Java –インターネットからファイルをダウンロードする方法
この記事では、次の方法を使用してURLからファイルをダウンロードする方法を示します。
-
Apache Commons IO
-
Java NIO
1. Apache Commons IO
1.1 This is still my prefer way to download a file from the Internet, simple and clean. 署名を読む：
org.apache.commons.io.FileUtils
//int = number of milliseconds
public static void copyURLToFile(URL source, File destination,
int connectionTimeout, int readTimeout) throws IOException
1.2 Full example.
HttpUtils.java
package com.example;
import org.apache.commons.io.FileUtils;
import java.io.File;
import java.io.IOException;
import java.net.URL;
public class HttpUtils {
public static void main(String[] args) {
String fromFile = "ftp://ftp.arin.net/pub/stats/arin/delegated-arin-extended-latest";
String toFile = "F:\\arin.txt";
try {
//connectionTimeout, readTimeout = 10 seconds
FileUtils.copyURLToFile(new URL(fromFile), new File(toFile), 10000, 10000);
} catch (IOException e) {
e.printStackTrace();
}
}
}
1.3 Maven
pom.xml
commons-io commons-io 2.5
1.4 Gradle
build.gradle
dependencies {
compile 'commons-io:commons-io:2.5'
}
2. Java NIO
2.1 Try Java 7 NIO example.
URL website = new URL(fromFile);
ReadableByteChannel rbc = Channels.newChannel(website.openStream());
FileOutputStream fos = new FileOutputStream(toFile);
fos.getChannel().transferFrom(rbc, 0, Long.MAX_VALUE);
fos.close();
rbc.close();
2.2 Full example.
HttpUtils.java
package com.example;
import java.io.FileOutputStream;
import java.io.IOException;
import java.net.URL;
import java.nio.channels.Channels;
import java.nio.channels.ReadableByteChannel;
public class HttpUtils {
public static void main(String[] args) {
String fromFile = "ftp://ftp.arin.net/pub/stats/arin/delegated-arin-extended-latest";
String toFile = "F:\\arin.txt";
try {
URL website = new URL(fromFile);
ReadableByteChannel rbc = Channels.newChannel(website.openStream());
FileOutputStream fos = new FileOutputStream(toFile);
fos.getChannel().transferFrom(rbc, 0, Long.MAX_VALUE);
fos.close();
rbc.close();
} catch (IOException e) {
e.printStackTrace();
}
}
}