httpClient----java基础

在http请求失败是要进行下列操作：

 if (response.getStatusLine ().getStatusCode () != 200) {          get.abort();         return null;  } 

HttpGet操作：

    public final static void main(String[] args) throws Exception {        HttpClient httpclient = new DefaultHttpClient();        try {            HttpGet httpget = new HttpGet("http://www.apache.org/");            System.out.println("executing request " + httpget.getURI());            HttpResponse response = httpclient.execute(httpget);            HttpEntity entity = response.getEntity();            System.out.println("----------------------------------------");            System.out.println(response.getStatusLine());            if (entity != null) {                System.out.println("Response content length: " + entity.getContentLength());            }            System.out.println("----------------------------------------");            InputStream inSm = entity.getContent();            Scanner inScn = new Scanner(inSm);            while (inScn.hasNextLine()) {                System.out.println(inScn.nextLine());            }            // Do not feel like reading the response body            // Call abort on the request object            httpget.abort();        } finally {            // When HttpClient instance is no longer needed,            // shut down the connection manager to ensure            // immediate deallocation of all system resources            httpclient.getConnectionManager().shutdown();        }    }

读取response响应内容部分，也可以借助于 httpcore-4.1.2.jar 里面的：

public class Demo1 {    /**     * 用 get 方法访问 www.apache.org 并返回内容     *     * @param args     */    public static void main(String[] args) {        //创建默认的 HttpClient 实例        HttpClient httpClient = new DefaultHttpClient();        try {            //创建 httpUriRequest 实例            HttpGet httpGet = new HttpGet("http://www.apache.org/");            System.out.println("uri=" + httpGet.getURI());            //执行 get 请求            HttpResponse httpResponse = httpClient.execute(httpGet);            //获取响应实体            HttpEntity httpEntity = httpResponse.getEntity();            //打印响应状态            System.out.println(httpResponse.getStatusLine());            if (httpEntity != null) {                //响应内容的长度                long length = httpEntity.getContentLength();                //响应内容                String content = EntityUtils.toString(httpEntity);                System.out.println("Response content length:" + length);                System.out.println("Response content:" + content);            }            //有些教程里没有下面这行            httpGet.abort();        } catch (Exception e) {            e.printStackTrace();        } finally {            //关闭连接，释放资源            httpClient.getConnectionManager().shutdown();        }    }}

分析请求包中这六个头信息：httpget.setHeader("Accept-Encoding", "gzip, deflate")可能产生乱码

    /**     * @param args     * @throws IOException     */    public static void main(String[] args) {        HttpClient httpClient = new DefaultHttpClient();        try {            HttpGet httpget = new HttpGet("http://www.iteye.com");            httpget.setHeader("Accept", "text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8");            httpget.setHeader("Accept-Language", "zh-cn,zh;q=0.5");            httpget.setHeader("User-Agent", "Mozilla/5.0 (Windows NT 5.1; rv:7.0.1) Gecko/20100101 Firefox/7.0.1)");            httpget.setHeader("Accept-Encoding", "gzip, deflate");            httpget.setHeader("Accept-Charset", "GB2312,utf-8;q=0.7,*;q=0.7");            httpget.setHeader("Host", "www.iteye.com");            httpget.setHeader("Connection", "Keep-Alive");            HttpResponse response = httpClient.execute(httpget);            HttpEntity entity = response.getEntity();            System.out.println("----------------------------------------");            System.out.println(response.getStatusLine());            if (entity != null) {                System.out.println("Response content length: " + entity.getContentLength());            }            System.out.println("----------------------------------------");            InputStream inSm = entity.getContent();            Scanner inScn = new Scanner(inSm);            while (inScn.hasNextLine()) {                System.out.println(inScn.nextLine());            }            // Do not feel like reading the response body            // Call abort on the request object            httpget.abort();        } catch (Exception e) {            e.printStackTrace();        } finally {            // When HttpClient instance is no longer needed,            // shut down the connection manager to ensure            // immediate deallocation of all system resources            httpClient.getConnectionManager().shutdown();        }    }

HttpPost操作：

public class Demo2 {    /**     * 用post方法访问本地应用根据传递参数不同，返回不同结果     *     * @param args     */    public static void main(String[] args) {        //创建默认的 HttpClient 实例        HttpClient httpClient = new DefaultHttpClient();        HttpPost httpPost = new HttpPost("http://localhost:86/test1Servlet");        List<NameValuePair> formParams = new ArrayList<NameValuePair>();        formParams.add(new BasicNameValuePair("param1", "***"));        UrlEncodedFormEntity urlEncodedFormEntity;        try {            urlEncodedFormEntity = new UrlEncodedFormEntity(formParams, "UTF-8");            httpPost.setEntity(urlEncodedFormEntity);            System.out.println("execurting request:" + httpPost.getURI());            HttpResponse httpResponse = null;            httpResponse = httpClient.execute(httpPost);            HttpEntity httpEntity = httpResponse.getEntity();            if (httpEntity != null) {                String content = EntityUtils.toString(httpEntity, "UTF-8");                System.out.println("Response content:" + content);            }        } catch (ClientProtocolException e) {            e.printStackTrace();        } catch (UnsupportedEncodingException e) {            e.printStackTrace();        } catch (IOException e) {            e.printStackTrace();        } finally {            //关闭连接，释放资源            httpClient.getConnectionManager().shutdown();        }    }}