JAVA的GET和POST請求實現方式

1、介紹 使用Java實現GET和POST請求的方法經常使用的有兩種：HTTPClient和HttpURLConnection。前者是第三方開源框架實現，對HTTP請求的封裝很好，使用HTTPClient基本能夠知足工做須要，其中HTTPClient3.1是org.apache.commons.httpclient下操做遠程url的工具包，HTTPClient4.5.5是org.apache.http.client下操做遠程url的工具包。而HttpURLConnection是java的標準請求方式。

2、實現 1.HttpURLConnection原生實現方式：

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.OutputStream;
import java.net.HttpURLConnection;
import java.net.MalformedURLException;
import java.net.URL;
 
public class HttpClient {
    public static String doGet(String httpurl) {
        HttpURLConnection connection = null;
        InputStream is = null;
        BufferedReader br = null;
        String result = null;// 返回結果字符串
        try {
            // 建立遠程url鏈接對象
            URL url = new URL(httpurl);
            // 經過遠程url鏈接對象打開一個鏈接，強轉成httpURLConnection類
            connection = (HttpURLConnection) url.openConnection();
            // 設置鏈接方式：get
            connection.setRequestMethod("GET");
            // 設置鏈接主機服務器的超時時間：15000毫秒
            connection.setConnectTimeout(15000);
            // 設置讀取遠程返回的數據時間：60000毫秒
            connection.setReadTimeout(60000);
            // 發送請求
            connection.connect();
            // 經過connection鏈接，獲取輸入流
            if (connection.getResponseCode() == 200) {
                is = connection.getInputStream();
                // 封裝輸入流is，並指定字符集
                br = new BufferedReader(new InputStreamReader(is, "UTF-8"));
                // 存放數據
                StringBuffer sbf = new StringBuffer();
                String temp = null;
                while ((temp = br.readLine()) != null) {
                    sbf.append(temp);
                    sbf.append("\r\n");
                }
                result = sbf.toString();
            }
        } catch (MalformedURLException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        } finally {
            // 關閉資源
            if (null != br) {
                try {
                    br.close();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
 
            if (null != is) {
                try {
                    is.close();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
 
            connection.disconnect();// 關閉遠程鏈接
        }
 
        return result;
    }
 
    public static String doPost(String httpUrl, String param) {
 
        HttpURLConnection connection = null;
        InputStream is = null;
        OutputStream os = null;
        BufferedReader br = null;
        String result = null;
        try {
            URL url = new URL(httpUrl);
            // 經過遠程url鏈接對象打開鏈接
            connection = (HttpURLConnection) url.openConnection();
            // 設置鏈接請求方式
            connection.setRequestMethod("POST");
            // 設置鏈接主機服務器超時時間：15000毫秒
            connection.setConnectTimeout(15000);
            // 設置讀取主機服務器返回數據超時時間：60000毫秒
            connection.setReadTimeout(60000);
 
            // 默認值爲：false，當向遠程服務器傳送數據/寫數據時，須要設置爲true
            connection.setDoOutput(true);
            // 默認值爲：true，當前向遠程服務讀取數據時，設置爲true，該參數無關緊要
            connection.setDoInput(true);
            // 設置傳入參數的格式:請求參數應該是 name1=value1&name2=value2 的形式。
            connection.setRequestProperty("Content-Type", "application/x-www-form-urlencoded");
            // 設置鑑權信息：Authorization: Bearer da3efcbf-0845-4fe3-8aba-ee040be542c0
            connection.setRequestProperty("Authorization", "Bearer da3efcbf-0845-4fe3-8aba-ee040be542c0");
            // 經過鏈接對象獲取一個輸出流
            os = connection.getOutputStream();
            // 經過輸出流對象將參數寫出去/傳輸出去,它是經過字節數組寫出的
            os.write(param.getBytes());
            // 經過鏈接對象獲取一個輸入流，向遠程讀取
            if (connection.getResponseCode() == 200) {
 
                is = connection.getInputStream();
                // 對輸入流對象進行包裝:charset根據工做項目組的要求來設置
                br = new BufferedReader(new InputStreamReader(is, "UTF-8"));
 
                StringBuffer sbf = new StringBuffer();
                String temp = null;
                // 循環遍歷一行一行讀取數據
                while ((temp = br.readLine()) != null) {
                    sbf.append(temp);
                    sbf.append("\r\n");
                }
                result = sbf.toString();
            }
        } catch (MalformedURLException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        } finally {
            // 關閉資源
            if (null != br) {
                try {
                    br.close();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
            if (null != os) {
                try {
                    os.close();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
            if (null != is) {
                try {
                    is.close();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
            // 斷開與遠程地址url的鏈接
            connection.disconnect();
        }
        return result;
    }
}
--------------------- 
做者：zkzqzzz 
來源：CSDN 
原文：https://blog.csdn.net/u012513972/article/details/79569888 
版權聲明：本文爲博主原創文章，轉載請附上博文連接！

2.java原生HttpClient3.1

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.UnsupportedEncodingException;
import java.util.Iterator;
import java.util.Map;
import java.util.Map.Entry;
import java.util.Set;
 
import org.apache.commons.httpclient.DefaultHttpMethodRetryHandler;
import org.apache.commons.httpclient.HttpClient;
import org.apache.commons.httpclient.HttpStatus;
import org.apache.commons.httpclient.NameValuePair;
import org.apache.commons.httpclient.methods.GetMethod;
import org.apache.commons.httpclient.methods.PostMethod;
import org.apache.commons.httpclient.params.HttpMethodParams;
 
public class HttpClient3 {
 
    public static String doGet(String url) {
        // 輸入流
        InputStream is = null;
        BufferedReader br = null;
        String result = null;
        // 建立httpClient實例
        HttpClient httpClient = new HttpClient();
        // 設置http鏈接主機服務超時時間：15000毫秒
        // 先獲取鏈接管理器對象，再獲取參數對象,再進行參數的賦值
        httpClient.getHttpConnectionManager().getParams().setConnectionTimeout(15000);
        // 建立一個Get方法實例對象
        GetMethod getMethod = new GetMethod(url);
        // 設置get請求超時爲60000毫秒
        getMethod.getParams().setParameter(HttpMethodParams.SO_TIMEOUT, 60000);
        // 設置請求重試機制，默認重試次數：3次，參數設置爲true，重試機制可用，false相反
        getMethod.getParams().setParameter(HttpMethodParams.RETRY_HANDLER, new DefaultHttpMethodRetryHandler(3, true));
        try {
            // 執行Get方法
            int statusCode = httpClient.executeMethod(getMethod);
            // 判斷返回碼
            if (statusCode != HttpStatus.SC_OK) {
                // 若是狀態碼返回的不是ok,說明失敗了,打印錯誤信息
                System.err.println("Method faild: " + getMethod.getStatusLine());
            } else {
                // 經過getMethod實例，獲取遠程的一個輸入流
                is = getMethod.getResponseBodyAsStream();
                // 包裝輸入流
                br = new BufferedReader(new InputStreamReader(is, "UTF-8"));
 
                StringBuffer sbf = new StringBuffer();
                // 讀取封裝的輸入流
                String temp = null;
                while ((temp = br.readLine()) != null) {
                    sbf.append(temp).append("\r\n");
                }
 
                result = sbf.toString();
            }
 
        } catch (IOException e) {
            e.printStackTrace();
        } finally {
            // 關閉資源
            if (null != br) {
                try {
                    br.close();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
            if (null != is) {
                try {
                    is.close();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
            // 釋放鏈接
            getMethod.releaseConnection();
        }
        return result;
    }
 
    public static String doPost(String url, Map<String, Object> paramMap) {
        // 獲取輸入流
        InputStream is = null;
        BufferedReader br = null;
        String result = null;
        // 建立httpClient實例對象
        HttpClient httpClient = new HttpClient();
        // 設置httpClient鏈接主機服務器超時時間：15000毫秒
        httpClient.getHttpConnectionManager().getParams().setConnectionTimeout(15000);
        // 建立post請求方法實例對象
        PostMethod postMethod = new PostMethod(url);
        // 設置post請求超時時間
        postMethod.getParams().setParameter(HttpMethodParams.SO_TIMEOUT, 60000);
 
        NameValuePair[] nvp = null;
        // 判斷參數map集合paramMap是否爲空
        if (null != paramMap && paramMap.size() > 0) {// 不爲空
            // 建立鍵值參數對象數組，大小爲參數的個數
            nvp = new NameValuePair[paramMap.size()];
            // 循環遍歷參數集合map
            Set<Entry<String, Object>> entrySet = paramMap.entrySet();
            // 獲取迭代器
            Iterator<Entry<String, Object>> iterator = entrySet.iterator();
 
            int index = 0;
            while (iterator.hasNext()) {
                Entry<String, Object> mapEntry = iterator.next();
                // 從mapEntry中獲取key和value建立鍵值對象存放到數組中
                try {
                    nvp[index] = new NameValuePair(mapEntry.getKey(),
                            new String(mapEntry.getValue().toString().getBytes("UTF-8"), "UTF-8"));
                } catch (UnsupportedEncodingException e) {
                    e.printStackTrace();
                }
                index++;
            }
        }
        // 判斷nvp數組是否爲空
        if (null != nvp && nvp.length > 0) {
            // 將參數存放到requestBody對象中
            postMethod.setRequestBody(nvp);
        }
        // 執行POST方法
        try {
            int statusCode = httpClient.executeMethod(postMethod);
            // 判斷是否成功
            if (statusCode != HttpStatus.SC_OK) {
                System.err.println("Method faild: " + postMethod.getStatusLine());
            }
            // 獲取遠程返回的數據
            is = postMethod.getResponseBodyAsStream();
            // 封裝輸入流
            br = new BufferedReader(new InputStreamReader(is, "UTF-8"));
 
            StringBuffer sbf = new StringBuffer();
            String temp = null;
            while ((temp = br.readLine()) != null) {
                sbf.append(temp).append("\r\n");
            }
 
            result = sbf.toString();
        } catch (IOException e) {
            e.printStackTrace();
        } finally {
            // 關閉資源
            if (null != br) {
                try {
                    br.close();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
            if (null != is) {
                try {
                    is.close();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
            // 釋放鏈接
            postMethod.releaseConnection();
        }
        return result;
    }
}
--------------------- 
做者：zkzqzzz 
來源：CSDN 
原文：https://blog.csdn.net/u012513972/article/details/79569888 
版權聲明：本文爲博主原創文章，轉載請附上博文連接！

3.java原生httpClient4.5

 

 

import java.io.IOException;
import java.io.UnsupportedEncodingException;
import java.util.ArrayList;
import java.util.Iterator;
import java.util.List;
import java.util.Map;
import java.util.Map.Entry;
import java.util.Set;
 
import org.apache.http.HttpEntity;
import org.apache.http.NameValuePair;
import org.apache.http.client.ClientProtocolException;
import org.apache.http.client.config.RequestConfig;
import org.apache.http.client.entity.UrlEncodedFormEntity;
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.impl.client.CloseableHttpClient;
import org.apache.http.impl.client.HttpClients;
import org.apache.http.message.BasicNameValuePair;
import org.apache.http.util.EntityUtils;
 
public class HttpClient4 {
 
    public static String doGet(String url) {
        CloseableHttpClient httpClient = null;
        CloseableHttpResponse response = null;
        String result = "";
        try {
            // 經過址默認配置建立一個httpClient實例
            httpClient = HttpClients.createDefault();
            // 建立httpGet遠程鏈接實例
            HttpGet httpGet = new HttpGet(url);
            // 設置請求頭信息，鑑權
            httpGet.setHeader("Authorization", "Bearer da3efcbf-0845-4fe3-8aba-ee040be542c0");
            // 設置配置請求參數
            RequestConfig requestConfig = RequestConfig.custom().setConnectTimeout(35000)// 鏈接主機服務超時時間
                    .setConnectionRequestTimeout(35000)// 請求超時時間
                    .setSocketTimeout(60000)// 數據讀取超時時間
                    .build();
            // 爲httpGet實例設置配置
            httpGet.setConfig(requestConfig);
            // 執行get請求獲得返回對象
            response = httpClient.execute(httpGet);
            // 經過返回對象獲取返回數據
            HttpEntity entity = response.getEntity();
            // 經過EntityUtils中的toString方法將結果轉換爲字符串
            result = EntityUtils.toString(entity);
        } catch (ClientProtocolException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        } finally {
            // 關閉資源
            if (null != response) {
                try {
                    response.close();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
            if (null != httpClient) {
                try {
                    httpClient.close();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
        }
        return result;
    }
 
    public static String doPost(String url, Map<String, Object> paramMap) {
        CloseableHttpClient httpClient = null;
        CloseableHttpResponse httpResponse = null;
        String result = "";
        // 建立httpClient實例
        httpClient = HttpClients.createDefault();
        // 建立httpPost遠程鏈接實例
        HttpPost httpPost = new HttpPost(url);
        // 配置請求參數實例
        RequestConfig requestConfig = RequestConfig.custom().setConnectTimeout(35000)// 設置鏈接主機服務超時時間
                .setConnectionRequestTimeout(35000)// 設置鏈接請求超時時間
                .setSocketTimeout(60000)// 設置讀取數據鏈接超時時間
                .build();
        // 爲httpPost實例設置配置
        httpPost.setConfig(requestConfig);
        // 設置請求頭
        httpPost.addHeader("Content-Type", "application/x-www-form-urlencoded");
        // 封裝post請求參數
        if (null != paramMap && paramMap.size() > 0) {
            List<NameValuePair> nvps = new ArrayList<NameValuePair>();
            // 經過map集成entrySet方法獲取entity
            Set<Entry<String, Object>> entrySet = paramMap.entrySet();
            // 循環遍歷，獲取迭代器
            Iterator<Entry<String, Object>> iterator = entrySet.iterator();
            while (iterator.hasNext()) {
                Entry<String, Object> mapEntry = iterator.next();
                nvps.add(new BasicNameValuePair(mapEntry.getKey(), mapEntry.getValue().toString()));
            }
 
            // 爲httpPost設置封裝好的請求參數
            try {
                httpPost.setEntity(new UrlEncodedFormEntity(nvps, "UTF-8"));
            } catch (UnsupportedEncodingException e) {
                e.printStackTrace();
            }
        }
        try {
            // httpClient對象執行post請求,並返回響應參數對象
            httpResponse = httpClient.execute(httpPost);
            // 從響應對象中獲取響應內容
            HttpEntity entity = httpResponse.getEntity();
            result = EntityUtils.toString(entity);
        } catch (ClientProtocolException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        } finally {
            // 關閉資源
            if (null != httpResponse) {
                try {
                    httpResponse.close();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
            if (null != httpClient) {
                try {
                    httpClient.close();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
        }
        return result;
    }
}
--------------------- 
做者：zkzqzzz 
來源：CSDN 
原文：https://blog.csdn.net/u012513972/article/details/79569888 
版權聲明：本文爲博主原創文章，轉載請附上博文連接！

 

傳入的參數是json或者其餘格式須要更改請求頭及參數的設置信息，httpPost.setEntity(new StringEntity("你的json串"));      httpPost.addHeader("Content-Type", "application/json")。