多线程断点下载

import java.io.*;
import java.net.HttpURLConnection;
import java.net.URL;

public class MultiDownload {
long beginTime;
int threadCount;
int runningThread;
int fileSize;
FileLog fileLog = null;

public MultiDownload(int threadCount, FileLog fileLog) {
this.beginTime = System.currentTimeMillis();
this.threadCount = threadCount;
this.runningThread = threadCount;
this.fileLog = fileLog;
}

public void multiThreadDownload(String sourcePath, File targetFile) {
fileSize = getFileSize(sourcePath);
int blockSize = fileSize / threadCount;
System.out.println("blockSize=" + blockSize);
for (int threadId = 1; threadId <= threadCount; threadId++) {
int beginIndex = (threadId - 1) * blockSize;
int endIndex = threadId * blockSize - 1;
if (threadId == threadCount) {
endIndex = fileSize - 1;
}
System.out.println("thread=" + threadId + " " + beginIndex + " -- " + endIndex);
if (!targetFile.getParentFile().exists())
targetFile.getParentFile().mkdirs();
if (!targetFile.exists())
try {
targetFile.createNewFile();
} catch (IOException e) {
e.printStackTrace();
}
new DownloadThread(threadId, sourcePath, beginIndex, endIndex, targetFile).start();
}
}

public class DownloadThread extends Thread {
private String sourcePath;
private int beginIndex;
private int endIndex;
private int threadId;
private File targetFile;

public DownloadThread(int threadId, String sourcePath, int beginIndex, int endIndex, File targetFile) {
this.sourcePath = sourcePath;
this.beginIndex = beginIndex;
this.endIndex = endIndex;
this.threadId = threadId;
this.targetFile = targetFile;
}

@Override
public void run() {
HttpURLConnection conn = null;
RandomAccessFile raf;

try {
raf = new RandomAccessFile(targetFile, "rwd");
URL url = new URL(sourcePath);
conn = (HttpURLConnection) url.openConnection();
conn.setRequestMethod("GET");
conn.setConnectTimeout(10000);
if (fileLog.getAlreadyData(threadId) != -1)
beginIndex = fileLog.getAlreadyData(threadId);
conn.setRequestProperty("Range", "bytes=" + beginIndex + "-" + endIndex);
int code = conn.getResponseCode();
int total = 0;
if (code == 206) {
InputStream is = conn.getInputStream();
raf.seek(beginIndex);
int len;
byte[] buff = new byte[1024];
while ((len = is.read(buff)) != -1) {
raf.write(buff, 0, len);
total += len;
fileLog.set(String.valueOf(threadId), total + beginIndex - 1 + "");
//System.out.println("线程" + threadId + " 开始下载=" + String.valueOf(total + beginIndex - 1));
}
}
runningThread--;
} catch (IOException e) {
e.printStackTrace();
} finally {
if (runningThread == 0) {
long endTime = System.currentTimeMillis();
long time = (endTime - beginTime) / 1000;
double speed = (double) fileSize / 1024 / 1024 / time;

System.out.println("下载完成用时" + time + "秒" + " " + Math.ceil(speed * 100) / 100 + "MB/S");
fileLog.deleteFile();
}
if (conn != null) {
conn.disconnect();
}
}
}
}

private static int getFileSize(String sourcePath) {
int fileSize = 0;
HttpURLConnection conn = null;
try {
URL url = new URL(sourcePath);
conn = (HttpURLConnection) url.openConnection();
conn.setRequestMethod("GET");
conn.setConnectTimeout(10000);
int code = conn.getResponseCode();
if (code == 200) {
fileSize = conn.getContentLength();
double d = fileSize / 1024 / 1024;
System.out.println("文件总大小=" + Math.ceil(d * 100) / 100 + "MB");
}
} catch (java.io.IOException e) {
e.printStackTrace();
} finally {
if (conn != null) {
conn.disconnect();
}
}
return fileSize;
}
}

import java.io.*;
import java.util.*;

public class FileLog {
Properties properties = new Properties();
File file;
public FileLog(File file) {
this.file = file;
if (!file.getParentFile().exists())
file.getParentFile().mkdirs();
if (!file.exists())
try {
file.createNewFile();
} catch (IOException e) {
e.printStackTrace();
}
}

public synchronized void set(String key,String value) {
InputStream is = null;
OutputStream os = null;
try {
is = new FileInputStream(file);

properties.load(is);
Enumeration e = properties.propertyNames();
while (e.hasMoreElements()) {
String mKey = (String) e.nextElement();
String mValue = properties.getProperty(mKey);
if (mKey.equals(key)) {
properties.setProperty(key, value);
} else {
properties.setProperty(mKey, mValue);
}
}
properties.setProperty(key, value);
is.close();
os = new FileOutputStream(file);
properties.store(os, "");
os.close();
} catch (IOException e) {
e.printStackTrace();
}
}
public String get(String key) {
String value = null;
try {
InputStream is = new FileInputStream(file);
properties.load(is);
value = properties.getProperty(key);
System.out.println("FileLog get() "+"key="+key + " "+"value="+value);
} catch (IOException e) {
e.printStackTrace();
}
return value;
}
public int getAlreadyData(int key){
int data = -1;
if (file.exists()&& file.length()>0) {
String value = get(String.valueOf(key));
if (value != null)
data = Integer.parseInt(value);
}
return data;
}
public void getAll(){
InputStream is = null;
try {
is = new FileInputStream(file);
properties.load(is);
Enumeration e = properties.propertyNames();
while (e.hasMoreElements()) {
String key = (String) e.nextElement();
String value = properties.getProperty(key);
//System.out.println(key+" "+value);
}
} catch (IOException e) {
e.printStackTrace();
}
}
public void deleteFile() {
file.delete();
}

}

String targetPathDir = "z:\\";
String targetFileName = "setup.exe";
String sourcePath = "http://down.360safe.com/setup.exe";

File targetFile = new File(targetPathDir, targetFileName);
FileLog fileLog = new FileLog(new File(targetPathDir, targetFileName.substring(0,targetFileName.indexOf('.')) + ".txt"));
MultiDownload multiDownload = new MultiDownload(2, fileLog);
multiDownload.multiThreadDownload(sourcePath, targetFile);