需求
业务背景是需要某单机程序需要把正在进行的任务导出,然后另一台电脑上单机继续运行,我这里选择的方案是同步SQL形式,并保证ID随机,多个数据库不会重复。
实现
package com.nari.web.controller.demo.controller; import cn.hutool.core.io.FileUtil; import cn.hutool.core.util.StrUtil; import org.springframework.core.io.InputStreamResource; import org.springframework.http.HttpHeaders; import org.springframework.http.MediaType; import org.springframework.http.ResponseEntity; import org.springframework.jdbc.core.JdbcTemplate; import org.springframework.web.bind.annotation.GetMapping; import org.springframework.web.bind.annotation.PathVariable; import org.springframework.web.bind.annotation.RequestMapping; import org.springframework.web.bind.annotation.RestController; import javax.annotation.Resource; import javax.servlet.http.HttpServletResponse; import java.io.*; import java.util.List; import java.util.Map; @RestController @RequestMapping("/download") public class DemoController { @Resource private JdbcTemplate jdbcTemplate; /** * 二进制转成十六进制 * 这里主要是处理图片数据,因为数据库存了图片Base64 */ private String bytesToHexString(byte[] bytes) { StringBuilder hexString = new StringBuilder(); for (byte b : bytes) { String hex = Integer.toHexString(0xff & b); if (hex.length() == 1) { hexString.append('0'); } hexString.append(hex); } return hexString.toString(); } /** * 导出指定表SQL * */ @GetMapping("/table/{tableName}") public void downloadTable(@PathVariable String tableName, HttpServletResponse response) throws IOException { // 查询表数据 List<Map<String, Object>> tableData = jdbcTemplate.queryForList("SELECT * FROM " + tableName); // 查询表结构 List<Map<String, Object>> tableStructure = jdbcTemplate.queryForList("SHOW CREATE TABLE " + tableName); // 拼接SQL插入语句 StringBuilder sqlBuilder = new StringBuilder(); sqlBuilder.append(tableStructure.get(0).get("Create Table")).append(";\n\n"); for (Map<String, Object> row : tableData) { StringBuilder valuesBuilder = new StringBuilder(); StringBuilder columnsBuilder = new StringBuilder(); for (Map.Entry<String, Object> entry : row.entrySet()) { columnsBuilder.append(entry.getKey()).append(", "); if (entry.getValue() instanceof byte[]) { byte[] binaryData = (byte[]) entry.getValue(); String hexString = bytesToHexString(binaryData); valuesBuilder.append("0x").append(hexString).append(", "); } else { valuesBuilder.append("'").append(entry.getValue()).append("', "); } } String columns = columnsBuilder.substring(0, columnsBuilder.length() - 2); String values = valuesBuilder.substring(0, valuesBuilder.length() - 2); sqlBuilder.append("INSERT INTO ").append(tableName).append(" (").append(columns).append(") VALUES (").append(values).append(");\n"); } // 构建响应 response.setHeader(HttpHeaders.CONTENT_DISPOSITION, "attachment; filename=" + tableName+".sql"); response.getWriter().write(sqlBuilder.toString()); } }
结果
能看到这边图片已经正常导出了