一、前言
如何通過Java發(fā)送HTTP請求，通俗點(diǎn)講，如何通過Java（模擬瀏覽器）發(fā)送HTTP請求。
Java有原生的API可用于發(fā)送HTTP請求，即java.net.URL、java.net.URLConnection，這些API很好用、很常用，但不夠簡便；
所以，也流行有許多Java HTTP請求的framework，如，Apache的HttpClient。
目前項(xiàng)目主要用到Java原生的方式，所以，這里主要介紹此方式。
二、運(yùn)用原生Java Api發(fā)送簡單的Get請求、Post請求步驟
1.通過統(tǒng)一資源定位器（java.net.URL）獲取連接器（java.net.URLConnection）
2.設(shè)置請求的參數(shù)
3.發(fā)送請求
4.以輸入流的形式獲取返回內(nèi)容
5.關(guān)閉輸入流
三、發(fā)送請求與接收響應(yīng)流類 HttpRequestor
|
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
|
package me.http;import java.io.BufferedReader;import java.io.IOException;import java.io.InputStream;import java.io.InputStreamReader;import java.io.OutputStream;import java.io.OutputStreamWriter;import java.net.HttpURLConnection;import java.net.InetSocketAddress;import java.net.Proxy;import java.net.URL;import java.net.URLConnection;import java.util.Iterator;import java.util.Map;public class HttpRequestor { private String charset = "utf-8"; private Integer connectTimeout = null; private Integer socketTimeout = null; private String proxyHost = null; private Integer proxyPort = null; /** * Do GET request * @param url * @return * @throws Exception * @throws IOException */ public String doGet(String url) throws Exception { URL localURL = new URL(url); URLConnection connection = this.openConnection(localURL); HttpURLConnection httpURLConnection = (HttpURLConnection)connection; httpURLConnection.setRequestProperty("Accept-Charset", charset); httpURLConnection.setRequestProperty("Content-Type", "application/x-www-form-urlencoded"); InputStream inputStream = null; InputStreamReader inputStreamReader = null; BufferedReader reader = null; StringBuffer resultBuffer = new StringBuffer(); String tempLine = null; //響應(yīng)失敗 if (httpURLConnection.getResponseCode() >= 300) { throw new Exception("HTTP Request is not success, Response code is " + httpURLConnection.getResponseCode()); } try { inputStream = httpURLConnection.getInputStream(); inputStreamReader = new InputStreamReader(inputStream); reader = new BufferedReader(inputStreamReader); while ((tempLine = reader.readLine()) != null) { resultBuffer.append(tempLine); } } finally { if (reader != null) { reader.close(); } if (inputStreamReader != null) { inputStreamReader.close(); } if (inputStream != null) { inputStream.close(); } } return resultBuffer.toString(); } /** * Do POST request * @param url * @param parameterMap * @return * @throws Exception */ public String doPost(String url, Map parameterMap) throws Exception { /* Translate parameter map to parameter date string */ StringBuffer parameterBuffer = new StringBuffer(); if (parameterMap != null) { Iterator iterator = parameterMap.keySet().iterator(); String key = null; String value = null; while (iterator.hasNext()) { key = (String)iterator.next(); if (parameterMap.get(key) != null) { value = (String)parameterMap.get(key); } else { value = ""; } parameterBuffer.append(key).append("=").append(value); if (iterator.hasNext()) { parameterBuffer.append("&"); } } } System.out.println("POST parameter : " + parameterBuffer.toString()); URL localURL = new URL(url); URLConnection connection = this.openConnection(localURL); HttpURLConnection httpURLConnection = (HttpURLConnection)connection; httpURLConnection.setDoOutput(true); httpURLConnection.setRequestMethod("POST"); httpURLConnection.setRequestProperty("Accept-Charset", charset); httpURLConnection.setRequestProperty("Content-Type", "application/x-www-form-urlencoded"); httpURLConnection.setRequestProperty("Content-Length", String.valueOf(parameterBuffer.length())); OutputStream outputStream = null; OutputStreamWriter outputStreamWriter = null; InputStream inputStream = null; InputStreamReader inputStreamReader = null; BufferedReader reader = null; StringBuffer resultBuffer = new StringBuffer(); String tempLine = null; try { outputStream = httpURLConnection.getOutputStream(); outputStreamWriter = new OutputStreamWriter(outputStream); outputStreamWriter.write(parameterBuffer.toString()); outputStreamWriter.flush(); //響應(yīng)失敗 if (httpURLConnection.getResponseCode() >= 300) { throw new Exception("HTTP Request is not success, Response code is " + httpURLConnection.getResponseCode()); } //接收響應(yīng)流 inputStream = httpURLConnection.getInputStream(); inputStreamReader = new InputStreamReader(inputStream); reader = new BufferedReader(inputStreamReader); while ((tempLine = reader.readLine()) != null) { resultBuffer.append(tempLine); } } finally { if (outputStreamWriter != null) { outputStreamWriter.close(); } if (outputStream != null) { outputStream.close(); } if (reader != null) { reader.close(); } if (inputStreamReader != null) { inputStreamReader.close(); } if (inputStream != null) { inputStream.close(); } } return resultBuffer.toString(); } private URLConnection openConnection(URL localURL) throws IOException { URLConnection connection; if (proxyHost != null && proxyPort != null) { Proxy proxy = new Proxy(Proxy.Type.HTTP, new InetSocketAddress(proxyHost, proxyPort)); connection = localURL.openConnection(proxy); } else { connection = localURL.openConnection(); } return connection; } /** * Render request according setting * @param request */ private void renderRequest(URLConnection connection) { if (connectTimeout != null) { connection.setConnectTimeout(connectTimeout); } if (socketTimeout != null) { connection.setReadTimeout(socketTimeout); } } /* * Getter & Setter */ public Integer getConnectTimeout() { return connectTimeout; } public void setConnectTimeout(Integer connectTimeout) { this.connectTimeout = connectTimeout; } public Integer getSocketTimeout() { return socketTimeout; } public void setSocketTimeout(Integer socketTimeout) { this.socketTimeout = socketTimeout; } public String getProxyHost() { return proxyHost; } public void setProxyHost(String proxyHost) { this.proxyHost = proxyHost; } public Integer getProxyPort() { return proxyPort; } public void setProxyPort(Integer proxyPort) { this.proxyPort = proxyPort; } public String getCharset() { return charset; } public void setCharset(String charset) { this.charset = charset; } } |
四、為測試方便,新建一個(gè)項(xiàng)目,并新建一個(gè)Servlet,接收post請求并對HttpRequestor請求響應(yīng),發(fā)出響應(yīng)流
LoginServlet.java代碼:此處使用了
注解: @WebServlet("/LoginServlet") ,也可以在web.xml配置Servlet
|
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
|
package me.loginServlet;import java.io.IOException;import javax.servlet.ServletException;import javax.servlet.annotation.WebServlet;import javax.servlet.http.HttpServlet;import javax.servlet.http.HttpServletRequest;import javax.servlet.http.HttpServletResponse;/** * Servlet implementation class LoginServlet */@WebServlet("/LoginServlet")public class LoginServlet extends HttpServlet { private static final long serialVersionUID = 1L; /** * @see HttpServlet#HttpServlet() */ public LoginServlet() { super(); // TODO Auto-generated constructor stub } /** * @see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse response) */ protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { // TODO Auto-generated method stub System.out.println("111"); } /** * @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse response) */ protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { // TODO Auto-generated method stub String username = request.getParameter("username"); String blog = request.getParameter("blog"); System.out.println(username); System.out.println(blog); response.setContentType("text/plain; charset=UTF-8"); response.setCharacterEncoding("UTF-8");//響應(yīng)流 response.getWriter().write("It is ok!"); }} |
五.測試類Test.java
|
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
|
package me.http;import java.util.HashMap;import java.util.Map;public class Test {public static void main(String[] args) { /* Post Request */ Map dataMap = new HashMap(); dataMap.put("username", "Nick Huang"); dataMap.put("blog", "IT"); try { System.out.println(new HttpRequestor().doPost("http://localhost:8081/TestProgect2/LoginServlet", dataMap)); //System.out.println(new HttpRequestor().doGet("http://localhost:8081/TestProgect2/LoginServlet")); } catch (Exception e) { // TODO Auto-generated catch block e.printStackTrace(); } /* Get Request */ }} |
1.接收post請求類LoginServlet,控制臺測試結(jié)果
2.HttpRequestor接收LoginServlet返回的流
OK,完成
六.對于接收TestProgect2項(xiàng)目中LoginServlet.java類返回的流,在真實(shí)環(huán)境中可能是異步接收返回的流的,當(dāng)一臺機(jī)器A向另外一臺機(jī)器B發(fā)送請求,B接收到A的信息,將信息處理后,需要將處理結(jié)果返回即響應(yīng)返回給A,A會接收到B返回的信息
可以另外建一個(gè)Servlet類HttpListenerServlet.java來專門異步接收返回的信息
|
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
|
package me.http;import java.io.BufferedReader;import java.io.IOException;import java.io.InputStream;import java.io.InputStreamReader;import javax.servlet.ServletException;import javax.servlet.annotation.WebServlet;import javax.servlet.http.HttpServlet;import javax.servlet.http.HttpServletRequest;import javax.servlet.http.HttpServletResponse;/** * Servlet implementation class HttpListenerServlet */@WebServlet("/HttpListenerServlet")public class HttpListenerServlet extends HttpServlet { private static final long serialVersionUID = 1L; /** * @see HttpServlet#HttpServlet() */ public HttpListenerServlet() { super(); // TODO Auto-generated constructor stub } /** * @see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse response) */ protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { // TODO Auto-generated method stub } /** * @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse response) */ protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { // TODO Auto-generated method stub InputStream inputStream = null; inputStream = request.getInputStream(); InputStreamReader inputStreamReader = new InputStreamReader(inputStream); BufferedReader reader = new BufferedReader(inputStreamReader); String tempLine = null; StringBuffer resultBuffer=new StringBuffer(); while ((tempLine = reader.readLine()) != null) { resultBuffer.append(tempLine); } System.out.println(resultBuffer.toString()); }} |
總結(jié)
以上就是這篇文章的全部內(nèi)容了，希望本文的內(nèi)容對大家的學(xué)習(xí)或者工作能帶來一定的幫助，如果有疑問大家可以留言交流，謝謝大家對服務(wù)器之家的支持。
原文鏈接：http://www.cnblogs.com/cl1255674805/p/5708735.html
