JAX-RS之jackson去处理json

在JAX-RS中使用jackson去处理json，例子如下。下文讲解了，如何将一个对象转变为JSON对象，使用的是jackson。

1 放置resteasy-jackson-provider.jar

2
一个简单对象

Java代码

1.   
2. public class Product {   
3.     
4.     String name;   
5.     int qty;   
6.     
7.     public String getName() {   
8.         return name;   
9.     }   
10.     
11.     public void setName(String name) {   
12.         this.name = name;   
13.     }   
14.     
15.     public int getQty() {   
16.         return qty;   
17.     }   
18.     
19.     public void setQty(int qty) {   
20.         this.qty = qty;   
21.     }   
22.     
23. }  

public class Product { String name;int qty; public String getName() {return name;} public void setName(String name) {this.name = name;} public int getQty() {return qty;} public void setQty(int qty) {this.qty = qty;} }

3 使用注解@Produces("application/json").就可以转换JSON了

Java代码

1. import javax.ws.rs.Consumes;   
2. import javax.ws.rs.GET;   
3. import javax.ws.rs.POST;   
4. import javax.ws.rs.Path;   
5. import javax.ws.rs.Produces;   
6. import javax.ws.rs.core.Response;   
7.     
8. @Path("/json/product")   
9. public class JSONService {   
10.     
11.     @GET  
12.     @Path("/get")   
13.     @Produces("application/json")   
14.     public Product getProductInJSON() {   
15.     
16.         Product product = new Product();   
17.         product.setName("iPad 3");   
18.         product.setQty(999);   
19.     
20.         return product;    
21.     
22.     }   
23.     
24.     @POST  
25.     @Path("/post")   
26.     @Consumes("application/json")   
27.     public Response createProductInJSON(Product product) {   
28.     
29.         String result = "Product created : " + product;   
30.         return Response.status(201).entity(result).build();   
31.     
32.     }   
33.     
34. }  

import javax.ws.rs.Consumes;import javax.ws.rs.GET;import javax.ws.rs.POST;import javax.ws.rs.Path;import javax.ws.rs.Produces;import javax.ws.rs.core.Response; @Path("/json/product")public class JSONService { @GET@Path("/get")@Produces("application/json")public Product getProductInJSON() { Product product = new Product();product.setName("iPad 3");product.setQty(999); return product;  } @POST@Path("/post")@Consumes("application/json")public Response createProductInJSON(Product product) { String result = "Product created : " + product;return Response.status(201).entity(result).build(); } }

  注意，要把web.xml中的自动扫描注释掉，否则会出错：
<!-- disabled auto scan
        <context-param>
             <param-name>resteasy.scan</param-name>
             <param-value>true</param-value>
</context-param> -->

<context-param>
<param-name>resteasy.resources</param-name>
<param-value>com.mkyong.rest.JSONService</param-value>
</context-param>

4 客户端调用服务端的GET,用于将服务端的对象转为JSON,如下:
 

Java代码

1. try {   
2.   
3.             URL url = new URL(   
4.                     "http://localhost:8085/Resetjason/json/product/get");   
5.             HttpURLConnection conn = (HttpURLConnection) url.openConnection();   
6.             conn.setRequestMethod("GET");   
7.             conn.setRequestProperty("Accept", "application/json");   
8.   
9.             if (conn.getResponseCode() != 200) {   
10.                 throw new RuntimeException("Failed : HTTP error code : " + conn.getResponseCode());   
11.             }   
12.   
13.             BufferedReader br = new BufferedReader(new InputStreamReader(   
14.                     (conn.getInputStream())));   
15.   
16.             String output;   
17.             System.out.println("Output from Server .... \n");   
18.             while ((output = br.readLine()) != null) {   
19.   
20.                 System.out.println(output);   
21.             }   
22.                
23.             conn.disconnect();   
24.   
25.         } catch (MalformedURLException e) {   
26.   
27.             e.printStackTrace();   
28.         } catch (IOException e) {   
29.   
30.             e.printStackTrace();   
31.                
32.         }  

try {URL url = new URL("http://localhost:8085/Resetjason/json/product/get");HttpURLConnection conn = (HttpURLConnection) url.openConnection();conn.setRequestMethod("GET");conn.setRequestProperty("Accept", "application/json");if (conn.getResponseCode() != 200) {throw new RuntimeException("Failed : HTTP error code : " + conn.getResponseCode());}BufferedReader br = new BufferedReader(new InputStreamReader((conn.getInputStream())));String output;System.out.println("Output from Server .... \n");while ((output = br.readLine()) != null) {System.out.println(output);}conn.disconnect();} catch (MalformedURLException e) {e.printStackTrace();} catch (IOException e) {e.printStackTrace();}

运行后,输出:
Output from Server ....

{"qty":999,"name":"iPad 3"}

5 调用服务端的POST,将JSON传入,看其如何转化位product
 

Java代码

1. try {   
2.   
3.         URL url = new URL(   
4.                 "http://localhost:8085/Resetjason/json/product/post");   
5.         HttpURLConnection conn = (HttpURLConnection) url.openConnection();   
6.         conn.setDoOutput(true);   
7.         conn.setRequestMethod("POST");   
8.         conn.setRequestProperty("Content-Type", "application/json");   
9.   
10.         String input = "{\"qty\":100,\"name\":\"iPad 4\"}";   
11.   
12.         OutputStream os = conn.getOutputStream();   
13.         os.write(input.getBytes());   
14.         os.flush();   
15.   
16.         if (conn.getResponseCode() != HttpURLConnection.HTTP_CREATED) {   
17.             throw new RuntimeException("Failed : HTTP error code : "  
18.                     + conn.getResponseCode());   
19.         }   
20.   
21.         BufferedReader br = new BufferedReader(new InputStreamReader(   
22.                 (conn.getInputStream())));   
23.   
24.         String output;   
25.         System.out.println("Output from Server .... \n");   
26.         while ((output = br.readLine()) != null) {   
27.   
28.             System.out.println(output);   
29.         }   
30.   
31.         conn.disconnect();   
32.   
33.     } catch (MalformedURLException e) {   
34.   
35.         e.printStackTrace();   
36.     } catch (IOException e) {   
37.   
38.         e.printStackTrace();   
39.   
40.     }   
41.   
42. }  

try {URL url = new URL("http://localhost:8085/Resetjason/json/product/post");HttpURLConnection conn = (HttpURLConnection) url.openConnection();conn.setDoOutput(true);conn.setRequestMethod("POST");conn.setRequestProperty("Content-Type", "application/json");String input = "{\"qty\":100,\"name\":\"iPad 4\"}";OutputStream os = conn.getOutputStream();os.write(input.getBytes());os.flush();if (conn.getResponseCode() != HttpURLConnection.HTTP_CREATED) {throw new RuntimeException("Failed : HTTP error code : "+ conn.getResponseCode());}BufferedReader br = new BufferedReader(new InputStreamReader((conn.getInputStream())));String output;System.out.println("Output from Server .... \n");while ((output = br.readLine()) != null) {System.out.println(output);}conn.disconnect();} catch (MalformedURLException e) {e.printStackTrace();} catch (IOException e) {e.printStackTrace();}}

输出为:
  Output from Server ....

Product created : Product [name=iPad 4, qty=100]