HttpClient httpClient = new HttpClient(); //构造HttpClient的实例 GetMethod getMethod = new GetMethod("http://www.ibm.com"); //创建GET方法的实 try { int statusCode = httpClient.executeMethod(getMethod); //执行getMethod String response = getMethod.getResponseBodyAsString(); //读取服务器返回的页面代码,这里用的是字符读法 }catch (HttpException e) { System.out.println("Please check your provided http address!"); //发生致命的异常,可能是协议不对或者返回的内容有问题 e.printStackTrace(); } catch (IOException e) { //发生网络异常 e.printStackTrace(); } finally { //释放连接 getMethod.releaseConnection(); }
Jakarta的httpclient3.1是最新版本,基本使用方法如下:
一,模拟get方法:
一般步骤:
1. 创建 HttpClient 的实例
2. 创建某种连接方法的实例,在这里是 GetMethod。在 GetMethod 的构造函数中传入待连接的地址
3. 调用第一步中创建好的实例的 execute 方法来执行第二步中创建好的 method 实例
4. 读 response
5. 释放连接。无论执行方法是否成功,都必须释放连接
6. 对得到后的内容进行处理
代码如下:
二,模拟POST方法提交表单。
1)一般POST表单,最简单的示例
String url = "*******"; //提交的地址 PostMethod post = new PostMethod(url); NameValuePair[] pairs = new NameValuePair[ 2 ]; //设置FORM表单里各项内容 NameValuePair p1 = new NameValuePair("login", username); NameValuePair p2 = new NameValuePair("passwd", password); NameValuePair[] pairs = { p1, p2 }; post.setRequestBody(pairs); //将设置好的表单提交上去 HttpClient client = new HttpClient(); try { int status = client.executeMethod(post); //执行,模拟POST方法提交到服务器 if (status == HttpStatus.SC_MOVED_PERMANENTLY || // 处理转向 status == HttpStatus.SC_MOVED_TEMPORARILY) { // 从头中取出转向地址 Header locationHeader = post.getResponseHeader("location"); if (locationHeader != null) { String location = locationHeader.getValue(); logger.info("頁面跳轉地址是:" + location); } else { logger.info("跳轉值為空。"); } } } catch (HttpException e) { e.printStackTrace(); } catch (IOException e) { e.printStackTrace(); }finally{ post. releaseConnection(); }
2)带附件的POST表单提交, 最主要的类是Part(代表一种post object),它有二个比较重要的子类:FilePart和StringPart,一个 是文件的参数,另一个就是普通的文本参数。它的典型使用方法如下:
String url = " http://localhost:8080/HttpTest/Test " ; PostMethod postMethod = new PostMethod(url); StringPart sp = new StringPart( " TEXT " , " testValue " ); FilePart fp = new FilePart( " file " , " test.txt " , new File( " ./temp/test.txt " )); MultipartRequestEntity mrp = new MultipartRequestEntity( new Part[] {sp, fp } , postMethod.getParams() ); postMethod.setRequestEntity(mrp); HttpClient httpClient = new HttpClient(); try { httpClient.executeMethod(postMethod); } catch (HttpException e) { e.printStackTrace(); } catch (IOException e) { e.printStackTrace(); } finally{ postMethod .releaseConnection(); }