JackSon学习笔记(二)

概述

jackson解析json例子

准备工作

基于JDK1.7,依赖Jackson框架类库：

jackson-core-2.5.3.jar
jackson-databind-2.5.3.jar

Example

下面的例子是基于Jackson 2.x版本的树模型的Json解析。

要解析的Json字符串：

String data = {  
            "type":2,"range":1,"start":1368417600,"end":1368547140,"cityName":"天津",  
            "companyIds":["12000001"],  
            "companyNames":["天津"],  
            "12000001":{  
                "data":[47947,48328,48573,48520],  
                "timestamps":[1368417600,1368417900,1368418200,1368418500]  
            }  
    }  

示例代码：

package com.cennavi.dqe.test;  
  
import java.io.IOException;  
import java.text.SimpleDateFormat;  
import java.util.Date;  
import java.util.TimeZone;  
  
import com.fasterxml.jackson.core.JsonProcessingException;  
import com.fasterxml.jackson.databind.JsonNode;  
import com.fasterxml.jackson.databind.ObjectMapper;  
  
public class ParseJsonTest {  
  
    /** 
     * @param args 
     */  
    public static void main(String[] args) {  
        String data = "{\"type\":2,\"range\":1,\"start\":1368417600,\"end\":1368547140,"  
                + "\"cityName\":\"天津\",\"companyIds\":[\"12000001\"],\"companyNames\":[\"天津\"],"  
                + "\"12000001\":{\"data\":[47947,48328,48573,48520],"  
                + "\"timestamps\":[1368417600,1368417900,1368418200,1368418500]}}";  
        String data2 = parseJson(data);  
        System.out.println(data2);  
    }  
  
    public static String parseJson(String data) {  
        // 用来展现解析Json得到的值  
        StringBuffer buf = new StringBuffer();  
        try {  
            ObjectMapper mapper = new ObjectMapper();  
            JsonNode rootNode = mapper.readTree(data); // 读取Json  
            // rootNode.path("xx")返回的还是一个JsonNode对象，调用该JsonNode的相应方法，得到键对应的值  
            int type = rootNode.path("type").asInt();  
            int range = rootNode.path("range").asInt();  
            long start = rootNode.path("start").asLong();  
            long end = rootNode.path("end").asLong();  
            String cityName = rootNode.path("cityName").asText();  
  
            // 转换时间格式  
            SimpleDateFormat sdf = new SimpleDateFormat("yyyyMMddHHmm");  
            sdf.setTimeZone(TimeZone.getTimeZone("GMT+8"));  
  
            String str = "类型(type):" + type + "\r\n" + "范围(range):" + range  
                    + "\r\n" + "开始时间(start):"  
                    + sdf.format(new Date(start * 1000)) + "\r\n"  
                    + "结束时间(end):" + sdf.format(new Date(end * 1000)) + "\r\n"  
                    + "城市名称(cityName):" + cityName;  
            buf.append(str);  
            // 得到companyIds的JsonNode对象  
            JsonNode companyIds = rootNode.path("companyIds");  
            JsonNode companyNames = rootNode.path("companyNames");  
  
            // 遍历companyIds中的内容  
            for (int i = 0; i < companyIds.size(); i++) {  
                String companyId = companyIds.get(i).asText();  
                // 本例解析的Json字符串中companyIds与companyNames的长度是相同的，所有直接遍历companyNames  
                String companyName = companyNames.get(i).asText();  
                // companyId的值：12000001，对应Json串中的  
                // "12000001":{"data":[...],"timestamps":[....]}  
                JsonNode infoNode = rootNode.path(companyId);  
                // 得到"12000001":{"data":[...],"timestamps":[....]}中的data和timestamps的JsonNode对象  
                JsonNode dataNode = infoNode.path("data");  
                JsonNode timestampsNode = infoNode.path("timestamps");  
                // 遍历data和timestamps 本例中data.size与timestamps.size是相等的  
  
                buf.append("\r\n{\r\n  公司ID(companyId):" + companyId  
                        + "\r\n  公司名称(companyName):" + companyName + "\r\n"  
                        + " data:");  
                for (int j = 0; j < dataNode.size(); j++) {  
                    long dataValue = dataNode.get(j).asLong();  
                    buf.append(dataValue + ",");  
                }  
                buf.append("\r\n time:");  
                for (int k = 0; k < timestampsNode.size(); k++) {  
                    long timeValue = timestampsNode.get(k).asLong();  
                    buf.append(sdf.format(new Date(timeValue * 1000)) + ",");  
                }  
                buf.append("\r\n}\r\n");  
            }  
        } catch (JsonProcessingException e) {  
            e.printStackTrace();  
        } catch (IOException e) {  
            // TODO 自动生成的 catch 块  
            e.printStackTrace();  
        }  
        return buf.toString();  
    }  
  
}  

测试结果：

类型(type):2  
范围(range):1  
开始时间(start):201305131200  
结束时间(end):201305142359  
城市名称(cityName):天津  
{  
  公司ID(companyId):12000001  
  公司名称(companyName):天津  
  data:47947,48328,48573,48520,  
  time:201305131200,201305131205,201305131210,201305131215  
} 

转载来源：http://blog.csdn.net/java_huashan/article/details/9353903