HTTP
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1.什么是HTTP协议?
超文本传送协议(http)定义了浏览器怎么向万维网服务器请求万维网文档,以及服务器怎样把文档传给浏览器。从层次的角度看,HTTP是面向应用层协议的,它是万维网上能够可靠地交换文件(文本,声音,图片等)的重要基础
2.HTTP工作流程
一次HTTP操作称为一个事务,其工作过程可分为四步
1.)首先客户机与服务器需要建立连接。重要单机某个超级链接,HTTP的工作就开始了。
2.)建立连接后,客户机发送一个请求给服务器,请求方式为:统一资源定位符(URL)、协议版本号、后边是MIME信息包括请求修饰符、客户机信息和可能的内容。
3.)服务器接受到请求后,给了相应的响应信息,其格式为一个状态行,包括信息的协议版本号,一个成功或错误的代码,后边是MIME信息包括服务器信息,实体信息和可能的内容
4.)客户端接收服务器返回的信息通过浏览器显示在用户的显示屏上,然后客户机与服务器断开连接。
2.1HTTP是在TCP/IP协议之上的的,先进行TCP/IP连接,即进行三次握手
2.2HTTP协议永远都是客户端发起请求,服务器回送响应,这样就限制了使用HTTP协议,无法实现客户端没有发生请求的时候,服务器将消息推送给客户端。HTTP协议是一个无状态的协议,同一个客户端的这次请求与上次请求是没有对应关系的
2.3URL(统一资源定位符)
3.TCP/IP基础-三次握手
3.1SYN(synchronous)是TCP/IP建立连接时使用的握手信号。在客户机和服务器之间建立正常连接的TCP网络连接时,客户机首先发送一个SYN消息,服务器使用SYN+ACK应答表示接收到了这个消息,最后客户机再以ACK消息响应。这样客户机和服务器之间才能建立可靠的TCP连接,数据才可以在客户机和服务器之间传递。
ACK(Acknowledgement),即确认字符,在数据通信中接收站发给发送站的一种传输类控制字符。表示发来的数据已确认接收无误。
4.HTTP请求头信息
Request URL: http://www.baidu.com/
Request Method:GET、POST
Request Code:200 ok
…等
5.HTTP响应头信息
响应码
客户端错误:
200 Ok // 客户端请求成功
400 Bad Request // 客户端请求有语法错误,不能被服务器所理解
401 Unauthorized // 请求未经授权,这个状态代码必须和www-Authenticate报头域一起使用
403 Forbidden // 服务器收到请求,但是拒绝提供服务
404 Not Found // 请求资源不存在 eg.输入错误的URL
服务器错误:
500 Internal Server Error // 服务器发送不可预计的错误
503 Server Unavailable // 服务器当前不能处理客户机的请求,一段时间后可能恢复
6.HTTP协议的特点
1.)支持客户/服务器模式(B/S)
2.)简单快速:客户向服务器请求服务时,只需传送请求方法和路径。请求方法常用的又GET、POST、HEAD。每种方法规定了客户与服务器联系的类型不同。由于HTTP协议简单,使得HTTP服务器的程序规模小,因此通信速度很快。
3.)灵活:HTTP允许传输任何类型的数据对象。正在传输的类型由Content-Type加以标记。
4.)无连接:无连接的含义是限制每次连接只处理一个请求。服务器处理完客户的请求,并受到客户的应答后,即断开连接。采用这种方式可以节省传输时间。
5.)无状态:HTTP协议是无状态协议。无状态是指协议对于事务没有记忆能力。缺少状态意味着如果后续处理需要前面的信息,则它必须重传,这样可能导致每次连接传送的数据量增大。另一方面,在服务器不需要先前信息时它的应答就较快
7.七层协议
国际标准化组织ISO于1981年正式推荐了一个网络系统结构—七层参考模型,也叫做开放系统互连模型(Open System Interconnection,OSI).
OSI参考模型将整个网络通信功能划分为七个层次。
它们由低到高分别是 物理层(PH),数据链路层(DL),网络层(N),传输层(T),会话层(S),表示层(P),应用层(A)
8.HTTP1.0和HTTP1.1的区别
HTTP/1.0 每次请求都需要建立新的TCP连接,连接不能复用
HTTP/1.1 新的请求可以在上次请求建立的TCP连接之上发送,连接可以复用。优点是减少重复进行TCP三次握手的开销,提高效率
HTTP1.1 在Request消息头里多了一个Host域,HTTP/1.0则没有这个域。Host:www.w3.org
HTTP1.1 增加了OPTIONS,PUT,DELETE.TRACE,CONNECT这些Request方法
9.HttpUrlConnection的使用
http://blog.csdn.net/u010542146/article/details/50088261
10.GET、POST传递参数
Main
final EditText edName = (EditText) findViewById(R.id.editText1); final EditText edPsw = (EditText) findViewById(R.id.editText2); final String url = "http://192.168.56.1:8080/Day0225/MyServlet"; Button bt = (Button) findViewById(R.id.button1); bt.setOnClickListener(new OnClickListener() { @Override public void onClick(View v) { final String name = edName.getText().toString(); final String psw = edPsw.getText().toString(); new MyThread(url, name, psw).start(); } });
MyThread
public class MyThread extends Thread { String url; String name; String psw; public MyThread(String url,String name,String psw) { this.url = url; this.name = name; this.psw = psw; } @Override public void run() {// doGet(); doPost(); } private void doGet() { url = url+"?name="+name+"&psw="+psw; try { URL httpUrl = new URL(url); HttpURLConnection conn = (HttpURLConnection) httpUrl.openConnection(); conn.setConnectTimeout(5000); conn.setRequestMethod("GET"); BufferedReader reader = new BufferedReader(new InputStreamReader(conn.getInputStream())); StringBuilder builder = new StringBuilder(); String line; if ((line=reader.readLine())!=null) { builder.append(line); } } catch (MalformedURLException e) { e.printStackTrace(); } catch (IOException e) { e.printStackTrace(); } } private void doPost() { try { URL httpUrl = new URL(url); HttpURLConnection conn = (HttpURLConnection) httpUrl.openConnection(); conn.setConnectTimeout(5000);//数据添加 OutputStream out = conn.getOutputStream(); String string = "name="+name+"&psw="+psw; out.write(string.getBytes());// BufferedReader reader = new BufferedReader(new InputStreamReader(conn.getInputStream())); StringBuilder builder = new StringBuilder(); String line; if ((line=reader.readLine())!=null) { builder.append(line); } } catch (MalformedURLException e) { e.printStackTrace(); } catch (IOException e) { e.printStackTrace(); } } }
11.乱码处理
服务端
String name = (String) request.getParameter("name"); String name1 = new String(name.getBytes("iso-8859-1"),"utf-8"); //**name1为转码后的** String psw = (String) request.getParameter("psw"); System.out.println("name = "+name+" name1 = "+name1+" psw = "+psw); response.setContentType("text/html;charset=utf-8"); PrintWriter out = response.getWriter(); out.write("name = "+name+" name1 = "+name1+" psw = "+psw);
客户端使用GET方法传递参数(好像不需要使用URLEncoder也不会出现“??”)
try { url = url+"?name="+URLEncoder.encode(name,"utf-8")+"&psw="+psw; } catch (UnsupportedEncodingException e1) { e1.printStackTrace(); }
12.多线程下载资源(图片为例)
图片资源放置WebContent目录下
Main
public class MainActivity extends Activity { TextView textView; private int count = 0; @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_main); final Handler handler = new Handler(){ @Override public void handleMessage(Message msg) { if(msg.what == 1) { count++; if (count == 3) { textView.setText("ok"); } } } }; textView = (TextView) findViewById(R.id.textView1); Button button = (Button) findViewById(R.id.button1); button.setOnClickListener(new OnClickListener() { @Override public void onClick(View v) { new Thread(new Runnable() { @Override public void run() { new DownLoad(handler).downLoadFile("http://192.168.56.1:8080/Day0225/girl.jpg"); } }).start(); } }); }}
DownLoad
package com.example.day0226;import java.io.File;import java.io.IOException;import java.io.InputStream;import java.io.RandomAccessFile;import java.net.HttpURLConnection;import java.net.MalformedURLException;import java.net.URL;import java.util.concurrent.Executor;import java.util.concurrent.Executors;import android.os.Environment;import android.os.Handler;public class DownLoad { Handler handler; public DownLoad(Handler handler) { this.handler = handler; } //创建线程池 private Executor threadPool = Executors.newFixedThreadPool(3); public void downLoadFile(String url) { try { URL httpUrl = new URL(url); HttpURLConnection conn = (HttpURLConnection) httpUrl.openConnection(); conn.setReadTimeout(5000); conn.setRequestMethod("GET"); //拿到下载图片总体的长度 int count = conn.getContentLength(); int block = count/3; String fileName = getFileName(url); File parent = Environment.getExternalStorageDirectory(); File fileDownload = new File(parent,fileName); /** 11 个字节 * 第一个线程 0-2 * 第二个线程 3-5 * 第三个线程 6-10 */ for(int i=0; i<3; i++) { long start = i*block; long end = (i+1)*block-1; if (i == 2) { end = count; } DownLoadRunnable runnable = new DownLoadRunnable(url, fileDownload.getAbsolutePath(), start, end,handler); //通过线程池提交任务 threadPool.execute(runnable); } } catch (MalformedURLException e) { e.printStackTrace(); } catch (IOException e) { e.printStackTrace(); } } static class DownLoadRunnable implements Runnable { private String url; private String fileName; private long start; private long end; private Handler handler; public DownLoadRunnable(String url,String fileName,long start,long end,Handler handler) { this.url = url; this.fileName = fileName; this.start = start; this.end = end; this.handler = handler; } @Override public void run() { try { URL httpUrl = new URL(url); HttpURLConnection conn = (HttpURLConnection) httpUrl.openConnection(); conn.setReadTimeout(5000); conn.setRequestMethod("GET"); //指定请求的长度 conn.setRequestProperty("Range", "bytes="+start+"-"+end); //往本地文件进行写,"rwd"=可读可写可执行 RandomAccessFile access = new RandomAccessFile(new File(fileName), "rwd"); //对指定区域进行读写 access.seek(start); InputStream in = conn.getInputStream(); byte[] b = new byte[1024*4]; int len = 0; while((len=in.read(b))!=-1) { access.write(b,0,len); } if (access != null) { access.close(); } if(in != null) { in.close(); } handler.sendEmptyMessage(1); } catch (MalformedURLException e) { e.printStackTrace(); } catch (IOException e) { e.printStackTrace(); } } } public String getFileName(String url) { return url.substring(url.lastIndexOf("/")); }}
用到的知识点:
1.HTTP协议字段 Range “bytes=”+start+”-“+end
2.RandomAccessFile 设置吸入的位置
3.开启线程发送网络请求
13.上传图片
tomcat版本选择7.0的3.0
JSP
<form action="UploadServlet" method="post" enctype="multipart/form-data"><input type="file" name="file"><br><input type="submit" value="submit"><br></form>
UploadServlet
import java.io.IOException;import javax.servlet.ServletException;import javax.servlet.annotation.MultipartConfig;import javax.servlet.annotation.WebServlet;import javax.servlet.http.HttpServlet;import javax.servlet.http.HttpServletRequest;import javax.servlet.http.HttpServletResponse;import javax.servlet.http.Part;/** * Servlet implementation class UploadServlet */@WebServlet("/UploadServlet")//指定路径为D盘下@MultipartConfig( location = "D:\\" )public class UploadServlet extends HttpServlet { private static final long serialVersionUID = 1L; /** * @see HttpServlet#HttpServlet() */ public UploadServlet() { super(); // TODO Auto-generated constructor stub } /** * @see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse response) */ protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { doPost(request, response); } /** * @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse response) */ protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { Part part = request.getPart("file"); part.write("girl.jpg"); System.out.println("ok"); }}
即把图片上传到D盘下,固定文件名为”girl.jpg“
HttpUrlConnection上传
实际上是要按照下图的格式才能上传
Main
File parent = Environment.getExternalStorageDirectory(); File file = new File(parent,"girl.jpg"); String fileName = file.getAbsolutePath(); String url = "http://192.168.56.1:8080/Day0226/UploadServlet"; new UpLoadThread(url, fileName).start();
UpLoadThread
public class UpLoadThread extends Thread { String url; String fileName; String boundary = "---------------------------184811307910651"; String prefix = "--"; String end = "\r\n"; public UpLoadThread(String url, String fileName) { this.url = url; this.fileName = fileName; } @Override public void run() { try { URL httpUrl = new URL(url); HttpURLConnection conn = (HttpURLConnection) httpUrl.openConnection(); conn.setReadTimeout(5000); conn.setRequestMethod("POST"); //允许读入 conn.setDoInput(true); //允许输出 conn.setDoOutput(true); conn.setRequestProperty("Content-Type", "multipart/form-data;boundary="+boundary); DataOutputStream out = new DataOutputStream(conn.getOutputStream()); out.writeBytes(prefix+boundary+end); out.writeBytes("Content-Disposition: form-data; "+"name=\"file\";filename=\""+"girl.jpg"+"\""+end); out.writeBytes(end); @SuppressWarnings("resource") FileInputStream fileInputStream = new FileInputStream(new File(fileName)); byte[] b = new byte[1024*4]; int len = 0; while((len=fileInputStream.read(b))!=-1) { out.write(b,0,len); } out.writeBytes(end); out.writeBytes(prefix+boundary+prefix+end); out.flush(); BufferedReader reader = new BufferedReader(new InputStreamReader(conn.getInputStream())); StringBuffer buffer = new StringBuffer(); String str; while((str=reader.readLine())!=null) { buffer.append(str); } Log.v("TAG", buffer.toString()); if (out != null) { out.close(); } if (reader != null) { reader.close(); } } catch (MalformedURLException e) { e.printStackTrace(); } catch (IOException e) { e.printStackTrace(); } } }
使用HttpClient上传
要导入2个jar包
httpmime-4.4-beta1
httpcore-4.4-beta1
注意:高版本的jar会报错!(如httpmime-4.5.1)
public class ClientPostThread extends Thread { @SuppressWarnings("deprecation") @Override public void run() { HttpClient client = new DefaultHttpClient(); String url = "http://192.168.56.1:8080/Day0226/UploadServlet"; HttpPost post = new HttpPost(url); MultipartEntity entity = new MultipartEntity(); File parent = Environment.getExternalStorageDirectory(); File file = new File(parent,"girl.jpg"); FileBody body = new FileBody(file); entity.addPart("file",body); post.setEntity(entity); try { HttpResponse response = client.execute(post); if (response.getStatusLine().getStatusCode() == HttpStatus.SC_OK) { Log.v("TAG", EntityUtils.toString(response.getEntity())); } } catch (ClientProtocolException e) { e.printStackTrace(); } catch (IOException e) { e.printStackTrace(); } } }
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