Java 如何从 Spring Controller 返回浏览器中的 CSV 数据
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How to Return CSV Data in Browser From Spring Controller
提问by David Williams
Let say I have CSV data in a string and want to return it from a Spring controller. Imagine the data looks like this
假设我有一个字符串中的 CSV 数据，并希望从 Spring 控制器返回它。想象一下数据是这样的
a,b,c
1,2,3
4,5,6
No matter what I have tried, the newlines come out as literally '\n' in the response content, and if I double escape them as in "\n", the response just contains the double backslashes too. In general, how to I return plain text data with newlines in it without the newlines being modified? I know how to return plain text, but still, the content comes with escaped newlines... This is what I current have (using Spring 3.0.5, not by choice)
无论我尝试过什么，换行符都会在响应内容中以字面意义的 '\n' 形式出现，如果我像在“\n”中那样对它们进行双重转义，则响应也只包含双反斜杠。一般来说，如何在不修改换行符的情况下返回带有换行符的纯文本数据？我知道如何返回纯文本，但内容仍然带有转义的换行符......这就是我目前拥有的（使用 Spring 3.0.5，而不是选择）
@RequestMapping(value = "/api/foo.csv")
public ResponseEntity<String> fooAsCSV() {
HttpHeaders responseHeaders = new HttpHeaders();
responseHeaders.add("Content-Type", "text/plain; charset=utf-8");
String data = "a,b,c\n1,2,3\n3,4,5";
return new ResponseEntity<>(data, responseHeaders, HttpStatus.OK);
}
Which produces literally the string
从字面上产生字符串
"a,b,c\n1,2,3\n,3,4,5"
In the browser. How do I make it produce the correct data with new lines in tact as shown above?
在浏览器中。我如何使它产生正确的数据，如上图所示，新行完好无损？
采纳答案by Bart
You could write to the response directly using e.g.
您可以使用例如直接写入响应
@RequestMapping(value = "/api/foo.csv")
public void fooAsCSV(HttpServletResponse response) {
response.setContentType("text/plain; charset=utf-8");
response.getWriter().print("a,b,c\n1,2,3\n3,4,5");
}
Since the return type is voidand HttpServletResponseis declared as a method argument the request is assumed to be completed when this method returns.
由于返回类型是void并且HttpServletResponse被声明为方法参数，因此假定该方法返回时请求已完成。
回答by nickdos
Have you tried @ResponseBodyon your controller method?
你试过@ResponseBody你的控制器方法吗？
@RequestMapping(value = "/api/foo.csv")
@ResponseBody
public String fooAsCSV(HttpServletResponse response) {
response.setContentType("text/plain; charset=utf-8");
String data = "a,b,c\n1,2,3\n3,4,5";
return data;
}
Edit: Spring docs explain it here: http://docs.spring.io/spring/docs/3.0.x/spring-framework-reference/html/mvc.html#mvc-ann-responsebody
编辑：Spring 文档在这里解释：http: //docs.spring.io/spring/docs/3.0.x/spring-framework-reference/html/mvc.html#mvc-ann-responsebody
回答by Abdulhafeth Sartawi
You can use the library supercsv.
您可以使用库supercsv。
<dependency>
<groupId>net.sf.supercsv</groupId>
<artifactId>super-csv</artifactId>
<version>2.1.0</version>
</dependency>
Here is how to use it:
以下是如何使用它：
1- define your model class that you want to write as csv:
1- 定义您要编写为 csv 的模型类：
public class Book {
private String title;
private String description;
private String author;
private String publisher;
private String isbn;
private String publishedDate;
private float price;
public Book() {
}
public Book(String title, String description, String author, String publisher,
String isbn, String publishedDate, float price) {
this.title = title;
this.description = description;
this.author = author;
this.publisher = publisher;
this.isbn = isbn;
this.publishedDate = publishedDate;
this.price = price;
}
// getters and setters...
}
2- Do the following magic:
2- 做以下魔术：
import java.io.IOException;
import java.util.Arrays;
import java.util.List;
import javax.servlet.http.HttpServletResponse;
import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.RequestMapping;
import org.supercsv.io.CsvBeanWriter;
import org.supercsv.io.ICsvBeanWriter;
import org.supercsv.prefs.CsvPreference;
/**
* This Spring controller class implements a CSV file download functionality.
*
*/
@Controller
public class CSVFileDownloadController {
@RequestMapping(value = "/downloadCSV")
public void downloadCSV(HttpServletResponse response) throws IOException {
String csvFileName = "books.csv";
response.setContentType("text/csv");
// creates mock data
String headerKey = "Content-Disposition";
String headerValue = String.format("attachment; filename=\"%s\"",
csvFileName);
response.setHeader(headerKey, headerValue);
Book book1 = new Book("Effective Java", "Java Best Practices",
"Joshua Bloch", "Addision-Wesley", "0321356683", "05/08/2008",
38);
Book book2 = new Book("Head First Java", "Java for Beginners",
"Kathy Sierra & Bert Bates", "O'Reilly Media", "0321356683",
"02/09/2005", 30);
Book book3 = new Book("Thinking in Java", "Java Core In-depth",
"Bruce Eckel", "Prentice Hall", "0131872486", "02/26/2006", 45);
Book book4 = new Book("Java Generics and Collections",
"Comprehensive guide to generics and collections",
"Naftalin & Philip Wadler", "O'Reilly Media", "0596527756",
"10/24/2006", 27);
List<Book> listBooks = Arrays.asList(book1, book2, book3, book4);
// uses the Super CSV API to generate CSV data from the model data
ICsvBeanWriter csvWriter = new CsvBeanWriter(response.getWriter(),
CsvPreference.STANDARD_PREFERENCE);
String[] header = { "Title", "Description", "Author", "Publisher",
"isbn", "PublishedDate", "Price" };
csvWriter.writeHeader(header);
for (Book aBook : listBooks) {
csvWriter.write(aBook, header);
}
csvWriter.close();
}
}
