0
点赞
收藏
分享

微信扫一扫

使用Apache HttpClient实现多线程下载的小例子

Ichjns 2022-09-13 阅读 30
多线程apacheexceptionthreadfileLinux系统/运维
加载失败


网上类似的文章很多，参考了很多人的，大部分人都是用URLConnection写的。

原理一：HTTP多线程下载原理

1、发送一个含有Rang头的Head请求，如果返回状态码为206，则允许多线程下载

 

原理二：多线程下载原理

1、使用HttpClient的Head请求获取请求文件的信息

2、发送一个Rang的Head请求判断是否允许多线程下载

3、通过主任务创建多个分段下载线程，分段下载文件，然后用Java的随机读写文件类保存下载的内容

 

（等有时间了再添加内容吧，先简单写这么多）

调度功能代码片段

Java代码 

/**
   * 开始下载
   * @throws Exception
   */
  public void startDown() throws Exception{
    HttpClient httpClient = new DefaultHttpClient();
    try {
      //获取下载文件信息
      getDownloadFileInfo(httpClient);
      //启动多个下载线程
      startDownloadThread();
      //开始监视下载数据
      monitor();
    } catch (Exception e) {
      throw e;
    } finally {
      httpClient.getConnectionManager().shutdown();
    }
  }

  /**
   * 获取下载文件信息
   */
  private void getDownloadFileInfo(HttpClient httpClient) throws IOException,
      ClientProtocolException, Exception {
    HttpHead httpHead = new HttpHead(url);
    HttpResponse response = httpClient.execute(httpHead);
    //获取HTTP状态码
    int statusCode = response.getStatusLine().getStatusCode();

    if(statusCode != 200) throw new Exception("资源不存在!");
    if(getDebug()){
      for(Header header : response.getAllHeaders()){
        System.out.println(header.getName()+":"+header.getValue());
      }
    }

    //Content-Length
    Header[] headers = response.getHeaders("Content-Length");
    if(headers.length > 0)
      contentLength = Long.valueOf(headers[0].getValue());

    httpHead.abort();
    
    httpHead = new HttpHead(url);
    httpHead.addHeader("Range", "bytes=0-"+(contentLength-1));
    response = httpClient.execute(httpHead);
    if(response.getStatusLine().getStatusCode() == 206){
      acceptRanges = true;
    }
    httpHead.abort();
  }

  /**
   * 启动多个下载线程
   * @throws IOException
   * @throws FileNotFoundException
   */
  private void startDownloadThread() throws IOException,
      FileNotFoundException {
    //创建下载文件
    File file = new File(localPath);
    file.createNewFile();
    RandomAccessFile raf = new RandomAccessFile(file, "rw");
    raf.setLength(contentLength);
    raf.close();
    
    //定义下载线程事件实现类
    DownloadThreadListener listener = new DownloadThreadListener() {
      public void afterPerDown(DownloadThreadEvent event) {
        //下载完一个片段后追加已下载字节数
        synchronized (object) {
          DownloadTask.this.receivedCount += event.getCount();
        }
      }

      public void downCompleted(DownloadThreadEvent event) {
        //下载线程执行完毕后从主任务中移除
        threads.remove(event.getTarget());
        if(getDebug()){
          System.out.println("剩余线程数："+threads.size());
        }
      }
    };
    
    //不支持多线程下载时
    if (!acceptRanges) {
      if(getDebug()){
        System.out.println("该地址不支持多线程下载");
      }
      //定义普通下载
      DownloadThread thread = new DownloadThread(url, 0, contentLength, file, false);
      thread.addDownloadListener(listener);
      thread.start();
      threads.add(thread);
      return;
    }
    
    //每个请求的大小
    long perThreadLength = contentLength / threadCount + 1;
    long startPosition = 0;
    long endPosition = perThreadLength;
    //循环创建多个下载线程
    do{
      if(endPosition >= contentLength)
        endPosition = contentLength - 1;

      DownloadThread thread = new DownloadThread(url, startPosition, endPosition, file);
      thread.addDownloadListener(listener);
      thread.start();
      threads.add(thread);

      startPosition = endPosition + 1;//此处加 1,从结束位置的下一个地方开始请求
      endPosition += perThreadLength;
    } while (startPosition < contentLength);
  }

/**
   * 开始下载
   * @throws Exception
   */
  public void startDown() throws Exception{
    HttpClient httpClient = new DefaultHttpClient();
    try {
      //获取下载文件信息
      getDownloadFileInfo(httpClient);
      //启动多个下载线程
      startDownloadThread();
      //开始监视下载数据
      monitor();
    } catch (Exception e) {
      throw e;
    } finally {
      httpClient.getConnectionManager().shutdown();
    }
  }

  /**
   * 获取下载文件信息
   */
  private void getDownloadFileInfo(HttpClient httpClient) throws IOException,
      ClientProtocolException, Exception {
    HttpHead httpHead = new HttpHead(url);
    HttpResponse response = httpClient.execute(httpHead);
    //获取HTTP状态码
    int statusCode = response.getStatusLine().getStatusCode();

    if(statusCode != 200) throw new Exception("资源不存在!");
    if(getDebug()){
      for(Header header : response.getAllHeaders()){
        System.out.println(header.getName()+":"+header.getValue());
      }
    }

    //Content-Length
    Header[] headers = response.getHeaders("Content-Length");
    if(headers.length > 0)
      contentLength = Long.valueOf(headers[0].getValue());

    httpHead.abort();
    
    httpHead = new HttpHead(url);
    httpHead.addHeader("Range", "bytes=0-"+(contentLength-1));
    response = httpClient.execute(httpHead);
    if(response.getStatusLine().getStatusCode() == 206){
      acceptRanges = true;
    }
    httpHead.abort();
  }

  /**
   * 启动多个下载线程
   * @throws IOException
   * @throws FileNotFoundException
   */
  private void startDownloadThread() throws IOException,
      FileNotFoundException {
    //创建下载文件
    File file = new File(localPath);
    file.createNewFile();
    RandomAccessFile raf = new RandomAccessFile(file, "rw");
    raf.setLength(contentLength);
    raf.close();
    
    //定义下载线程事件实现类
    DownloadThreadListener listener = new DownloadThreadListener() {
      public void afterPerDown(DownloadThreadEvent event) {
        //下载完一个片段后追加已下载字节数
        synchronized (object) {
          DownloadTask.this.receivedCount += event.getCount();
        }
      }

      public void downCompleted(DownloadThreadEvent event) {
        //下载线程执行完毕后从主任务中移除
        threads.remove(event.getTarget());
        if(getDebug()){
          System.out.println("剩余线程数："+threads.size());
        }
      }
    };
    
    //不支持多线程下载时
    if (!acceptRanges) {
      if(getDebug()){
        System.out.println("该地址不支持多线程下载");
      }
      //定义普通下载
      DownloadThread thread = new DownloadThread(url, 0, contentLength, file, false);
      thread.addDownloadListener(listener);
      thread.start();
      threads.add(thread);
      return;
    }
    
    //每个请求的大小
    long perThreadLength = contentLength / threadCount + 1;
    long startPosition = 0;
    long endPosition = perThreadLength;
    //循环创建多个下载线程
    do{
      if(endPosition >= contentLength)
        endPosition = contentLength - 1;

      DownloadThread thread = new DownloadThread(url, startPosition, endPosition, file);
      thread.addDownloadListener(listener);
      thread.start();
      threads.add(thread);

      startPosition = endPosition + 1;//此处加 1,从结束位置的下一个地方开始请求
      endPosition += perThreadLength;
    } while (startPosition < contentLength);
  }

1. /**
2. * 开始下载
3. * @throws Exception
4. */
5. public void startDown() throws
6. new
7. try
8. //获取下载文件信息
9. getDownloadFileInfo(httpClient);
10. //启动多个下载线程
11. startDownloadThread();
12. //开始监视下载数据
13. monitor();
14. catch
15. throw
16. finally
17. httpClient.getConnectionManager().shutdown();
18. }
19. }
20. 
21. /**
22. * 获取下载文件信息
23. */
24. private void getDownloadFileInfo(HttpClient httpClient) throws
25. ClientProtocolException, Exception {
26. new
27. HttpResponse response = httpClient.execute(httpHead);
28. //获取HTTP状态码
29. int
30. 
31. if(statusCode != 200) throw new Exception("资源不存在!");
32. if(getDebug()){
33. for(Header header : response.getAllHeaders()){
34. ":"+header.getValue());
35. }
36. }
37. 
38. //Content-Length
39. "Content-Length");
40. if(headers.length > 0)
41. 0].getValue());
42. 
43. httpHead.abort();
44. 
45. new
46. "Range", "bytes=0-"+(contentLength-1));
47. response = httpClient.execute(httpHead);
48. if(response.getStatusLine().getStatusCode() == 206){
49. true;
50. }
51. httpHead.abort();
52. }
53. 
54. /**
55. * 启动多个下载线程
56. * @throws IOException
57. * @throws FileNotFoundException
58. */
59. private void startDownloadThread() throws
60. FileNotFoundException {
61. //创建下载文件
62. new
63. file.createNewFile();
64. new RandomAccessFile(file, "rw");
65. raf.setLength(contentLength);
66. raf.close();
67. 
68. //定义下载线程事件实现类
69. new
70. public void
71. //下载完一个片段后追加已下载字节数
72. synchronized
73. this.receivedCount += event.getCount();
74. }
75. }
76. 
77. public void
78. //下载线程执行完毕后从主任务中移除
79. threads.remove(event.getTarget());
80. if(getDebug()){
81. "剩余线程数："+threads.size());
82. }
83. }
84. };
85. 
86. //不支持多线程下载时
87. if
88. if(getDebug()){
89. "该地址不支持多线程下载");
90. }
91. //定义普通下载
92. new DownloadThread(url, 0, contentLength, file, false);
93. thread.addDownloadListener(listener);
94. thread.start();
95. threads.add(thread);
96. return;
97. }
98. 
99. //每个请求的大小
100. long perThreadLength = contentLength / threadCount + 1;
101. long startPosition = 0;
102. long
103. //循环创建多个下载线程
104. do{
105. if(endPosition >= contentLength)
106. 1;
107. 
108. new
109. thread.addDownloadListener(listener);
110. thread.start();
111. threads.add(thread);
112. 
113. 1;//此处加 1,从结束位置的下一个地方开始请求
114. endPosition += perThreadLength;
115. while
116. }

 分段下载线程代码片段：

Java代码 ​​​​ 

1. 
2. /**
3. * 现在过程代码
4. */
5. public void
6. if(DownloadTask.getDebug()){
7. "Start:" + startPosition + "-"
8. }
9. new
10. try
11. new
12. if(isRange){//多线程下载
13. "Range", "bytes="+startPosition+"-"+endPosition);
14. }
15. HttpResponse response = httpClient.execute(httpGet);
16. int
17. if(DownloadTask.getDebug()){
18. for(Header header : response.getAllHeaders()){
19. ":"+header.getValue());
20. }
21. "statusCode:"
22. }
23. if(statusCode == 206 || (statusCode == 200
24. InputStream inputStream = response.getEntity().getContent();
25. //创建随机读写类
26. new RandomAccessFile(file, "rw");
27. //跳到指定位置
28. outputStream.seek(startPosition);
29. int count = 0;byte[] buffer=new byte[1024];
30. while((count = inputStream.read(buffer, 0, buffer.length))>0){
31. 0, count);
32. //触发下载事件
33. new DownloadThreadEvent(this,count));
34. }
35. outputStream.close();
36. }
37. httpGet.abort();
38. catch
39. e.printStackTrace();
40. finally
41. //触发下载完成事件
42. new DownloadThreadEvent(this, endPosition));
43. if(DownloadTask.getDebug()){
44. "End:" + startPosition + "-"
45. }
46. httpClient.getConnectionManager().shutdown();
47. }
48. }
/**
   * 现在过程代码
   */
  public void run() {
    if(DownloadTask.getDebug()){
      System.out.println("Start:" + startPosition + "-" +endPosition);
    }
    HttpClient httpClient = new DefaultHttpClient();
    try {
      HttpGet httpGet = new HttpGet(url);
      if(isRange){//多线程下载
        httpGet.addHeader("Range", "bytes="+startPosition+"-"+endPosition);
      }
      HttpResponse response = httpClient.execute(httpGet);
      int statusCode = response.getStatusLine().getStatusCode();
      if(DownloadTask.getDebug()){
        for(Header header : response.getAllHeaders()){
          System.out.println(header.getName()+":"+header.getValue());
        }
        System.out.println("statusCode:" + statusCode);
      }
      if(statusCode == 206 || (statusCode == 200 && !isRange)){
        InputStream inputStream = response.getEntity().getContent();
        //创建随机读写类
        RandomAccessFile outputStream = new RandomAccessFile(file, "rw");
        //跳到指定位置
        outputStream.seek(startPosition);
        int count = 0;byte[] buffer=new byte[1024];
        while((count = inputStream.read(buffer, 0, buffer.length))>0){
          outputStream.write(buffer, 0, count);
          //触发下载事件
          fireAfterPerDown(new DownloadThreadEvent(this,count));
        }
        outputStream.close();
      }
      httpGet.abort();
    } catch (Exception e) {
      e.printStackTrace();
    } finally {
      //触发下载完成事件
      fireDownCompleted(new DownloadThreadEvent(this, endPosition));
      if(DownloadTask.getDebug()){
        System.out.println("End:" + startPosition + "-" +endPosition);
      }
      httpClient.getConnectionManager().shutdown();
    }
  }

/**
   * 现在过程代码
   */
  public void run() {
    if(DownloadTask.getDebug()){
      System.out.println("Start:" + startPosition + "-" +endPosition);
    }
    HttpClient httpClient = new DefaultHttpClient();
    try {
      HttpGet httpGet = new HttpGet(url);
      if(isRange){//多线程下载
        httpGet.addHeader("Range", "bytes="+startPosition+"-"+endPosition);
      }
      HttpResponse response = httpClient.execute(httpGet);
      int statusCode = response.getStatusLine().getStatusCode();
      if(DownloadTask.getDebug()){
        for(Header header : response.getAllHeaders()){
          System.out.println(header.getName()+":"+header.getValue());
        }
        System.out.println("statusCode:" + statusCode);
      }
      if(statusCode == 206 || (statusCode == 200 && !isRange)){
        InputStream inputStream = response.getEntity().getContent();
        //创建随机读写类
        RandomAccessFile outputStream = new RandomAccessFile(file, "rw");
        //跳到指定位置
        outputStream.seek(startPosition);
        int count = 0;byte[] buffer=new byte[1024];
        while((count = inputStream.read(buffer, 0, buffer.length))>0){
          outputStream.write(buffer, 0, count);
          //触发下载事件
          fireAfterPerDown(new DownloadThreadEvent(this,count));
        }
        outputStream.close();
      }
      httpGet.abort();
    } catch (Exception e) {
      e.printStackTrace();
    } finally {
      //触发下载完成事件
      fireDownCompleted(new DownloadThreadEvent(this, endPosition));
      if(DownloadTask.getDebug()){
        System.out.println("End:" + startPosition + "-" +endPosition);
      }
      httpClient.getConnectionManager().shutdown();
    }
  }

 附件说明：

1、Download.jar为编译好的可运行程序

2、Download.zip为Eclipse项目文件

3、运行截图

使用Apache HttpClient实现多线程下载的小例子_file


 

 

  • ​​Download.jar​​ (928.1 KB)
  • 下载次数: 44
  • ​​DownLoad.zip​​ (832.5 KB)
  • 下载次数: 70

 

举报

相关推荐

Python简单实现多线程例子

停止线程主线程线程安全Python后端开发yyds干货盘点

多线程和Socket结合使用的例子

多线程SocketJava编程.netHarmonyOS后端开发

android实现多线程下载

android线程网络java.net系统/运维

Python 多线程例子

python

Java多线程____线程死锁例子

Systemide死锁Html/CSS前端开发

Python简单的多线程例子

python

java实现多线程下载器

javaSystem输入流jQuery前端开发

Apache HttpClient 和 OkHttpClient 的使用

1024程序员节matlab

java多线程售票例子

ideSystemHtml/CSS前端开发

多线程下载

java文件大小数据库虚拟化云计算
0 条评论
加载失败