Http使用post方式提交数据(使用java标准接口)
本文内容:使用java标准接口,实现http用post方式提交数据。
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程序组成部分:
1.客户端用eclipse HttpUtils.java 标准java接口,实现http用post方式提交数据。 (用post方式提交 username 和 password)
2.服务器端用myeclipse+tomcat 对客户端请求进行相应。(若用户名密码正确,则返回字符串"login is success !" ,不正确则返回字符串“login is fail !”)
重点注意点:
1. public static String sendPostMessage(Map<String,String> params , String encode)
目的: 在客户端向服务器端发送 数据 params , 最终获取从服务器返回的输入流,最终将该输入流转换成字符串。注意使用标准java接口如何实现http的post请求,成功与服务器连接,并且获得从服务器端响应返回的数据。
2. public String String changInputStream(InputStream inputStream , String encode)
目的: 将一个输入流按照指定编码方式转变成一个字符串。(本例中是指,将从服务器端返回的输入流InputStream转变成一个字符串String,编码方式是encode方式)
3. Map<String ,String> 的实例化方法及迭代方法
Map 的实例化方法:
Map<String, String> params = new HashMap<String, String>();
params.put("username", "admin");
params.put("password", "123");
Map 的迭代方法:
StringBuffer stringBuffer = new StringBuffer();
for (Map.Entry<String, String> entry : params.entrySet()) {
try {
stringBuffer
.append(entry.getKey())
.append("=")
.append(URLEncoder.encode(entry.getValue(), encode))
.append("&");
} catch (UnsupportedEncodingException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
// 删掉最后一个 & 字符
stringBuffer.deleteCharAt(stringBuffer.length() - 1);
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程序思路:
1. 客户端建立http链接httpURLConnection,使用OutputStream向服务器传入数据
2. 获得从服务器端返回的输入流InputStream
3. 将InputStream转换成字符串String
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程序运行效果:
1.客户端运行效果
2. 服务器端运行结果
关键代码:
1. 客户端 HttpUtils.java
package com.http.post; 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 { // 表示服务器端的url private static String PATH = "http://192.168.0.100:8080/myhttp/servlet/LoginAction"; private static URL url; public HttpUtils() { // TODO Auto-generated constructor stub } static { try { url = new URL(PATH); } catch (MalformedURLException e) { // TODO Auto-generated catch block e.printStackTrace(); } } /* * params 填写的URL的参数 encode 字节编码 */ public static String sendPostMessage(Map<String, String> params, String encode) { StringBuffer stringBuffer = new StringBuffer(); if (params != null && !params.isEmpty()) { for (Map.Entry<String, String> entry : params.entrySet()) { try { stringBuffer .append(entry.getKey()) .append("=") .append(URLEncoder.encode(entry.getValue(), encode)) .append("&"); } catch (UnsupportedEncodingException e) { // TODO Auto-generated catch block e.printStackTrace(); } } // 删掉最后一个 & 字符 stringBuffer.deleteCharAt(stringBuffer.length() - 1); System.out.println("-->>" + stringBuffer.toString()); try { HttpURLConnection httpURLConnection = (HttpURLConnection) url .openConnection(); httpURLConnection.setConnectTimeout(3000); httpURLConnection.setDoInput(true);// 从服务器获取数据 httpURLConnection.setDoOutput(true);// 向服务器写入数据 // 获得上传信息的字节大小及长度 byte[] mydata = stringBuffer.toString().getBytes(); // 设置请求体的类型 httpURLConnection.setRequestProperty("Content-Type", "application/x-www-form-urlencoded"); httpURLConnection.setRequestProperty("Content-Lenth", String.valueOf(mydata.length)); // 获得输出流,向服务器输出数据 OutputStream outputStream = (OutputStream) httpURLConnection .getOutputStream(); outputStream.write(mydata); // 获得服务器响应的结果和状态码 int responseCode = httpURLConnection.getResponseCode(); if (responseCode == 200) { // 获得输入流,从服务器端获得数据 InputStream inputStream = (InputStream) httpURLConnection .getInputStream(); return (changeInputStream(inputStream, encode)); } } 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 Map<String, String> params = new HashMap<String, String>(); params.put("username", "admin"); params.put("password", "123"); String result = sendPostMessage(params, "utf-8"); System.out.println("-result->>" + result); } }
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. <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"); //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. <br> * * @throws ServletException * if an error occurs */ public void init() throws ServletException { // Put your code here } }
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