Android 网络编程（一）

概述

一。Android平台网络相关API接口

　　1.java.net.*(标准Java接口)

　　　　java.net.*提供与联网有关的类，包括流、数据包套接字(socket)、Internet协议、常见Http处理等。比如：创建URL，以及URLConnection/HttpURLConnection对象、设置链接参数、链接到服务器、向服务器写数据、从服务器读取数据等通信。这些在Java网络编程中均有涉及。

　　

　　2.org.apache 接口

　　　　

　　　　对于大部分应用程序而言JDK本身提供的网络功能已远远不够，这时就需要Android提供的Apache HttpClient了。它是一个开源项目，功能更加完善，为客户端的Http编程提供高效、最新、功能丰富的工具包支持。

　　3.Android.net.*(Android网络接口)

　　　　常常使用此包下的类进行Android特有的网络编程，如：访问WiFi，访问Android联网信息，邮件等功能。

二。服务器端返回客户端的内容有三种方式

　　

　　1.以HTML代码的形式返回。

　　2.以XML字符串的形式返回，做Android开发时这种方式比较多。返回的数据需要通过XML解析（SAX、DOM，Pull,等）器进行解析（必备知识）。

　　3.以json对象的方式返回。

封装的工具类

发送GET请求；

发送POST请求；

发送文件上传请求；

　发送XML数据；

package com.kest.util;

import java.io.BufferedReader;
import java.io.ByteArrayOutputStream;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.OutputStream;
import java.net.HttpURLConnection;
import java.net.InetAddress;
import java.net.Socket;
import java.net.URL;
import java.net.URLConnection;
import java.net.URLEncoder;
import java.util.Map;

/**
*
*
*         (1)发送GET请求；
*
*         (2)发送POST请求；
*
*         (3)发送文件上传请求；
*
*         (4)发送XML数据；
*/

public class HttpRequestUtil {
/**
* 发送GET请求
*
* @param url
* @param params
* @param headers
* @return URLConnection
* @throws Exception
*/
public static URLConnection sendGetRequest(String url,
Map<String, String> params, Map<String, String> headers)
throws Exception {
StringBuilder sb = new StringBuilder(url);
// 如果是GET请求，则请求参数在URL中
if (params != null && !params.isEmpty()) {
sb.append("?");
for (Map.Entry<String, String> entry : params.entrySet()) {
sb.append(entry.getKey()).append("=")
.append(URLEncoder.encode(entry.getValue(), "UTF-8"))
.append("&");
}
sb.deleteCharAt(sb.length() - 1);
}
URL url1 = new URL(sb.toString());
HttpURLConnection conn = (HttpURLConnection) url1.openConnection();
conn.setRequestMethod("GET");
// 设置请求头
if (headers != null && !headers.isEmpty()) {
for (Map.Entry<String, String> entry : headers.entrySet()) {
conn.setRequestProperty(entry.getKey(), entry.getValue());
}
}
conn.getResponseCode();
return conn;
}

/**
* 发送POST请求
*
* @param url
* @param params
* @param headers
* @return URLConnection
* @throws Exception
*/
public static URLConnection sendPostRequest(String url,
Map<String, String> params, Map<String, String> headers)
throws Exception {
StringBuilder sb = new StringBuilder();
// 如果存在参数，则放在HTTP请求体，形如name=aaa&age=10
if (params != null && !params.isEmpty()) {
for (Map.Entry<String, String> entry : params.entrySet()) {
sb.append(entry.getKey()).append("=")
.append(URLEncoder.encode(entry.getValue(), "UTF-8"))
.append("&");
}
sb.deleteCharAt(sb.length() - 1);
}
URL url1 = new URL(url);
HttpURLConnection conn = (HttpURLConnection) url1.openConnection();
conn.setRequestMethod("POST");
conn.setDoOutput(true);
OutputStream out = conn.getOutputStream();
out.write(sb.toString().getBytes("UTF-8"));
if (headers != null && !headers.isEmpty()) {
for (Map.Entry<String, String> entry : headers.entrySet()) {
conn.setRequestProperty(entry.getKey(), entry.getValue());
}
}
conn.getResponseCode(); // 为了发送成功
return conn;
}

/**
* 直接通过HTTP协议提交数据到服务器,实现如下面表单提交功能: <FORM METHOD=POST
* ACTION="http://192.168.0.200:8080/ssi/fileload/test.do"
* enctype="multipart/form-data"> <INPUT TYPE="text" NAME="name"> <INPUT
* TYPE="text" NAME="id"> <input type="file" name="imagefile"/> <input
* type="file" name="zip"/> </FORM>
*
* @param path
*
* @param params
*            请求参数 key为参数名,value为参数值
* @param file
*            上传文件
*/
public static boolean uploadFiles(String path, Map<String, String> params,
FormFile[] files) throws Exception {
final String BOUNDARY = "---------------------------7da2137580612"; // 数据分隔线
final String endline = "--" + BOUNDARY + "--\r\n";// 数据结束标志

int fileDataLength = 0;
if (files != null && files.length != 0) {
for (FormFile uploadFile : files) {// 得到文件类型数据的总长度
StringBuilder fileExplain = new StringBuilder();
fileExplain.append("--");
fileExplain.append(BOUNDARY);
fileExplain.append("\r\n");
fileExplain.append("Content-Disposition: form-data;name=\""
+ uploadFile.getParameterName() + "\";filename=\""
+ uploadFile.getFilname() + "\"\r\n");
fileExplain.append("Content-Type: "
+ uploadFile.getContentType() + "\r\n\r\n");
fileExplain.append("\r\n");
fileDataLength += fileExplain.length();
if (uploadFile.getInStream() != null) {
fileDataLength += uploadFile.getFile().length();
} else {
fileDataLength += uploadFile.getData().length;
}
}
}
StringBuilder textEntity = new StringBuilder();
if (params != null && !params.isEmpty()) {
for (Map.Entry<String, String> entry : params.entrySet()) {// 构造文本类型参数的实体数据
textEntity.append("--");
textEntity.append(BOUNDARY);
textEntity.append("\r\n");
textEntity.append("Content-Disposition: form-data; name=\""
+ entry.getKey() + "\"\r\n\r\n");
textEntity.append(entry.getValue());
textEntity.append("\r\n");
}
}
// 计算传输给服务器的实体数据总长度
int dataLength = textEntity.toString().getBytes().length
+ fileDataLength + endline.getBytes().length;

URL url = new URL(path);
int port = url.getPort() == -1 ? 80 : url.getPort();
Socket socket = new Socket(InetAddress.getByName(url.getHost()), port);
OutputStream outStream = socket.getOutputStream();
// 下面完成HTTP请求头的发送
String requestmethod = "POST " + url.getPath() + " HTTP/1.1\r\n";
outStream.write(requestmethod.getBytes());
String accept = "Accept: image/gif, image/jpeg, image/pjpeg, image/pjpeg, application/x-shockwave-flash, application/xaml+xml, application/vnd.ms-xpsdocument, application/x-ms-xbap, application/x-ms-application, application/vnd.ms-excel, application/vnd.ms-powerpoint, application/msword, */*\r\n";
outStream.write(accept.getBytes());
String language = "Accept-Language: zh-CN\r\n";
outStream.write(language.getBytes());
String contenttype = "Content-Type: multipart/form-data; boundary="
+ BOUNDARY + "\r\n";
outStream.write(contenttype.getBytes());
String contentlength = "Content-Length: " + dataLength + "\r\n";
outStream.write(contentlength.getBytes());
String alive = "Connection: Keep-Alive\r\n";
outStream.write(alive.getBytes());
String host = "Host: " + url.getHost() + ":" + port + "\r\n";
outStream.write(host.getBytes());
// 写完HTTP请求头后根据HTTP协议再写一个回车换行
outStream.write("\r\n".getBytes());
// 把所有文本类型的实体数据发送出来
outStream.write(textEntity.toString().getBytes());
// 把所有文件类型的实体数据发送出来
if (files != null && files.length != 0) {
for (FormFile uploadFile : files) {
StringBuilder fileEntity = new StringBuilder();
fileEntity.append("--");
fileEntity.append(BOUNDARY);
fileEntity.append("\r\n");
fileEntity.append("Content-Disposition: form-data;name=\""
+ uploadFile.getParameterName() + "\";filename=\""
+ uploadFile.getFilname() + "\"\r\n");
fileEntity.append("Content-Type: "
+ uploadFile.getContentType() + "\r\n\r\n");
outStream.write(fileEntity.toString().getBytes());
if (uploadFile.getInStream() != null) {
byte[] buffer = new byte[1024];
int len = 0;
while ((len = uploadFile.getInStream()
.read(buffer, 0, 1024)) != -1) {
outStream.write(buffer, 0, len);
}
uploadFile.getInStream().close();
} else {
outStream.write(uploadFile.getData(), 0,
uploadFile.getData().length);
}
outStream.write("\r\n".getBytes());
}
}
// 下面发送数据结束标志，表示数据已经结束
outStream.write(endline.getBytes());
BufferedReader reader = new BufferedReader(new InputStreamReader(
socket.getInputStream()));
if (reader.readLine().indexOf("200") == -1) {// 读取web服务器返回的数据，判断请求码是否为200，如果不是200，代表请求失败
return false;
}
outStream.flush();
outStream.close();
reader.close();
socket.close();
return true;
}

/**
* 提交数据到服务器
*
* @param path
*
* @param params
*            请求参数 key为参数名,value为参数值
* @param file
*            上传文件
*/
public static boolean uploadFile(String path, Map<String, String> params,
FormFile file) throws Exception {
return uploadFiles(path, params, new FormFile[] { file });
}

/**
* 将输入流转为字节数组
*
* @param inStream
* @return
* @throws Exception
*/
public static byte[] read2Byte(InputStream inStream) throws Exception {
ByteArrayOutputStream outSteam = new ByteArrayOutputStream();
byte[] buffer = new byte[1024];
int len = 0;
while ((len = inStream.read(buffer)) != -1) {
outSteam.write(buffer, 0, len);
}
outSteam.close();
inStream.close();
return outSteam.toByteArray();
}

/**
* 将输入流转为字符串
*
* @param inStream
* @return
* @throws Exception
*/
public static String read2String(InputStream inStream) throws Exception {
ByteArrayOutputStream outSteam = new ByteArrayOutputStream();
byte[] buffer = new byte[1024];
int len = 0;
while ((len = inStream.read(buffer)) != -1) {
outSteam.write(buffer, 0, len);
}
outSteam.close();
inStream.close();
return new String(outSteam.toByteArray(), "UTF-8");
}

/**
* 发送xml数据
*
* @param path
*            请求地址
* @param xml
*            xml数据
* @param encoding
*            编码
* @return
* @throws Exception
*/
public static byte[] postXml(String path, String xml, String encoding)
throws Exception {
byte[] data = xml.getBytes(encoding);
URL url = new URL(path);
HttpURLConnection conn = (HttpURLConnection) url.openConnection();
conn.setRequestMethod("POST");
conn.setDoOutput(true);
conn.setRequestProperty("Content-Type", "text/xml; charset=" + encoding);
conn.setRequestProperty("Content-Length", String.valueOf(data.length));
conn.setConnectTimeout(5 * 1000);
OutputStream outStream = conn.getOutputStream();
outStream.write(data);
outStream.flush();
outStream.close();
if (conn.getResponseCode() == 200) {
return read2Byte(conn.getInputStream());
}
return null;
}
}