Java 使用Json导入数据、数据导出Json文件

简介

通过json格式的文件导入一条数据记录，或导出一条记录的Json内容。

Maven

只列出主要依赖

		<dependency>
			<groupId>commons-io</groupId>
			<artifactId>commons-io</artifactId>
			<version>2.8.0</version>
		</dependency>
		<dependency>
			<groupId>com.alibaba</groupId>
			<artifactId>fastjson</artifactId>
			<version>1.2.70</version>
		</dependency>

JsonUtil 工具类

package com.levi.uitls;

import com.alibaba.fastjson.JSON;
import com.alibaba.fastjson.serializer.SerializerFeature;
import org.apache.commons.io.FileUtils;
import org.springframework.web.multipart.MultipartFile;

import javax.servlet.http.HttpServletResponse;
import java.io.*;
import java.net.URLEncoder;
import java.nio.charset.StandardCharsets;
import java.util.HashMap;
import java.util.Map;

/**
 * Json export or import.
 *
 * @author levi
 * @version 1.0
 **/
public class JsonUtil {

    /**
     * readJson.
     * @param multipartFile multipartFile
     * @return obj
     */
    public static Map<String, String> readJson(MultipartFile multipartFile) {
        Map<String, String> result = new HashMap<>();
        try {
            String fileName = multipartFile.getOriginalFilename();
            String suffixName = fileName.substring(fileName.lastIndexOf("."));
            //MultipartFile to string
            File file = new File("/" + fileName);
            FileUtils.copyInputStreamToFile(multipartFile.getInputStream(), file);
            String jsonString = FileUtils.readFileToString(file, "UTF-8");

            if (".json".equals(suffixName) || ".txt".equals(suffixName)) {
                result.put("result", jsonString);
                result.put("code", "200");
                result.put("message", "上传成功！");
            } else {
                result.put("result", "");
                result.put("code", "500");
                result.put("message", "请上传正确格式的.json或.txt文件！");
            }
        } catch (Exception e) {
            e.printStackTrace();
            result.put("result", "");
            result.put("code", "500");
            result.put("message", e.getMessage());
        }
        return result;
    }

    /**
     * exportJson.
     * @param response response
     * @param obj obj
     * @param fileName fileName
     */
    public static void exportJson(HttpServletResponse response, Object obj, String fileName){
        try {
            String jsonString = JSON.toJSONString(obj,
                    SerializerFeature.PrettyFormat,
                    SerializerFeature.WriteMapNullValue,
                    SerializerFeature.WriteDateUseDateFormat);

            String fullPath = "/" + fileName;
            File file = new File(fullPath);

            Writer write = new OutputStreamWriter(new FileOutputStream(file), StandardCharsets.UTF_8);
            write.write(jsonString);
            write.flush();
            write.close();

            FileInputStream fis = new FileInputStream(file);
            // force-download
            response.setContentType("application/force-download");
            response.setHeader("Content-Disposition", "attachment;filename="
                    .concat(String.valueOf(URLEncoder.encode(fileName, "UTF-8"))));
            response.setCharacterEncoding("utf-8");

            OutputStream os = response.getOutputStream();
            byte[] buf = new byte[1024];
            int len = 0;
            while((len = fis.read(buf)) != -1) {
                os.write(buf, 0, len);
            }
            fis.close();
            os.close();

        } catch (Exception e) {
            e.printStackTrace();
        }
    }

}

接口层使用

@RestController
@RequestMapping("/api/test")
public class TestController {

        @Autowired
	private IUserService userService;

	/**
	 * 使用Json导出
	 * @param response response
	 * @param id id
	 */
	@GetMapping(value = "/export")
	public void exportJson(HttpServletResponse response,
				@RequestParam(name="id",required=false)String id,
				@RequestParam(name="name",required=false)String name) {
		final User user = userService.getById(id); //根据具体业务定义
		if (null == user) {
			throw new AppException("未找到实体！");
		}
		//导出
		JsonUtil.exportJson(response, user, name  + "-" + UUIDUitl.getUUID8() + ".json");
	}

	/**
	 * 使用Json导入
	 * @param multipartFile multipartFile
	 * @return Object
	 */
	@PostMapping(value = "/import")
	public Object importJson(MultipartFile multipartFile) {
		final Map<String, String> result = JsonUtil.readJson(multipartFile);
		if ("200".equals(result.get("code"))) {
			final String jsonString = result.get("result");
			final User user = JSON.parseObject(jsonString, User.class);
			//导入
			userService.save(user);
		}
		return result;
	}

}