Spring MVC JSON自定义类型转换

类型有很多，这里只用日期为例说明。

在Spring MVC中存在两大类的类型转换，一类是Json，一个是Spring的Binder转换。

JSON：

使用Json转换时，可以如下使用：

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1. public class Test { 
2.      
3.     private Date createdate; 
4.  
5.     @JsonSerialize(using = DateYMDHMSJsonSerializer.class) 
6.     public Date getCreatedate() { 
7.         return createdate; 
8.     } 
9.  
10.     @JsonDeserialize(using = DateYMDHMSJsonDeserializer.class) 
11.     public void setCreatedate(Date createdate) { 
12.         this.createdate = createdate; 
13.     } 
14. } 

public class Test {        private Date createdate;    @JsonSerialize(using = DateYMDHMSJsonSerializer.class)    public Date getCreatedate() {        return createdate;    }    @JsonDeserialize(using = DateYMDHMSJsonDeserializer.class)    public void setCreatedate(Date createdate) {        this.createdate = createdate;    }}

可以看到这里使用了两个Json转换的注解：

第一个@JsonSerialize是转换为字符串，主要是后台传递给前台时的日期格式；

第二个@JsonDeserialize是转换字符串为日期类型，主要是从前台往后台传递时的日期。

两个具体转换类的实现：

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1. /**
2. * Description: 日期转换 - "yyyy-MM-dd HH:mm:ss"
3. * Author: liuzh
4. * Update: liuzh(2014-04-17 10:59)
5. */ 
6. public class DateYMDHMSJsonSerializerextends JsonSerializer<Date>{ 
7.     @Override 
8.     public void serialize(Date date, JsonGenerator jsonGenerator, SerializerProvider serializerProvider)throws IOException, JsonProcessingException { 
9.         try { 
10.             jsonGenerator.writeString(DateUtil.formatDate(date, DateUtil.DATE_FORMAT_TIME_T)); 
11.         } catch (BusinessException e) { 
12.             jsonGenerator.writeString(String.valueOf(date.getTime())); 
13.         } 
14.     } 
15. } 

/** * Description: 日期转换 - "yyyy-MM-dd HH:mm:ss" * Author: liuzh * Update: liuzh(2014-04-17 10:59) */public class DateYMDHMSJsonSerializer extends JsonSerializer<Date>{    @Override    public void serialize(Date date, JsonGenerator jsonGenerator, SerializerProvider serializerProvider) throws IOException, JsonProcessingException {        try {            jsonGenerator.writeString(DateUtil.formatDate(date, DateUtil.DATE_FORMAT_TIME_T));        } catch (BusinessException e) {            jsonGenerator.writeString(String.valueOf(date.getTime()));        }    }}

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1. /**
2. * Description: 日期转换 - "yyyy-MM-dd HH:mm:ss"
3. * Author: liuzh
4. * Update: liuzh(2014-04-17 10:59)
5. */ 
6. public class DateYMDHMSJsonDeserializerextends JsonDeserializer<Date> { 
7.     @Override 
8.     public Date deserialize(JsonParser jp, DeserializationContext ctxt)throws IOException, JsonProcessingException { 
9.         try { 
10.             return DateUtil.formatStringToDate(jp.getText(), DateUtil.DATE_FORMAT_TIME_T); 
11.         } catch (BusinessException e) { 
12.             return new Date(jp.getLongValue()); 
13.         } 
14.     } 
15. } 

/** * Description: 日期转换 - "yyyy-MM-dd HH:mm:ss" * Author: liuzh * Update: liuzh(2014-04-17 10:59) */public class DateYMDHMSJsonDeserializer extends JsonDeserializer<Date> {    @Override    public Date deserialize(JsonParser jp, DeserializationContext ctxt) throws IOException, JsonProcessingException {        try {            return DateUtil.formatStringToDate(jp.getText(), DateUtil.DATE_FORMAT_TIME_T);        } catch (BusinessException e) {            return new Date(jp.getLongValue());        }    }}

其中DateUtil是一个对日期格式转换的工具类，使用的SimpleDateFormat进行转换。

Binder：

这种类型转换的时候，使用的是Spring的参数绑定，代码如下：

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1. /**
2. * Description: 全局类型转换
3. * Author: liuzh
4. * Update: liuzh(2014-05-26 13:08)
5. */ 
6. public class GlobalDataBinderimplements WebBindingInitializer { 
7.     /**
8.      * 智能日期转换，针对四种格式日期：
9.      * 1.2014-05-26
10.      * 2.1401951570548
11.      * 3.2014-05-26 00:00
12.      * 4.2014-05-26 00:00:00
13.      */ 
14.     private class SmartDateEditorextends PropertyEditorSupport { 
15.         /**
16.          * 根据2014-05-26 00:00:00长度来判断选择哪种转换方式
17.          */ 
18.         @Override 
19.         public void setAsText(String text)throws IllegalArgumentException { 
20.             if (text == null || text.length() ==0) { 
21.                 setValue(null); 
22.             } else { 
23.                 try { 
24.                     if (text.length() ==10) { 
25.                         setValue(DateUtil.formatStringToDate(text, DateUtil.DATE_FORMAT_YYYYMMDD)); 
26.                     } else if (text.length() ==13) { 
27.                         setValue(new Date(Long.parseLong(text))); 
28.                     } else if (text.length() ==16) { 
29.                         setValue(DateUtil.formatStringToDate(text, DateUtil.DATE_FORMAT_TIME_R)); 
30.                     } else if (text.length() ==19) { 
31.                         setValue(DateUtil.formatStringToDate(text, DateUtil.DATE_FORMAT_TIME_T)); 
32.                     } else { 
33.                         thrownew IllegalArgumentException("转换日期失败: 日期长度不符合要求!"); 
34.                     } 
35.                 } catch (Exception ex) { 
36.                     throw new IllegalArgumentException("转换日期失败: " + ex.getMessage(), ex); 
37.                 } 
38.             } 
39.         } 
40.  
41.         /**
42.          * 转换为日期字符串
43.          */ 
44.         @Override 
45.         public String getAsText() { 
46.             Date value = (Date) getValue(); 
47.             String dateStr = null; 
48.             if (value == null) { 
49.                 return ""; 
50.             } else { 
51.                 try { 
52.                     dateStr = DateUtil.formatDate(value, DateUtil.DATE_FORMAT_TIME_T); 
53.                     if (dateStr.endsWith(" 00:00:00")) { 
54.                         dateStr = dateStr.substring(0,10); 
55.                     } elseif (dateStr.endsWith(":00")) { 
56.                         dateStr = dateStr.substring(0,16); 
57.                     } 
58.                     return dateStr; 
59.                 } catch (Exception ex) { 
60.                     throw new IllegalArgumentException("转换日期失败: " + ex.getMessage(), ex); 
61.                 } 
62.             } 
63.         } 
64.     } 
65.  
66.     @Override 
67.     public void initBinder(WebDataBinder binder, WebRequest request) { 
68.         //日期格式转换 
69.         binder.registerCustomEditor(Date.class,new SmartDateEditor()); 
70.     } 
71.  
72. } 

/** * Description: 全局类型转换 * Author: liuzh * Update: liuzh(2014-05-26 13:08) */public class GlobalDataBinder implements WebBindingInitializer {    /**     * 智能日期转换，针对四种格式日期：     * 1.2014-05-26     * 2.1401951570548     * 3.2014-05-26 00:00     * 4.2014-05-26 00:00:00     */    private class SmartDateEditor extends PropertyEditorSupport {        /**         * 根据2014-05-26 00:00:00长度来判断选择哪种转换方式         */        @Override        public void setAsText(String text) throws IllegalArgumentException {            if (text == null || text.length() == 0) {                setValue(null);            } else {                try {                    if (text.length() == 10) {                        setValue(DateUtil.formatStringToDate(text, DateUtil.DATE_FORMAT_YYYYMMDD));                    } else if (text.length() == 13) {                        setValue(new Date(Long.parseLong(text)));                    } else if (text.length() == 16) {                        setValue(DateUtil.formatStringToDate(text, DateUtil.DATE_FORMAT_TIME_R));                    } else if (text.length() == 19) {                        setValue(DateUtil.formatStringToDate(text, DateUtil.DATE_FORMAT_TIME_T));                    } else {                        throw new IllegalArgumentException("转换日期失败: 日期长度不符合要求!");                    }                } catch (Exception ex) {                    throw new IllegalArgumentException("转换日期失败: " + ex.getMessage(), ex);                }            }        }        /**         * 转换为日期字符串         */        @Override        public String getAsText() {            Date value = (Date) getValue();            String dateStr = null;            if (value == null) {                return "";            } else {                try {                    dateStr = DateUtil.formatDate(value, DateUtil.DATE_FORMAT_TIME_T);                    if (dateStr.endsWith(" 00:00:00")) {                        dateStr = dateStr.substring(0, 10);                    } else if (dateStr.endsWith(":00")) {                        dateStr = dateStr.substring(0, 16);                    }                    return dateStr;                } catch (Exception ex) {                    throw new IllegalArgumentException("转换日期失败: " + ex.getMessage(), ex);                }            }        }    }    @Override    public void initBinder(WebDataBinder binder, WebRequest request) {        //日期格式转换        binder.registerCustomEditor(Date.class, new SmartDateEditor());    }}

这里对日期类型进行了一些判断来特殊处理。该类需要在Spring的xml进行配置：

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1. <beanclass="org.springframework.web.servlet.mvc.annotation.AnnotationMethodHandlerAdapter"> 
2.     <propertyname="webBindingInitializer"> 
3.       <beanclass="com.easternie.sys.common.GlobalDataBinder"/> 
4.     </property> 
5. </bean> 

<bean class="org.springframework.web.servlet.mvc.annotation.AnnotationMethodHandlerAdapter">    <property name="webBindingInitializer">      <bean class="com.easternie.sys.common.GlobalDataBinder"/>    </property></bean>

通过这种配置之后，Spring就能对日期进行智能转换了。