post提交数据

我们知道通过Get方式提交的数据是作为Url地址的一部分进行提交，而且对字节数的长度也有限制，与Get方式类似，http-post参数也是被URL编码的，然而它的变量名和变量值不作为URL的一部分被传送，而是放在实际的HTTP请求消息内部被传送。

可以通过如下的代码设置POST提交方式参数：

HttpURLConnection urlConnection = (HttpURLConnection)url.openConnection();
urlConnection.setConnectTimeout(3000);
urlConnection.setRequestMethod("POST"); //以post请求方式提交
urlConnection.setDoInput(true);     //读取数据
urlConnection.setDoOutput(true);    //向服务器写数据
//获取上传信息的大小和长度
byte[] myData =  stringBuilder.toString().getBytes();
//设置请求体的类型是文本类型,表示当前提交的是文本数据
urlConnection.setRequestProperty("Content-Type", "application/x-www-form-urlencoded");
urlConnection.setRequestProperty("Content-Length", String.valueOf(myData.length));

	HttpURLConnection urlConnection = (HttpURLConnection)url.openConnection();
	urlConnection.setConnectTimeout(3000);
	urlConnection.setRequestMethod("POST");	//以post请求方式提交
	urlConnection.setDoInput(true);		//读取数据
	urlConnection.setDoOutput(true);	//向服务器写数据
	//获取上传信息的大小和长度
	byte[] myData = stringBuilder.toString().getBytes();
	//设置请求体的类型是文本类型,表示当前提交的是文本数据
	urlConnection.setRequestProperty("Content-Type", "application/x-www-form-urlencoded");
	urlConnection.setRequestProperty("Content-Length", String.valueOf(myData.length));

这里使用一个案例来看一下如何使用post方式提交数据到服务器：

首先我们创建一个java project，只要创建一个类就行，我们创建一个HttpUtils.java类，

【代码如下】：

package com.wujay.utils;

import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.io.UnsupportedEncodingException;
import java.net.HttpURLConnection;
import java.net.MalformedURLException;
import java.net.URL;
import java.net.URLEncoder;
import java.util.HashMap;
import java.util.Map;

public class HttpUtils {
    private static String PATH =  "http://bdfngdg:8080/myhttp/servlet/LoginAction"; // 服务端地址
    private static URL url;

    public HttpUtils() {
        super();
    }

    // 静态代码块实例化url
    static {
        try {
            url = new URL(PATH);
        } catch (MalformedURLException e) {
            e.printStackTrace();
        }
    }

    /**
     * 发送消息体到服务端
     *
     * @param params
     * @param encode
     * @return
     */
    public static String sendPostMessage(Map<String, String> params,
            String encode) {
        StringBuilder stringBuilder = new StringBuilder();
        if (params != null && !params.isEmpty()) {
            for (Map.Entry<String, String> entry : params.entrySet()) {
                try {
                    stringBuilder
                            .append(entry.getKey())
                            .append("=")
                            .append(URLEncoder.encode(entry.getValue(), encode))
                            .append("&");
                } catch (UnsupportedEncodingException e) {
                    e.printStackTrace();
                }
            }
            stringBuilder.deleteCharAt(stringBuilder.length() - 1);
            try {
                HttpURLConnection urlConnection = (HttpURLConnection) url
                        .openConnection();
                urlConnection.setConnectTimeout(3000);
                urlConnection.setRequestMethod("POST"); // 以post请求方式提交
                urlConnection.setDoInput(true); // 读取数据
                urlConnection.setDoOutput(true); // 向服务器写数据
                // 获取上传信息的大小和长度
                byte[] myData = stringBuilder.toString().getBytes();
                // 设置请求体的类型是文本类型,表示当前提交的是文本数据
                urlConnection.setRequestProperty("Content-Type",
                        "application/x-www-form-urlencoded");
                urlConnection.setRequestProperty("Content-Length",
                        String.valueOf(myData.length));
                // 获得输出流，向服务器输出内容
                OutputStream outputStream = urlConnection.getOutputStream();
                // 写入数据
                outputStream.write(myData, 0, myData.length);
                outputStream.close();
                // 获得服务器响应结果和状态码
                int responseCode = urlConnection.getResponseCode();
                if (responseCode == 200) {
                    // 取回响应的结果
                    return changeInputStream(urlConnection.getInputStream(),
                            encode);
                }
            } catch (IOException e) {
                e.printStackTrace();
            }

        }
        return "";
    }

    /**
     * 将一个输入流转换成指定编码的字符串
     *
     * @param inputStream
     * @param encode
     * @return
     */
    private static String changeInputStream(InputStream inputStream,
            String encode) {

        // 内存流
        ByteArrayOutputStream byteArrayOutputStream = new ByteArrayOutputStream();
        byte[] data =  new byte[1024];
        int len = 0;
        String result = null;
        if (inputStream != null) {
            try {
                while ((len =  inputStream.read(data)) != -1) {
                    byteArrayOutputStream.write(data, 0, len);
                }
                result = new String(byteArrayOutputStream.toByteArray(), encode);
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
        return result;
    }

    /**
     * @param args
     */
    public static void main(String[] args) {
        Map<String, String> map = new HashMap<String, String>();
        map.put("username", "admin");
        map.put("password", "123456");
        String result = sendPostMessage(map, "UTF-8");
        System.out.println(">>>" + result);
    }

}

package com.wujay.utils;

import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.io.UnsupportedEncodingException;
import java.net.HttpURLConnection;
import java.net.MalformedURLException;
import java.net.URL;
import java.net.URLEncoder;
import java.util.HashMap;
import java.util.Map;

public class HttpUtils {
	private static String PATH = "http://bdfngdg:8080/myhttp/servlet/LoginAction"; // 服务端地址
	private static URL url;

	public HttpUtils() {
		super();
	}

	// 静态代码块实例化url
	static {
		try {
			url = new URL(PATH);
		} catch (MalformedURLException e) {
			e.printStackTrace();
		}
	}

	/**
	 * 发送消息体到服务端
	 * 
	 * @param params
	 * @param encode
	 * @return
	 */
	public static String sendPostMessage(Map<String, String> params,
			String encode) {
		StringBuilder stringBuilder = new StringBuilder();
		if (params != null && !params.isEmpty()) {
			for (Map.Entry<String, String> entry : params.entrySet()) {
				try {
					stringBuilder
							.append(entry.getKey())
							.append("=")
							.append(URLEncoder.encode(entry.getValue(), encode))
							.append("&");
				} catch (UnsupportedEncodingException e) {
					e.printStackTrace();
				}
			}
			stringBuilder.deleteCharAt(stringBuilder.length() - 1);
			try {
				HttpURLConnection urlConnection = (HttpURLConnection) url
						.openConnection();
				urlConnection.setConnectTimeout(3000);
				urlConnection.setRequestMethod("POST"); // 以post请求方式提交
				urlConnection.setDoInput(true); // 读取数据
				urlConnection.setDoOutput(true); // 向服务器写数据
				// 获取上传信息的大小和长度
				byte[] myData = stringBuilder.toString().getBytes();
				// 设置请求体的类型是文本类型,表示当前提交的是文本数据
				urlConnection.setRequestProperty("Content-Type",
						"application/x-www-form-urlencoded");
				urlConnection.setRequestProperty("Content-Length",
						String.valueOf(myData.length));
				// 获得输出流，向服务器输出内容
				OutputStream outputStream = urlConnection.getOutputStream();
				// 写入数据
				outputStream.write(myData, 0, myData.length);
				outputStream.close();
				// 获得服务器响应结果和状态码
				int responseCode = urlConnection.getResponseCode();
				if (responseCode == 200) {
					// 取回响应的结果
					return changeInputStream(urlConnection.getInputStream(),
							encode);
				}
			} catch (IOException e) {
				e.printStackTrace();
			}

		}
		return "";
	}

	/**
	 * 将一个输入流转换成指定编码的字符串
	 * 
	 * @param inputStream
	 * @param encode
	 * @return
	 */
	private static String changeInputStream(InputStream inputStream,
			String encode) {

		// 内存流
		ByteArrayOutputStream byteArrayOutputStream = new ByteArrayOutputStream();
		byte[] data = new byte[1024];
		int len = 0;
		String result = null;
		if (inputStream != null) {
			try {
				while ((len = inputStream.read(data)) != -1) {
					byteArrayOutputStream.write(data, 0, len);
				}
				result = new String(byteArrayOutputStream.toByteArray(), encode);
			} catch (IOException e) {
				e.printStackTrace();
			}
		}
		return result;
	}

	/**
	 * @param args
	 */
	public static void main(String[] args) {
		Map<String, String> map = new HashMap<String, String>();
		map.put("username", "admin");
		map.put("password", "123456");
		String result = sendPostMessage(map, "UTF-8");
		System.out.println(">>>" + result);
	}

}

我们再创建一个服务端工程，一个web project，这里创建一个myhttp的工程，先给它创建一个servlet，用来接收参数访问。

创建的servlet配置如下：

<servlet>
        <description>This is the description of my J2EE component</description>
        <display-name>This is the display name of my J2EE component</display-name>
        <servlet-name>LoginAction</servlet-name>
        <servlet-class>com.login.manager.LoginAction</servlet-class>
    </servlet>

    <servlet-mapping>
        <servlet-name>LoginAction</servlet-name>
        <url-pattern>/servlet/LoginAction</url-pattern>
    </servlet-mapping>

<servlet>
		<description>This is the description of my J2EE component</description>
		<display-name>This is the display name of my J2EE component</display-name>
		<servlet-name>LoginAction</servlet-name>
		<servlet-class>com.login.manager.LoginAction</servlet-class>
	</servlet>

	<servlet-mapping>
		<servlet-name>LoginAction</servlet-name>
		<url-pattern>/servlet/LoginAction</url-pattern>
	</servlet-mapping>

建立的LoginAction.java类继承HttpServlet:

[html] view plain copy print ?

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

    /**
     * The doGet method of the servlet. <br>
     *
     * 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. <br>
     *
     * 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");
        PrintWriter out = response.getWriter();
        String userName = request.getParameter("username");
        String passWord = request.getParameter("password");
        System.out.println("userName:"+userName);
        System.out.println("passWord:"+passWord);
        if(userName.equals("admin") && passWord.equals("123456")){
            out.print("login successful!");
        }else{
            out.print("login failed");
        }
        out.flush();
        out.close();
    }

    /**
     * Initialization of the servlet. <br>
     *
     * @throws ServletException if an error occurs
     */
    public void init() throws ServletException {
        // Put your code here
    }

}

转自：http://blog.csdn.net/wulianghuan/article/details/8626551