Http使用post方式提交数据（使用apache标准接口）

本文：目的和前一篇一样，唯一区别是本文用apache标准接口进行http的post提交数据，而前一篇是用 java标准接口实现。

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重点：

1. public static String sendHttpClientPost(String path, Map params, String encode)

    内部用apache接口实现http的post提交数据。

2. public static String changeInputStream(InputStream inputStream, String encode)

     实现 将一个输入流转变成一个字符串，用指定编码。

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注意点：

一.用apache标准接口实现http 的Post提交数据的 关键步骤？

1. 将参数封装到表单请求体中。

    UrlEncodedFormEntity entity = new UrlEncodedFormEntity(list, encode);

2. 使用post方式提交数据
    HttpPost httpPost = new HttpPost(path);
    httpPost.setEntity(entity);

3. 执行post请求，并获取服务器端的响应HttpResponse

   DefaultHttpClient client = new DefaultHttpClient();
   HttpResponse httpResponse = client.execute(httpPost);

4. 获取服务器端返回的状态码和输入流，将输入流转换成字符串

    if (httpResponse.getStatusLine().getStatusCode() == 200) {
       InputStream inputStream = httpResponse.getEntity().getContent();
       return changeInputStream(inputStream, encode);
    }

二. 编写次程序，要将http协议包添加到 build path , http 协议包在我的资源中。

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程序运行结果图：

1. 客户端结果图

2. 服务器端结果图

关键代码：

1. 客户端 HttpUtil.java

package com.httpclient.post;

import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.UnsupportedEncodingException;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import org.apache.http.HttpResponse;
import org.apache.http.NameValuePair;
import org.apache.http.client.ClientProtocolException;
import org.apache.http.client.entity.UrlEncodedFormEntity;
import org.apache.http.client.methods.HttpPost;
import org.apache.http.impl.client.DefaultHttpClient;
import org.apache.http.message.BasicNameValuePair;

public class HttpUtils {

	public HttpUtils() {
		// TODO Auto-generated constructor stub
	}

	//用apache接口实现http的post提交数据
	public static String sendHttpClientPost(String path,
			Map params, String encode) {

		List list = new ArrayList();
		if (params != null && !params.isEmpty()) {
			for (Map.Entry entry : params.entrySet()) {
				list.add(new BasicNameValuePair(entry.getKey(), entry
						.getValue()));
			}
		}

		try {
			// 实现将请求的参数封装到表单中，即请求体中
			UrlEncodedFormEntity entity = new UrlEncodedFormEntity(list, encode);
			// 使用post方式提交数据
			HttpPost httpPost = new HttpPost(path);
			httpPost.setEntity(entity);
            // 执行post请求，并获取服务器端的响应HttpResponse
			DefaultHttpClient client = new DefaultHttpClient();
			HttpResponse httpResponse = client.execute(httpPost);
			
			//获取服务器端返回的状态码和输入流，将输入流转换成字符串
			if (httpResponse.getStatusLine().getStatusCode() == 200) {
				InputStream inputStream = httpResponse.getEntity().getContent();
				return changeInputStream(inputStream, encode);
			}

		} catch (UnsupportedEncodingException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		} catch (ClientProtocolException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		} catch (IOException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}

		return "";

	}

	/*
	 * // 把从输入流InputStream按指定编码格式encode变成字符串String
	 */
	public static String changeInputStream(InputStream inputStream,
			String encode) {

		// ByteArrayOutputStream 一般叫做内存流
		ByteArrayOutputStream byteArrayOutputStream = new ByteArrayOutputStream();
		byte[] data = new byte[1024];
		int len = 0;
		String result = "";
		if (inputStream != null) {

			try {
				while ((len = inputStream.read(data)) != -1) {
					byteArrayOutputStream.write(data, 0, len);

				}
				result = new String(byteArrayOutputStream.toByteArray(), encode);

			} catch (IOException e) {
				// TODO Auto-generated catch block
				e.printStackTrace();
			}

		}

		return result;
	}

	/**
	 * @param args
	 */
	public static void main(String[] args) {
		// TODO Auto-generated method stub
		String path = "http://192.168.0.100:8080/myhttp/servlet/LoginAction";
		Map params = new HashMap();
		params.put("username", "admin");
		params.put("password", "123");
		String result = sendHttpClientPost(path, params, "utf-8");
		System.out.println("-result->>" + result);

	}

}

2. 服务器端servlet LoginAction.java

package com.login.manager;

import java.io.IOException;
import java.io.PrintWriter;

import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

public class LoginAction extends HttpServlet {

	/**
	 * Constructor of the object.
	 */
	public LoginAction() {
		super();
	}

	/**
	 * Destruction of the servlet. 

	 */
	public void destroy() {
		super.destroy(); // Just puts "destroy" string in log
		// Put your code here
	}

	/**
	 * The doGet method of the servlet. 

	 * 
	 * This method is called when a form has its tag value method equals to get.
	 * 
	 * @param request
	 *            the request send by the client to the server
	 * @param response
	 *            the response send by the server to the client
	 * @throws ServletException
	 *             if an error occurred
	 * @throws IOException
	 *             if an error occurred
	 */
	public void doGet(HttpServletRequest request, HttpServletResponse response)
			throws ServletException, IOException {

		this.doPost(request, response);
	}

	/**
	 * The doPost method of the servlet. 

	 * 
	 * This method is called when a form has its tag value method equals to
	 * post.
	 * 
	 * @param request
	 *            the request send by the client to the server
	 * @param response
	 *            the response send by the server to the client
	 * @throws ServletException
	 *             if an error occurred
	 * @throws IOException
	 *             if an error occurred
	 */
	public void doPost(HttpServletRequest request, HttpServletResponse response)
			throws ServletException, IOException {

		response.setContentType("text/html;charset=utf-8");
		request.setCharacterEncoding("utf-8");
		response.setCharacterEncoding("utf-8");
		//客户端 HttpUtils并没有写request方法是post ,但服务器端可自动识别
		String method = request.getMethod();
		System.out.println("request method :"+method);
		
		
		PrintWriter out = response.getWriter();
		String username = request.getParameter("username");
		System.out.println("-username->>"+username);
		
		String password = request.getParameter("password");
		System.out.println("-password->>"+password);

		if (username.equals("admin") && password.equals("123")) {
			// 表示服务器段返回的结果
			out.print("login is success !");

		} else {
			out.print("login is fail !");
		}

		out.flush();
		out.close();
	}

	/**
	 * Initialization of the servlet. 

	 * 
	 * @throws ServletException
	 *             if an error occurs
	 */
	public void init() throws ServletException {
		// Put your code here
	}

}