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 }
HttpRequest类
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 }
HttpResponse类 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 }
View Code 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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