[英]How to return JSON data from spring Controller using @ResponseBody
[英]How to Return CSV Data in Browser From Spring Controller
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
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);
}
从字面上产生字符串
"a,b,c\n1,2,3\n,3,4,5"
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?
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");
}
由于返回类型为void
并且HttpServletResponse
被声明为方法参数,因此当此方法返回时,假定请求已完成。
您可以使用库supercsv 。
<dependency>
<groupId>net.sf.supercsv</groupId>
<artifactId>super-csv</artifactId>
<version>2.1.0</version>
</dependency>
以下是如何使用它:
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- 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();
}
}
您是否在控制器方法上尝试过@ResponseBody
?
@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;
}
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
这是巴特回答的更详细示例:
@GetMapping(value = "csv")
public void exportCsv(HttpServletResponse response) {
try {
// prepare response encoding and Headers
response.setContentType("text/csv");
response.setCharacterEncoding(StandardCharsets.UTF_8.name());
response.setHeader("Content-Disposition", "attachment; filename=a.csv"); // specify the real file name users will get when download
try (Writer writer = new OutputStreamWriter(response.getOutputStream(), StandardCharsets.UTF_8)) {
// writer.write('\uFEFF'); // BOM is essential in some scenary
writer.write("key,value\n");
List<Row> row = rowService.getAll();
for (Column column : row) {
writer.write(String.format("%d,%s)\n",column.getKey(), column.getValue()));
}
writer.flush(); // DONNOT forget to flush writer after everything done
} // writer will be closed automatically
} catch (IOException e) {
log.error("failed to export csv", e);
}
}
我最近有一个类似的任务。 使用ResponseEntity<byte[]>和响应头Content-Disposition 。 像这样:
@RequestMapping(value = "/api/foo.csv")
public ResponseEntity<byte[]> fooAsCSV() {
HttpHeaders responseHeaders = new HttpHeaders();
responseHeaders.add("Content-Type", "application/vnd.ms-excel");
responseHeaders.add("Content-Disposition", "attachment; filename=abc.csv");
String data = "a,b,c\n1,2,3\n3,4,5";
return new ResponseEntity<>(data.getBytes("ISO8859-15"), responseHeaders, HttpStatus.OK);
}
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