get/post方式调用http接口

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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：

<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:

package httpcall;

import java.io.IOException;
import java.io.PrintWriter;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

/**
*Module:       TestHTTPServer.java
*Description:  为了验证http接口的调用，编写了一个模拟的http接口
*Company:      
*Author:       ptp
*Date:         Feb 22, 2012
*/

public class TestHTTPServer  extends HttpServlet{
   
   private static final long serialVersionUID = 1L;

   public void doGet(HttpServletRequest request, HttpServletResponse response)
           throws ServletException, IOException {
       response.setCharacterEncoding("gbk");

       PrintWriter out = response.getWriter();
       String param1 = request.getParameter("param1");
       out.println("param1=" + param1);
       String param2 = request.getParameter("param2");
       out.println("param2=" + param2);
       if (param1 == null || "".equals("param1") || param1.length() <= 0) {
           out.println("http call failed,参数param1不能为空,程序退出");
       } else if (param2 == null || "".equals("param2")
               || param2.length() <= 0) {
           out.println("http call failed,参数param2不能为空,程序退出");
       } else {
           out.println("---http call success---");
       }
       out.close();
   }

   public void doPost(HttpServletRequest request, HttpServletResponse response)
           throws ServletException, IOException {
       this.doGet(request, response);
   }
}

HttpClientUtil.java的代码如下：

package httpcall;

import java.io.IOException;
import org.apache.commons.httpclient.DefaultHttpMethodRetryHandler;
//import org.apache.commons.httpclient.Header;
import org.apache.commons.httpclient.HttpClient;
import org.apache.commons.httpclient.HttpException;
//import org.apache.commons.httpclient.HttpStatus;
import org.apache.commons.httpclient.methods.GetMethod;
import org.apache.commons.httpclient.methods.PostMethod;
import org.apache.commons.httpclient.params.HttpMethodParams;
//import org.apache.commons.httpclient.NameValuePair;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;

/**
* 
*Module:       HttpClientUtil.java
*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
*Company:      
*Author:       ptp
*Date:         Feb 22, 2012
*/

public class HttpClientUtil {
   
   private static final Log log = LogFactory
   .getLog(HttpClientUtil.class);

   /**
    * get方式
    * @param param1
    * @param param2
    * @return
*/
   public static String getHttp(String param1,String param2){
       String responseMsg = "";

       // 1.构造HttpClient的实例
       HttpClient httpClient = new HttpClient();

       // 用于测试的http接口的url
       String url="http://localhost:8080/UpDown/httpServer?param1="+param1+"&param2="+param2;

       // 2.创建GetMethod的实例
       GetMethod getMethod = new GetMethod(url);

       // 使用系统系统的默认的恢复策略
       getMethod.getParams().setParameter(HttpMethodParams.RETRY_HANDLER,
               new DefaultHttpMethodRetryHandler());
       
       try {
           //3.执行getMethod,调用http接口
           httpClient.executeMethod(getMethod);

           //4.读取内容
           byte[] responseBody = getMethod.getResponseBody();
           
           //5.处理返回的内容
           responseMsg = new String(responseBody);
           log.info(responseMsg);
           
       } catch (HttpException e) {
           e.printStackTrace();
       } catch (IOException e) {
           e.printStackTrace();
       }finally{
           //6.释放连接
           getMethod.releaseConnection();
       }
       return responseMsg;
   }

   /**
    * post方式 
    * @param param1 
    * @param param2
    * @return
*/
   public static String postHttp(String param1,String param2) {
       String responseMsg = "";
       
       //1.构造HttpClient的实例
       HttpClient httpClient=new HttpClient();
       
       httpClient.getParams().setContentCharset("GBK");
       
       String url="http://localhost:8080/UpDown/httpServer";
       
       //2.构造PostMethod的实例
       PostMethod postMethod=new PostMethod(url);
       
       //3.把参数值放入到PostMethod对象中
//方式1：
/*        NameValuePair[] data = { new NameValuePair("param1", param1),
               new NameValuePair("param2", param2) };
       postMethod.setRequestBody(data);*/
       
       //方式2：    
       postMethod.addParameter("param1", param1);
       postMethod.addParameter("param2", param2);
       
       
       try {
           // 4.执行postMethod,调用http接口
           httpClient.executeMethod(postMethod);//200
           
//5.读取内容
           responseMsg = postMethod.getResponseBodyAsString().trim();
           log.info(responseMsg);
           
           //6.处理返回的内容

       } catch (HttpException e) {
           e.printStackTrace();
       } catch (IOException e) {
           e.printStackTrace();
       } finally {
           //7.释放连接
           postMethod.releaseConnection();
       }
       return responseMsg;
   }

   /**
    * 测试的main方法
    * @param args
*/
   public static void main(String[] args) {
   
       String param1="111";
       String param2="222";
       //get
//        System.out.println("get方式调用http接口\n"+getHttp(param1, param2));
       
//post
       System.out.println("post方式调用http接口\n"+postHttp(param1,param2));
   }
}

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

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