<二> Google Gson 转换Json字符串和对象（日期，枚举的转化）

例子肯定能运行成功，考虑到面向对象，所以多写了几个类。

 

一、日期的转换需要在Create GsonBuilder时注册日期的格式。

 

二、对于枚举类，如果是默认转换，则不需要做任何操作，Gson会将枚举类转换为字符串。但如果需要自定义规则来进行枚举类和字符串的转换，则需要自定义相关的类实现JsonSerializer和JsonDeserializer类。

 

三、含有枚举类型的Java Object：NucleonEvent

 

/**
 * 
 */
package com.ebay.montage.pm.model;

import java.util.List;
import java.util.Map;

/**
 * @author Josh Wang(Sheng)
 *
 * @email  [email protected]
 */
public class NucleonEvent {
	
	private String id;
	
	private String host;
	
	private String odbFunction;
	
	private String source;
	
	private String format;
	
	private String classification;
	
	private long detectionTime;
	
	private long reportedTime;
	
	private Severity severity;
	
	private NucleonEventType type;
	
	private NucleonMetadata metadata;

	public String getId() {
		return id;
	}

	public void setId(String id) {
		this.id = id;
	}

	public NucleonEventType getType() {
		return type;
	}

	public void setType(NucleonEventType type) {
		this.type = type;
	}
	
	public enum NucleonEventType {
		
		nwmon_checkMem,nwmon_checkCPU_busyio;

	}
	
	public enum Severity {
		low;
	}
	
	public static class NucleonMetadata {
		private boolean passed;
		
		private String name;
		
		private List<Map<String, String>> msgs;
		
		private Map<String , Object> resultDataMap;

		public boolean isPassed() {
			return passed;
		}

		public void setPassed(boolean passed) {
			this.passed = passed;
		}

		public String getName() {
			return name;
		}

		public void setName(String name) {
			this.name = name;
		}

		public List<Map<String, String>> getMsgs() {
			return msgs;
		}

		public void setMsgs(List<Map<String, String>> msgs) {
			this.msgs = msgs;
		}

		public Map<String, Object> getResultDataMap() {
			return resultDataMap;
		}

		public void setResultDataMap(Map<String, Object> resultDataMap) {
			this.resultDataMap = resultDataMap;
		}
		
		
	}

	public String getHost() {
		return host;
	}

	public void setHost(String host) {
		this.host = host;
	}

	public String getOdbFunction() {
		return odbFunction;
	}

	public void setOdbFunction(String odbFunction) {
		this.odbFunction = odbFunction;
	}

	public String getSource() {
		return source;
	}

	public void setSource(String source) {
		this.source = source;
	}

	public String getClassification() {
		return classification;
	}

	public void setClassification(String classification) {
		this.classification = classification;
	}

	public long getDetectionTime() {
		return detectionTime;
	}

	public void setDetectionTime(long detectionTime) {
		this.detectionTime = detectionTime;
	}

	public long getReportedTime() {
		return reportedTime;
	}

	public void setReportedTime(long reportedTime) {
		this.reportedTime = reportedTime;
	}

	public Severity getSeverity() {
		return severity;
	}

	public void setSeverity(Severity severity) {
		this.severity = severity;
	}

	public String getFormat() {
		return format;
	}

	public void setFormat(String format) {
		this.format = format;
	}

	public NucleonMetadata getMetadata() {
		return metadata;
	}

	public void setMetadata(NucleonMetadata metadata) {
		this.metadata = metadata;
	}

	@Override
	public String toString() {
		return "NucleonEvent [id=" + id + ", host=" + host + ", odbFunction="
				+ odbFunction + ", source=" + source + ", format=" + format
				+ ", classification=" + classification + ", detectionTime="
				+ detectionTime + ", reportedTime=" + reportedTime
				+ ", severity=" + severity + ", type=" + type + ", metadata="
				+ metadata.getName() + ":" + metadata.isPassed() + metadata.getMsgs() + "]";
	}

	

	
}

 

 

四、抽象的转换类： EventDataparser

 

/**
 * 
 */
package com.ebay.montage.pm.handler;

import com.ebay.montage.pm.model.NucleonEvent;
import com.ebay.montage.pm.model.NucleonEvent.NucleonEventType;
import com.ebay.montage.pm.utils.DateUtils;
import com.google.gson.Gson;
import com.google.gson.GsonBuilder;

/**
 * @author Josh Wang(Sheng)
 *
 * @email  [email protected]
 */
public abstract class EventDataParser {
	
	public static Gson createGson() {
		GsonBuilder builder = new GsonBuilder();
		builder.setDateFormat("yyyy-MM-dd HH:mm:ss");
		builder.registerTypeAdapter(NucleonEventType.class, new NucleonEventTypeSerializer());
		
		Gson gson = builder.create();
		return gson;
	}

	/**
	 * Parse the given JSON String to NucleonEvent
	 * @param jsonStr
	 * @return
	 */
	public abstract NucleonEvent fromGson(String jsonStr);
	
	/**
	 * Parse the NucleonEvent to JSON String
	 * @return
	 */
	public abstract String toGson(NucleonEvent event);
}

 

如果需要使用自定义的日期转换器，需要自定义相应的Adapter 并注册相关的Adapter，如下面的Adapter将会处理所有的类型为Calendar的字段：

public static Gson createGson() {
		GsonBuilder builder = new GsonBuilder();
		builder.registerTypeAdapter(NucleonEventType.class, new NucleonEventTypeAdapter());
		builder.registerTypeAdapter(Calendar.class, new NucleonEventCalendarAdapter());
		builder.setDateFormat(DateUtils.MIDDLE_LINE_TIMESTAMP);
		
		Gson gson = builder.create();
		return gson;
	}

 

package com.ebay.montage.pm.handler;

import java.lang.reflect.Type;
import java.util.Calendar;

import com.google.gson.JsonDeserializationContext;
import com.google.gson.JsonDeserializer;
import com.google.gson.JsonElement;
import com.google.gson.JsonParseException;
import com.google.gson.JsonPrimitive;
import com.google.gson.JsonSerializationContext;
import com.google.gson.JsonSerializer;

/**
 * @author Josh Wang(Sheng)
 *
 * @email  [email protected]
 */
public class NucleonEventCalendarAdapter implements JsonSerializer<Calendar>,
		JsonDeserializer<Calendar> {

	public Calendar deserialize(JsonElement json, Type arg1,
			JsonDeserializationContext arg2) throws JsonParseException {
		Calendar calendar = Calendar.getInstance();
		calendar.setTimeInMillis(json.getAsJsonPrimitive().getAsLong());
		return calendar;
	}

	public JsonElement serialize(Calendar calendar, Type arg1,
			JsonSerializationContext arg2) {
		return new JsonPrimitive(Long.valueOf(calendar.getTimeInMillis()));
	}

	

}

 

五、实际进行转换的类

 

/**
 * 
 */
package com.ebay.montage.pm.handler;

import com.ebay.montage.pm.model.NucleonEvent;

/**
 * @author Josh Wang(Sheng)
 *
 * @email  [email protected]
 */
public class NucleonEventDataParser extends EventDataParser {

	@Override
	public NucleonEvent fromGson(String jsonStr) {
		return NucleonEventDataParser.createGson().fromJson(jsonStr, NucleonEvent.class);
	}

	@Override
	public String toGson(NucleonEvent event) {
		return NucleonEventDataParser.createGson().toJson(event);
	}

}

 

六、 上面的NucleonEvent中有两个枚举类：NucleonEventType 和 NucleonMetadata

我们只对NucleonEventType进行自定义的枚举类和json的转换，而对NucleonMetadata采用默认的转换。

package com.ebay.montage.pm.handler;

import java.lang.reflect.Type;

import com.ebay.montage.pm.model.NucleonEvent.NucleonEventType;
import com.google.gson.JsonDeserializationContext;
import com.google.gson.JsonDeserializer;
import com.google.gson.JsonElement;
import com.google.gson.JsonParseException;
import com.google.gson.JsonPrimitive;
import com.google.gson.JsonSerializationContext;
import com.google.gson.JsonSerializer;

/**
 * 
 * @author Josh Wang(Sheng)
 *
 * @email  [email protected]
 */
public class NucleonEventTypeSerializer implements JsonSerializer<NucleonEventType>,
		JsonDeserializer<NucleonEventType> {

	/**
	 * JSON to Object
	 */
	public NucleonEventType deserialize(JsonElement json, Type arg1,
			JsonDeserializationContext arg2) throws JsonParseException {
        return NucleonEventType.valueOf(json.getAsString()) ; 
	}

	/**
	 * Object to JSON
	 */
	public JsonElement serialize(NucleonEventType type, Type arg1,
			JsonSerializationContext arg2) {
		return new JsonPrimitive(type.name());
	}


}

 

 

七、Unit Test类

 

/**
 * 
 */
package com.ebay.montage.pm;


import org.junit.Assert;
import org.junit.BeforeClass;
import org.junit.Test;

import com.ebay.montage.pm.handler.NucleonEventDataParser;
import com.ebay.montage.pm.model.NucleonEvent;
import com.ebay.montage.pm.model.NucleonEvent.NucleonEventType;

/**
 * @author Josh Wang(Sheng)
 *
 * @email  [email protected]
 */
public class TestNucleonEventParser {

	private static String json;
	
	@BeforeClass
	public static void init() {
		json = "{\"id\": \"eventId\", \"type\":\"nwmon_checkCPU_busyio\", "
				+ "\"format\" : \"normalizedEvent\", \"detectionTime\": \"23424234234\", "
				+ " \"severity\":\"low\", "
				+ "\"metadata\":{\"passed\": true,\"name\": \"Recent Changes Check\", \"msgs\": [{\"data\": \"<HTML Allowed>\"}, {\"eve\": \"<Pdf Allowed>\"}]}}";
	}
	
	@Test
	public void fromGson() {
		NucleonEvent event = new NucleonEventDataParser().fromGson(json);
		
		Assert.assertEquals("eventId", event.getId());
		Assert.assertEquals("nwmon_checkCPU_busyio", event.getType().toString());
		
		System.out.println(event.toString());
	}
	
	@Test 
	public void toGson() {
		NucleonEvent event = new NucleonEvent();
		
		event.setId("eventId2");
		event.setType(NucleonEventType.nwmon_checkCPU_busyio);
		
		Assert.assertTrue(new NucleonEventDataParser().toGson(event).contains("eventId2"));
	}
}