通过http协议发送json格式请求并解析

private BackData getDataFromDH(String method,String param){
URL url=null;
//自定义实体类，我自定义的是和对方返回的json对应的类型
BackData data=null;
try {
//此处参数baseurl、method、param合成一个完整的url 如 http://192.168.29.200:8080/dahuaIS/rest/statistic/picrecord/参数
//这里的参数param在后文会特别说明
url=new URL("http://"+baseurl+method+param);
HttpURLConnection connection = (HttpURLConnection) url.openConnection();//获取连接
//这里的set方法主要设置一些请求头的参数
connection.setRequestMethod("GET");//设置请求方式
connection.setRequestProperty("Accept", "application/json");
connection.setRequestProperty("Content-Type", "application/json");
connection.setRequestProperty("authorization",authorization);//按照对方要求设置的相关认证内容
connection.connect();
Gson gson=new GsonBuilder().create();//这里使用到了google 的Gson.jar 可以方便地把对象和json格式互转
InputStream is = connection.getInputStream();
InputStreamReader r=new InputStreamReader(is,"utf-8");
BufferedReader br=new BufferedReader(r);
String s = br.readLine();//这里偷懒直接读了一个完整的字符串，因为返回的json实际上也是一个完整的行字符串
data = gson.fromJson(s, BackData.class);
//最后关闭流
br.close();
r.close();
is.close();
connection.disconnect();//断开连接
} catch (MalformedURLException e) { //以下异常具体情况具体处理
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
}
return data;
}

public class SearchParam {
private String devChnId;
private String startDate;
private String endDate; public String getDevChnId() {
return devChnId;
}
public void setDevChnId(String devChnId) {
this.devChnId = devChnId;
}
public String getStartDate() {
return startDate;
}
public void setStartDate(String startDate) {
this.startDate = startDate;
}
public String getEndDate() {
return endDate;
}
public void setEndDate(String endDate) {
this.endDate = endDate;
}
@Override
public String toString() {
String str="";
try {
str=URLEncoder.encode("{\"devChnId\":\""+devChnId+"\",\"startDate\":\""+startDate+"\",\"endDate\":\""+endDate+"\"}", "UTF-8");
} catch (UnsupportedEncodingException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
return "q="+str;
}}

public String toString(){
return new GsonBuilder().create().toJson(this);
}
//以下是测试返回结果
{"devChnId":"#34523@34","startDate":"2011-12-15 12:23:43","endDate":"2016-12-12 12:02:24"}