Background:

At work, we may encounter situations where we need to quickly move some data in one environment to another environment. At this time, we This can be achieved by importing and exporting json files.

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Example:

We export the user information in the database of this environment into a json format file , and then directly copy the json file to another environment and import it into the database, this can achieve our purpose.

Below I will use springboot to build an import and export case of user data information, and implement the import and export functions of single-user and multi-user database information. After reading this article carefully, you will definitely be able to master the core of importing and exporting json files

Preparation work

Requires maven dependency coordinates:

        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-actuator</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-thymeleaf</artifactId>
        </dependency>
        <dependency>
            <groupId>org.projectlombok</groupId>
            <artifactId>lombok</artifactId>
            <optional>true</optional>
        </dependency>
        <dependency>
            <groupId>org.mybatis.spring.boot</groupId>
            <artifactId>mybatis-spring-boot-starter</artifactId>
            <version>2.1.0</version>
        </dependency>
        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
            <version>8.0.18</version>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-jdbc</artifactId>
        </dependency>
        <dependency>
            <groupId>com.alibaba</groupId>
            <artifactId>fastjson</artifactId>
            <version>1.2.29</version>
        </dependency>
        <dependency>
            <groupId>org.codehaus.jackson</groupId>
            <artifactId>jackson-mapper-asl</artifactId>
            <version>1.9.13</version>
        </dependency>

User information in the database:

These field information corresponds one-to-one with the UserEntity entity class in Java

Function implementation

Prepare dependencies and database information After that, we started to build a specific framework for user import and export:

Import and export single-user and multi-user functions to implement UserUtil

package com.leige.test.util;

import com.alibaba.fastjson.JSON;
import com.alibaba.fastjson.JSONObject;
import com.alibaba.fastjson.serializer.SerializerFeature;
import com.leige.test.entity.UserEntity;
import com.leige.test.entity.UserEntityList;
import com.leige.test.model.ResultModel;
import com.leige.test.service.UserService;
import org.apache.commons.io.FileUtils;
import org.codehaus.jackson.map.ObjectMapper;
import org.springframework.util.ObjectUtils;
import org.springframework.web.multipart.MultipartFile;

import javax.servlet.http.HttpServletResponse;
import java.io.*;
import java.net.URLEncoder;
import java.util.List;
import java.util.UUID;

public class UserUtil {
    //導(dǎo)入用戶
    public static ResultModel importUser(MultipartFile multipartFile, UserService userService) {
        ResultModel resultModel = new ResultModel();
        try {
            // 獲取原始名字
            String fileName = multipartFile.getOriginalFilename();
            // 獲取后綴名
            String suffixName = fileName.substring(fileName.lastIndexOf("."));
            //先將.json文件轉(zhuǎn)為字符串類型
            File file = new File("/"+ fileName);
            //將MultipartFile類型轉(zhuǎn)換為File類型
            FileUtils.copyInputStreamToFile(multipartFile.getInputStream(),file);
            String jsonString = FileUtils.readFileToString(file, "UTF-8");

            //如果是json或者txt文件
            if (".json".equals(suffixName) || ".txt".equals(suffixName)) {

                //再將json字符串轉(zhuǎn)為實(shí)體類
                JSONObject jsonObject = JSONObject.parseObject(jsonString);

                UserEntity userEntity = JSONObject.toJavaObject(jsonObject, UserEntity.class);

                userEntity.setId(null);
                userEntity.setToken(UUID.randomUUID().toString());
                //調(diào)用創(chuàng)建用戶的接口
                userService.addUser(userEntity);

            } else {
                resultModel.setStatusCode(0);
                resultModel.setStatusMes("請(qǐng)上傳正確格式的.json或.txt文件！");
            }
        } catch (Exception e) {
            e.printStackTrace();
        }
        return resultModel;
    }
    //批量導(dǎo)入用戶
    public static ResultModel importUsers(MultipartFile multipartFile, UserService userService) {
        ResultModel resultModel = new ResultModel();
        try {
            // 獲取原始名字
            String fileName = multipartFile.getOriginalFilename();
            // 獲取后綴名
            String suffixName = fileName.substring(fileName.lastIndexOf("."));
            //先將.json文件轉(zhuǎn)為字符串類型
            File file = new File("/"+ fileName);
            //將MultipartFile類型轉(zhuǎn)換為File類型
            FileUtils.copyInputStreamToFile(multipartFile.getInputStream(),file);
            String jsonString = FileUtils.readFileToString(file, "UTF-8");

            //如果是json或者txt文件
            if (".json".equals(suffixName) || ".txt".equals(suffixName)) {

                //再將json字符串轉(zhuǎn)為實(shí)體類
                JSONObject jsonObject = JSONObject.parseObject(jsonString);

                UserEntityList userEntityList = JSONObject.toJavaObject(jsonObject, UserEntityList.class);

                List<UserEntity> userEntities = userEntityList.getUserEntities();
                for (UserEntity userEntity : userEntities) {
                    userEntity.setId(null);
                    userEntity.setToken(UUID.randomUUID().toString());
                    //調(diào)用創(chuàng)建用戶的接口
                    userService.addUser(userEntity);
                }
            } else {
                resultModel.setStatusCode(0);
                resultModel.setStatusMes("請(qǐng)上傳正確格式的.json或.txt文件！");
            }
        } catch (Exception e) {
            e.printStackTrace();
        }
        return resultModel;
    }
    //導(dǎo)出某個(gè)用戶
    public static ResultModel exportUser(HttpServletResponse response, UserEntity userEntity, String fileName){
        ResultModel resultModel = new ResultModel();
        ObjectMapper objectMapper = new ObjectMapper();
        if (ObjectUtils.isEmpty(userEntity)){
            resultModel.setStatusCode(0);
            resultModel.setStatusMes("此用戶id沒有對(duì)應(yīng)的用戶");
            return resultModel;
        }else {
            try {
                String jsonString = objectMapper.writeValueAsString(userEntity);

                // 拼接文件完整路徑// 生成json格式文件
                String fullPath = "/" + fileName;

                // 保證創(chuàng)建一個(gè)新文件
                File file = new File(fullPath);
                if (!file.getParentFile().exists()) { // 如果父目錄不存在，創(chuàng)建父目錄
                    file.getParentFile().mkdirs();
                }
                if (file.exists()) { // 如果已存在,刪除舊文件
                    file.delete();
                }
                file.createNewFile();//創(chuàng)建新文件

                //將字符串格式化為json格式
                jsonString = jsonFormat(jsonString);
                // 將格式化后的字符串寫入文件
                Writer write = new OutputStreamWriter(new FileOutputStream(file), "UTF-8");
                write.write(jsonString);
                write.flush();
                write.close();

                FileInputStream fis = new FileInputStream(file);
                // 設(shè)置相關(guān)格式
                response.setContentType("application/force-download");
                // 設(shè)置下載后的文件名以及header
                response.setHeader("Content-Disposition", "attachment;filename="
                        .concat(String.valueOf(URLEncoder.encode(fileName, "UTF-8"))));
                response.setCharacterEncoding("utf-8");
                // 創(chuàng)建輸出對(duì)象
                OutputStream os = response.getOutputStream();
                // 常規(guī)操作
                byte[] buf = new byte[1024];
                int len = 0;
                while((len = fis.read(buf)) != -1) {
                    os.write(buf, 0, len);
                }
                fis.close();
                os.close();  //一定要記得關(guān)閉輸出流，不然會(huì)繼續(xù)寫入返回實(shí)體模型
                return resultModel;
            } catch (Exception e) {
                resultModel.setStatusCode(0);
                resultModel.setStatusMes(e.getMessage());
                e.printStackTrace();
                return resultModel;
            }
        }
    }
    //導(dǎo)出所有用戶
    public static ResultModel exportAllUser(HttpServletResponse response, UserEntityList userEntityList, String fileName){
        ResultModel resultModel = new ResultModel();
        ObjectMapper objectMapper = new ObjectMapper();
        if (ObjectUtils.isEmpty(userEntityList)){
            resultModel.setStatusCode(0);
            resultModel.setStatusMes("此用戶id沒有對(duì)應(yīng)的用戶");
            return resultModel;
        }else {
            try {
                String jsonString = objectMapper.writeValueAsString(userEntityList);

                // 拼接文件完整路徑// 生成json格式文件
                String fullPath = "/" + fileName;

                // 保證創(chuàng)建一個(gè)新文件
                File file = new File(fullPath);
                if (!file.getParentFile().exists()) { // 如果父目錄不存在，創(chuàng)建父目錄
                    file.getParentFile().mkdirs();
                }
                if (file.exists()) { // 如果已存在,刪除舊文件
                    file.delete();
                }
                file.createNewFile();//創(chuàng)建新文件

                //將字符串格式化為json格式
                jsonString = jsonFormat(jsonString);
                // 將格式化后的字符串寫入文件
                Writer write = new OutputStreamWriter(new FileOutputStream(file), "UTF-8");
                write.write(jsonString);
                write.flush();
                write.close();

                FileInputStream fis = new FileInputStream(file);
                // 設(shè)置相關(guān)格式
                response.setContentType("application/force-download");
                // 設(shè)置下載后的文件名以及header
                response.setHeader("Content-Disposition", "attachment;filename="
                        .concat(String.valueOf(URLEncoder.encode(fileName, "UTF-8"))));
                response.setCharacterEncoding("utf-8");
                // 創(chuàng)建輸出對(duì)象
                OutputStream os = response.getOutputStream();
                // 常規(guī)操作
                byte[] buf = new byte[1024];
                int len = 0;
                while((len = fis.read(buf)) != -1) {
                    os.write(buf, 0, len);
                }
                fis.close();
                os.close();     //一定要記得關(guān)閉輸出流，不然會(huì)繼續(xù)寫入返回實(shí)體模型
                return resultModel;
            } catch (Exception e) {
                resultModel.setStatusCode(0);
                resultModel.setStatusMes(e.getMessage());
                e.printStackTrace();
                return resultModel;
            }
        }
    }
    //將字符串格式化為json格式的字符串
    public static String jsonFormat(String jsonString) {
        JSONObject object= JSONObject.parseObject(jsonString);
        jsonString = JSON.toJSONString(object, SerializerFeature.PrettyFormat, SerializerFeature.WriteMapNullValue, SerializerFeature.WriteDateUseDateFormat);
        return jsonString;
    }
}

1. Start the project and enter in the browser Visit http://localhost:8888/export/users to export all existing user json files

##2. Open the json file to check whether the format is correct

3. Enter the browser to access http://localhost:8888/ to import users in batches

Import users.json file

Enter the address and click Submit

Check the database and find that the two added test users 1 and 2 were successful!

Import and export of a single user will not be tested here, it is simpler, and other information about the springboot configuration file and the database information corresponding to the entity class will not be explained in detail.

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