java之HttpClient简单使用
最近在做微信公众号开发，需要用java代码访问微信端接口来请求数据。
由于博主java的网络通信也不是很精通，只是粗略了解皮毛，等以后知识上来了再深入研究java的网络编程。
所以这篇文章就先介绍简单使用。
需要的jar包：
<dependency> <groupId>org.apache.httpcomponents</groupId> <artifactId>httpclient</artifactId> <version>4.3.6</version> </dependency> <dependency> <groupId>org.apache.httpcomponents</groupId> <artifactId>httpcore</artifactId> <version>4.4</version> </dependency>
本篇博客分为几块部分：http的get、post请求，https的get、post请求
新建一个类HttpUtil:
public class HttpUtil {
private static PoolingHttpClientConnectionManager connMgr;
private static RequestConfig requestConfig;
private static final int MAX_TIMEOUT = 7000;
static {
// 设置连接池
connMgr = new PoolingHttpClientConnectionManager();
// 设置连接池大小
connMgr.setMaxTotal(100);
connMgr.setDefaultMaxPerRoute(connMgr.getMaxTotal());
RequestConfig.Builder configBuilder = RequestConfig.custom();
// 设置连接超时
configBuilder.setConnectTimeout(MAX_TIMEOUT);
// 设置读取超时
configBuilder.setSocketTimeout(MAX_TIMEOUT);
// 设置从连接池获取连接实例的超时
configBuilder.setConnectionRequestTimeout(MAX_TIMEOUT);
// 在提交请求之前 测试连接是否可用
configBuilder.setStaleConnectionCheckEnabled(true);
requestConfig = configBuilder.build();
}
}
http部分
get请求：
/**
* 发送 GET 请求（HTTP），不带输入数据
*
* @param url
* @return
*/
public static String doGet(String url) {
return doGet(url, new HashMap<String, Object>());
}
/**
* 发送 GET 请求（HTTP），K-V形式
*
* @param url
* @param params
* @return
*/
public static String doGet(String url, Map<String, Object> params) {
String apiUrl = url;
StringBuffer param = new StringBuffer();
//拼接get请求参数
int i = 0;
for (String key : params.keySet()) {
if (i == 0)
param.append("?");
else
param.append("&");
param.append(key).append("=").append(params.get(key));
i++;
}
//往url后面添加所有的请求参数
apiUrl += param;
String result = null;
//开始执行get请求，新建一个DefaultHttpClient对象
HttpClient httpclient = new DefaultHttpClient();
try {
//新建一个处理特定url的HttpGet对象
HttpGet httpGet = new HttpGet(apiUrl);
//执行请求，得到response对象
HttpResponse response = httpclient.execute(httpGet);
//获取响应状态码
int statusCode = response.getStatusLine().getStatusCode();
System.out.println("执行状态码 : " + statusCode);
HttpEntity entity = response.getEntity();
if (entity != null) {
//处理结果
// result = EntityUtils.toString(entity, "UTF-8");
InputStream instream = entity.getContent();
result = inputStream2String(instream, "UTF-8");
}
} catch (IOException e) {
e.printStackTrace();
}
return result;
}
inputStream2String：
private static String inputStream2String(InputStream is, String encode) {
String result = "";
try {
if (encode == null || encode.equals("")) {
// 默认以utf-8形式
encode = "utf-8";
}
BufferedReader reader = new BufferedReader(new InputStreamReader(is, encode));
StringBuffer sb = new StringBuffer();
while ((result = reader.readLine()) != null) {
sb.append(result).append("\n");
}
return sb.toString();
} catch (UnsupportedEncodingException e1) {
e1.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
}
return result;
}
post请求：
/**
* 发送 POST 请求（HTTP），不带输入数据
*
* @param apiUrl
* @return
*/
public static String doPost(String apiUrl) {
return doPost(apiUrl, new HashMap<String, Object>());
}
/**
* 发送 POST 请求（HTTP），K-V形式
*
* @param apiUrl
* API接口URL
* @param params
* 参数map
* @return
*/
public static String doPost(String apiUrl, Map<String, Object> params) {
//新建一个可以关闭的httpClient对象
CloseableHttpClient httpClient = HttpClients.createDefault();
String httpStr = null;
//新建一个处理特定请求的httpPost对象
HttpPost httpPost = new HttpPost(apiUrl);
//可以关闭的HttpResponse
CloseableHttpResponse response = null;
try {
//post请求设置
httpPost.setConfig(requestConfig);
//参数键值对对象（NameValuePair）的List
List<NameValuePair> pairList = new ArrayList<NameValuePair>(params.size());
for (Map.Entry<String, Object> entry : params.entrySet()) {
NameValuePair pair = new BasicNameValuePair(entry.getKey(), entry.getValue().toString());
pairList.add(pair);
}
//设置请求实体（参数）
httpPost.setEntity(new UrlEncodedFormEntity(pairList, Charset.forName("UTF-8")));
//执行请求
response = httpClient.execute(httpPost);
System.out.println(response.toString());
//获取响应实体
HttpEntity entity = response.getEntity();
//将响应实体以字符串形式变成结果
httpStr = EntityUtils.toString(entity, "UTF-8");
} catch (IOException e) {
e.printStackTrace();
} finally {
if (response != null) {
try {
//关闭流
EntityUtils.consume(response.getEntity());
} catch (IOException e) {
e.printStackTrace();
}
}
}
return httpStr;
}
/**
* 发送 POST 请求（HTTP），JSON形式
*
* @param apiUrl
* @param json
* json对象
* @return
*/
public static String doPost(String apiUrl, Object json) {
CloseableHttpClient httpClient = HttpClients.createDefault();
String httpStr = null;
HttpPost httpPost = new HttpPost(apiUrl);
CloseableHttpResponse response = null;
//大体过程和上面类似
try {
httpPost.setConfig(requestConfig);
StringEntity stringEntity = new StringEntity(json.toString(), "UTF-8");// 解决中文乱码问题
stringEntity.setContentEncoding("UTF-8");
//内容类型设置成json格式
stringEntity.setContentType("application/json");
httpPost.setEntity(stringEntity);
response = httpClient.execute(httpPost);
HttpEntity entity = response.getEntity();
System.out.println(response.getStatusLine().getStatusCode());
httpStr = EntityUtils.toString(entity, "UTF-8");
} catch (IOException e) {
e.printStackTrace();
} finally {
if (response != null) {
try {
EntityUtils.consume(response.getEntity());
} catch (IOException e) {
e.printStackTrace();
}
}
}
return httpStr;
}
HTTPS
我新建了一个类SSLClient：
import java.security.cert.CertificateException;
import java.security.cert.X509Certificate;
import javax.net.ssl.SSLContext;
import javax.net.ssl.TrustManager;
import javax.net.ssl.X509TrustManager;
import org.apache.http.conn.ClientConnectionManager;
import org.apache.http.conn.HttpClientConnectionManager;
import org.apache.http.conn.scheme.Scheme;
import org.apache.http.conn.scheme.SchemeRegistry;
import org.apache.http.conn.ssl.SSLSocketFactory;
import org.apache.http.impl.client.DefaultHttpClient;
//用于进行Https请求的HttpClient
public class SSLClient extends DefaultHttpClient{
public SSLClient() throws Exception{
super();
SSLContext ctx = SSLContext.getInstance("TLS");
X509TrustManager tm = new X509TrustManager() {
public void checkClientTrusted(X509Certificate[] chain,
String authType) throws CertificateException {
}
public void checkServerTrusted(X509Certificate[] chain,
String authType) throws CertificateException {
}
public X509Certificate[] getAcceptedIssuers() {
return null;
}
};
ctx.init(null, new TrustManager[]{tm}, null);
//当前对象的管理
ClientConnectionManager ccm = this.getConnectionManager();
SchemeRegistry sr = ccm.getSchemeRegistry();//当前管理者的注册方案
//SSL工厂
SSLSocketFactory ssf = new SSLSocketFactory(ctx,SSLSocketFactory.ALLOW_ALL_HOSTNAME_VERIFIER);
sr.register(new Scheme("https", 443, ssf));//注册SSL
}
}
get请求：
/**
* 发送get请求
*
* @param url
* 链接地址
* @param charset
* 字符编码，若为null则默认utf-8
* @return
*/
public static String doGetSSL(String url, String charset) {
if (null == charset) {
charset = "utf-8";
}
HttpClient httpClient = null;
HttpGet httpGet = null;
String result = null;
try {
httpClient = new SSLClient();
httpGet = new HttpGet(url);
HttpResponse response = httpClient.execute(httpGet);
if (response != null) {
HttpEntity resEntity = response.getEntity();
if (resEntity != null) {
result = EntityUtils.toString(resEntity, charset);
}
}
} catch (Exception e) {
e.printStackTrace();
}
return result;
}
post请求：
/**
* 发送 SSL POST 请求（HTTPS），K-V形式
*
* @param apiUrl
* API接口URL
* @param params
* 参数map
* @return
*/
public static String doPostSSL(String apiUrl, Map<String, Object> params){
//会发生unable to find valid certification path to requested target异常
//CloseableHttpClient httpClient = HttpClients.custom().setSSLSocketFactory(createSSLConnSocketFactory())
// .setConnectionManager(connMgr).setDefaultRequestConfig(requestConfig).build();
HttpPost httpPost = new HttpPost(apiUrl);
CloseableHttpResponse response = null;
String httpStr = null;
SSLClient httpClient = null;
try {
httpClient = new SSLClient();
httpPost.setConfig(requestConfig);
List<NameValuePair> pairList = new ArrayList<NameValuePair>(params.size());
for (Map.Entry<String, Object> entry : params.entrySet()) {
NameValuePair pair = new BasicNameValuePair(entry.getKey(), entry.getValue().toString());
pairList.add(pair);
}
httpPost.setEntity(new UrlEncodedFormEntity(pairList, Charset.forName("utf-8")));
response = httpClient.execute(httpPost);
int statusCode = response.getStatusLine().getStatusCode();
if (statusCode != HttpStatus.SC_OK) {
return null;
}
HttpEntity entity = response.getEntity();
if (entity == null) {
return null;
}
httpStr = EntityUtils.toString(entity, "utf-8");
} catch (Exception e) {
e.printStackTrace();
} finally {
if (response != null) {
try {
EntityUtils.consume(response.getEntity());
} catch (IOException e) {
e.printStackTrace();
}
}
}
return httpStr;
}
/**
* 发送 SSL POST 请求（HTTPS），JSON形式
*
* @param apiUrl
* API接口URL
* @param json
* JSON对象
* @return
*/
public static String doPostSSL(String apiUrl, Object json) {
//CloseableHttpClient httpClient = HttpClients.custom().setSSLSocketFactory(createSSLConnSocketFactory())
// .setConnectionManager(connMgr).setDefaultRequestConfig(requestConfig).build();
HttpPost httpPost = new HttpPost(apiUrl);
CloseableHttpResponse response = null;
String httpStr = null;
SSLClient httpClient = null;
try {
httpClient = new SSLClient();
httpPost.setConfig(requestConfig);
StringEntity stringEntity = new StringEntity(json.toString(), "UTF-8");// 解决中文乱码问题
stringEntity.setContentEncoding("UTF-8");
stringEntity.setContentType("application/json");
httpPost.setEntity(stringEntity);
response = httpClient.execute(httpPost);
int statusCode = response.getStatusLine().getStatusCode();
if (statusCode != HttpStatus.SC_OK) {
return null;
}
HttpEntity entity = response.getEntity();
if (entity == null) {
return null;
}
httpStr = EntityUtils.toString(entity, "utf-8");
} catch (Exception e) {
e.printStackTrace();
} finally {
if (response != null) {
try {
EntityUtils.consume(response.getEntity());
} catch (IOException e) {
e.printStackTrace();
}
}
}
return httpStr;
}
以上方法都属于HttpUtil类中。
SSL部分不涉及具体证书的使用。
还有很多不懂请见谅。只知道大概怎么用，大体的意思是知道的。
代码片段：
