java之HttpClient 使用[get/post]

在介绍 java 上的 网页的获取工具之前， 这里先介绍 linux 下自带的一个好用的网页获取工具 curl,有兴趣的可以去详细了解下。

HttpClient

HttpClient通过提供一个高效，最新和功能丰富的软件包来实现客户端的最新HTTP标准和建议

依赖

<dependency>    <groupId>org.apache.httpcomponents</groupId>    <artifactId>httpclient</artifactId>    <version>4.5.3</version></dependency>

发送 get 请求并获取数据

public static BufferedReader httpGetMethod(String uri) throws IOException {    // 创建客户端对象    CloseableHttpClient httpClient = HttpClients.createDefault();    // 跟据对象获取请求 -- get    HttpGet get = new HttpGet(uri);    // 接受响应对象    CloseableHttpResponse response = null;    BufferedReader buffer = null;    try{        response = httpClient.execute(get);        String str = EntityUtils.toString(response.getEntity(), "utf-8");        buffer = new BufferedReader(new InputStreamReader(new ByteArrayInputStream(str.getBytes("utf-8"))));        return buffer;    }catch (IOException e){        if(buffer != null){            buffer.close();        }        return null;    }finally {        if(response != null){            response.close();        }        httpClient.close();    }}

发送　post 请求

public static BufferedReader httpPostMethod(String uri, Map<String, String> map) throws IOException {    CloseableHttpClient httpClient = HttpClients.createDefault();    HttpPost post = new HttpPost(uri);    CloseableHttpResponse response = null;    BufferedReader buffer = null;    if(map != null || map.size() != 0){        for(String key : map.keySet()){            post.setHeader(key, map.get(key));        }    }    try{        response = httpClient.execute(post);        String str = EntityUtils.toString(response.getEntity(), "utf-8");        buffer = new BufferedReader(new InputStreamReader(new ByteArrayInputStream(str.getBytes("utf-8"))));        return buffer;    }catch (IOException e){        if(buffer != null){            buffer.close();        }        return null;    }finally {        if(response != null){            response.close();        }        httpClient.close();    }}

使用post 发送json 数据:

    public static BufferedReader httpPostMethod(String uri, Map<String, String> map, String data) throws IOException {        CloseableHttpClient httpClient = HttpClients.createDefault();        HttpPost post = new HttpPost(uri);        CloseableHttpResponse response = null;        BufferedReader buffer = null;        String e;        if(map != null || map.size() != 0) {            Iterator entity = map.keySet().iterator();            while(entity.hasNext()) {                e = (String)entity.next();                post.setHeader(e, (String)map.get(e));            }        }        StringEntity entity1 = new StringEntity(data);        entity1.setContentType("application/json");        entity1.setContentEncoding("utf-8");        post.setEntity(entity1);        BufferedReader var9;        try {            response = httpClient.execute(post);            e = EntityUtils.toString(response.getEntity(), "utf-8");            buffer = new BufferedReader(new InputStreamReader(new ByteArrayInputStream(e.getBytes("utf-8"))));            var9 = buffer;            return var9;        } catch (IOException var13) {            var13.printStackTrace();            if(buffer != null) {                buffer.close();            }            System.exit(-1);            var9 = null;        } finally {            if(response != null) {                response.close();            }            httpClient.close();        }        return var9;    }