使用Java写入文件并将文件上传到Amazon S3时出现多个问题

Question

while playing around with writing text to file and then uploading it to AmazonS3 bucket I encountered these problems:

• text is written to file and when opening it I can see it
• file is uploaded to S3 bucket but doesObjectExist()method returns false
• the uploaded file is empty

Below is my test code:

import java.io.BufferedWriter;
import java.io.File;
import java.io.FileWriter;
import java.io.IOException;
import java.io.PrintWriter;

import com.amazonaws.AmazonServiceException;
import com.amazonaws.auth.AWSStaticCredentialsProvider;
import com.amazonaws.auth.BasicAWSCredentials;
import com.amazonaws.services.s3.AmazonS3;
import com.amazonaws.services.s3.AmazonS3ClientBuilder;

public class Main {

public static void main(String[] args) { 

    File test;
    File log;
    String [] messages = {"one", "two", "three"};
    PrintWriter testOut = null;
    PrintWriter logOut = null;

    test = new File(System.getProperty("user.home") + File.separator + "Desktop" + File.separator + "test.txt");
    log = new File(System.getProperty("user.home") + File.separator + "Desktop" + File.separator + "log.txt");

    try {
        testOut = new PrintWriter(new BufferedWriter(new FileWriter(test)));
        logOut = new PrintWriter(new BufferedWriter(new FileWriter(log)));
        for(int i = 0; i < messages.length; i++) {
            testOut.write(messages[i]);
            logOut.write("Writing message: " + messages[i] + " to test file.");
            testOut.write(System.lineSeparator());
            logOut.write(System.lineSeparator());
        }
    } catch (IOException e) {
        // TODO Auto-generated catch block
        e.printStackTrace();            
    } 

    BasicAWSCredentials credentials = new BasicAWSCredentials("ACCESS_KEY_ID", "SECRET_ACCESS_KEY");
    AWSStaticCredentialsProvider credentialsProvider = new AWSStaticCredentialsProvider(credentials);
    AmazonS3 s3Client = AmazonS3ClientBuilder.standard().withCredentials(credentialsProvider).withRegion("eu-west-1").build();
    try {
        s3Client.putObject("test", "test/test.txt", test);
    } catch (AmazonServiceException e) {
        System.err.println(e.getErrorMessage());
        System.exit(1);
    }


    logOut.write("Uploading test.txt to test");
    logOut.write(System.lineSeparator());
    boolean b1 = s3Client.doesObjectExist("test", "test.txt");
    logOut.write("File test.txt uploaded to test: " + b1);
    logOut.write(System.lineSeparator());

    testOut.flush();
    testOut.close();
    logOut.write("Closing testOut PrintWriter");
    logOut.write(System.lineSeparator());
    logOut.flush();
    logOut.close();
}
}

Can anyone help?

Answer 1

Looks like you're flushing and closing testOut after you upload it. You should move those 2 commands before the upload.