我使用的net.sf.json是json-lib-2.4-jdk15.jar,把json对象转换为普通java实体对象时候有个问题，josn对象转换为java对象之后，json串里面的那几个小数点的值对应的java属性的值取不到。
json串如下所示:
{"Average":0.28,"Maximum":0.32,"Minimum":0.2,"instanceId":"i-426auf2hf","timestamp":1449938400000,"userId":"1467232540347717"}
java实体对象如下:
public class Model {private double Average;private double Maximum;private double Minimum;private String instanceId;private long timestamp;private String userId;public double getAverage() {return Average;}public void setAverage(double average) {Average = average;}public double getMaximum() {return Maximum;}public void setMaximum(double maximum) {Maximum = maximum;}public double getMinimum() {return Minimum;}public void setMinimum(double minimum) {Minimum = minimum;}public String getInstanceId() {return instanceId;}public void setInstanceId(String instanceId) {this.instanceId = instanceId;}public long getTimestamp() {return timestamp;}public void setTimestamp(long timestamp) {this.timestamp = timestamp;}public String getUserId() {return userId;}public void setUserId(String userId) {this.userId = userId;}}
转换代码如下:
JSONObject sfObject = JSONObject.fromObject(str);// 转换方法Model ecs = (Model) JSONObject.toBean(sfObject, Model.class);System.out.println(ecs.getAverage());
Average的值拿不到，所以输出的结果是:0.0,而不是0.28。
解决方案:
我放弃了json.lib,用google的Gson能够完美的解决。
Gson把json串转换成java实体对象的方法如下：
1.首页导入Gson的jar包，网上可以下载。
2. 实体类还是使用上面的实体类，转换代码如下所示:
String str = "{\"Average\":0.29,\"Maximum\":0.32,\"Minimum\":0.25,\"instanceId\":\"i-426auf2hf\",\"timestamp\":1449939900000,\"userId\":\"1467232540347717\"}";Model model = new Gson().fromJson(str, Model.class);System.out.println(model.getAverage());
使用Gson之后，打印结果正确。
