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服务器之家 - 编程语言 - Android - Android中使用HttpURLConnection实现GET POST JSON数据与下载图片

Android中使用HttpURLConnection实现GET POST JSON数据与下载图片

2021-05-10 13:23gloomyfish Android

这篇文章主要介绍了Android中使用HttpURLConnection实现GET POST JSON数据与下载图片,需要的朋友可以参考下

android6.0中把apache http client所有的包与类都标记为deprecated不再建议使用所有跟http相关的数据请求与提交操作都通过httpurlconnection类实现,现实是很多android开发者一直都apache http client来做andoird客户端与后台http接口数据交互,小编刚刚用httpurlconnection做了一个android的app,不小心踩到了几个坑,总结下最常用的就通过httpurlconnection来post提交json数据与get请求json数据。此外就是下载图片,下载图片分为显示进度与不显示进度两种。其中提交数据的时候涉及中文一定要先把中文转码成utf-8之后在post提交,否则就会一直遇到http 400的错误。

一、get请求json数据的例子

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public userdto execute(string... params) {
 inputstream inputstream = null;
 httpurlconnection urlconnection = null;
 
 try {
  // read responseurlencoder.encode(para, "gbk");
  string urlwithparams = domain_address + member_request_token_url + "?username=" + java.net.urlencoder.encode(params[0],"utf-8") + "&password=" + params[1];
  url url = new url(urlwithparams);
  urlconnection = (httpurlconnection) url.openconnection();
 
  /* optional request header */
  urlconnection.setrequestproperty("content-type", "application/json; charset=utf-8");
 
  /* optional request header */
  urlconnection.setrequestproperty("accept", "application/json");
 
  /* for get request */
  urlconnection.setrequestmethod("get");
  int statuscode = urlconnection.getresponsecode();
 
  /* 200 represents http ok */
  if (statuscode == 200) {
   inputstream = new bufferedinputstream(urlconnection.getinputstream());
   string response = httputil.convertinputstreamtostring(inputstream);
   gson gson = new gson();
   userdto dto = gson.fromjson(response, userdto.class);
   if (dto != null && dto.gettoken() != null) {
    log.i("token", "find the token = " + dto.gettoken());
   }
   return dto;
  }
 
 } catch (exception e) {
  e.printstacktrace();
 } finally {
  if (inputstream != null) {
   try {
    inputstream.close();
   } catch (ioexception e) {
    e.printstacktrace();
   }
  }
  if (urlconnection != null) {
   urlconnection.disconnect();
  }
 }
 return null;
}

二、post提交json数据

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public map<string, string> execute(notificationdto dto) {
 inputstream inputstream = null;
 httpurlconnection urlconnection = null;
 try {
  url url = new url(geturl);
  urlconnection = (httpurlconnection) url.openconnection();
 
  /* optional request header */
  urlconnection.setrequestproperty("content-type", "application/json; charset=utf-8");
 
  /* optional request header */
  urlconnection.setrequestproperty("accept", "application/json");
  dto.setcreator(java.net.urlencoder.encode(dto.getcreator(), "utf-8"));
   
  // read response
  /* for get request */
  urlconnection.setrequestmethod("post");
  urlconnection.setdooutput(true);
  dataoutputstream wr = new dataoutputstream(urlconnection.getoutputstream());
  gson gson = new gson();
  string jsonstring = gson.tojson(dto);
  wr.writebytes(jsonstring);
  wr.flush();
  wr.close();
  // try to get response
  int statuscode = urlconnection.getresponsecode();
  if (statuscode == 200) {
   inputstream = new bufferedinputstream(urlconnection.getinputstream());
   string response = httputil.convertinputstreamtostring(inputstream);
   map<string, string> resultmap = gson.fromjson(response, map.class);
   if (resultmap != null && resultmap.size() > 0) {
    log.i("applydesigner", "please check the map with key");
   }
   return resultmap;
  }
 }
 catch(exception e)
 {
  e.printstacktrace();
 }
 finally
 {
  if (inputstream != null) {
   try {
    inputstream.close();
   } catch (ioexception e) {
    e.printstacktrace();
   }
  }
  if (urlconnection != null) {
   urlconnection.disconnect();
  }
 }
 return null;
}

三、下载图片显示下载进度

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package com.example.demo;
 
import java.io.bytearrayinputstream;
import java.io.bytearrayoutputstream;
import java.io.ioexception;
import java.io.inputstream;
import java.net.httpurlconnection;
import java.net.url;
 
import android.graphics.bitmap;
import android.graphics.bitmapfactory;
import android.os.asynctask;
import android.os.handler;
import android.os.message;
import android.util.log;
 
public class imageloadtask extends asynctask<string, void, bitmap> {
 private handler handler;
 
 public imageloadtask(handler handler) {
  this.handler = handler;
 }
 
 protected void onpostexecute(bitmap result) {
  message msg = new message();
  msg.obj = result;
  handler.sendmessage(msg);
 }
 
 protected bitmap doinbackground(string... geturls) {
  inputstream inputstream = null;
  httpurlconnection urlconnection = null;
 
  try {
   // open connection
   url url = new url(geturls[0]);
   urlconnection = (httpurlconnection) url.openconnection();
   /* for get request */
   urlconnection.setrequestmethod("get");
   int filelength = urlconnection.getcontentlength();
   int statuscode = urlconnection.getresponsecode();
   if (statuscode == 200) {
    inputstream = urlconnection.getinputstream();
    byte data[] = new byte[4096];
    long total = 0;
    int count;
    bytearrayoutputstream output = new bytearrayoutputstream();
    while ((count = inputstream.read(data)) != -1) {
     total += count;
     // publishing the progress....
     if (filelength > 0 && handler != null) {
      handler.sendemptymessage(((int) (total * 100 / filelength)) - 1);
     }
     output.write(data, 0, count);
    }
    bytearrayinputstream bufferinput = new bytearrayinputstream(output.tobytearray());
    bitmap bitmap = bitmapfactory.decodestream(bufferinput);
    inputstream.close();
    bufferinput.close();
    output.close();
    log.i("image", "already get the image by uuid : " + geturls[0]);
    handler.sendemptymessage(100);
    return bitmap;
   }
  } catch (exception e) {
   e.printstacktrace();
  } finally {
   if (inputstream != null) {
    try {
     inputstream.close();
    } catch (ioexception e) {
     e.printstacktrace();
    }
   }
   if (urlconnection != null) {
    urlconnection.disconnect();
   }
  }
  return null;
 }
 
}

总结:使用httpurlconnection提交json数据的时候编码方式为utf-8所有中文字符请一定要预先转码为utf-8,然后在后台服务器对应的api中解码为utf-8,不然就会报错http 400。

以上就是本文的全部内容,希望对大家的学习android软件编程有所帮助。

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