如今，大多數(shù)用于與某些服務(wù)器通信的移動應(yīng)用程序都使用REST服務(wù)。 這些服務(wù)也是與JavaScript或jQuery一起使用的常見做法。 現(xiàn)在，我知道在Java中為REST服務(wù)創(chuàng)建客戶端的2種方法，在本文中，我將嘗試演示這兩種方法，希望它們能以某種方式對某人有所幫助。

1.使用Apache HttpClient

Apache HttpClient庫簡化了HTTP請求的處理。 要使用此庫，您必須從其網(wǎng)站下載具有相關(guān)性的二進(jìn)制文件。
這是HTTP GET方法的代碼：

import java.io.BufferedReader; import java.io.IOException; import java.io.InputStreamReader; import org.apache.http.HttpResponse; import org.apache.http.client.ClientProtocolException; import org.apache.http.client.HttpClient; import org.apache.http.client.methods.HttpGet; import org.apache.http.impl.client.DefaultHttpClient; public class Test {public static void main(String[] args) throws ClientProtocolException, IOException {HttpClient client = new DefaultHttpClient();HttpGet request = new HttpGet('http://restUrl');HttpResponse response = client.execute(request);BufferedReader rd = new BufferedReader (new InputStreamReader(response.getEntity().getContent()));String line = '';while ((line = rd.readLine()) != null) {System.out.println(line);}} }

對于Post方法； 用于在帖子中發(fā)送簡單的字符串：

import java.io.BufferedReader; import java.io.IOException; import java.io.InputStreamReader; import org.apache.http.HttpResponse; import org.apache.http.client.ClientProtocolException; import org.apache.http.client.HttpClient; import org.apache.http.client.methods.HttpPost; import org.apache.http.entity.StringEntity; import org.apache.http.impl.client.DefaultHttpClient; public class Test {public static void main(String[] args) throws ClientProtocolException, IOException {HttpClient client = new DefaultHttpClient();HttpPost post = new HttpPost('http://restUrl');StringEntity input = new StringEntity('product');post.setEntity(input);HttpResponse response = client.execute(post);BufferedReader rd = new BufferedReader(new InputStreamReader(response.getEntity().getContent()));String line = '';while ((line = rd.readLine()) != null) {System.out.println(line);}} }

您還可以通過以下方式發(fā)送POJO的完整JSON或XML ：將表示JSON或XML的String用作StringEntity的參數(shù)，然后設(shè)置輸入內(nèi)容類型。 像這樣：

StringEntity input = new StringEntity('{\'name1\':\'value1\',\'name2\':\'value2\'}'); //here instead of JSON you can also have XML input.setContentType('application/json');

對于JSON，您可以使用JSONObject創(chuàng)建JSON的字符串表示形式。

JSONObject json = new JSONObject(); json.put('name1', 'value1'); json.put('name2', 'value2'); StringEntity se = new StringEntity( json.toString());

并在后請求中發(fā)送多個參數(shù)：

import java.io.BufferedReader; import java.io.IOException; import java.io.InputStreamReader; import java.util.ArrayList; import java.util.List; import org.apache.http.HttpResponse; import org.apache.http.client.ClientProtocolException; import org.apache.http.client.HttpClient; import org.apache.http.client.entity.UrlEncodedFormEntity; import org.apache.http.client.methods.HttpPost; import org.apache.http.impl.client.DefaultHttpClient; import org.apache.http.message.BasicNameValuePair; public class Test {public static void main(String[] args) throws ClientProtocolException, IOException {HttpClient client = new DefaultHttpClient();HttpPost post = new HttpPost('http://restUrl');List nameValuePairs = new ArrayList(1);nameValuePairs.add(new BasicNameValuePair('name', 'value')); //you can as many name value pair as you want in the list.post.setEntity(new UrlEncodedFormEntity(nameValuePairs));HttpResponse response = client.execute(post);BufferedReader rd = new BufferedReader(new InputStreamReader(response.getEntity().getContent()));String line = '';while ((line = rd.readLine()) != null) {System.out.println(line);}} }

2.使用球衣

Jersey是JSR-311規(guī)范（Java中REST支持的規(guī)范）的參考實(shí)現(xiàn)。 澤西島基本上包含一個REST服務(wù)器和一個REST客戶端。 它提供了一個庫來與產(chǎn)生REST服務(wù)的服務(wù)器通信。 對于http get方法：

import java.io.IOException; import javax.ws.rs.core.MediaType; import javax.ws.rs.core.UriBuilder; import org.apache.http.client.ClientProtocolException; import com.sun.jersey.api.client.Client; import com.sun.jersey.api.client.WebResource; import com.sun.jersey.api.client.config.ClientConfig; import com.sun.jersey.api.client.config.DefaultClientConfig; public class Test {public static void main(String[] args) throws ClientProtocolException, IOException {ClientConfig config = new DefaultClientConfig();Client client = Client.create(config);WebResource service = client.resource(UriBuilder.fromUri('http://restUrl').build());// getting XML dataSystem.out.println(service. path('restPath').path('resourcePath').accept(MediaType.APPLICATION_JSON).get(String.class));// getting JSON dataSystem.out.println(service. path('restPath').path('resourcePath').accept(MediaType.APPLICATION_XML).get(String.class));} }

您還可以通過其他媒體格式獲得響應(yīng)，例如PLAIN或HTML。
對于HTTP POST方法：

import java.io.IOException; import javax.ws.rs.core.MediaType; import javax.ws.rs.core.MultivaluedMap; import javax.ws.rs.core.UriBuilder; import org.apache.http.client.ClientProtocolException; import com.sun.jersey.api.client.Client; import com.sun.jersey.api.client.ClientResponse; import com.sun.jersey.api.client.WebResource; import com.sun.jersey.api.client.config.ClientConfig; import com.sun.jersey.api.client.config.DefaultClientConfig; import com.sun.jersey.core.util.MultivaluedMapImpl; public class Test {public static void main(String[] args) throws ClientProtocolException, IOException {ClientConfig config = new DefaultClientConfig();Client client = Client.create(config);WebResource webResource = client.resource(UriBuilder.fromUri('http://restUrl').build());MultivaluedMap formData = new MultivaluedMapImpl();formData.add('name1', 'val1');formData.add('name2', 'val2');ClientResponse response = webResource.type(MediaType.APPLICATION_FORM_URLENCODED_TYPE).post(ClientResponse.class, formData);System.out.println('Response ' + response.getEntity(String.class));} }

如果您在POST中使用POJO，則可以執(zhí)行以下操作：

ClientResponse response = webResource.path('restPath').path('resourcePath'). type(MediaType.APPLICATION_JSON).accept(MediaType.APPLICATION_JSON).post(ClientResponse.class, myPojo); System.out.println('Response ' + response.getEntity(String.class));

這里的myPojo是自定義POJO類的實(shí)例。
您還可以使用Jersey的Form類在POST請求中提交多個參數(shù)：

import java.io.IOException; import javax.ws.rs.core.MediaType; import javax.ws.rs.core.UriBuilder; import org.apache.http.client.ClientProtocolException; import com.sun.jersey.api.client.Client; import com.sun.jersey.api.client.ClientResponse; import com.sun.jersey.api.client.WebResource; import com.sun.jersey.api.client.config.ClientConfig; import com.sun.jersey.api.client.config.DefaultClientConfig; import com.sun.jersey.api.representation.Form; public class Test {public static void main(String[] args) throws ClientProtocolException, IOException {ClientConfig config = new DefaultClientConfig();Client client = Client.create(config);WebResource service = client.resource(UriBuilder.fromUri('http://restUrl').build());Form form = new Form();form.add('name1', 'value1');form.add('name2', 'value1');ClientResponse response = service.path('restPath').path('resourcePath').type(MediaType.APPLICATION_FORM_URLENCODED).post(ClientResponse.class, form);System.out.println('Response ' + response.getEntity(String.class));} }

祝您編程愉快，別忘了分享！

參考：來自harryjoy博客的JCG合作伙伴 Harsh Raval的Java中的簡單REST客戶端 。

翻譯自: https://www.javacodegeeks.com/2012/09/simple-rest-client-in-java.html

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