前言:我们在项目中经常用到的是Json格式的数据,如果是将一个被Jackson转化为JSON数据格式的Java对象进行操作,我们就需要将JSON数据再反序列化为Java对象。
1、实体对象
class="java" name="code">package com.boonya.gps;
import java.io.Serializable;
import org.codehaus.jackson.annotate.JsonProperty;
public class Point implements Serializable{
private static final long serialVersionUID = -8359918523259373062L;
private double lat;
private double lng;
public double getLat() {
return lat;
}
public Point(@JsonProperty("lat") double lat,@JsonProperty("lng") double lng) {
this.lat = lat;
this.lng = lng;
}
public void setLat(double lat) {
this.lat = lat;
}
public double getLng() {
return lng;
}
public void setLng(double lng) {
this.lng = lng;
}
@Override
public String toString() {
return "Point(lat,lng)="+" {lat:"+lat+","+"lng:"+lng+"}";
}
}
2、实现JSON数据反序列化为Java对象
package com.boonya.gps;
import java.io.IOException;
import java.util.ArrayList;
import java.util.List;
import org.codehaus.jackson.JsonGenerationException;
import org.codehaus.jackson.JsonNode;
import org.codehaus.jackson.JsonParseException;
import org.codehaus.jackson.map.JsonMappingException;
import org.codehaus.jackson.map.ObjectMapper;
import org.codehaus.jackson.type.TypeReference;
/**
* JSON数据反序列化为Java对象或对象集合
* @author BOONYACHENGDU@GMAIL.COM
* @date 2013-8-28
*/
public class JSONSeriaToObject {
/**
* 对象转JSON
* @param obj
* @return
*/
public String getJsonFromObject(Object obj){
ObjectMapper om = new ObjectMapper();
try {
return om.writeValueAsString(obj);
} catch (JsonGenerationException e) {
e.printStackTrace();
} catch (JsonMappingException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
}
return "";
}
/**
* JSON反序列化为Java对象
* @param jsonStr
* @return
*/
public Point getPointByJsonString(String jsonStr){
Point point =null;
ObjectMapper om = new ObjectMapper();
try {
JsonNode node=om.readTree(jsonStr);
point= (Point) om.readValue(node.toString(),Point.class);
} catch (JsonParseException e) {
e.printStackTrace();
} catch (JsonMappingException e) {
e.printStackTrace();
} catch (JsonGenerationException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
}
System.out.println("<:success single point:>"+point.toString());
return point;
}
/**
* JSON反序列化为Java对象集合
* @param jsonStr
* @return
*/
@SuppressWarnings("unchecked")
public List<Point> getPointsByJsonString(String jsonStr){
List<Point> points = new ArrayList<Point>();
ObjectMapper om = new ObjectMapper();
try {
JsonNode node=om.readTree(jsonStr);
points= (List<Point>) om.readValue(node.toString(), new TypeReference<List<Point>>() {});
} catch (JsonParseException e) {
e.printStackTrace();
} catch (JsonMappingException e) {
e.printStackTrace();
} catch (JsonGenerationException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
}
for (int i = 0; i < points.size(); i++) {
System.out.println("<:success index "+i+":>"+points.get(i).toString());
}
return points;
}
/**
* JSON数据反序列化为Java对象的测试入口
* @param args
* @throws JsonGenerationException
* @throws JsonMappingException
* @throws IOException
*/
public static void main(String[] args) throws JsonGenerationException,JsonMappingException, IOException {
JSONSeriaToObject jsto=new JSONSeriaToObject();
//Jackson转化的原始数据格式
System.out.println("----------------------------------Jackson JSON(list<T>) to Java Object-----------------------------");
List<Point> points = new ArrayList<Point>();
points.add(new Point(34.2332,104.46664));
String json=jsto.getJsonFromObject(points);
System.out.println(json);
//JSON反序列化为Java对象
jsto.getPointsByJsonString(json);
//JSON数据反序列化Java对象
System.out.println("----------------------------------Jackson JSON(T) to Java Object-----------------------------");
Point point=new Point(34.5332,104.76664);
String json2=jsto.getJsonFromObject(point);
System.out.println(json2);
//JSON反序列化为Java对象
jsto.getPointByJsonString(json2);
//测试数据------经测试以下数据不规范--JSON反序列化为Java对象时异常
System.out.println("----------------------------------Ping string JSON to Java Object-----------------------------");
String latlngs =new String("[{\"lat\":34.232013,\"lng\":103.466002},{\"lat\":34.531939,\"lng\":103.665816}]");
String json3=jsto.getJsonFromObject(latlngs);
System.out.println(json3);
//JSON反序列化为Java对象
//jsto.getPointsByJsonString(json3);//exception
}
}
3、打印结果
----------------------------------Jackson JSON(list<T>) to Java Object-----------------------------
[{"lat":34.2332,"lng":104.46664}]
<:success index 0:>Point(lat,lng)= {lat:34.2332,lng:104.46664}
----------------------------------Jackson JSON(T) to Java Object-----------------------------
{"lat":34.5332,"lng":104.76664}
<:success single point:>Point(lat,lng)= {lat:34.5332,lng:104.76664}
----------------------------------Ping string JSON to Java Object-----------------------------
"[{\"lat\":34.232013,\"lng\":103.466002},{\"lat\":34.531939,\"lng\":103.665816}]"