一、 總體說明

XML和JSON 是最為常用的資料交換格式。本例子演示如何將java物件，轉成JSON輸出。

二、流程

1.在上文專案中，

在“com.waylau.rest.resources.UserResource“中增加程式碼，程式碼如下：

    @GET  
    @Path("/getUserJson")  
    @Produces(MediaType.APPLICATION_JSON)  
    public User getUserJson() {  
     User user  = new User();  
     user.setAge("27");  
     user.setUserId("005");  
     user.setUserName("Fmand");  
     return user;  
    } 
 

期望獲取到json的資料，此時，專案報錯

org.glassfish.jersey.message.internal.MessageBodyProviderNotFoundException: MessageBodyWriter not found for media type=application/json, type=class com.waylau.rest.bean.User, genericType=class com.waylau.rest.bean.User.
	at org.glassfish.jersey.message.internal.WriterInterceptorExecutor$TerminalWriterInterceptor.aroundWriteTo(WriterInterceptorExecutor.java:247)
	at org.glassfish.jersey.message.internal.WriterInterceptorExecutor.proceed(WriterInterceptorExecutor.java:162)
	at org.glassfish.jersey.filter.LoggingFilter.aroundWriteTo(LoggingFilter.java:293)
	at org.glassfish.jersey.message.internal.WriterInterceptorExecutor.proceed(WriterInterceptorExecutor.java:162)
	at org.glassfish.jersey.server.internal.JsonWithPaddingInterceptor.aroundWriteTo(JsonWithPaddingInterceptor.java:103)
	at org.glassfish.jersey.message.internal.WriterInterceptorExecutor.proceed(WriterInterceptorExecutor.java:162)
	at org.glassfish.jersey.server.internal.MappableExceptionWrapperInterceptor.aroundWriteTo(MappableExceptionWrapperInterceptor.java:88)
	at org.glassfish.jersey.message.internal.WriterInterceptorExecutor.proceed(WriterInterceptorExecutor.java:162)
	at org.glassfish.jersey.message.internal.MessageBodyFactory.writeTo(MessageBodyFactory.java:1154)
	at org.glassfish.jersey.server.ServerRuntime$Responder.writeResponse(ServerRuntime.java:571)
	at org.glassfish.jersey.server.ServerRuntime$Responder.processResponse(ServerRuntime.java:378)
	at org.glassfish.jersey.server.ServerRuntime$Responder.process(ServerRuntime.java:368)
	at org.glassfish.jersey.server.ServerRuntime$1.run(ServerRuntime.java:262)
 

此時，需要獲取json轉換包的支援 。

可以由多種方式實現：MOXy、JSON-P、Jackson、Jettison等，本例為Jackson。

4. 專案中引入jackson-all-1.9.11.jar

5.在“com.waylau.rest”目錄下建立RestApplication.java

package com.waylau.rest;

import org.codehaus.jackson.jaxrs.JacksonJsonProvider;
import org.glassfish.jersey.filter.LoggingFilter;
import org.glassfish.jersey.server.ResourceConfig;
 
/**
 * 應用
 * @author waylau.com
 * 2014-3-18
 */
public class RestApplication extends ResourceConfig {
    public RestApplication() {
 
     //服務類所在的包路徑
     packages("com.waylau.rest.resources");
     //註冊JSON轉換器
     register(JacksonJsonProvider.class);
 
    }
}
 

<servlet>  
     <servlet-name>Way REST Service</servlet-name>
	 <servlet-class>org.glassfish.jersey.servlet.ServletContainer</servlet-class>
	  <init-param>
	       <param-name>javax.ws.rs.Application</param-name>
	       <param-value>com.waylau.rest.RestApplication</param-value>
	   </init-param>
	 
    <load-on-startup>1</load-on-startup>
  </servlet>
  
  <servlet-mapping>
    <servlet-name>Way REST Service</servlet-name>
    <url-pattern>/rest/*</url-pattern>
  </servlet-mapping>