Jersey框架二：Jersey对JSON的支持

Jersey提供3种基本方式来使用JSON格式

无论使用何种方式，在原有包的基础上，都需要在客户端和服务端Maven配置文件中添加jersey-json包以支持JSON格式

 <dependency>
     <groupId>com.sun.jerseygroupId>
     <artifactId>jersey-jsonartifactId>
     <version>1.18version>
 dependency>

一，基于POJO

Request类和Response类（服务端和客户端都需要）都是基本的POJO：

 package com.sean;

 public class Request {
     private String query;

     public String getQuery() {
         return query;
     }

     public void setQuery(String query) {
         this.query = query;
     }
 }

 package com.sean;

 public class Response {
     private int respCode;
     private String respDesc;

     public int getRespCode() {
         return respCode;
     }

     public void setRespCode(int respCode) {
         this.respCode = respCode;
     }

     public String getRespDesc() {
         return respDesc;
     }

     public void setRespDesc(String respDesc) {
         this.respDesc = respDesc;
     }
 }

服务端代码：

 package com.sean;

 import java.io.IOException;
 import java.net.URI;

 import javax.ws.rs.Consumes;
 import javax.ws.rs.POST;
 import javax.ws.rs.Path;
 import javax.ws.rs.Produces;
 import javax.ws.rs.core.MediaType;
 import javax.ws.rs.core.UriBuilder;

 import org.glassfish.grizzly.http.server.HttpServer;

 import com.sun.jersey.api.container.grizzly2.GrizzlyServerFactory;
 import com.sun.jersey.api.core.PackagesResourceConfig;
 import com.sun.jersey.api.core.ResourceConfig;
 import com.sun.jersey.api.json.JSONConfiguration;

 @Path("query")
 public class MyResource {

     @POST
     @Consumes(MediaType.APPLICATION_JSON)
     @Produces(MediaType.APPLICATION_JSON)
     public Response query(Request req) {
         System.out.println(req.getQuery());

         Response resp = new Response();
         resp.setRespCode(0);
         resp.setRespDesc(req.getQuery());
         return resp;
     }

     public static void main(String[] args) {
         URI uri = UriBuilder.fromUri("http://127.0.0.1").port(10000).build();
         ResourceConfig rc = new PackagesResourceConfig("com.sean");
         //使用Jersey对POJO的支持，必须设置为true
          rc.getFeatures().put(JSONConfiguration.FEATURE_POJO_MAPPING, true);
         try {
             HttpServer server = GrizzlyServerFactory.createHttpServer(uri, rc);
             server.start();
         } catch (IllegalArgumentException e) {
             e.printStackTrace();
         } catch (NullPointerException e) {
             e.printStackTrace();
         } catch (IOException e) {
             e.printStackTrace();
         }
         try {
             Thread.sleep(1000*1000);
         } catch (InterruptedException e) {
             e.printStackTrace();
         }
     }
 }

客户端代码：

 package com.sean;

 import javax.ws.rs.core.MediaType;

 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.json.JSONConfiguration;

 public class JerseyClient {

     public static void main(String[] args) {
         ClientConfig cc = new DefaultClientConfig();
         //使用Jersey对POJO的支持，必须设置为true
         cc.getFeatures().put(JSONConfiguration.FEATURE_POJO_MAPPING, Boolean.TRUE);
         Client client = Client.create(cc);

         WebResource resource = client.resource("http://127.0.0.1:10000/query");

         Request req = new Request();
         req.setQuery("name");

         ClientResponse response = resource
                 .accept(MediaType.APPLICATION_JSON)
                 .type(MediaType.APPLICATION_JSON)
                 .post(ClientResponse.class, req);

         Response resp = response.getEntity(Response.class);
         System.out.println(resp.getRespCode() + " " + resp.getRespDesc());
     }
 }

 

二，基于JAXB

使用JAXB的优点在于，无论使用XML格式还是JSON格式数据，都可以使用统一的JAVA模型

缺点很难找到一个合适的方式来生成特殊的JSON格式，这也是Jersey提供很多控制选项的原因

将Request类和Response类进行修改：

 package com.sean;

 import javax.xml.bind.annotation.XmlRootElement;

 @XmlRootElement
 public class Request {
     private String query;

     public String getQuery() {
         return query;
     }

     public void setQuery(String query) {
         this.query = query;
     }
 }

 package com.sean;

 import javax.xml.bind.annotation.XmlRootElement;

 @XmlRootElement
 public class Response {
     private int respCode;
     private String respDesc;

     public int getRespCode() {
         return respCode;
     }

     public void setRespCode(int respCode) {
         this.respCode = respCode;
     }

     public String getRespDesc() {
         return respDesc;
     }

     public void setRespDesc(String respDesc) {
         this.respDesc = respDesc;
     }
 }

服务端代码去掉下面的配置

 //       rc.getFeatures().put(JSONConfiguration.FEATURE_POJO_MAPPING, true);

客户端代码去掉下面的配置

 //      cc.getFeatures().put(JSONConfiguration.FEATURE_POJO_MAPPING, Boolean.TRUE);

Jersey提供很多控制选项以便更精细的控制JSON的解析、组装过程，但是就我个人来看，JAXB提供的标签足够使用了

 

三，基于底层JSONObject/JSONArray

最大的优势在于可以完全控制JSON的解析、组装过程，相应的，在处理数据对象时也要更复杂

服务端代码如下：

 package com.sean;

 import java.io.IOException;
 import java.net.URI;

 import javax.ws.rs.Consumes;
 import javax.ws.rs.POST;
 import javax.ws.rs.Path;
 import javax.ws.rs.Produces;
 import javax.ws.rs.core.MediaType;
 import javax.ws.rs.core.UriBuilder;

 import org.codehaus.jettison.json.JSONException;
 import org.codehaus.jettison.json.JSONObject;
 import org.glassfish.grizzly.http.server.HttpServer;

 import com.sun.jersey.api.container.grizzly2.GrizzlyServerFactory;
 import com.sun.jersey.api.core.PackagesResourceConfig;
 import com.sun.jersey.api.core.ResourceConfig;

 @Path("query")
 public class MyResource {

     @POST
     @Consumes(MediaType.APPLICATION_JSON)
     @Produces(MediaType.APPLICATION_JSON)
     public JSONObject query(JSONObject query) {
         //{"query":"name"}
         System.out.println(query.toString());

         JSONObject resp = new JSONObject();
         try {
             resp.put("respCode", 0);
             resp.put("respDesc", query.get("query"));
         } catch (JSONException e) {
             e.printStackTrace();
         }
         return resp;
     }

     public static void main(String[] args) {
         URI uri = UriBuilder.fromUri("http://127.0.0.1").port(10000).build();
         ResourceConfig rc = new PackagesResourceConfig("com.sean");
         try {
             HttpServer server = GrizzlyServerFactory.createHttpServer(uri, rc);
             server.start();
         } catch (IllegalArgumentException e) {
             e.printStackTrace();
         } catch (NullPointerException e) {
             e.printStackTrace();
         } catch (IOException e) {
             e.printStackTrace();
         }
         try {
             Thread.sleep(1000*1000);
         } catch (InterruptedException e) {
             e.printStackTrace();
         }
     }
 }

客户端代码如下：

 package com.sean;

 import javax.ws.rs.core.MediaType;

 import org.codehaus.jettison.json.JSONException;
 import org.codehaus.jettison.json.JSONObject;

 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;

 public class JerseyClient {

     public static void main(String[] args) {
         ClientConfig cc = new DefaultClientConfig();
         Client client = Client.create(cc);

         WebResource resource = client.resource("http://127.0.0.1:10000/query");

         JSONObject req = new JSONObject();
         try {
             req.put("query", "name");
         } catch (JSONException e) {
             e.printStackTrace();
         }

         ClientResponse response = resource
                 .accept(MediaType.APPLICATION_JSON)
                 .type(MediaType.APPLICATION_JSON)
                 .post(ClientResponse.class, req);

         JSONObject resp = response.getEntity(JSONObject.class);
         //{"respCode":0,"respDesc":"name"}
         System.out.println(resp.toString());
     }
 }

与JAXB相比，结果是相同的，但是处理过程（主要是组装JSON对象）要复杂

对于上面3种方式，均可使用String类代替Request类、Response类或JSONObject类，Jersey会自动将对象转换为JSON串

当然，如果客户端修改为String，服务端也要相应的修改为String类型

修改客户端代码：

 public class JerseyClient {

     public static void main(String[] args) {
         ClientConfig cc = new DefaultClientConfig();
         Client client = Client.create(cc);

         WebResource resource = client.resource("http://127.0.0.1:10000/query");

         JSONObject req = new JSONObject();
         try {
             req.put("query", "name");
         } catch (JSONException e) {
             e.printStackTrace();
         }

         String response = resource
                 .accept(MediaType.APPLICATION_JSON)
                 .type(MediaType.APPLICATION_JSON)
                 .post(String.class, req.toString());
     }
 }