Java模拟Http访问将返回的JSON解析为Bean对象
应用场景：某系统访问另一个系统获取一些数据，其中这些返回数据类型必须是JSON格式，接受系统可以将结果转换为简单的Bean对象，也可以将返回的是集合数据转换成List。这就需要我们模拟一个Http访问，然后处理返回的JSON数据。
方案选型：看了看网上的很多Demo，都是比较老的。其中应用的apache的框架现在也已经找不到了。所以决定亲自去apache官网去看看。发现以前的httpclient包已经独立出来命名为Apache HttpComponents。当前最新包为4.3.3。我采用的是OSChina的Maven源，还不错，已经有资源了。而JSON解析才用了最为流行的Jackson。
Demo示例：
Test.java 返回的JSON数据将要被解析成为的对象类
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package org.uugu.common.http; public class Test { private String userName; private String password; public String getUserName() { return userName; } public void setUserName(String userName) { this.userName = userName; } public String getPassword() { return password; } public void setPassword(String password) { this.password = password; } } |
HttpUtil.java Http访问工具类
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package org.uugu.common.http; import java.net.URI; import java.util.ArrayList; import java.util.HashMap; import java.util.List; import java.util.Map; import java.util.Map.Entry; import org.apache.http.HttpEntity; import org.apache.http.NameValuePair; import org.apache.http.client.ClientProtocolException; import org.apache.http.client.entity.UrlEncodedFormEntity; import org.apache.http.client.methods.CloseableHttpResponse; import org.apache.http.client.methods.HttpPost; import org.apache.http.client.methods.HttpUriRequest; import org.apache.http.client.methods.RequestBuilder; import org.apache.http.entity.ContentType; 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; import org.codehaus.jackson.map.ObjectMapper; import org.codehaus.jackson.type.JavaType; /** * Http访问工具类 * @author Silence * */ public class HttpUtil { public static void main(String[] args) throws Exception { Map<String, String> params = new HashMap<>(); params.put("userName","abc"); params.put("password","123"); Test test = doGet("http://www.uugu.org/abc.do", params, Test.class); Test test2 = doPost("http://www.uugu.org/abc.do", params, Test.class); System.out.println(test.getUserName()); System.out.println(test2.getPassword()); } /** * Get访问方式 * @param url 访问地址 * @param params 请求参数 * @param clazz 返回数据背解析成为的对象类型 * @param argClasses 返回集合类型时的泛型类型 * @return * @throws Exception */ public static <T> T doGet(String url, Map<String, String> params, Class<T> clazz, Class<?>... argClasses) throws Exception { CloseableHttpClient httpclient = HttpClients.createDefault(); ObjectMapper objectMapper = new ObjectMapper(); String responseBody = ""; try { RequestBuilder requestBuilder = RequestBuilder.get().setUri( new URI(url)); if (params != null) { for (Entry<String, String> entry : params.entrySet()) { requestBuilder.addParameter(entry.getKey(), entry.getValue()); } } HttpUriRequest httpGet = requestBuilder.build(); httpGet.addHeader("Content-Type", "text/html;charset=UTF-8"); CloseableHttpResponse response = httpclient.execute(httpGet); try { HttpEntity entity = response.getEntity(); // 判断执行结果返回状态 int status = response.getStatusLine().getStatusCode(); if (status >= 200 && status < 300) { responseBody = entity != null ? EntityUtils .toString(entity) : null; } else { throw new ClientProtocolException( "Unexpected response status: " + status); } // 判断返回类型是否为JSON ContentType contentType = ContentType.getOrDefault(entity); if (!contentType.getMimeType().equals( ContentType.APPLICATION_JSON.getMimeType())) { throw new ClientProtocolException( "Unexpected content type: " + contentType); } EntityUtils.consume(entity); } finally { response.close(); } } finally { httpclient.close(); } if (argClasses.length > 0) { JavaType javaType = objectMapper.getTypeFactory() .constructParametricType(clazz, argClasses); return objectMapper.readValue(responseBody, javaType); } else { return objectMapper.readValue(responseBody, clazz); } } /** * Post访问方式 * @param url 访问地址 * @param params 请求参数 * @param clazz 返回数据背解析成为的对象类型 * @param argClasses 返回集合类型时的泛型类型 * @return * @throws Exception */ public static <T> T doPost(String url, Map<String, String> params, Class<T> clazz, Class<?>... argClasses) throws Exception { CloseableHttpClient httpclient = HttpClients.createDefault(); ObjectMapper objectMapper = new ObjectMapper(); String responseBody = ""; HttpPost httpPost = new HttpPost(); //httpPost.addHeader("Content-Type", "text/html;charset=UTF-8"); List<NameValuePair> nvps = new ArrayList<NameValuePair>(); if (params != null) { for (Entry<String, String> entry : params.entrySet()) { nvps.add(new BasicNameValuePair(entry.getKey(), entry .getValue())); } } httpPost.setEntity(new UrlEncodedFormEntity(nvps)); CloseableHttpResponse response = httpclient.execute(httpPost); try { HttpEntity entity = response.getEntity(); // 判断执行结果返回状态 int status = response.getStatusLine().getStatusCode(); if (status >= 200 && status < 300) { responseBody = entity != null ? EntityUtils.toString(entity) : null; } else { throw new ClientProtocolException( "Unexpected response status: " + status); } // 判断返回类型是否为JSON ContentType contentType = ContentType.getOrDefault(entity); if (!contentType.getMimeType().equals( ContentType.APPLICATION_JSON.getMimeType())) { throw new ClientProtocolException("Unexpected content type: " + contentType); } EntityUtils.consume(entity); } finally { response.close(); httpclient.close(); } if (argClasses.length > 0) { JavaType javaType = objectMapper.getTypeFactory() .constructParametricType(clazz, argClasses); return objectMapper.readValue(responseBody, javaType); } else { return objectMapper.readValue(responseBody, clazz); } } } |
需求简单，实现也没什么难度，仅为工作总结。