ava 序列化對象如何排除指定屬性呢?

java 中序列化對象有多種方式:struts2 ,jackson,json-lib

(1)使用struts2 json插件

依賴的jar包:struts2-json-plugin-2.3.15.3.jar,xwork-core-2.3.15.3.jar,當然還有servlet-api.jar

範例:

private String getMessageJson(PushMessage message) {  
        List<Pattern> excludeProperties = new ArrayList<Pattern>();  
        Pattern pattern1 
 
= Pattern.compile("description");  
        Pattern pattern2 = Pattern.compile("creator");// 創建者ID  
        Pattern pattern3 = Pattern.compile("modifier");// 修改者ID  
        Pattern pattern4 = Pattern.compile("deliverTime");//   
        Pattern pattern5 = Pattern.compile("description");//   
        Pattern pattern6 = Pattern.compile("createTime");//
 
   
        Pattern pattern7 = Pattern.compile("modifyTime");//   
          
        excludeProperties.add(pattern1);  
        excludeProperties.add(pattern2);  
        excludeProperties.add(pattern3);  
        excludeProperties.add(pattern4);  
        excludeProperties.add(pattern5);  
        excludeProperties.add(pattern6);  
        excludeProperties.add(pattern7);  
          
        String pushJsonStr 
 
= null;  
        try {  
            PushMessage pushMessage = null;  
            try {  
                  
                pushMessage = message.clone();  
            } catch (CloneNotSupportedException e) {  
                logger.error("pushmessage clone failed.", e);  
            }  
            pushJsonStr = JSONUtil.serialize(pushMessage, excludeProperties,  
                    null, false, false);  
            logger.info("after struts serialize:" + pushJsonStr);  
        } catch (JSONException e) {  
            logger.error("struts serialize failed.", e);  
        }// TOOD 判斷json字符串的長度是否超過了256  
        return pushJsonStr;  
    }  

註意:Pattern.compile 的參數就是要排除的成員變量名稱(即description,creator,modifier都是成員變量名稱)

(2)使用Jackson

官網：http://jackson.codehaus.org/

參考：http://blog.csdn.net/sciurid/article/details/8624107

http://www.cnblogs.com/hoojo/archive/2011/04/22/2024628.html

依賴的jar:jackson-mapper-lgpl-1.9.9.jar,jackson-core-lgpl-1.9.9.jar

如果使用maven,則在pom.xml中添加依賴

1. <!-- Json轉化模塊 -->
2. <dependency>
3. <groupId>org.codehaus.jackson</groupId>
4. <artifactId>jackson-mapper-lgpl</artifactId>
5. <version>1.9.9</version>
6. </dependency>

如何排除指定屬性呢?

方式一:

先把要準備排除的屬性的值設置為null

然後設置mapper的包含策略,看下面的實例:

public void test_jackson(){  
//      Map map=new HashMap();  
//      map.put("name", "黃威");  
        List<Student2> stus=null;  
        stus=new ArrayList<Student2>();  
        Student2 stu=new Student2();  
        stus.add(stu);  
        stu.setAddress(null);  
        ObjectMapper mapper = new ObjectMapper();  
        mapper.setSerializationInclusion(Inclusion.NON_NULL);  
        String content = null;  
        try {  
            content = mapper.writeValueAsString(stus);  
            System.out.println(content);  
        } catch (JsonGenerationException e) {  
            e.printStackTrace();  
        } catch (JsonMappingException e) {  
            e.printStackTrace();  
        } catch (IOException e) {  
            e.printStackTrace();  
        }  
          
    }  

我把Student2對象的屬性address設置為null,那麽序列化時就會排除address屬性.

註意:mapper.setSerializationInclusion(Inclusion.NON_NULL); 表示排除值為null的屬性(成員變量)

方式二:使用FilterProvider

@Test  
    public void test_jackson2(){  
        List<Student2> stus=null;  
        stus=new ArrayList<Student2>();  
        Student2 stu=new Student2();  
        stus.add(stu);  
        stu.setClassroom("36班");  
        ObjectMapper mapper = new ObjectMapper();  
        String content = null;  
        try {  
//          content = mapper.writeValueAsString(stus);  
            SimpleBeanPropertyFilter theFilter = SimpleBeanPropertyFilter.serializeAllExcept("schoolNumber");  
            FilterProvider filters = new SimpleFilterProvider().addFilter("myFilter", theFilter);  
           
            content = mapper.writer(filters).writeValueAsString(stu);  
            System.out.println(content);  
        } catch (JsonGenerationException e) {  
            e.printStackTrace();  
        } catch (JsonMappingException e) {  
            e.printStackTrace();  
        } catch (IOException e) {  
            e.printStackTrace();  
        }  
          
    }  

註意:在排除屬性的對象上面增加註解:@JsonFilter("myFilter")

參考:http://www.baeldung.com/jackson-ignore-properties-on-serialization

http://stackoverflow.com/questions/11757487/how-to-tell-jackson-to-ignore-a-field-during-serialization-if-its-value-is-null

http://www.cnblogs.com/yangy608/p/3936848.html

附件是json學習筆記

java 序列化時排除指定屬性