Post方式比Get方式要复杂一点,因为该方式需要将请求的参数放在http请求的正文中,所以需要构造请求体。
步骤:
1.构造URL
URL url = new URL(PATH);
2.设置连接
HttpURLConnection connection = (HttpURLConnection) url.openConnection(); connection.setConnectTimeout(3000); connection.setDoInput(true);//表示从服务器获取数据 connection.setDoOutput(true);//表示向服务器写数据 //获得上传信息的字节大小以及长度 connection.setRequestMethod("POST"); //是否使用缓存 connection.setUseCaches(false); //表示设置请求体的类型是文本类型 connection.setRequestProperty("Content-Type", "application/x-www-form-urlencoded"); connection.setRequestProperty("Content-Length", String.valueOf(mydata.length)); connection.connect();
3.写入请求正文
Map<String, String> params = new HashMap<String, String>(); params.put("username", "lili"); params.put("password", "123"); StringBuffer buffer = new StringBuffer(); try {//把请求的主体写入正文!! if(params != null&&!params.isEmpty()){ //迭代器 for(Map.Entry<String, String> entry : params.entrySet()){ buffer.append(entry.getKey()).append("="). append(URLEncoder.encode(entry.getValue(),encode)). append("&"); } } // System.out.println(buffer.toString()); //删除最后一个字符&,多了一个;主体设置完毕 buffer.deleteCharAt(buffer.length()-1); byte[] mydata = buffer.toString().getBytes(); //获得输出流,向服务器输出数据 OutputStream outputStream = connection.getOutputStream(); outputStream.write(mydata,0,mydata.length);
4.读取返回数据,关闭连接
//通常叫做内存流,写在内存中的 ByteArrayOutputStream outputStream = new ByteArrayOutputStream(); byte[] data = new byte[1024]; int len = 0; String result = ""; if(inputStream != null){ try { while((len = inputStream.read(data))!=-1){ data.toString(); outputStream.write(data, 0, len); } //result是在服务器端设置的doPost函数中的 result = new String(outputStream.toByteArray(),encode); outputStream.flush();
下面上代码:一个简单的Demo访问一个自建的Servlet:
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 { private static String PATH = "http://172.24.87.47:8088/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(); } } /** * @param params 填写的url的参数 * @param encode 字节编码 * @return */ public static String sendPostMessage(Map<String, String> params,String encode){ StringBuffer buffer = new StringBuffer(); try {//把请求的主体写入正文!! if(params != null&&!params.isEmpty()){ //迭代器 for(Map.Entry<String, String> entry : params.entrySet()){ buffer.append(entry.getKey()).append("="). append(URLEncoder.encode(entry.getValue(),encode)). append("&"); } } // System.out.println(buffer.toString()); //删除最后一个字符&,多了一个;主体设置完毕 buffer.deleteCharAt(buffer.length()-1); byte[] mydata = buffer.toString().getBytes(); HttpURLConnection connection = (HttpURLConnection) url.openConnection(); connection.setConnectTimeout(3000); connection.setDoInput(true);//表示从服务器获取数据 connection.setDoOutput(true);//表示向服务器写数据 //获得上传信息的字节大小以及长度 connection.setRequestMethod("POST"); //是否使用缓存 connection.setUseCaches(false); //表示设置请求体的类型是文本类型 connection.setRequestProperty("Content-Type", "application/x-www-form-urlencoded"); connection.setRequestProperty("Content-Length", String.valueOf(mydata.length)); connection.connect(); //连接,不写也可以。。??有待了解 //获得输出流,向服务器输出数据 OutputStream outputStream = connection.getOutputStream(); outputStream.write(mydata,0,mydata.length); //获得服务器响应的结果和状态码 int responseCode = connection.getResponseCode(); if(responseCode == HttpURLConnection.HTTP_OK){ return changeInputeStream(connection.getInputStream(),encode); } } catch (UnsupportedEncodingException e) { // TODO Auto-generated catch block e.printStackTrace(); } catch (IOException e) { // TODO Auto-generated catch block e.printStackTrace(); } return ""; } /** * 将一个输入流转换成字符串 * @param inputStream * @param encode * @return */ private static String changeInputeStream(InputStream inputStream,String encode) { //通常叫做内存流,写在内存中的 ByteArrayOutputStream outputStream = new ByteArrayOutputStream(); byte[] data = new byte[1024]; int len = 0; String result = ""; if(inputStream != null){ try { while((len = inputStream.read(data))!=-1){ data.toString(); outputStream.write(data, 0, len); } //result是在服务器端设置的doPost函数中的 result = new String(outputStream.toByteArray(),encode); outputStream.flush(); } catch (IOException e) { // TODO Auto-generated catch block e.printStackTrace(); } } return result; } public static void main(String[] arsg){ Map<String, String> params = new HashMap<String, String>(); params.put("username", "lili"); params.put("password", "123"); String result = sendPostMessage(params,"utf-8"); System.out.println("result->"+result); } }
下边是服务端的Servlet代码:
package com.login.manager; import java.io.ByteArrayOutputStream; import java.io.IOException; import java.io.InputStream; import java.io.InputStreamReader; 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 } 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"); //传过来的内容是:password=123&username=lili System.out.println("username:"+username); String pswd = request.getParameter("password"); System.out.println("password:"+pswd); if(username.equals("张三")&&pswd.equals("123")){ //表示服务器端返回的结果 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 } }
服务端代码使用servlet搭建的。。。
这是运行结果:
服务端的:
在服务端接收的内容是:password=123&username=lili 被它解析啦。。
时间: 2024-11-03 11:37:48