首页 > 代码库 > 如何在BPM中使用REST服务（1）：通过程序访问网页内容
如何在BPM中使用REST服务（1）：通过程序访问网页内容
这篇文章主要描述如何通过程序来访问网页内容，这是访问REST服务的基础。
在Java中，我们可以使用HttpUrlConnection类来实现，代码如下。
1 package http.base; 2 3 import java.io.BufferedReader; 4 import java.io.IOException; 5 import java.io.InputStream; 6 import java.io.InputStreamReader; 7 import java.net.HttpURLConnection; 8 import java.net.URL; 9 import java.nio.charset.Charset; 10 import java.util.Map; 11 import java.util.Vector; 12 13 14 public class HttpRequester { 15 private String defaultContentEncoding; 16 17 public HttpRequester() { 18 this.defaultContentEncoding = Charset.defaultCharset().name(); 19 } 20 21 public HttpResponse sendGet(String urlString) throws IOException { 22 return this.send(urlString, "GET", null, null); 23 } 24 25 public HttpResponse sendGet(String urlString, Map<String, String> params) 26 throws IOException { 27 return this.send(urlString, "GET", params, null); 28 } 29 30 public HttpResponse sendGet(String urlString, Map<String, String> params, 31 Map<String, String> propertys) throws IOException { 32 return this.send(urlString, "GET", params, propertys); 33 } 34 35 public HttpResponse sendPost(String urlString) throws IOException { 36 return this.send(urlString, "POST", null, null); 37 } 38 39 public HttpResponse sendPost(String urlString, Map<String, String> params) 40 throws IOException { 41 return this.send(urlString, "POST", params, null); 42 } 43 44 public HttpResponse sendPost(String urlString, Map<String, String> params, 45 Map<String, String> propertys) throws IOException { 46 return this.send(urlString, "POST", params, propertys); 47 } 48 49 private HttpResponse send(String urlString, String method, 50 Map<String, String> parameters, Map<String, String> propertys) 51 throws IOException { 52 HttpURLConnection urlConnection = null; 53 54 if (method.equalsIgnoreCase("GET") && parameters != null) { 55 StringBuffer param = new StringBuffer(); 56 int i = 0; 57 for (String key : parameters.keySet()) { 58 if (i == 0) 59 param.append("?"); 60 else 61 param.append("&"); 62 param.append(key).append("=").append(parameters.get(key)); 63 i++; 64 } 65 urlString += param; 66 } 67 URL url = new URL(urlString); 68 urlConnection = (HttpURLConnection) url.openConnection(); 69 70 urlConnection.setRequestMethod(method); 71 urlConnection.setDoOutput(true); 72 urlConnection.setDoInput(true); 73 urlConnection.setUseCaches(false); 74 75 if (propertys != null) 76 for (String key : propertys.keySet()) { 77 urlConnection.addRequestProperty(key, propertys.get(key)); 78 } 79 80 if (method.equalsIgnoreCase("POST") && parameters != null) { 81 StringBuffer param = new StringBuffer(); 82 for (String key : parameters.keySet()) { 83 param.append("&"); 84 param.append(key).append("=").append(parameters.get(key)); 85 } 86 urlConnection.getOutputStream().write(param.toString().getBytes()); 87 urlConnection.getOutputStream().flush(); 88 urlConnection.getOutputStream().close(); 89 } 90 91 return this.makeContent(urlString, urlConnection); 92 } 93 94 private HttpResponse makeContent(String urlString, 95 HttpURLConnection urlConnection) throws IOException { 96 HttpResponse httpResponser = new HttpResponse(); 97 try { 98 InputStream in = urlConnection.getInputStream(); 99 BufferedReader bufferedReader = new BufferedReader(100 new InputStreamReader(in));101 httpResponser.contentCollection = new Vector<String>();102 StringBuffer temp = new StringBuffer();103 String line = bufferedReader.readLine();104 while (line != null) {105 httpResponser.contentCollection.add(line);106 temp.append(line).append("/r/n");107 line = bufferedReader.readLine();108 }109 bufferedReader.close();110 111 String ecod = urlConnection.getContentEncoding();112 if (ecod == null)113 ecod = this.defaultContentEncoding;114 115 httpResponser.urlString = urlString;116 117 httpResponser.defaultPort = urlConnection.getURL().getDefaultPort();118 httpResponser.file = urlConnection.getURL().getFile();119 httpResponser.host = urlConnection.getURL().getHost();120 httpResponser.path = urlConnection.getURL().getPath();121 httpResponser.port = urlConnection.getURL().getPort();122 httpResponser.protocol = urlConnection.getURL().getProtocol();123 httpResponser.query = urlConnection.getURL().getQuery();124 httpResponser.ref = urlConnection.getURL().getRef();125 httpResponser.userInfo = urlConnection.getURL().getUserInfo();126 127 httpResponser.content = new String(temp.toString().getBytes(), ecod);128 httpResponser.contentEncoding = ecod;129 httpResponser.code = urlConnection.getResponseCode();130 httpResponser.message = urlConnection.getResponseMessage();131 httpResponser.contentType = urlConnection.getContentType();132 httpResponser.method = urlConnection.getRequestMethod();133 httpResponser.connectTimeout = urlConnection.getConnectTimeout();134 httpResponser.readTimeout = urlConnection.getReadTimeout();135 136 return httpResponser;137 } catch (IOException e) {138 throw e;139 } finally {140 if (urlConnection != null)141 urlConnection.disconnect();142 }143 }144 145 public String getDefaultContentEncoding() {146 return this.defaultContentEncoding;147 }148 149 public void setDefaultContentEncoding(String defaultContentEncoding) {150 this.defaultContentEncoding = defaultContentEncoding;151 }152 }
1 package http.base; 2 3 import java.util.Vector; 4 5 public class HttpResponse { 6 7 String urlString; 8 int defaultPort; 9 String file; 10 String host; 11 String path; 12 int port; 13 String protocol; 14 String query; 15 String ref; 16 String userInfo; 17 String contentEncoding; 18 String content; 19 String contentType; 20 int code; 21 String message; 22 String method; 23 int connectTimeout; 24 int readTimeout; 25 Vector<String> contentCollection; 26 27 public String getContent() { 28 return content; 29 } 30 31 public String getContentType() { 32 return contentType; 33 } 34 35 public int getCode() { 36 return code; 37 } 38 39 public String getMessage() { 40 return message; 41 } 42 43 public Vector<String> getContentCollection() { 44 return contentCollection; 45 } 46 47 public String getContentEncoding() { 48 return contentEncoding; 49 } 50 51 public String getMethod() { 52 return method; 53 } 54 55 public int getConnectTimeout() { 56 return connectTimeout; 57 } 58 59 public int getReadTimeout() { 60 return readTimeout; 61 } 62 63 public String getUrlString() { 64 return urlString; 65 } 66 67 public int getDefaultPort() { 68 return defaultPort; 69 } 70 71 public String getFile() { 72 return file; 73 } 74 75 public String getHost() { 76 return host; 77 } 78 79 public String getPath() { 80 return path; 81 } 82 83 public int getPort() { 84 return port; 85 } 86 87 public String getProtocol() { 88 return protocol; 89 } 90 91 public String getQuery() { 92 return query; 93 } 94 95 public String getRef() { 96 return ref; 97 } 98 99 public String getUserInfo() {100 return userInfo;101 }102 103 }
下面是一个简单的测试类。
1 package http.base; 2 3 public class HttpTest { 4 public static void main(String[] args) { 5 try { 6 HttpRequester request = new HttpRequester(); 7 HttpResponse hr = request.sendGet("http://www.baidu.com"); 8 9 System.out.println(hr.getUrlString());10 System.out.println(hr.getProtocol());11 System.out.println(hr.getHost());12 System.out.println(hr.getPort());13 System.out.println(hr.getContentEncoding());14 System.out.println(hr.getMethod());15 16 System.out.println(hr.getContent());17 18 } catch (Exception e) {19 e.printStackTrace();20 }21 }22 }
因为REST服务的返回值一般都是JSON对象，下一篇文章中，我们来看Java对象和JSON之间如何转换。
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