Java笔记7：最简单的网络请求Demo

一、服务器端

1 新建一个工程，建立一个名为MyRequest的工程。

2 FileàProject StructureàModulesà点击最右侧的“+”àLibraryàJava

找到Tomcat中的lib目录下的servlet-api.jar，添加进来

3 建立LoginServlet类，内容如下

1. import java.io.IOException;
2. import javax.servlet.ServletException;
3. import javax.servlet.http.HttpServlet;
4. import javax.servlet.http.HttpServletRequest;
5. import javax.servlet.http.HttpServletResponse;
6. public class LoginServlet extends HttpServlet {
7. private static final long serialVersionUID = 1L;
8. public LoginServlet() {
9. super();
10. }
11. protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
12. this.doPost(request, response);
13. }
14. protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
15. String username = request.getParameter("username");
16. String blog = request.getParameter("blog");
17. System.out.println(username);
18. System.out.println(blog);
19. response.setContentType("text/plain; charset=UTF-8");
20. response.setCharacterEncoding("UTF-8");
21. response.getWriter().write("It is ok!");
22. }
23. }

4 编译LoginServlet.java，得到LoginServlet.class

5 在Tomcat中的webapps中添加MyHttpServer\WEB-INF\classes，并把上一步生成的LoginServlet.class拷进来

6 在WEB-INF目录下建立web.xml文件，内容如下：

1. <?xml version="1.0" encoding="UTF-8"?>
2. <web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns="http://java.sun.com/xml/ns/javaee" xmlns:web="http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd" xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd" id="WebApp_ID" version="2.5">
3. <display-name>OneHttpServer</display-name>
4. <welcome-file-list>
5. <welcome-file>LoginServlet</welcome-file>
6. </welcome-file-list>
7. <servlet>
8. <description></description>
9. <display-name>LoginServlet</display-name>
10. <servlet-name>LoginServlet</servlet-name>
11. <servlet-class>LoginServlet</servlet-class>
12. </servlet>
13. <servlet-mapping>
14. <servlet-name>LoginServlet</servlet-name>
15. <url-pattern>/LoginServlet</url-pattern>
16. </servlet-mapping>
17. </web-app>

7 执行Tomcat下的bin目录下的startup.bat来启动Tomcat

8 在浏览器中输入http://localhost:8080/MyHttpServer，若见到页面显示“It is ok!”则表示服务器端配置成功。

二、客户端

1 Get请求

在MyRequest工程新建HttpGetRequest类，内容如下：

1. import java.io.BufferedReader;
2. import java.io.InputStream;
3. import java.io.InputStreamReader;
4. import java.net.HttpURLConnection;
5. import java.net.URL;
6. import java.net.URLConnection;
7. public class HttpGetRequest {
8. /**
9. * Main
10. * @param args
11. * @throws Exception
12. */
13. public static void main(String[] args) throws Exception {
14. System.out.println(doGet());
15. }
16. /**
17. * Get Request
18. * @return
19. * @throws Exception
20. */
21. public static String doGet() throws Exception {
22. URL localURL = new URL("http://localhost:8080/MyHttpServer/");
23. URLConnection connection = localURL.openConnection();
24. HttpURLConnection httpURLConnection = (HttpURLConnection)connection;
25. httpURLConnection.setRequestProperty("Accept-Charset", "utf-8");
26. httpURLConnection.setRequestProperty("Content-Type", "application/x-www-form-urlencoded");
27. InputStream inputStream = null;
28. InputStreamReader inputStreamReader = null;
29. BufferedReader reader = null;
30. StringBuffer resultBuffer = new StringBuffer();
31. String tempLine = null;
32. if (httpURLConnection.getResponseCode() >= 300) {
33. throw new Exception("HTTP Request is not success, Response code is " + httpURLConnection.getResponseCode());
34. }
35. try {
36. inputStream = httpURLConnection.getInputStream();
37. inputStreamReader = new InputStreamReader(inputStream);
38. reader = new BufferedReader(inputStreamReader);
39. while ((tempLine = reader.readLine()) != null) {
40. resultBuffer.append(tempLine);
41. }
42. } finally {
43. if (reader != null) {
44. reader.close();
45. }
46. if (inputStreamReader != null) {
47. inputStreamReader.close();
48. }
49. if (inputStream != null) {
50. inputStream.close();
51. }
52. }
53. return resultBuffer.toString();
54. }
55. }

运行结果：

It is ok!

2 Post请求

新建HttpPostRequest.java类，内容如下：

1. import java.io.BufferedReader;
2. import java.io.InputStream;
3. import java.io.InputStreamReader;
4. import java.io.OutputStream;
5. import java.io.OutputStreamWriter;
6. import java.net.HttpURLConnection;
7. import java.net.URL;
8. import java.net.URLConnection;
9. public class HttpPostRequest {
10. /**
11. * Main
12. * @param args
13. * @throws Exception
14. */
15. public static void main(String[] args) throws Exception {
16. System.out.println(doPost());
17. }
18. /**
19. * Post Request
20. * @return
21. * @throws Exception
22. */
23. public static String doPost() throws Exception {
24. String parameterData = "username=nickhuang&blog=http://www.cnblogs.com/nick-huang/";
25. URL localURL = new URL("http://localhost:8080/MyHttpServer/");
26. URLConnection connection = localURL.openConnection();
27. HttpURLConnection httpURLConnection = (HttpURLConnection)connection;
28. httpURLConnection.setDoOutput(true);
29. httpURLConnection.setRequestMethod("POST");
30. httpURLConnection.setRequestProperty("Accept-Charset", "utf-8");
31. httpURLConnection.setRequestProperty("Content-Type", "application/x-www-form-urlencoded");
32. httpURLConnection.setRequestProperty("Content-Length", String.valueOf(parameterData.length()));
33. OutputStream outputStream = null;
34. OutputStreamWriter outputStreamWriter = null;
35. InputStream inputStream = null;
36. InputStreamReader inputStreamReader = null;
37. BufferedReader reader = null;
38. StringBuffer resultBuffer = new StringBuffer();
39. String tempLine = null;
40. try {
41. outputStream = httpURLConnection.getOutputStream();
42. outputStreamWriter = new OutputStreamWriter(outputStream);
43. outputStreamWriter.write(parameterData.toString());
44. outputStreamWriter.flush();
45. if (httpURLConnection.getResponseCode() >= 300) {
46. throw new Exception("HTTP Request is not success, Response code is " + httpURLConnection.getResponseCode());
47. }
48. inputStream = httpURLConnection.getInputStream();
49. inputStreamReader = new InputStreamReader(inputStream);
50. reader = new BufferedReader(inputStreamReader);
51. while ((tempLine = reader.readLine()) != null) {
52. resultBuffer.append(tempLine);
53. }
54. } finally {
55. if (outputStreamWriter != null) {
56. outputStreamWriter.close();
57. }
58. if (outputStream != null) {
59. outputStream.close();
60. }
61. if (reader != null) {
62. reader.close();
63. }
64. if (inputStreamReader != null) {
65. inputStreamReader.close();
66. }
67. if (inputStream != null) {
68. inputStream.close();
69. }
70. }
71. return resultBuffer.toString();
72. }
73. }

运行结果：

It is ok!

3 对Get和Post进行封装

封装类：

1. import java.io.BufferedReader;
2. import java.io.IOException;
3. import java.io.InputStream;
4. import java.io.InputStreamReader;
5. import java.io.OutputStream;
6. import java.io.OutputStreamWriter;
7. import java.net.HttpURLConnection;
8. import java.net.InetSocketAddress;
9. import java.net.Proxy;
10. import java.net.URL;
11. import java.net.URLConnection;
12. import java.util.Iterator;
13. import java.util.Map;
14. public class HttpRequestor {
15. private String charset = "utf-8";
16. private Integer connectTimeout = null;
17. private Integer socketTimeout = null;
18. private String proxyHost = null;
19. private Integer proxyPort = null;
20. /**
21. * Do GET request
22. * @param url
23. * @return
24. * @throws Exception
25. * @throws IOException
26. */
27. public String doGet(String url) throws Exception {
28. URL localURL = new URL(url);
29. URLConnection connection = openConnection(localURL);
30. HttpURLConnection httpURLConnection = (HttpURLConnection)connection;
31. httpURLConnection.setRequestProperty("Accept-Charset", charset);
32. httpURLConnection.setRequestProperty("Content-Type", "application/x-www-form-urlencoded");
33. InputStream inputStream = null;
34. InputStreamReader inputStreamReader = null;
35. BufferedReader reader = null;
36. StringBuffer resultBuffer = new StringBuffer();
37. String tempLine = null;
38. if (httpURLConnection.getResponseCode() >= 300) {
39. throw new Exception("HTTP Request is not success, Response code is " + httpURLConnection.getResponseCode());
40. }
41. try {
42. inputStream = httpURLConnection.getInputStream();
43. inputStreamReader = new InputStreamReader(inputStream);
44. reader = new BufferedReader(inputStreamReader);
45. while ((tempLine = reader.readLine()) != null) {
46. resultBuffer.append(tempLine);
47. }
48. } finally {
49. if (reader != null) {
50. reader.close();
51. }
52. if (inputStreamReader != null) {
53. inputStreamReader.close();
54. }
55. if (inputStream != null) {
56. inputStream.close();
57. }
58. }
59. return resultBuffer.toString();
60. }
61. /**
62. * Do POST request
63. * @param url
64. * @param parameterMap
65. * @return
66. * @throws Exception
67. */
68. public String doPost(String url, Map parameterMap) throws Exception {
69. /* Translate parameter map to parameter date string */
70. StringBuffer parameterBuffer = new StringBuffer();
71. if (parameterMap != null) {
72. Iterator iterator = parameterMap.keySet().iterator();
73. String key = null;
74. String value = null;
75. while (iterator.hasNext()) {
76. key = (String)iterator.next();
77. if (parameterMap.get(key) != null) {
78. value = (String)parameterMap.get(key);
79. } else {
80. value = "";
81. }
82. parameterBuffer.append(key).append("=").append(value);
83. if (iterator.hasNext()) {
84. parameterBuffer.append("&");
85. }
86. }
87. }
88. System.out.println("POST parameter : " + parameterBuffer.toString());
89. URL localURL = new URL(url);
90. URLConnection connection = openConnection(localURL);
91. HttpURLConnection httpURLConnection = (HttpURLConnection)connection;
92. httpURLConnection.setDoOutput(true);
93. httpURLConnection.setRequestMethod("POST");
94. httpURLConnection.setRequestProperty("Accept-Charset", charset);
95. httpURLConnection.setRequestProperty("Content-Type", "application/x-www-form-urlencoded");
96. httpURLConnection.setRequestProperty("Content-Length", String.valueOf(parameterBuffer.length()));
97. OutputStream outputStream = null;
98. OutputStreamWriter outputStreamWriter = null;
99. InputStream inputStream = null;
100. InputStreamReader inputStreamReader = null;
101. BufferedReader reader = null;
102. StringBuffer resultBuffer = new StringBuffer();
103. String tempLine = null;
104. try {
105. outputStream = httpURLConnection.getOutputStream();
106. outputStreamWriter = new OutputStreamWriter(outputStream);
107. outputStreamWriter.write(parameterBuffer.toString());
108. outputStreamWriter.flush();
109. if (httpURLConnection.getResponseCode() >= 300) {
110. throw new Exception("HTTP Request is not success, Response code is " + httpURLConnection.getResponseCode());
111. }
112. inputStream = httpURLConnection.getInputStream();
113. inputStreamReader = new InputStreamReader(inputStream);
114. reader = new BufferedReader(inputStreamReader);
115. while ((tempLine = reader.readLine()) != null) {
116. resultBuffer.append(tempLine);
117. }
118. } finally {
119. if (outputStreamWriter != null) {
120. outputStreamWriter.close();
121. }
122. if (outputStream != null) {
123. outputStream.close();
124. }
125. if (reader != null) {
126. reader.close();
127. }
128. if (inputStreamReader != null) {
129. inputStreamReader.close();
130. }
131. if (inputStream != null) {
132. inputStream.close();
133. }
134. }
135. return resultBuffer.toString();
136. }
137. private URLConnection openConnection(URL localURL) throws IOException {
138. URLConnection connection;
139. if (proxyHost != null && proxyPort != null) {
140. Proxy proxy = new Proxy(Proxy.Type.HTTP, new InetSocketAddress(proxyHost, proxyPort));
141. connection = localURL.openConnection(proxy);
142. } else {
143. connection = localURL.openConnection();
144. }
145. return connection;
146. }
147. /**
148. * Render request according setting
149. * @param request
150. */
151. private void renderRequest(URLConnection connection) {
152. if (connectTimeout != null) {
153. connection.setConnectTimeout(connectTimeout);
154. }
155. if (socketTimeout != null) {
156. connection.setReadTimeout(socketTimeout);
157. }
158. }
159. /*
160. * Getter & Setter
161. */
162. public Integer getConnectTimeout() {
163. return connectTimeout;
164. }
165. public void setConnectTimeout(Integer connectTimeout) {
166. this.connectTimeout = connectTimeout;
167. }
168. public Integer getSocketTimeout() {
169. return socketTimeout;
170. }
171. public void setSocketTimeout(Integer socketTimeout) {
172. this.socketTimeout = socketTimeout;
173. }
174. public String getProxyHost() {
175. return proxyHost;
176. }
177. public void setProxyHost(String proxyHost) {
178. this.proxyHost = proxyHost;
179. }
180. public Integer getProxyPort() {
181. return proxyPort;
182. }
183. public void setProxyPort(Integer proxyPort) {
184. this.proxyPort = proxyPort;
185. }
186. public String getCharset() {
187. return charset;
188. }
189. public void setCharset(String charset) {
190. this.charset = charset;
191. }
192. }

客户端测试代码：

1. import java.util.HashMap;
2. import java.util.Map;
3. public class Call {
4. public static void main(String[] args) throws Exception {
5. /* Post Request */
6. Map dataMap = new HashMap();
7. dataMap.put("username", "Zheng");
8. dataMap.put("blog", "IT");
9. System.out.println(new HttpRequestor().doPost("http://localhost:8080/MyHttpServer/", dataMap));
10. /* Get Request */
11. System.out.println(new HttpRequestor().doGet("http://localhost:8080/MyHttpServer/"));
12. }
13. }

运行结果：

POST parameter : blog=IT&username=Zheng

It is ok!

It is ok!