Java CSV导出
1.Maven依赖
//用的是javacsv开源工具
<dependency>
<groupId>net.sourceforge.javacsvgroupId>
<artifactId>javacsvartifactId>
<version>2.0version>
dependency>
<dependency>
<groupId>commons-collectionsgroupId>
<artifactId>commons-collectionsartifactId>
<version>3.2.2version>
dependency>
<dependency>
<groupId>commons-langgroupId>
<artifactId>commons-langartifactId>
<version>2.6version>
dependency>
2.工具类
import com.csvreader.CsvWriter;
import org.apache.commons.collections.CollectionUtils;
import javax.servlet.http.HttpServletResponse;
import java.io.File;
import java.io.IOException;
import java.nio.charset.Charset;
import java.util.*;
/**
* Created by John on 2017/12/30.
*/
public class CsvUtil {
public static void main(String[] args) {
String filePath = "D://study.csv";
CsvWriter csvWriter = new CsvWriter(filePath, ',', Charset.forName("GBK"));
// 写表头
String[] headers = {"编号", "姓名", "年龄"};
String[] content = {"12365", "张山", "34"};
try {
csvWriter.writeRecord(headers);
csvWriter.writeRecord(content);
} catch (IOException e) {
e.printStackTrace();
}
csvWriter.close();
}
/**
* 导出.csv文件在浏览器端下载(可选择保存路径)
*
* @param fileName 文件名
* @param columnKeyMap 列名-属性,这里用LinkedHashMap是为了保证导出去的Excel列名顺序不会乱
* @param dataList 数据源
* @param response HttpServletResponse
*/
public static void writeData(String fileName, LinkedHashMap columnKeyMap, List> dataList, HttpServletResponse response) {
if (Objects.isNull(columnKeyMap) || columnKeyMap.isEmpty()) {
throw new RuntimeException("Excel没有设置列名和对应的属性!");
}
if (CollectionUtils.isNotEmpty(dataList)) {
//写入临时文件
File tempFile = null;
List recordData = null;
try {
tempFile = File.createTempFile(fileName, ".csv");
// 创建CSV写对象
CsvWriter csvWriter = new CsvWriter(tempFile.getCanonicalPath(), ',', Charset.forName("UTF-8"));
// 写入表头
csvWriter.writeRecord(columnKeyMap.values().toArray(new String[columnKeyMap.values().size()]));
//第一种写入方式
/*for (Map data:dataList) {
for (String key:columnKeyMap.keySet()){
csvWriter.write(Objects.isNull(data.get(key)) ? "":data.get(key).toString());
}
csvWriter.endRecord();
}*/
//第二种写入方式
for (Map data : dataList) {
//先将每一行record的数据准备好,封装成一个String[]
recordData = new ArrayList<>(data.size());
for (String key : columnKeyMap.keySet()) {
recordData.add(Objects.isNull(data.get(key)) ? "" : data.get(key).toString());
}
csvWriter.writeRecord(recordData.toArray(new String[recordData.size()]));
}
csvWriter.close();
/**
* 写入csv结束，写出流,设置响应头直接在浏览器端下载
* 因为csvWriter不提供类似Poi的写入流workbook.write(out);
* 故在csv写入数据完之后,要手动把文件写入流；
*/
response.reset();
response.setContentType("application/csv");
response.setHeader("content-disposition", "attachment; filename=" + fileName + ".csv");
File fileLoad = new File(tempFile.getCanonicalPath());
String fileLength = String.valueOf(fileLoad.length());
response.setHeader("Content_Length", fileLength);
java.io.FileInputStream in = new java.io.FileInputStream(fileLoad);
java.io.OutputStream out = response.getOutputStream();
int eof;
byte[] b = new byte[2048];
while ((eof = in.read(b)) != -1) {
out.write(b, 0, eof); //每次写入out 2048字节
}
in.close();
out.close();
//下载完成,删除临时文件
tempFile.delete();
} catch (IOException e) {
e.printStackTrace();
}
}
}
/**
* 除了可以查询出所有要的数据一次性导出外,
* 还可以边查边导,循环写入,只不过这种方式没法做到通用性,
* 对于数据量特别大的可以考虑
*/
public static void batchWriteData(String fileName, LinkedHashMap columnKeyMap, HttpServletResponse response) {
if (Objects.isNull(columnKeyMap) || columnKeyMap.isEmpty()) {
throw new RuntimeException("Excel没有设置列名和对应的属性!");
}
//伪代码
int totalRows = studentService.countAll(param);
if (totalRows > 0) {
//写入临时文件
File tempFile = null;
List recordData = null;
try {
tempFile = File.createTempFile(fileName, ".csv");
// 创建CSV写对象
CsvWriter csvWriter = new CsvWriter(tempFile.getCanonicalPath(), ',', Charset.forName("UTF-8"));
// 写入表头
csvWriter.writeRecord(columnKeyMap.values().toArray(new String[columnKeyMap.values().size()]));
int loop = 0;
int limit = 2000;//每次循环写入2000条数据
while (totalRows > 0){
int startRow = loop * limit;
Map pageParam = new HashMap<>();
pageParam.put("startRow",startRow);
pageParam.put("pageSize",limit);
List list = studentService.pageQuery(pageParam);
/**
* 这里可以把list中的POJO转换成Map,因为我们并不总是需要所有属性,
* 还有可以需要对属性值做一些转换,如时间,金钱格式的转换,或者枚举价值的中文描述
*/
List> dataMap = studentService.listToMap(list);
for (Map data:dataMap){
//先将每一行record的数据准备好,封装成一个String[]
recordData = new ArrayList<>(data.size());
for (String key : columnKeyMap.keySet()) {
recordData.add(Objects.isNull(data.get(key)) ? "" : data.get(key).toString());
}
csvWriter.writeRecord(recordData.toArray(new String[recordData.size()]));
}
loop++;
totalRows = totalRows - limit;
}
csvWriter.close();
/**
* 写入csv结束，写出流,设置响应头直接在浏览器端下载
* 因为csvWriter不提供类似Poi的写入流workbook.write(out);
* 故在csv写入数据完之后,要手动把文件写入流；
*/
response.reset();
response.setContentType("application/csv");
response.setHeader("content-disposition", "attachment; filename=" + fileName + ".csv");
File fileLoad = new File(tempFile.getCanonicalPath());
String fileLength = String.valueOf(fileLoad.length());
response.setHeader("Content_Length", fileLength);
java.io.FileInputStream in = new java.io.FileInputStream(fileLoad);
java.io.OutputStream out = response.getOutputStream();
int eof;
byte[] b = new byte[2048];
while ((eof = in.read(b)) != -1) {
out.write(b, 0, eof); //每次写入out 2048字节
}
in.close();
out.close();
//下载完成,删除临时文件
tempFile.delete();
} catch (IOException e) {
e.printStackTrace();
}
}
}
}
3.使用示例
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.EnableAutoConfiguration;
import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.ResponseBody;
import javax.servlet.http.HttpServletResponse;
import java.util.*;
/**
* Created by John on 2017/12/30.
*/
@Controller
@EnableAutoConfiguration
public class SampleController {
@RequestMapping("/")
@ResponseBody
String home() {
return "Hello World!";
}
@RequestMapping("/csv")
public void csv(HttpServletResponse response){
// 创建CSV写对象
List> ls=new ArrayList<>();
/*for (int i = 0; i <10000; i++) {
Student s=new Student();
s.setName("小帅"+i);
s.setAge(i);
s.setScore("100"+i);
s.setSex("男"+i);
ls.add(s);
}*/
Map map = null;
for (int i=0;i<100000;i++){
map = new HashMap<>();
map.put("name","你妹" + i);
map.put("age",i);
map.put("score",i);
map.put("sex","男");
ls.add(map);
}
String fileName = "vehicle";
LinkedHashMap keyMap = new LinkedHashMap<>();
keyMap.put("name","姓名");
keyMap.put("age","年龄");
keyMap.put("score","编号");
keyMap.put("sex","性别");
long start = System.currentTimeMillis();
CsvUtil.writeData(fileName,keyMap,ls,response);
System.out.println("耗时:" + (System.currentTimeMillis() - start) + "ms");
}
public static void main(String[] args) throws Exception {
SpringApplication.run(SampleController.class, args);
}
}