一个java的http请求的封装工具类

java实现http请求的方法常用有两种，一种则是通过java自带的标准类HttpURLConnection去实现，另一种是通过apache的httpclient去实现。
本文用httpclient去实现，需要导入httpclient和httpcore两个jar包，测试时用的httpclient-4.5.1和httpcore-4.4.3。

HttpMethod.java

package demo;

public enum HttpMethod {
    GET, POST;
}

HttpHeader.java

package demo;

import java.util.HashMap;
import java.util.Map;

/**
 * 请求头
 */
public class HttpHeader {
    private Map<String, String> params = new HashMap<String, String>();
        
    public HttpHeader addParam(String name, String value) {
        this.params.put(name, value);
        return this;
    }
    
    public Map<String, String> getParams() {
        return this.params;
    }
}

HttpParamers.java

package demo;

import java.io.IOException;
import java.net.URLEncoder;
import java.util.HashMap;
import java.util.Map;
import java.util.Set;

import com.alibaba.fastjson.JSON;

/**
 * 请求参数
 */
public class HttpParamers {
    private Map<String, String> params = new HashMap<String, String>();
    private HttpMethod httpMethod;
    private String jsonParamer = "";

    public HttpParamers(HttpMethod httpMethod) {
        this.httpMethod = httpMethod;
    }

    public static HttpParamers httpPostParamers() {
        return new HttpParamers(HttpMethod.POST);
    }

    public static HttpParamers httpGetParamers() {
        return new HttpParamers(HttpMethod.GET);
    }
    
    public HttpParamers addParam(String name, String value) {
        this.params.put(name, value);
        return this;
    }

    public HttpMethod getHttpMethod() {
        return this.httpMethod;
    }

    public String getQueryString(String charset) throws IOException {
        if ((this.params == null) || (this.params.isEmpty())) {
            return null;
        }
        StringBuilder query = new StringBuilder();
        Set<Map.Entry<String, String>> entries = this.params.entrySet();

        for (Map.Entry<String, String> entry : entries) {
            String name = entry.getKey();
            String value = entry.getValue();
            query.append("&").append(name).append("=").append(URLEncoder.encode(value, charset));
        }
        return query.substring(1);
    }

    public boolean isJson() {
        return !isEmpty(this.jsonParamer);
    }

    public Map<String, String> getParams() {
        return this.params;
    }

    public String toString() {
        return "HttpParamers " + JSON.toJSONString(this);        
    }

    public String getJsonParamer() {
        return this.jsonParamer;
    }
    
    public void setJsonParamer() {
        this.jsonParamer = JSON.toJSONString(this.params);
    }
    
    private static boolean isEmpty(CharSequence cs) {
        return (cs == null) || (cs.length() == 0);
    }
}

HttpClient.java

package demo;

import java.io.IOException;
import java.util.Map;
import java.util.Set;

import org.apache.http.HttpEntity;
import org.apache.http.client.methods.CloseableHttpResponse;
import org.apache.http.client.methods.HttpGet;
import org.apache.http.client.methods.HttpPost;
import org.apache.http.client.methods.HttpRequestBase;
import org.apache.http.entity.StringEntity;
import org.apache.http.impl.client.CloseableHttpClient;
import org.apache.http.impl.client.HttpClients;
import org.apache.http.protocol.HTTP;
import org.apache.http.util.EntityUtils;

public class HttpClient {
    public static final String DEFAULT_CHARSET = "UTF-8";
    public static final String JSON_CONTENT_FORM = "application/json;charset=UTF-8";
    public static final String CONTENT_FORM = "application/x-www-form-urlencoded;charset=UTF-8";
    
    public static String doService(String url, HttpParamers paramers, HttpHeader header, int connectTimeout, int readTimeout) throws Exception {
        HttpMethod httpMethod = paramers.getHttpMethod();
        switch (httpMethod) {
            case GET:
                return doGet(url, paramers, header, connectTimeout, readTimeout);
            case POST:
                return doPost(url, paramers, header, connectTimeout, readTimeout);
        }
        return null;
    }
    
    /**
     * post方法
     * @param url
     * @param paramers
     * @param header
     * @param connectTimeout
     * @param readTimeout
     * @return
     * @throws IOException
     */
    public static String doPost(String url, HttpParamers paramers, HttpHeader header, int connectTimeout, int readTimeout) throws IOException  {
        String responseData = "";
        CloseableHttpClient httpClient = null;
        CloseableHttpResponse httpResponse = null;        
        try{
            String query = null;                    
            HttpPost httpPost = new HttpPost(url);
            setHeader(httpPost, header);                        
            if (paramers.isJson()) {
                //json数据
                httpPost.setHeader(HTTP.CONTENT_TYPE, JSON_CONTENT_FORM);                
                query = paramers.getJsonParamer();
            } else {
                //表单数据
                httpPost.setHeader(HTTP.CONTENT_TYPE, CONTENT_FORM);
                query = paramers.getQueryString(DEFAULT_CHARSET);
            }
            if(query != null){
                HttpEntity reqEntity = new StringEntity(query);
                httpPost.setEntity(reqEntity);
            }            
            httpClient = HttpClients.createDefault();                        
            httpResponse = httpClient.execute(httpPost);
            HttpEntity resEntity = httpResponse.getEntity();
            responseData = EntityUtils.toString(resEntity);
        } catch (Exception e){
            e.printStackTrace();
        } finally{
            httpResponse.close();
            httpClient.close();
        }
        return responseData;
    }
    
    
    /**
     * get方法
     * @param url
     * @param params
     * @param header
     * @param connectTimeout
     * @param readTimeout
     * @return
     * @throws IOException
     */
    public static String doGet(String url, HttpParamers params, HttpHeader header, int connectTimeout, int readTimeout) throws IOException {
        String responseData = "";
        CloseableHttpClient httpClient = null;
        CloseableHttpResponse httpResponse = null;        
        try{    
            String query = params.getQueryString(DEFAULT_CHARSET);    
            url = buildGetUrl(url, query);
            HttpGet httpGet = new HttpGet(url);
            setHeader(httpGet, header);    
            httpClient = HttpClients.createDefault();                        
            httpResponse = httpClient.execute(httpGet);
            HttpEntity resEntity = httpResponse.getEntity();
            responseData = EntityUtils.toString(resEntity);
        } catch (Exception e){
            e.printStackTrace();
        } finally{
            httpResponse.close();
            httpClient.close();
        }
        return responseData;
    }
    
    private static void setHeader(HttpRequestBase httpRequestBase, HttpHeader header){
        if(header != null){
            Map<String,String> headerMap = header.getParams();
            if (headerMap != null && !headerMap.isEmpty()) {        
                Set<Map.Entry<String, String>> entries = headerMap.entrySet();    
                for (Map.Entry<String, String> entry : entries) {
                    String name = entry.getKey();
                    String value = entry.getValue();
                    httpRequestBase.setHeader(name, value);
                }
            }
        }
    }
    
    private static String buildGetUrl(String url, String query) throws IOException {
        if (query == null || query.equals("")) {
            return url;
        }
        StringBuilder newUrl = new StringBuilder(url);
        boolean hasQuery = url.contains("?");
        boolean hasPrepend = (url.endsWith("?")) || (url.endsWith("&"));
        if (!hasPrepend) {
            if (hasQuery) {
                newUrl.append("&");
            } else {
                newUrl.append("?");
                hasQuery = true;
            }
        }
        newUrl.append(query);
        hasPrepend = false;
        return newUrl.toString();
    }
}

HttpService.java

package demo;

import java.util.Map;

import com.alibaba.fastjson.JSONObject;
import com.alibaba.fastjson.TypeReference;

public class HttpService {
    private String serverUrl;
    private int connectTimeout = 15000;
    private int readTimeout = 30000;
    public HttpService(String serverUrl) {
        this.serverUrl = serverUrl.trim();
    }
    public Map<String, Object> commonService(String serviceUrl, HttpParamers paramers) throws Exception{
        return commonService(serviceUrl, paramers, null);
    }
    public Map<String, Object> commonService(String serviceUrl, HttpParamers paramers, HttpHeader header) throws Exception{
        String response = service(serviceUrl, paramers, header);
        try {
            Map<String, Object> result = JSONObject.parseObject(response, new TypeReference<Map<String, Object>>() {});
            if ((result == null) || (result.isEmpty())) {
                throw new Exception("远程服务返回的数据无法解析");
            }
            Integer code = (Integer) result.get("code");
            if ((code == null) || (code.intValue() != 0)) {
                throw new Exception((String) result.get("message"));
            }
            return result;
        } catch (Exception e) {
            throw new Exception("返回结果异常,response:" + response, e);
        }
    }
    public String service(String serviceUrl, HttpParamers paramers) throws Exception {
        return service(serviceUrl, paramers, null);
    }
    public String service(String serviceUrl, HttpParamers paramers, HttpHeader header) throws Exception {
        String url = this.serverUrl + serviceUrl;
        String responseData = "";
        try {
            responseData = HttpClient.doService(url, paramers, header, this.connectTimeout, this.readTimeout);
        } catch (Exception e) {
            throw new Exception(e.getMessage(), e);
        }
        return responseData;
    }
    
    public String getServerUrl() {
        return this.serverUrl;
    }

    public int getConnectTimeout() {
        return this.connectTimeout;
    }

    public int getReadTimeout() {
        return this.readTimeout;
    }

    public void setConnectTimeout(int connectTimeout) {
        this.connectTimeout = connectTimeout;
    }

    public void setReadTimeout(int readTimeout) {
        this.readTimeout = readTimeout;
    }
}

测试例子Test1.java

package demo;

import org.junit.Ignore;
import org.junit.Test;

public class Test1 {

    //免费的在线REST服务, 提供测试用的HTTP请求假数据
    //接口信息说明可见：http://www.hangge.com/blog/cache/detail_2020.html
    String uri = "http://jsonplaceholder.typicode.com";
    
    //get方式请求数据
    //请求地址：http://jsonplaceholder.typicode.com/posts
    @Ignore("暂时忽略")
    @Test
    public void test1() {
        System.out.print("
" + "test1---------------------------"+ "
");
        HttpParamers paramers = HttpParamers.httpGetParamers();
        String response = "";
        try {
            HttpService httpService = new HttpService(uri);
            response = httpService.service("/posts", paramers);            
        } catch (Exception e) {
            e.printStackTrace();
        }
        System.out.print(response);
    }
    
    //get方式请求数据
    //请求地址：http://jsonplaceholder.typicode.com/posts?userId=5
    @Ignore("暂时忽略")
    @Test
    public void test2() {
        System.out.print("
" + "test2---------------------------"+ "
");
        HttpParamers paramers = HttpParamers.httpGetParamers();
        paramers.addParam("userId", "5");
        String response = "";
        try {
            HttpService httpService = new HttpService(uri);            
            response = httpService.service("/posts", paramers);            
        } catch (Exception e) {
            e.printStackTrace();
        }
        System.out.print(response);
    }
    
    //post方式请求数据
    //请求地址：http://jsonplaceholder.typicode.com/posts    
    @Test
    public void test3() {
        System.out.print("
" + "test3---------------------------"+ "
");
        HttpParamers paramers = HttpParamers.httpPostParamers();
        paramers.addParam("time", String.valueOf(System.currentTimeMillis()));
        String response = "";
        try {
            HttpService httpService = new HttpService(uri);
            response = httpService.service("/posts", paramers);            
        } catch (Exception e) {
            e.printStackTrace();
        }
        System.out.print(response);
    }
}