Android 最早使用的简单的网络请求

下面是最早从事android开发的时候写的网络请求的代码，简单高效，对于理解http请求有帮助。直接上代码，不用解释，因为非常简单。

 import java.io.BufferedReader;
 import java.io.DataOutputStream;
 import java.io.FileInputStream;
 import java.io.InputStream;
 import java.io.InputStreamReader;
 import java.net.HttpURLConnection;
 import java.net.URL;
 import java.net.URLEncoder;
 import java.util.List;
 import java.util.Map;

 import org.apache.http.entity.mime.content.FileBody;

 import android.util.Log;

 public class HttpRequest {

     public static final String UTF_8 = "UTF-8";

     private static String cookie = null;

     /**
      * GET请求
      *
      * @param actionUrl
      * @param params
      * @return
      */
     public static String httpGet(String actionUrl, Map<String, String> params) {
         try{
             StringBuffer urlbuff = new StringBuffer(actionUrl);
             if (params != null && params.size() > 0) {
                 if (actionUrl.indexOf("?") >= 0) {
                     urlbuff.append("&");
                 } else {
                     urlbuff.append("?");
                 }
                 for (String key : params.keySet()) {
                     urlbuff.append(key).append("=").append(URLEncoder.encode(params.get(key), UTF_8)).append("&");
                 }
                 urlbuff.deleteCharAt(urlbuff.length() - 1);
                 Log.v("---request---Get---", urlbuff.toString());
             }
             URL url = new URL(urlbuff.toString());
             HttpURLConnection conn = (HttpURLConnection) url.openConnection();
             conn.setDoInput(true);// 允许输入
             conn.setDoOutput(false);// 允许输出
             conn.setUseCaches(false);// 不使用Cache
             conn.setRequestMethod("GET");
             conn.setRequestProperty("Charset", UTF_8);
             if (cookie != null) {
                 conn.setRequestProperty("Cookie", cookie);
             }
             int cah = conn.getResponseCode();
             if (cah != 200)
                 throw new RuntimeException("请求url失败");
             if (conn.getHeaderField("Set-Cookie") != null) {
                 cookie = conn.getHeaderField("Set-Cookie");
             }
             Log.i("", "------------------cookie:" + cookie);
             Map<String, List<String>> keys =  conn.getHeaderFields();
             for(String key : keys.keySet()) {
                 List<String> list = keys.get(key);
                 for(String value : list) {
                     Log.i("", "header: key:" + key + "  values:" + value);
                 }
             }

             InputStream is = conn.getInputStream();
             int ch;
             StringBuilder b = new StringBuilder();
             while ((ch = is.read()) != -1) {
                 b.append((char) ch);
             }
             is.close();
             conn.disconnect();
             return b.toString();
         }catch(Exception e) {
             e.printStackTrace();
         }
         return null;
     }

     /**
      * post 带文件上传
      * @param actionUrl
      * @param params
      * @param files
      * @return
      */
     public static String httpPost(String actionUrl, Map<String, String> params, Map<String, FileBody> files) {
         String LINE_START = "--";
         String LINE_END = "\r\n";
         String BOUNDRY =  "*****";

         try{
             HttpURLConnection conn = null;
             DataOutputStream dos = null;

             int bytesRead, bytesAvailable, bufferSize;
             long totalBytes;
             byte[] buffer;
             int maxBufferSize = 8096;

             URL url = new URL(actionUrl);
             conn = (HttpURLConnection) url.openConnection();

             // Allow Inputs
             conn.setDoInput(true);

             // Allow Outputs
             conn.setDoOutput(true);

             // Don't use a cached copy.
             conn.setUseCaches(false);

             // Use a post method.
             conn.setRequestMethod("POST");
             //if (files != null && files.size() > 0) {
                 conn.setRequestProperty("Connection", "Keep-Alive");
                 conn.setRequestProperty("Content-Type", "multipart/form-data;boundary="+BOUNDRY);
             //}

             Log.i("", "cookie:" + cookie);
             if (cookie != null) {
                 conn.setRequestProperty("Cookie", cookie);
             }
 //            // Set the cookies on the response
 //            String cookie = CookieManager.getInstance().getCookie(server);
 //            if (cookie != null) {
 //                conn.setRequestProperty("Cookie", cookie);
 //            }

 //            // Should set this up as an option
 //            if (chunkedMode) {
 //                conn.setChunkedStreamingMode(maxBufferSize);
 //            }

             dos = new DataOutputStream(conn.getOutputStream());

             // Send any extra parameters
             for (Object key : params.keySet()) {
                 dos.writeBytes(LINE_START + BOUNDRY + LINE_END);
                 dos.writeBytes("Content-Disposition: form-data; name=\"" +  key.toString() + "\"" + LINE_END);
                 dos.writeBytes(LINE_END);
                 dos.write(params.get(key).getBytes());
                 dos.writeBytes(LINE_END); 

                 Log.i("", "-----key:" + key + "  value:" + params.get(key));
             }
             //-----------
             if (files != null && files.size() > 0) {
                 for (String key : files.keySet()) {
                      Log.i("", "-----key:" + key + "  value:" + params.get(key));
                      FileBody fileBody = files.get(key);
                      dos.writeBytes(LINE_START + BOUNDRY + LINE_END);
                      dos.writeBytes("Content-Disposition: form-data; name=\"" + key + "\";" + " filename=\"" + fileBody.getFilename() +"\"" + LINE_END);
                      dos.writeBytes("Content-Type: " + fileBody.getMimeType() + LINE_END);
                       dos.writeBytes(LINE_END);

                      // Get a input stream of the file on the phone
                      InputStream fileInputStream = new FileInputStream(fileBody.getFile());
                      bytesAvailable = fileInputStream.available();
                     bufferSize = Math.min(bytesAvailable, maxBufferSize);
                     buffer = new byte[bufferSize];
                     // read file and write it into form...
                     bytesRead = fileInputStream.read(buffer, 0, bufferSize);
                     totalBytes = 0;
                     while (bytesRead > 0) {
                         totalBytes += bytesRead;
                         //result.setBytesSent(totalBytes);
                         dos.write(buffer, 0, bufferSize);
                         bytesAvailable = fileInputStream.available();
                         bufferSize = Math.min(bytesAvailable, maxBufferSize);
                         bytesRead = fileInputStream.read(buffer, 0, bufferSize);
                     }
                     dos.writeBytes(LINE_END);
                     // close streams
                     fileInputStream.close();
                 }
             }
             dos.writeBytes(LINE_START + BOUNDRY + LINE_START + LINE_END);
             dos.flush();
             dos.close(); 

             int statusCode = conn.getResponseCode();
             Log.i("", "---------------statusCode:" + statusCode);
             if (statusCode != 200) {
                 throw new HttpRequestException("server error");
             }

             //------------------ read the SERVER RESPONSE
             InputStream is = conn.getInputStream();
             int ch;
             StringBuilder b = new StringBuilder();
             while ((ch = is.read()) != -1) {
                 b.append((char) ch);
             }
             conn.disconnect();

             return b.toString();
         }catch(Exception e){
             Log.i("", "---------------" + e.getMessage(), e.fillInStackTrace());
             e.printStackTrace();
         }
         return null;
     }

     /**
      * post请求
      * @param actionUrl
      * @param params
      * @return
      */
     public static String httpPost(String actionUrl, Map<String, String> params){
         try{
             URL url = new URL(actionUrl);
             HttpURLConnection conn = (HttpURLConnection) url.openConnection();
             //因为这个是post请求,设立需要设置为true
             conn.setDoOutput(true);
             conn.setDoInput(true);
             // 设置以POST方式
             conn.setRequestMethod("POST");
             // Post 请求不能使用缓存
             conn.setUseCaches(false);
             conn.setInstanceFollowRedirects(true);
             // 配置本次连接的Content-type，配置为application/x-www-form-urlencoded的
             conn.setRequestProperty("Content-Type","application/x-www-form-urlencoded");
             // 连接，从postUrl.openConnection()至此的配置必须要在connect之前完成，
             // 要注意的是connection.getOutputStream会隐含的进行connect。
             if (cookie != null) {
                 conn.setRequestProperty("Cookie", cookie);
             }
             conn.connect();
             //DataOutputStream流
             DataOutputStream out = new DataOutputStream(conn.getOutputStream());
             //要上传的参数
             StringBuffer content = new StringBuffer();
             for (String key : params.keySet()) {
                 //String content = "par=" + URLEncoder.encode("ABCDEFG", "gb2312");
                 content.append(key).append("=").append(params.get(key)).append("&");
             }
             //将要上传的内容写入流中
             out.writeBytes(content.toString());
             //刷新、关闭
             out.flush();
             out.close();

             int statusCode = conn.getResponseCode();
             Log.i("", "---------------statusCode:" + statusCode);
             if (statusCode != 200) {
                 throw new HttpRequestException("server error");
             }
             if (conn.getHeaderField("Set-Cookie") != null) {
                 cookie = conn.getHeaderField("Set-Cookie");
             }
             //获取数据
             InputStream is = conn.getInputStream();
             int ch;
             StringBuilder b = new StringBuilder();
             while ((ch = is.read()) != -1) {
                 b.append((char) ch);
             }
             conn.disconnect();
             return b.toString();
         }catch(Exception e) {
             Log.i("", "---------------" + e.getMessage(), e.fillInStackTrace());
             e.printStackTrace();
         }
         return null;
     }

 }

1. application/x-www-form-urlencoded

最常见的 POST 提交数据的方式了。浏览器的原生 form 表单，如果不设置 enctype 属性，那么最终就会以 application/x-www-form-urlencoded方式提交数据。 
传递的key/val会经过URL转码，所以如果传递的参数存在中文或者特殊字符需要注意。

 //例子
 //b=曹,a=1

 POST  HTTP/1.1(CRLF)
 Host: www.example.com(CRLF)
 Content-Type: application/x-www-form-urlencoded(CRLF)
 Cache-Control: no-cache(CRLF)
 (CRLF)
 b=%E6%9B%B9&a=1(CRLF)
 //这里b参数的值"曹"因为URL转码变成其他的字符串了

2. text/xml

 //例子

 POST http://www.example.com HTTP/1.1(CRLF)
 Content-Type: text/xml(CRLF)
 (CRLF)
 <?xml version="1.0"?>
 <resource>
     <id>123</id>
     <params>
         <name>
             <value>homeway</value>
         </name>
         <age>
             <value>22</value>
         </age>
     </params>
 </resource>

3.application/json

 //例子
 //传递json

 POST  HTTP/1.1(CRLF)
 Host: www.example.com(CRLF)
 Content-Type: application/json(CRLF)
 Cache-Control: no-cache(CRLF)
 Content-Length: 24(CRLF)
 (CRLF)
 {
     "a":1,
     "b":"hello"
 }

4. multipart/form-data

使用表单上传文件时，必须让 form 的 enctyped 等于这个值。 
并且Http协议会使用boundary来分割上传的参数

 //例子
 //a="曹",file1是一个文件

 POST  HTTP/1.1(CRLF)
 Host: www.example.com(CRLF)
 //注意data;和boundary之间有一个空格,并且----WebKitFormBoundary7MA4YWxkTrZu0gW是可以自定义的
 Content-Type: multipart/form-data; boundary=----WebKitFormBoundary7MA4YWxkTrZu0gW(CRLF)
 Cache-Control: no-cache(CRLF)
 Content-Length: 728
 (CRLF)
 //如果有Content-Length的话，则Content-Length指下面所有的字节总数，包括boundary
 //这里用自定义的boundary来进行分割,注意会在头部加多"--"
 ------WebKitFormBoundary7MA4YWxkTrZu0gW(CRLF)
 Content-Disposition: form-data; name="a"(CRLF)
 (CRLF)
 曹(CRLF)
 ------WebKitFormBoundary7MA4YWxkTrZu0gW(CRLF)
 Content-Disposition: form-data; name="file1"; filename="1.jpg"
 Content-Type: application/octet-stream(CRLF)
 (CRLF)
 //此处是参数file1 对应的文件的二进制数据
 [654dfasalk;af&6…](CRLF)
 //最后一个boundary会分别在头部和尾部加多"--"
 ------WebKitFormBoundary7MA4YWxkTrZu0gW--(CRLF)

//多个文件同时上传

 POST  HTTP/1.1(CRLF)
 Host: www.example.com(CRLF)
 //注意data;和boundary之间有一个空格,并且----WebKitFormBoundary7MA4YWxkTrZu0gW是可以自定义的
 Content-Type: multipart/form-data; boundary=---------------------------418888951815204591197893077
 Cache-Control: no-cache(CRLF)
 Content-Length: 12138(CRLF)
 (CRLF)
 -----------------------------418888951815204591197893077(CRLF)
 // 文件1的头部boundary
 Content-Disposition: form-data; name="userfile[]"; filename="文件1.md"(CRLF)
 Content-Type: text/markdown(CRLF)
 (CRLF)
 // 文件1内容开始
 // ...
 // 文件1内容结束
 -----------------------------418888951815204591197893077(CRLF)
 // 文件2的头部boundary
 Content-Disposition: form-data; name="userfile[]"; filename="文件2"(CRLF)
 Content-Type: application/octet-stream(CRLF)
 (CRLF)
 // 文件2内容开始
 // ...
 // 文件2内容结束
 -----------------------------418888951815204591197893077(CRLF)
 // 文件3的头部boundary
 Content-Disposition: form-data; name="userfile[]"; filename="文件3"(CRLF)
 Content-Type: application/octet-stream(CRLF)
 (CRLF)
 // 文件3内容开始
 // ...
 // 文件3内容结束
 -----------------------------418888951815204591197893077(CRLF)
 // 参数username的头部boundary
 Content-Disposition: form-data; name="username"(CRLF)
 (CRLF)
 zhangsan
 -----------------------------418888951815204591197893077(CRLF)
 // 参数password的头部boundary
 Content-Disposition: form-data; name="password"(CRLF)
 (CRLF)
 zhangxx
 -----------------------------418888951815204591197893077--
 // 尾部boundary，表示结束

注意 ：(CRLF)指\r\n