本文參考： https://blog.csdn.net/fightingXia/article/details/71775516
https://www.cnblogs.com/jeffen/p/6937788.html
隨着網絡上java應用越來越多，場景越來越復雜，所以應用之間經常通過HTTP接口來訪問資源
首先了解了URL的最常用的兩種請求方式：第一種GET，第二種POST
GET：get請求可以獲取頁面，也可以把參數放到URL后面以?分割傳遞數據，參數之間以&關聯，例如 http://110.32.44.11:8086/sp-test/usertest/1.0/query?mobile=15334567890&name=zhansan
POST：post請求的參數是放在HTTP請求的正文里，請求的參數被封裝起來通過流的方式傳遞
1.HttpURLConnection
1.1簡介：
在java.net包中，已經提供訪問HTTP協議的基本功能類：HttpURLConnection，可以向其他系統發送GET，POST訪問請求
1.2 GET方式調用
1 private void httpURLGETCase() {
2 String methodUrl = "http://110.32.44.11:8086/sp-test/usertest/1.0/query";
3 HttpURLConnection connection = null;
4 BufferedReader reader = null;
5 String line = null;
6 try {
7 URL url = new URL(methodUrl + "?mobile=15334567890&name=zhansan");
8 connection = (HttpURLConnection) url.openConnection();// 根據URL生成HttpURLConnection
9 connection.setRequestMethod("GET");// 默認GET請求
10 connection.connect();// 建立TCP連接
11 if (connection.getResponseCode() == HttpURLConnection.HTTP_OK) {
12 reader = new BufferedReader(new InputStreamReader(connection.getInputStream(), "UTF-8"));// 發送http請求
13 StringBuilder result = new StringBuilder();
14 // 循環讀取流
15 while ((line = reader.readLine()) != null) {
16 result.append(line).append(System.getProperty("line.separator"));// "\n"
17 }
18 System.out.println(result.toString());
19 }
20 } catch (IOException e) {
21 e.printStackTrace();
22 } finally {
23 try {
24 reader.close();
25 } catch (IOException e) {
26 e.printStackTrace();
27 }
28 connection.disconnect();
29 }
30 }
1.3 POST方式調用
1.3.1 帶授權的傳遞json格式參數調用
1 private static void httpURLPOSTCase() {
2 String methodUrl = "http://xxx.xxx.xx.xx:8280/xx/adviserxx/1.0 ";
3 HttpURLConnection connection = null;
4 OutputStream dataout = null;
5 BufferedReader reader = null;
6 String line = null;
7 try {
8 URL url = new URL(methodUrl);
9 connection = (HttpURLConnection) url.openConnection();// 根據URL生成HttpURLConnection
10 connection.setDoOutput(true);// 設置是否向connection輸出，因為這個是post請求，參數要放在http正文內，因此需要設為true,默認情況下是false
11 connection.setDoInput(true); // 設置是否從connection讀入，默認情況下是true;
12 connection.setRequestMethod("POST");// 設置請求方式為post,默認GET請求
13 connection.setUseCaches(false);// post請求不能使用緩存設為false
14 connection.setConnectTimeout(3000);// 連接主機的超時時間
15 connection.setReadTimeout(3000);// 從主機讀取數據的超時時間
16 connection.setInstanceFollowRedirects(true);// 設置該HttpURLConnection實例是否自動執行重定向
17 connection.setRequestProperty("connection", "Keep-Alive");// 連接復用
18 connection.setRequestProperty("charset", "utf-8");
19
20 connection.setRequestProperty("Content-Type", "application/json");
21 connection.setRequestProperty("Authorization", "Bearer 66cb225f1c3ff0ddfdae31rae2b57488aadfb8b5e7");
22 connection.connect();// 建立TCP連接,getOutputStream會隱含的進行connect,所以此處可以不要
23
24 dataout = new DataOutputStream(connection.getOutputStream());// 創建輸入輸出流,用於往連接里面輸出攜帶的參數
25 String body = "[{\"orderNo\":\"44921902\",\"adviser\":\"張怡筠\"}]";
26 dataout.write(body.getBytes());
27 dataout.flush();
28 dataout.close();
29
30 if (connection.getResponseCode() == HttpURLConnection.HTTP_OK) {
31 reader = new BufferedReader(new InputStreamReader(connection.getInputStream(), "UTF-8"));// 發送http請求
32 StringBuilder result = new StringBuilder();
33 // 循環讀取流
34 while ((line = reader.readLine()) != null) {
35 result.append(line).append(System.getProperty("line.separator"));//
36 }
37 System.out.println(result.toString());
38 }
39 } catch (IOException e) {
40 e.printStackTrace();
41 } finally {
42 try {
43 reader.close();
44 } catch (IOException e) {
45 e.printStackTrace();
46 }
47 connection.disconnect();
48 }
49 }
1.3.2 傳遞鍵值對的參數
URL url = new URL(getUrl);
HttpURLConnection connection = (HttpURLConnection) url.openConnection();
connection.setRequestMethod("POST");
connection.setDoOutput(true);
connection.setDoInput(true);
connection.setUseCaches(false);
connection.connect();
String body = "userName=zhangsan&password=123456";
BufferedWriter writer = new BufferedWriter(new OutputStreamWriter(connection.getOutputStream(), "UTF-8"));
writer.write(body);
writer.close();
1.3.3 在post請求上傳文件
try {
URL url = new URL(getUrl);
HttpURLConnection connection = (HttpURLConnection) url.openConnection();
connection.setRequestMethod("POST");
connection.setDoOutput(true);
connection.setDoInput(true);
connection.setUseCaches(false);
connection.setRequestProperty("Content-Type", "file/*");//設置數據類型
connection.connect();
OutputStream outputStream = connection.getOutputStream();
FileInputStream fileInputStream = new FileInputStream("file");//把文件封裝成一個流
int length = -1;
byte[] bytes = new byte[1024];
while ((length = fileInputStream.read(bytes)) != -1){
outputStream.write(bytes,0,length);//寫的具體操作
}
fileInputStream.close();
outputStream.close();
int responseCode = connection.getResponseCode();
if(responseCode == HttpURLConnection.HTTP_OK){
InputStream inputStream = connection.getInputStream();
String result = is2String(inputStream);//將流轉換為字符串。
Log.d("kwwl","result============="+result);
}
} catch (Exception e) {
e.printStackTrace();
}
1.3.4 同時上傳參數和文件
在實際應用時，上傳文件的同時也常常需要上傳鍵值對參數。比如在微信中發朋友圈時，不僅有圖片，還有有文字。此時就需要同時上傳參數和文件。
在httpURLconnection中並沒有提供直接上傳參數和文件的API，需要我們自己去探索。我們知道在Web頁面上傳參數和文件很簡單，只需要在form標簽寫上contentype=”multipart/form-data”即可，剩余工作便都交給瀏覽器去完成數據收集並發送Http請求。但是如果沒有頁面的話要怎么上傳文件呢？
由於脫離了瀏覽器的環境，我們就要自己去完成數據的封裝並發送。首先我們來看web頁面上傳參數和文件是什么樣子的？
我們寫一個web表單，上傳兩個鍵值對參數和一個文件。使用抓包工具抓取的數據結果如下：
經過分析可知，上傳到服務器的數據除了鍵值對數據和文件數據外，還有其他字符串，使用這些這些字符串來拼接一定的格式。
那么我們只要模擬這個數據，並寫入到Http請求中便能實現同時傳遞參數和文件。
代碼如下：
try {
String BOUNDARY = java.util.UUID.randomUUID().toString();
String TWO_HYPHENS = "--";
String LINE_END = "\r\n";
URL url = new URL(URLContant.CHAT_ROOM_SUBJECT_IMAGE);
HttpURLConnection connection = (HttpURLConnection) url.openConnection();
connection.setRequestMethod("POST");
connection.setDoOutput(true);
connection.setDoInput(true);
connection.setUseCaches(false);
//設置請求頭
connection.setRequestProperty("Connection", "Keep-Alive");
connection.setRequestProperty("Charset", "UTF-8");
connection.setRequestProperty("Content-Type","multipart/form-data; BOUNDARY=" + BOUNDARY);
connection.setRequestProperty("Authorization","Bearer "+UserInfoConfigure.authToken);
connection.connect();
DataOutputStream outputStream = new DataOutputStream(connection.getOutputStream());
StringBuffer strBufparam = new StringBuffer();
//封裝鍵值對數據一
strBufparam.append(TWO_HYPHENS);
strBufparam.append(BOUNDARY);
strBufparam.append(LINE_END);
strBufparam.append("Content-Disposition: form-data; name=\"" + "groupId" + "\"");
strBufparam.append(LINE_END);
strBufparam.append("Content-Type: " + "text/plain" );
strBufparam.append(LINE_END);
strBufparam.append("Content-Lenght: "+(""+groupId).length());
strBufparam.append(LINE_END);
strBufparam.append(LINE_END);
strBufparam.append(""+groupId);
strBufparam.append(LINE_END);
//封裝鍵值對數據二
strBufparam.append(TWO_HYPHENS);
strBufparam.append(BOUNDARY);
strBufparam.append(LINE_END);
strBufparam.append("Content-Disposition: form-data; name=\"" + "title" + "\"");
strBufparam.append(LINE_END);
strBufparam.append("Content-Type: " + "text/plain" );
strBufparam.append(LINE_END);
strBufparam.append("Content-Lenght: "+"kwwl".length());
strBufparam.append(LINE_END);
strBufparam.append(LINE_END);
strBufparam.append("kwwl");
strBufparam.append(LINE_END);
//拼接完成后，一塊寫入
outputStream.write(strBufparam.toString().getBytes());
//拼接文件的參數
StringBuffer strBufFile = new StringBuffer();
strBufFile.append(LINE_END);
strBufFile.append(TWO_HYPHENS);
strBufFile.append(BOUNDARY);
strBufFile.append(LINE_END);
strBufFile.append("Content-Disposition: form-data; name=\"" + "image" + "\"; filename=\"" + file.getName() + "\"");
strBufFile.append(LINE_END);
strBufFile.append("Content-Type: " + "image/*" );
strBufFile.append(LINE_END);
strBufFile.append("Content-Lenght: "+file.length());
strBufFile.append(LINE_END);
strBufFile.append(LINE_END);
outputStream.write(strBufFile.toString().getBytes());
//寫入文件
FileInputStream fileInputStream = new FileInputStream(file);
byte[] buffer = new byte[1024*2];
int length = -1;
while ((length = fileInputStream.read(buffer)) != -1){
outputStream.write(buffer,0,length);
}
outputStream.flush();
fileInputStream.close();
//寫入標記結束位
byte[] endData = (LINE_END + TWO_HYPHENS + BOUNDARY + TWO_HYPHENS + LINE_END).getBytes();//寫結束標記位
outputStream.write(endData);
outputStream.flush();
//得到響應
int responseCode = connection.getResponseCode();
if(responseCode == HttpURLConnection.HTTP_OK){
InputStream inputStream = connection.getInputStream();
String result = is2String(inputStream);//將流轉換為字符串。
Log.d("kwwl","result============="+result);
}
} catch (Exception e) {
e.printStackTrace();
}
demo2
private static String imageIdentify(String card,String methodUrl, byte[] fileBytes, String file_id) {
HttpURLConnection connection = null;
OutputStream dataout = null;
BufferedReader bf = null;
String BOUNDARY = "----WebKitFormBoundary2NYA7hQkjRHg5WJk";
String END_DATA = ("\r\n--" + BOUNDARY + "--\r\n");
String BOUNDARY_PREFIX = "--";
String NEW_LINE = "\r\n";
try {
URL url = new URL(methodUrl+"?card="+card);
connection = (HttpURLConnection) url.openConnection();
connection.setConnectTimeout(3000);
connection.setReadTimeout(3000);
connection.setDoOutput(true);// 設置連接輸出流為true,默認false
connection.setDoInput(true);// 設置連接輸入流為true
connection.setRequestMethod("POST");// 設置請求方式為post
connection.setUseCaches(false);// post請求緩存設為false
connection.setInstanceFollowRedirects(true);// 設置該HttpURLConnection實例是否自動執行重定向
connection.setRequestProperty("connection", "Keep-Alive");// 連接復用
connection.setRequestProperty("charset", "utf-8");
connection.setRequestProperty("Content-Type", "multipart/form-data;boundary=" + BOUNDARY);
connection.connect();// 建立連接
dataout = new DataOutputStream(connection.getOutputStream());// 創建輸入輸出流,用於往連接里面輸出攜帶的參數
StringBuilder sb2 = new StringBuilder();
sb2.append(BOUNDARY_PREFIX);
sb2.append(BOUNDARY);
sb2.append(NEW_LINE);
sb2.append("Content-Disposition:form-data; name=\"type\"");
// 參數頭設置完成后需要2個換行，才是內容
sb2.append(NEW_LINE);
sb2.append(NEW_LINE);
sb2.append("0");
sb2.append(NEW_LINE);
dataout.write(sb2.toString().getBytes());
// 讀取文件上傳到服務器
StringBuilder sb1 = new StringBuilder();
sb1.append(BOUNDARY_PREFIX);
sb1.append(BOUNDARY);
sb1.append(NEW_LINE);
sb1.append("Content-Disposition:form-data; name=\"file\";filename=\"" + file_id + "\"");//文件名必須帶后綴
sb1.append(NEW_LINE);
sb1.append("Content-Type:application/octet-stream");
// 參數頭設置完成后需要2個換行，才是內容
sb1.append(NEW_LINE);
sb1.append(NEW_LINE);
dataout.write(sb1.toString().getBytes());
dataout.write(fileBytes);// 寫文件字節
dataout.write(NEW_LINE.getBytes());
dataout.write(END_DATA.getBytes());
dataout.flush();
dataout.close();
bf = new BufferedReader(new InputStreamReader(connection.getInputStream(), "UTF-8"));// 連接發起請求,處理服務器響應
String line;
StringBuilder result = new StringBuilder(); // 用來存儲響應數據
// 循環讀取流,若不到結尾處
while ((line = bf.readLine()) != null) {
result.append(line).append(System.getProperty("line.separator"));
}
bf.close();
connection.disconnect(); // 銷毀連接
return result.toString();
} catch (Exception e) {
LOGGER.error(e.getMessage(), e);
}
return "";
}
1.3.4
從服務器下載文件是比較簡單的操作，只要得到輸入流，就可以從流中讀出數據。使用示例如下：
try {
String urlPath = "https://www.baidu.com/";
URL url = new URL(urlPath);
HttpURLConnection connection = (HttpURLConnection) url.openConnection();
connection.setRequestMethod("GET");
connection.connect();
int responseCode = connection.getResponseCode();
if(responseCode == HttpURLConnection.HTTP_OK){
InputStream inputStream = connection.getInputStream();
File dir = new File("fileDir");
if (!dir.exists()){
dir.mkdirs();
}
File file = new File(dir, "fileName");//根據目錄和文件名得到file對象
FileOutputStream fos = new FileOutputStream(file);
byte[] buf = new byte[1024*8];
int len = -1;
while ((len = inputStream.read(buf)) != -1){
fos.write(buf, 0, len);
}
fos.flush();
}
} catch (Exception e) {
e.printStackTrace();
}
2.HttpClient
2.1簡介：
2.2 GET方式調用
2.3 POST方式調用
3.Spring RestTemplate
3.1簡介：
3.2 GET方式調用
3.3 POST方式調用