHeader = sheet.createRow(0); //添加header rowHeader.createCell(0).setCellValue("id"); rowHeader.createCell(1).setCellValue("名字"); for (int start = 0; start < dataList.size(); start++) { HSSFRow row = sheet.createRow(start + 1); String[] rowsText = dataList.get(start).toString().split(","); for (int col = 0; col < rowsText.length; col++) { HSSFCell cell = row.createCell(col); cell.setCellValue(rowsText[col]); } } } } } } 由於在AbstractXlsView里面，已經做了ContentType以及流的寫入，所以我們直接把HSSFSheet里面的數據設置下就可以了。
直接添加excel視圖到ModelAndView
這種方式和其他方式差不多，只是把ExcelView作為參數傳到ModelAndView，代碼如下：
@RequestMapping("/download") public ModelAndView test() { ModelAndView mav = new ModelAndView(); ExcelView excelView = new ExcelView(); List<Student> list = new ArrayList<>(); Student student = new Student(); student.setId(1); student.setName("hello"); list.add(student); student = new Student(); student.setId(2); student.setName("world"); list.add(student); mav.addObject("list", list); mav.setView(excelView); return mav; } 不用做其他配置，發送一個請求就可以得到excel文件了，結果如下：
自定義視圖解析器
類似於解析jsp，只要給定相應規則把請求指定到配置的解析器就可以了，代碼如下：
public class ExcelViewResolver extends AbstractCachingViewResolver implements Ordered { private ApplicationContext context; private int order = Integer.MAX_VALUE; // default: same as non-Ordered public void setOrder(int order) { this.order = order; } @Override public int getOrder() { return this.order; } @Override public boolean isCache() { return false; } /** * 直接在容器中配置視圖，單例獲取bean，不用每次新建，待優化 TODO */ @Override protected View loadView(String viewName, Locale locale) throws Exception { context = super.getApplicationContext(); if (context != null) { return context.getBean(viewName, View.class); } return null; } } 配置文件：
<bean class="com.myspring.web.view.ExcelViewResolver"> <property name="order" value="0"/> </bean> <bean id="excelView" class="com.myspring.web.view.ExcelView"/> 這種方式需要指定視圖的名字為excelView，controller代碼如下：
@RequestMapping("/download1") public ModelAndView excel1() { //針對指定的視圖解析 ModelAndView mv = new ModelAndView("excelView"); List<Student> list = new ArrayList<>(); Student student = new Student(); student.setId(1); student.setName("你好"); list.add(student); student = new Student(); student.setId(2); student.setName("世界"); list.add(student); mv.addObject("list", list); return mv; } 運行結果：
自定義注解解析返回值
spring解析json視圖的時候只要@ResponseBody注解就可以了，也不用其他配置，非常方便。解析excel一樣可以這樣做。首先自定義一個注解：
@Target({ElementType.TYPE, ElementType.METHOD}) @Retention(RetentionPolicy.RUNTIME) @Documented public @interface Excel { } 實現一個自定義的返回值處理器：
public class ExcelMethodProcessor implements HandlerMethodReturnValueHandler { @Override public boolean supportsReturnType(MethodParameter returnType) { return (AnnotationUtils.findAnnotation(returnType.getContainingClass(), Excel.class) != null || returnType.getMethodAnnotation(Excel.class) != null); } @Override public void handleReturnValue(Object returnValue, MethodParameter returnType, ModelAndViewContainer mavContainer, NativeWebRequest webRequest) throws Exception { mavContainer.setRequestHandled(true); HttpServletResponse response = webRequest.getNativeResponse(HttpServletResponse.class); HttpServletRequest request = webRequest.getNativeRequest(HttpServletRequest.class); ExcelView view = new ExcelView(); if (returnValue instanceof Map) { view.render( (Map)returnValue, request, response); } else { ModelMap model = new ModelMap(); model.addAttribute("returnValue", returnValue); view.render(model, request, response); } } } 配置文件里面需要把這個bean注入到容器：
<mvc:annotation-driven> <mvc:return-value-handlers> <bean class="com.myspring.web.view.ExcelMethodProcessor"/> </mvc:return-value-handlers> </mvc:annotation-driven> 配置完之后，我們就只需在Controller層加個注解就完事兒了，非常簡潔，代碼如下：
@RequestMapping("/download2") @Excel public List<Student> excel2() { List<Student> list = new ArrayList<>(); Student student = new Student(); student.setId(1); student.setName("Tom"); list.add(student); student = new Student(); student.setId(2); student.setName("Jerry"); list.add(student); return list; } 運行結果：
http://zeng233.github.io/2016/11/02/6.7spring%20MVC%E5%A4%84%E7%90%86Excel%E8%A7%86%E5%9B%BE%E7%9A%84%E4%B8%89%E7%A7%8D%E6%96%B9%E5%BC%8F/
Nowadays, exporting data into different format (Csv, Excel, Pdf ...) is a very general requirement in the most of any project. In this article, we demonstrate how to create an Excel, PDF and CSV views using Spring Boot. When configured properly, a Spring’s view resolver can generate the requested document from model data and send it to the client for downloading. the complete code can be found here.
Spring MVC View Configuration
First thing, We create a WebConfig class, Annotated with @Configuration to mark this class as a configuration file. I'm using contentNegotiatingViewResolver, which tells web controllers to return ModelAndViews or view names and based on various criteria, choose the right data representation strategy.
The highest priority hereby has the file extension which is used if available in the request. Next, the ViewResolver will look for a (definable) request parameter that identifies the view. If that does not help, the ViewResolver uses the Java Activation Framework to determine the Content-Type. If all fails, use the the HTTP Accept header. Of course the steps can be individually disabled. Check out this great article for more details.
In our example, we will be using the URL extension to help determine the media types. Also, we have set the default media type to TEXT_JSON in absence of file extension or when the filetype is unknown.
Also, We need to set theContentNegotiationManager which will be injected by Spring, and different resolvers for each possible output format our application might produce.
Finally, we have created different view resolvers for PDF, XLS and CSV output which we will discuss next.
@Configuration public class WebConfig extends WebMvcConfigurerAdapter { @Override public void configureContentNegotiation(ContentNegotiationConfigurer configurer) { configurer .defaultContentType(MediaType.APPLICATION_JSON) .favorPathExtension(true); } /* * Configure ContentNegotiatingViewResolver */ @Bean public ViewResolver contentNegotiatingViewResolver(ContentNegotiationManager manager) { ContentNegotiatingViewResolver resolver = new ContentNegotiatingViewResolver(); resolver.setContentNegotiationManager(manager); // Define all possible view resolvers List<ViewResolver> resolvers = new ArrayList<>(); resolvers.add(csvViewResolver()); resolvers.add(excelViewResolver()); resolvers.add(pdfViewResolver()); resolver.setViewResolvers(resolvers); return resolver; } /* * Configure View resolver to provide XLS output using Apache POI library to * generate XLS output for an object content */ @Bean public ViewResolver excelViewResolver() { return new ExcelViewResolver(); } /* * Configure View resolver to provide Csv output using Super Csv library to * generate Csv output for an object content */ @Bean public ViewResolver csvViewResolver() { return new CsvViewResolver(); } /* * Configure View resolver to provide Pdf output using iText library to * generate pdf output for an object content */ @Bean public ViewResolver pdfViewResolver() { return new PdfViewResolver(); } } Creating Controller
Nothing much to say here, The Export controller adds some data to the Model which we’ll display on the views.
@Controller public class Export { @Autowired UserService userService; /** * Handle request to download an Excel document */ @RequestMapping(value = "/download", method = RequestMethod.GET) public String download(Model model) { model.addAttribute("users", userService.findAllUsers()); return ""; } } Excel View
There are 2 file formats in which we can create an Excel document. The .xls is the old format, the .xlsx is the new format which is XML based. We are using apache POI to create excel files, when creating .xls documents make sure the org.apache.poi:poi dependency is on the classpath. When working with .xlsx files, you need the org.apache.poi:poi-ooxml dependency.
ExcelView which extends from AbstractXlsView. We create the excel document by overriding the buildExcelDocument, the rest is self explanatory.
public class ExcelView extends AbstractXlsView{
@Override
protected void buildExcelDocument(Map<String, Object> model, Workbook workbook, HttpServletRequest request, HttpServletResponse response) throws Exception { // change the file name response.setHeader("Content-Disposition", "attachment; filename=\"my-xls-file.xls\""); @SuppressWarnings("unchecked") List<User> users = (List<User>) model.get("users"); // create excel xls sheet Sheet sheet = workbook.createSheet("User Detail"); sheet.setDefaultColumnWidth(30); // create style for header cells CellStyle style = workbook.createCellStyle(); Font font = workbook.createFont(); font.setFontName("Arial"); style.setFillForegroundColor(HSSFColor.BLUE.index); style.setFillPattern(FillPatternType.SOLID_FOREGROUND); font.setBold(true); font.setColor(HSSFColor.WHITE.index); style.setFont(font); // create header row Row header = sheet.createRow(0); header.createCell(0).setCellValue("Firstname"); header.getCell(0).setCellStyle(style); header.createCell(1).setCellValue("LastName"); header.getCell(1).setCellStyle(style); header.createCell(2).setCellValue("Age"); header.getCell(2).setCellStyle(style); header.createCell(3).setCellValue("Job Title"); header.getCell(3).setCellStyle(style); header.createCell(4).setCellValue("Company"); header.getCell(4).setCellStyle(style); header.createCell(5).setCellValue("Address"); header.getCell(5).setCellStyle(style); header.createCell(6).setCellValue("City"); header.getCell(6).setCellStyle(style); header.createCell(7).setCellValue("Country"); header.getCell(7).setCellStyle(style); header.createCell(8).setCellValue("Phone Number"); header.getCell(8).setCellStyle(style); int rowCount = 1; for(User user : users){ Row userRow = sheet.createRow(rowCount++); userRow.createCell(0).setCellValue(user.getFirstName()); userRow.createCell(1).setCellValue(user.getLastName()); userRow.createCell(2).setCellValue(user.getAge()); userRow.createCell(3).setCellValue(user.getJobTitle()); userRow.createCell(4).setCellValue(user.getCompany()); userRow.createCell(5).setCellValue(user.getAddress()); userRow.createCell(6).setCellValue(user.getCity()); userRow.createCell(7).setCellValue(user.getCountry()); userRow.createCell(8).setCellValue(user.getPhoneNumber()); } } } Spring also provides 2 other abstract classesAbstractXlsxView and AbstractXlsxStreamingView to create xlsx files. When working with large excel documents it is profitable to use the streaming xlsx view. The streaming view uses less memory and can improve performance of large excel documents.
PDF view
For that we'll use iText library. Spring provides an AbstractPdfView abstract class which can be subclassed to create a helper class for generating PDF documents. However, it has a big drawback which the AbstractPdfView class only supports old API version of iText i.e. it is using the package com.lowagie.*(iText version <= 2.1.7) while the recent iText’s package changes to com.itextpdf.*(iText version >= 5.x)
The old iText version is no longer available nor supported, so subclassing AbstractPdfView class is discouraged. Instead, I recommend to subclass the AbstractView class to create an iText 5.x-compatible version.
public abstract class AbstractPdfView extends AbstractView { public AbstractPdfView() { setContentType("application/pdf"); } @Override protected boolean generatesDownloadContent() { return true; } @Override protected final void renderMergedOutputModel(Map<String, Object> model, HttpServletRequest request, HttpServletResponse response) throws Exception { // IE workaround: write into byte array first. ByteArrayOutputStream baos = createTemporaryOutputStream(); // Apply preferences and build metadata. Document document = new Document(PageSize.A4.rotate(), 36, 36, 54, 36); PdfWriter writer = PdfWriter.getInstance(document, baos); prepareWriter(model, writer, request); buildPdfMetadata(model, document, request); // Build PDF document. document.open(); buildPdfDocument(model, document, writer, request, response); document.close(); // Flush to HTTP response. response.setHeader("Content-Disposition", "attachment"); // make browser to ask for download/display writeToResponse(response, baos); } protected void prepareWriter(Map<String, Object> model, PdfWriter writer, HttpServletRequest request) throws DocumentException { writer.setViewerPreferences(getViewerPreferences()); } protected int getViewerPreferences() { return PdfWriter.ALLOW_PRINTING | PdfWriter.PageLayoutSinglePage; } protected void buildPdfMetadata(Map<String, Object> model, Document document, HttpServletRequest request) { } protected abstract void buildPdfDocument(Map<String, Object> model, Document document, PdfWriter writer, HttpServletRequest request, HttpServletResponse response) throws Exception; } After that, all what we need to do next is create PdfView class and extend from the previously created AbstractPdfView and override the buildPdfDocument(..) method to create our PDF document.
CSV View
For that, we will follow the exact same approach used for PDF generation, which involves creating an abstract view class, a concrete view class and view resolver. I'm using Super CSV to generate csv files.
So, below the code for AbstractCsvView that Subclass the Spring’s AbstractView class:
public abstract class AbstractCsvView extends AbstractView { private static final String CONTENT_TYPE = "text/csv"; private String url; public AbstractCsvView() { setContentType(CONTENT_TYPE); } public void setUrl(String url) { this.url = url; } @Override protected boolean generatesDownloadContent() { return true; } @Override protected final void renderMergedOutputModel( Map<String, Object> model, HttpServletRequest request, HttpServletResponse response) throws Exception { response.setContentType(getContentType()); buildCsvDocument(model, request, response); } protected abstract void buildCsvDocument( Map<String, Object> model, HttpServletRequest request, HttpServletResponse response) throws Exception; } Then, we write an implementation of the AbstractCsvView class and make it implements the buildCsvDocument() method as follows:
public class CsvView extends AbstractCsvView { @Override protected void buildCsvDocument(Map<String, Object> model, HttpServletRequest request, HttpServletResponse response) throws Exception { response.setHeader("Content-Disposition", "attachment; filename=\"my-csv-file.csv\""); List<User> users = (List<User>) model.get("users"); String[] header = {"Firstname","LastName","LastName","JobTitle","Company","Address","City","Country", "PhoneNumber"}; ICsvBeanWriter csvWriter = new CsvBeanWriter(response.getWriter(), CsvPreference.STANDARD_PREFERENCE); csvWriter.writeHeader(header); for(User user : users){ csvWriter.write(user, header); } csvWriter.close(); } } Demo
Run the app, and to download:
- pdf file use: localhost:8080/download.pdf
- XLS file use: localhost:8080/download.xls
- CSV file use: localhost:8080/download.csv
http://xieahui.com/2018/05/30/java/framework/springboot-%E7%94%9F%E6%88%90%E5%90%84%E4%B8%AA%E7%89%88%E6%9C%ACexcel%E5%92%8Cpdf%E4%BB%A5%E5%8F%8A%E9%81%87%E5%88%B0%E7%9A%84%E9%97%AE%E9%A2%98/
ContentNegotiatingViewResolver是 ViewResolver 使用所請求的媒體類型的一個實現(基於文件類型擴展，輸出格式URL參數指定類型或接受報頭)來選擇一個合適的視圖一個請求。ContentNegotiatingViewResolver本身並不解決視圖，只不表示為其他的 ViewResolver，您可以配置來處理特定的視圖(XML，JSON，PDF，XLS，HTML，..)。
這里需要使用到以下技術：
- Spring 4.0.6.RELEASE
- jackson-databind 2.4.1.3
- jackson-annotations 2.4.1
- lowagie itext 4.2.1
- Apache POI 3.10-beta2
- Maven 3
- JDK 1.6
- Tomcat 7.0.54
- Eclipse JUNO Service Release 2
我們現在就開始！
<?xml version="1.0"?> <project xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd" xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"> <modelVersion>4.0.0</modelVersion> <groupId>com.ctolib.springmvc</groupId> <artifactId>ContentNegotiatingViewResolver</artifactId> <packaging>war</packaging> <version>1.0.0</version> <name>Spring4MVCContentNegotiatingViewResolverExample</name> <properties> <springframework.version>4.0.6.RELEASE</springframework.version> </properties> <dependencies> <dependency> <groupId>org.springframework</groupId> <artifactId>spring-core</artifactId> <version>${springframework.version}</version> </dependency> <dependency> <groupId>org.springframework</groupId> <artifactId>spring-web</artifactId> <version>${springframework.version}</version> </dependency> <dependency> <groupId>org.springframework</groupId> <artifactId>spring-webmvc</artifactId> <version>${springframework.version}</version> </dependency> <!-- Needed for XML View (with JAXB2) --> <dependency> <groupId>org.springframework</groupId> <artifactId>spring-oxm</artifactId> <version>${springframework.version}</version> </dependency> <!-- Needed for JSON View --> <dependency> <groupId>com.fasterxml.jackson.core</groupId> <artifactId>jackson-databind</artifactId> <version>2.4.1.3</version> </dependency> <dependency> <groupId>com.fasterxml.jackson.core</groupId> <artifactId>jackson-annotations</artifactId> <version>2.4.1</version> </dependency> <!-- Needed for PDF View --> <dependency> <groupId>com.lowagie</groupId> <artifactId>itext</artifactId> <version>4.2.1</version> </dependency> <!-- Needed for XLS View --> <dependency> <groupId>org.apache.poi</groupId> <artifactId>poi</artifactId> <version>3.10-beta2</version> </dependency> <!-- Servlet dependencies --> <dependency> <groupId>javax.servlet</groupId> <artifactId>javax.servlet-api</artifactId> <version>3.1.0</version> </dependency> <dependency> <groupId>javax.servlet</groupId> <artifactId>jstl</artifactId> <version>1.2</version> </dependency> <dependency> <groupId>javax.servlet.jsp</groupId> <artifactId>javax.servlet.jsp-api</artifactId> <version>2.3.1</version> </dependency> </dependencies> <build> <pluginManagement> <plugins> <plugin> <groupId>org.apache.maven.plugins</groupId> <artifactId>maven-war-plugin</artifactId> <