HTTP之java实例

一、POST与GET的区别：

1、GET是从服务器上获取数据，POST是向服务器传送数据。

2、在客户端， GET方式在通过URL提交数据，数据在URL中可以看到；POST方式，数据放置在HTML HEADER内提交。

3、对于GET方式，服务器端用Request.QueryString获取变量的值，对于POST方式，服务器端用Request.Form获取提交的数。

4、GET方式提交的数据最多只能有1024字节，而POST则没有此限制。

5、安全性问题。正如在（2）中提到，使用 GET 的时候，参数会显示在地址栏上，而 POST 不会。所以，如果这些数据是中文数据而且是非敏感数据，那么使用 GET ；如果用户输入的数据不是中文字符而且包含敏感数据，那么还是使用 POST为好。

二、Java中的Http编程主要有两种

1、标准的Java接口

2、标准的Apache接口

三、标准的Java接口编程

1、GET方式

[java] view plain copy

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1. import java.io.ByteArrayOutputStream;  
2. import java.io.IOException;  
3. import java.io.InputStream;  
4. import java.io.OutputStream;  
5. import java.net.HttpURLConnection;  
6. import java.net.URL;  
7. import java.util.HashMap;  
8. import java.util.Map;  
9.   
10.   
11. public class http_get1 {  
12.   
13.   
14.     // public static final String path =  
15.     // "http://192.168.137.103:8080/MyHttp/servlet/LoginAction";  
16.     public static final String path = "http://localhost:8080/MyHttp/servlet/LoginAction";  
17.   
18.   
19.     public static String getStringFromStream(InputStream is) {  
20.         String str = "";  
21.         ByteArrayOutputStream bos = new ByteArrayOutputStream();  
22.         int len = 0;  
23.         byte[] data = new byte[1024];  
24.         if(is!=null){  
25.             try {  
26.                 while ((len = is.read(data)) != -1) {  
27.                     bos.write(data, 0, len);  
28.                 }  
29.   
30.   
31.                 str = new String(bos.toByteArray(), "utf-8");  
32.             } catch (IOException e) {  
33.                 // TODO Auto-generated catch block  
34.                 e.printStackTrace();  
35.             }  
36.   
37.   
38.         }  
39.           
40.         return str;  
41.     }  
42.   
43.   
44.     public static InputStream useGetMethod(Map<String, String> map,  
45.             String encode) {  
46.         InputStream is = null;  
47.         StringBuffer sb = new StringBuffer(path);  
48.         sb.append("?");  
49.         if (map != null && !map.isEmpty()) {  
50.             for (Map.Entry<String, String> entry : map.entrySet()) {  
51.                 sb.append(entry.getKey()).append("=").append(entry.getValue())  
52.                         .append("&");  
53.             }  
54.             sb.deleteCharAt(sb.length() - 1);  
55.             System.out.println(sb.toString());  
56.             URL url = null;  
57.   
58.   
59.             OutputStream os = null;  
60.             try {  
61.                 url = new URL(sb.toString());  
62.                 if (url != null) {  
63.                     HttpURLConnection con = (HttpURLConnection) url  
64.                             .openConnection();  
65.                     con.setRequestMethod("GET");  
66.                     con.setConnectTimeout(3000);  
67.                     con.setDoInput(true);  
68.                     con.setDoOutput(true);  
69.                     os = con.getOutputStream();  
70.                     os.write(sb.toString().getBytes(encode));  
71.                     os.close();  
72.                     if (con.getResponseCode() == 200) {  
73.                         is = con.getInputStream();  
74.                     }  
75.                 }  
76.   
77.   
78.             } catch (Exception e) {  
79.   
80.   
81.             }  
82.   
83.   
84.         }  
85.   
86.   
87.         return is;  
88.     }  
89.   
90.   
91.     public static void main(String[] args) {  
92.         // TODO Auto-generated method stub  
93.   
94.   
95.         Map<String, String> map = new HashMap<String, String>();  
96.         map.put("username", "admin");  
97.         map.put("password", "1243");  
98.         String str = getStringFromStream(useGetMethod(map, "utf-8"));  
99.         System.out.println(str);  
100.     }  
101.   
102.   
103. }  

import java.io.ByteArrayOutputStream;import java.io.IOException;import java.io.InputStream;import java.io.OutputStream;import java.net.HttpURLConnection;import java.net.URL;import java.util.HashMap;import java.util.Map;public class http_get1 {// public static final String path =// "http://192.168.137.103:8080/MyHttp/servlet/LoginAction";public static final String path = "http://localhost:8080/MyHttp/servlet/LoginAction";public static String getStringFromStream(InputStream is) {String str = "";ByteArrayOutputStream bos = new ByteArrayOutputStream();int len = 0;byte[] data = new byte[1024];if(is!=null){try {while ((len = is.read(data)) != -1) {bos.write(data, 0, len);}str = new String(bos.toByteArray(), "utf-8");} catch (IOException e) {// TODO Auto-generated catch blocke.printStackTrace();}}return str;}public static InputStream useGetMethod(Map<String, String> map,String encode) {InputStream is = null;StringBuffer sb = new StringBuffer(path);sb.append("?");if (map != null && !map.isEmpty()) {for (Map.Entry<String, String> entry : map.entrySet()) {sb.append(entry.getKey()).append("=").append(entry.getValue()).append("&");}sb.deleteCharAt(sb.length() - 1);System.out.println(sb.toString());URL url = null;OutputStream os = null;try {url = new URL(sb.toString());if (url != null) {HttpURLConnection con = (HttpURLConnection) url.openConnection();con.setRequestMethod("GET");con.setConnectTimeout(3000);con.setDoInput(true);con.setDoOutput(true);os = con.getOutputStream();os.write(sb.toString().getBytes(encode));os.close();if (con.getResponseCode() == 200) {is = con.getInputStream();}}} catch (Exception e) {}}return is;}public static void main(String[] args) {// TODO Auto-generated method stubMap<String, String> map = new HashMap<String, String>();map.put("username", "admin");map.put("password", "1243");String str = getStringFromStream(useGetMethod(map, "utf-8"));System.out.println(str);}}

2、POST方式

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1. import java.io.IOException;  
2. import java.io.InputStream;  
3. import java.io.OutputStream;  
4. import java.net.HttpURLConnection;  
5. import java.net.MalformedURLException;  
6. import java.net.URL;  
7. import java.util.HashMap;  
8. import java.util.Map;  
9.   
10.   
11. public class http_post1 {  
12.   
13.   
14.     // 使用POST请求与GET请求的区别就是POST请求不需要封装请求路径，只需要封装请求参数  
15.     public static InputStream usePostMethod(Map<String, String> map,  
16.             String encode) {  
17.         StringBuffer buffer = new StringBuffer();  
18.         InputStream is = null;  
19.         OutputStream os = null;  
20.         if (map != null && !map.isEmpty()) {  
21.             for (Map.Entry<String, String> entry : map.entrySet()) {  
22.                 try {  
23.                     buffer.append(entry.getKey()).append("=")  
24.                             .append(entry.getValue())  
25.                             // .append(URLEncoder.encode(entry.getValue(),  
26.                             // encode))  
27.                             .append("&");  
28.                 } catch (Exception e) {  
29.                     // TODO Auto-generated catch block  
30.                     e.printStackTrace();  
31.                 }  
32.             }  
33.             buffer.deleteCharAt(buffer.length() - 1);  
34.             System.out.println(buffer.toString());  
35.         }  
36.         try {  
37.             URL url = new URL(http_get1.path);  
38.             if (url != null) {  
39.                 HttpURLConnection con = (HttpURLConnection) url  
40.                         .openConnection();  
41.                 con.setDoInput(true);  
42.                 con.setDoOutput(true);  
43.                 con.setRequestMethod("POST");  
44.                 con.setConnectTimeout(3000);  
45.                 byte[] tdata = buffer.toString().getBytes();  
46.   
47.   
48.                 // con.setRequestProperty("Content-Type",  
49.                 // "application/x-www-form-urlencoded");  
50.                 // con.setRequestProperty("Content-Length",  
51.                 // String.valueOf(tdata.length));  
52.   
53.   
54.                 os = con.getOutputStream();  
55.                 os.write(tdata);  
56.                 os.close();  
57.                 if (con.getResponseCode() == 200) {  
58.   
59.   
60.                     is = con.getInputStream();  
61.                 }  
62.   
63.   
64.             }  
65.   
66.   
67.         } catch (MalformedURLException e) {  
68.             // TODO Auto-generated catch block  
69.             e.printStackTrace();  
70.         } catch (IOException e) {  
71.             // TODO Auto-generated catch block  
72.             e.printStackTrace();  
73.         }  
74.   
75.   
76.         return is;  
77.     }  
78.   
79.   
80.     public static void main(String[] args) {  
81.   
82.   
83.         Map<String, String> map = new HashMap<String, String>();  
84.         map.put("username", "admin");  
85.         map.put("password", "123");  
86.         System.out.println(http_get1.getStringFromStream(usePostMethod(map,  
87.                 "utf-8")));  
88.   
89.   
90.     }  
91.   
92.   
93. }  

import java.io.IOException;import java.io.InputStream;import java.io.OutputStream;import java.net.HttpURLConnection;import java.net.MalformedURLException;import java.net.URL;import java.util.HashMap;import java.util.Map;public class http_post1 {// 使用POST请求与GET请求的区别就是POST请求不需要封装请求路径，只需要封装请求参数public static InputStream usePostMethod(Map<String, String> map,String encode) {StringBuffer buffer = new StringBuffer();InputStream is = null;OutputStream os = null;if (map != null && !map.isEmpty()) {for (Map.Entry<String, String> entry : map.entrySet()) {try {buffer.append(entry.getKey()).append("=").append(entry.getValue())// .append(URLEncoder.encode(entry.getValue(),// encode)).append("&");} catch (Exception e) {// TODO Auto-generated catch blocke.printStackTrace();}}buffer.deleteCharAt(buffer.length() - 1);System.out.println(buffer.toString());}try {URL url = new URL(http_get1.path);if (url != null) {HttpURLConnection con = (HttpURLConnection) url.openConnection();con.setDoInput(true);con.setDoOutput(true);con.setRequestMethod("POST");con.setConnectTimeout(3000);byte[] tdata = buffer.toString().getBytes();// con.setRequestProperty("Content-Type",// "application/x-www-form-urlencoded");// con.setRequestProperty("Content-Length",// String.valueOf(tdata.length));os = con.getOutputStream();os.write(tdata);os.close();if (con.getResponseCode() == 200) {is = con.getInputStream();}}} catch (MalformedURLException e) {// TODO Auto-generated catch blocke.printStackTrace();} catch (IOException e) {// TODO Auto-generated catch blocke.printStackTrace();}return is;}public static void main(String[] args) {Map<String, String> map = new HashMap<String, String>();map.put("username", "admin");map.put("password", "123");System.out.println(http_get1.getStringFromStream(usePostMethod(map,"utf-8")));}}

四、Apache接口

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1. import java.io.InputStream;  
2. import java.util.ArrayList;  
3. import java.util.HashMap;  
4. import java.util.List;  
5. import java.util.Map;  
6.   
7.   
8. import org.apache.http.HttpResponse;  
9. import org.apache.http.NameValuePair;  
10. import org.apache.http.client.entity.UrlEncodedFormEntity;  
11. import org.apache.http.client.methods.HttpPost;  
12. import org.apache.http.impl.client.DefaultHttpClient;  
13. import org.apache.http.message.BasicNameValuePair;  
14.   
15.   
16. public class http_myapache {  
17.   
18.   
19.     public static InputStream useApacheMethod(Map<String, String> map,  
20.             String encode) {  
21.         InputStream is = null;  
22.         List<NameValuePair> list = new ArrayList<NameValuePair>();  
23.   
24.   
25.         for (Map.Entry<String, String> entry : map.entrySet()) {  
26.             list.add(new BasicNameValuePair(entry.getKey(), entry.getValue()));  
27.   
28.   
29.         }  
30.         try {  
31.             // 封装请求参数  
32.             UrlEncodedFormEntity entity = new UrlEncodedFormEntity(list, encode);  
33.             // 设置请求参数  
34.             HttpPost post = new HttpPost(http_get1.path);  
35.             post.setEntity(entity);  
36.             // 执行请求  
37.             DefaultHttpClient client = new DefaultHttpClient();  
38.             HttpResponse response = client.execute(post);  
39.             // 获取状态码  
40.             if (response.getStatusLine().getStatusCode() == 200) {  
41.                 is = response.getEntity().getContent();  
42.             }  
43.   
44.   
45.         } catch (Exception e) {  
46.             // TODO: handle exception  
47.         }  
48.   
49.   
50.         return is;  
51.   
52.   
53.     }  
54.   
55.   
56.     public static void main(String[] args) {  
57.   
58.   
59.         Map<String, String> map = new HashMap<String, String>();  
60.         map.put("username", "admin");  
61.         map.put("password", "123");  
62.         System.out.println(http_get1.getStringFromStream(useApacheMethod(map,  
63.                 "utf-8")));  
64.     }  
65.   
66.   
67. }  

import java.io.InputStream;import java.util.ArrayList;import java.util.HashMap;import java.util.List;import java.util.Map;import org.apache.http.HttpResponse;import org.apache.http.NameValuePair;import org.apache.http.client.entity.UrlEncodedFormEntity;import org.apache.http.client.methods.HttpPost;import org.apache.http.impl.client.DefaultHttpClient;import org.apache.http.message.BasicNameValuePair;public class http_myapache {public static InputStream useApacheMethod(Map<String, String> map,String encode) {InputStream is = null;List<NameValuePair> list = new ArrayList<NameValuePair>();for (Map.Entry<String, String> entry : map.entrySet()) {list.add(new BasicNameValuePair(entry.getKey(), entry.getValue()));}try {// 封装请求参数UrlEncodedFormEntity entity = new UrlEncodedFormEntity(list, encode);// 设置请求参数HttpPost post = new HttpPost(http_get1.path);post.setEntity(entity);// 执行请求DefaultHttpClient client = new DefaultHttpClient();HttpResponse response = client.execute(post);// 获取状态码if (response.getStatusLine().getStatusCode() == 200) {is = response.getEntity().getContent();}} catch (Exception e) {// TODO: handle exception}return is;}public static void main(String[] args) {Map<String, String> map = new HashMap<String, String>();map.put("username", "admin");map.put("password", "123");System.out.println(http_get1.getStringFromStream(useApacheMethod(map,"utf-8")));}}

总结：

对于普通的Http编程可以选择GET方式或者POST方式，但对于更高要求的HTTP编程，Apache提供 的标准接口则更为灵活。

附Apache编程的JAR包和XMLPull解析时用到的JAR包：

Apache编程时用到的JAR包：

点击打开链接

XMLPull解析时用到的JAR包：

点击打开链接