[Java] Source Builder

 

외부에 있는 json 파일을 읽어서
특정 위치의 특정 값만 바꾸어 값을 넘겨주는 작업이 필요해짐에 따라
아래 내용을 수행했다.

 

먼저, FileUtils 자바 파일을 생성하여 파일을 읽어오거나 삭제할 수 있는 메소드를 작성한다.

import java.io.BufferedReader;
import java.io.BufferedWriter;
import java.io.File;
import java.io.FileWriter;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.Reader;
import java.nio.charset.Charset;
import java.nio.charset.StandardCharsets;
import java.nio.file.Files;
import java.nio.file.Path;
import java.nio.file.Paths;
import org.apache.logging.log4j.LogManager;
import org.apache.logging.log4j.Logger;
import org.springframework.core.io.ClassPathResource;

public class FileUtils {
  private static final Logger log = LogManager.getLogger(FileUtils.class);

  private FileUtils() {
  }

  public static String randomFilename() {
    return String.format("rnd_%d", System.nanoTime());
  }

  public static boolean exists(String filepath) {
    File f = new File(filepath);
    return f.isFile();
  }

  public static boolean saveStringToFile(String str, String filepath) {
    BufferedWriter writer = null;

    try {
      writer = new BufferedWriter(new FileWriter(filepath));
      writer.write(str);
    } catch (IOException var12) {
      log.error("", var12);
    } finally {
      try {
        if (writer != null) {
          writer.close();
        }
      } catch (IOException var11) {
        log.info(var11);
      }

    }

    return true;
  }
  
  public static String readfile(String filepath) {
    Path path = Paths.get(filepath);

    try {
      return new String(Files.readAllBytes(path));
    } catch (IOException var3) {
      log.error("", var3);
      return null;
    }
  }

  public static String readResource(String resourceName) {
    ClassPathResource resource = new ClassPathResource(resourceName);

    try {
      StringBuilder textBuilder = new StringBuilder();
      Reader reader = new BufferedReader(new InputStreamReader(resource.getInputStream(), Charset.forName(StandardCharsets.UTF_8.name())));
      Throwable var4 = null;

      try {
        boolean var5 = false;

        int c;
        while((c = reader.read()) != -1) {
          textBuilder.append((char)c);
        }
      } catch (Throwable var14) {
        var4 = var14;
        throw var14;
      } finally {
        if (reader != null) {
          if (var4 != null) {
            try {
              reader.close();
            } catch (Throwable var13) {
              var4.addSuppressed(var13);
            }
          } else {
            reader.close();
          }
        }

      }

      return textBuilder.toString();
    } catch (IOException var16) {
      log.error("", var16);
      return null;
    }
  }
  
  public static boolean deleteFile(String filepath) {
    File file = new File(filepath);
    return file.delete();
  }

  public static boolean mkdir(String path) {
    File file = new File(path);
    return file.mkdirs();
  }

  public static boolean rmdir(String path) {
    File filePath = new File(path);
    File[] allContents = filePath.listFiles();
    if (allContents != null) {
      File[] var3 = allContents;
      int var4 = allContents.length;

      for(int var5 = 0; var5 < var4; ++var5) {
        File file = var3[var5];
        rmdir(file.toString());
      }
    }

    return filePath.delete();
  }
}

필요한 json 파일을 resources 디렉터리 안에 생성해준다.

{
  "coreThing" : {
    "caPath" : "root.ca.pem",
    "certPath" : "{{CERT_ID}}.cert.pem",
    "keyPath" : "{{CERT_ID}}.private.key",
    "thingArn" : "{{IOT_ARN}}:thing/{{CORE_NAME}}",
    "iotHost" : "{{ENDPOINT}}",
    "ggHost" : "greengrass-ats.iot.ap-northeast-2.amazonaws.com",
    "keepAlive" : 600
  },
  "runtime" : {
    "cgroup" : {
      "useSystemd" : "yes"
    }
  },
  "managedRespawn" : false,
  "crypto" : {
    "principals" : {
      "SecretsManager" : {
        "privateKeyPath" : "file:///greengrass/certs/{{CERT_ID}}.private.key"
      },
      "IoTCertificate" : {
        "privateKeyPath" : "file:///greengrass/certs/{{CERT_ID}}.private.key",
        "certificatePath" : "file:///greengrass/certs/{{CERT_ID}}.cert.pem"
      }
    },
    "caPath" : "file:///greengrass/certs/root.ca.pem"
  }
}

특정 부분의 값을 대체한 후 리턴해주는 메소드를 생성해준다.

public class GreengrassSourceBuilder {

  public String makeCorePolicyDocument(String iotArn, String groupId, String coreName) {
    String document = FileUtils.readResource("json/core-policy.json");

    document = document.replace("{{IOT_ARN}}", iotArn);
    document = document.replace("{{GROUP_ID}}", groupId);
    document = document.replace("{{CORE_NAME}}", coreName);

    return document;
  }

  public String makeDevicePolicyDocument(String iotArn, String groupId, String deviceName) {
    String document = FileUtils.readResource("json/core-policy.json");

    document = document.replace("{{IOT_ARN}}", iotArn);
    document = document.replace("{{GROUP_ID}}", groupId);
    document = document.replace("{{DEVICE_NAME}}", deviceName);

    return document;
  }

  public String makeCoreConfigFile(String endpoint, String iotArn, String certId, String coreName) {
    String document = FileUtils.readResource("json/core-config.json");

    document = document.replace("{{ENDPOINT}}", endpoint);
    document = document.replace("{{IOT_ARN}}", iotArn);
    document = document.replace("{{CERT_ID}}", certId);
    document = document.replace("{{CORE_NAME}}", coreName);

    return document;
  }

}