java 调用http接口
本节摘要:本节主要分别介绍如何用get方式、post方式向http接口发送数据。
preparation
1. 项目环境如下：
myeclipse6.5 、tomcat5.0、system:xp、JDK:开发1.5，编译1.4
为了方便,在原来的web项目UpDown中新建了一个httpcall包，用来保存http接口和调用的客户端。
2.准备需要的jar包
* commons-httpclient-3.0.jar
* commons-logging.jar
* commons-codec-1.3.jar
3.class&method
HttpClient：
GetMethod：
PostMethod：
start
接口写了一个servlet来接收客户端get/post的请求
web.xml需要加入以下配置：
<!-- 模拟HTTP的调用，写的一个http接口 -->
<servlet>
<servlet-name>TestHTTPServer</servlet-name>
<servlet-class>httpcall.TestHTTPServer</servlet-class>
</servlet>
<servlet-mapping>
<servlet-name>TestHTTPServer</servlet-name>
<url-pattern>/httpServer</url-pattern>
</servlet-mapping>
TestHTTPServer.java的代码如下:
TestHTTPServer
1 package httpcall;
2
3 import java.io.IOException;
4 import java.io.PrintWriter;
5 import javax.servlet.ServletException;
6 import javax.servlet.http.HttpServlet;
7 import javax.servlet.http.HttpServletRequest;
8 import javax.servlet.http.HttpServletResponse;
9
10 /**
11 *Module: TestHTTPServer.java
12 *Description: 为了验证http接口的调用，编写了一个模拟的http接口
13 *Company:
14 *Author: ptp
15 *Date: Feb 22, 2012
16 */
17
18 public class TestHTTPServer extends HttpServlet{
19
20 private static final long serialVersionUID = 1L;
21
22 public void doGet(HttpServletRequest request, HttpServletResponse response)
23 throws ServletException, IOException {
24 response.setCharacterEncoding("gbk");
25
26 PrintWriter out = response.getWriter();
27 String param1 = request.getParameter("param1");
28 out.println("param1=" + param1);
29 String param2 = request.getParameter("param2");
30 out.println("param2=" + param2);
31 if (param1 == null || "".equals("param1") || param1.length() <= 0) {
32 out.println("http call failed,参数param1不能为空,程序退出");
33 } else if (param2 == null || "".equals("param2")
34 || param2.length() <= 0) {
35 out.println("http call failed,参数param2不能为空,程序退出");
36 } else {
37 out.println("---http call success---");
38 }
39 out.close();
40 }
41
42 public void doPost(HttpServletRequest request, HttpServletResponse response)
43 throws ServletException, IOException {
44 this.doGet(request, response);
45 }
46 }
HttpClientUtil.java的代码如下：
HttpClientUtil
1 package httpcall;
2
3 import java.io.IOException;
4 import org.apache.commons.httpclient.DefaultHttpMethodRetryHandler;
5 //import org.apache.commons.httpclient.Header;
6 import org.apache.commons.httpclient.HttpClient;
7 import org.apache.commons.httpclient.HttpException;
8 //import org.apache.commons.httpclient.HttpStatus;
9 import org.apache.commons.httpclient.methods.GetMethod;
10 import org.apache.commons.httpclient.methods.PostMethod;
11 import org.apache.commons.httpclient.params.HttpMethodParams;
12 //import org.apache.commons.httpclient.NameValuePair;
13 import org.apache.commons.logging.Log;
14 import org.apache.commons.logging.LogFactory;
15
16 /**
17 *
18 *Module: HttpClientUtil.java
19 *Description: 以get/post的方式发送数据到指定的http接口---利用httpclient.jar包---HTTP接口的调用
20 *Company:
21 *Author: ptp
22 *Date: Feb 22, 2012
23 */
24
25 public class HttpClientUtil {
26
27 private static final Log log = LogFactory
28 .getLog(HttpClientUtil.class);
29
30 /**
31 * get方式
32 * @param param1
33 * @param param2
34 * @return
35 */
36 public static String getHttp(String param1,String param2){
37 String responseMsg = "";
38
39 // 1.构造HttpClient的实例
40 HttpClient httpClient = new HttpClient();
41
42 // 用于测试的http接口的url
43 String url="http://localhost:8080/UpDown/httpServer?param1="+param1+"¶m2="+param2;
44
45 // 2.创建GetMethod的实例
46 GetMethod getMethod = new GetMethod(url);
47
48 // 使用系统系统的默认的恢复策略
49 getMethod.getParams().setParameter(HttpMethodParams.RETRY_HANDLER,
50 new DefaultHttpMethodRetryHandler());
51
52 try {
53 //3.执行getMethod,调用http接口
54 httpClient.executeMethod(getMethod);
55
56 //4.读取内容
57 byte[] responseBody = getMethod.getResponseBody();
58
59 //5.处理返回的内容
60 responseMsg = new String(responseBody);
61 log.info(responseMsg);
62
63 } catch (HttpException e) {
64 e.printStackTrace();
65 } catch (IOException e) {
66 e.printStackTrace();
67 }finally{
68 //6.释放连接
69 getMethod.releaseConnection();
70 }
71 return responseMsg;
72 }
73
74 /**
75 * post方式
76 * @param param1
77 * @param param2
78 * @return
79 */
80 public static String postHttp(String param1,String param2) {
81 String responseMsg = "";
82
83 //1.构造HttpClient的实例
84 HttpClient httpClient=new HttpClient();
85
86 httpClient.getParams().setContentCharset("GBK");
87
88 String url="http://localhost:8080/UpDown/httpServer";
89
90 //2.构造PostMethod的实例
91 PostMethod postMethod=new PostMethod(url);
92
93 //3.把参数值放入到PostMethod对象中
94 //方式1：
95 /* NameValuePair[] data = { new NameValuePair("param1", param1),
96 new NameValuePair("param2", param2) };
97 postMethod.setRequestBody(data);*/
98
99 //方式2：
100 postMethod.addParameter("param1", param1);
101 postMethod.addParameter("param2", param2);
102
103
104 try {
105 // 4.执行postMethod,调用http接口
106 httpClient.executeMethod(postMethod);//200
107
108 //5.读取内容
109 responseMsg = postMethod.getResponseBodyAsString().trim();
110 log.info(responseMsg);
111
112 //6.处理返回的内容
113
114 } catch (HttpException e) {
115 e.printStackTrace();
116 } catch (IOException e) {
117 e.printStackTrace();
118 } finally {
119 //7.释放连接
120 postMethod.releaseConnection();
121 }
122 return responseMsg;
123 }
124
125 /**
126 * 测试的main方法
127 * @param args
128 */
129 public static void main(String[] args) {
130
131 String param1="111";
132 String param2="222";
133 //get
134 // System.out.println("get方式调用http接口\n"+getHttp(param1, param2));
135
136 //post
137 System.out.println("post方式调用http接口\n"+postHttp(param1,param2));
138 }
139 }
result
在HttpClientUtil运行main方法，分别运行以下几种情况：
1.get方式
设置
String param1="111";
String param2="222";
运行get方式，截图如下：
设置
String param1="111";
String param2="";
运行get方式，截图如下：
2.post方式
设置
String param1="111";
String param2="222";
运行post方式，截图如下：
设置
String param1="111";
String param2="";
运行post方式，截图如下：
通过get和post方式调用http接口，总结如下:
* get方式调用http接口的步骤：
* 1.构造HttpClient实例
* 2.构造GetMethod实例
* 3.执行getMethod,调用http接口
* 4.读取内容
* 5.处理返回的内容
* 6.释放连接
*
* post方式调用http接口的步骤：
* 1.构造HttpClient实例
* 2.构造PostMethod实例
* 3.把参数值放入到PostMethod对象中
* 方式1:利用NameValuePair类
* 方式2:直接用PostMethod实例对象的addParameter方法
* 4.执行postMethod,调用http接口
* 5.读取内容
* 6.处理返回的内容
* 7.释放连接
摘自 月月鸟0820
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