Android 网络编程实例

一、前端

•       网络请求库：okHttp3 版本3.10.0  https://blog.csdn.net/kangguang/article/details/104031756
•       图片加载库：Glide 

              annotationProcessor 'com.github.bumptech.glide:compiler:4.4.0'

              implementation 'jp.wasabeef:glide-transformations:2.0.2' i           

              mplementation 'com.squareup.okhttp3:okhttp:3.10.0'

•       Json解析：Fastjson      版本 com.alibaba:fastjson:1.2.41
•       采用组件ListView 并在Adapter 中做了缓存优化
•       数据返回处理数据bean 中的属性字段没有和后台一致，手动赋值处理
•       Activity：NetworkActivity
•       Adapter item：new_item.xml
•       网络请求错误处理 https://blog.csdn.net/kangguang/article/details/104031756

代码如下：

1.new_item.xml

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="65dp">
    <ImageView
        android:id="@+id/siv_icon"
        android:layout_width="80dp"
        android:layout_height="wrap_content"
        android:layout_marginTop="5dp"
        android:layout_marginBottom="5dp"/>
    <TextView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:id="@+id/tv_title"
        android:layout_marginLeft="5dp"
        android:layout_marginTop="10dp"
        android:layout_toRightOf="@id/siv_icon"
        android:ellipsize="end"
        android:maxLength="20"
        android:singleLine="true"
        android:textColor="#990000"
        android:textSize="18sp"
        android:text="我是标题"
        />
    <TextView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:id="@+id/tv_description"
        android:layout_marginLeft="5dp"
        android:layout_marginTop="10dp"
        android:layout_toRightOf="@id/siv_icon"
        android:layout_below="@id/tv_title"
        android:ellipsize="end"
        android:maxLength="16"
        android:singleLine="true"
        android:textColor="#990000"
        android:textSize="14sp"
        android:text="我是描述"
        />
    <TextView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:id="@+id/tv_type"
        android:layout_alignParentBottom="true"
        android:layout_alignParentRight="true"
        android:layout_marginBottom="5dp"
        android:layout_marginRight="10dp"
        android:textColor="#990000"
        android:textSize="12sp"
        android:text="评论"
        />
</RelativeLayout>

2.NetworkActivity

public class NetworkActivity extends AppCompatActivity {
    private LinearLayout  loading;
    private ListView      lvNews;
    private ArrayList<NewsInfo> newsInfos = new ArrayList<NewsInfo>();
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_network);

        initView();
        fillData();
    }
    private void initView()
    {
     loading = (LinearLayout) findViewById(R.id.loading);
     lvNews  = (ListView)findViewById(R.id.lv_news);
    }
    private  void fillData()
    {
        String url =getString(R.string.serverurl);
        OkHttpClient okHttpClient = new OkHttpClient();


        final Request request = new Request.Builder()
                .url(url)
                .get()//默认就是GET请求，可以不写
                .build();
        final Call call = okHttpClient.newCall(request);

        call.enqueue(new Callback() {
            @Override
            public void onFailure(Call call, IOException e) {

                Log.i("onfail",e.getMessage());

            }
            @Override
            public void onResponse(Call call, Response response) throws IOException {
                try(ResponseBody responseBody = response.body()) {
                  if (!response.isSuccessful())throw new IOException(("unexpected code"+response));
                   final String  mstring = responseBody.string();
                   final Runnable runnable = new Runnable() {
                       @Override
                       public void run() {
                           try {
                               dataProcessing(mstring);
                           } catch (Exception e) {
                               e.printStackTrace();
                           }
                       }
                   };
                   new Thread(){
                       public void  run(){
                           new Handler(Looper.getMainLooper()).post(runnable);
                       }
                   }.start();

                }
            }
        });
    }
    private  void dataProcessing(String jsonstr) throws Exception {
        JSONObject jsonObject = JSONObject.parseObject(jsonstr);;
        int reslut = jsonObject.getInteger("result");
        if ( reslut!= 1 )
        {
            Toast.makeText(NetworkActivity.this,jsonObject.getString("msg"),Toast.LENGTH_SHORT).show();
            return;
        }

        List<Map<String, Object>> list  = JSON.parseObject(String.valueOf(jsonObject.get("data")), List.class);
        if (list.size()>0)
        {
            for (int i = 0;i<list.size();i++)
            {
                NewsInfo newsInfo = new NewsInfo();
                Map<String, Object> mapList = list.get(i);
                for(Map.Entry<String, Object> entry : mapList.entrySet()){
                    String mapKey = entry.getKey();
                    String mapValue = (String) entry.getValue();
                    switch (mapKey){
                        case "news_title":
                            newsInfo.setTitle(mapValue);
                           break;
                        case "news_icon_path":
                            newsInfo.setIcon(mapValue);
                            break;
                        case "news_content":
                            newsInfo.setContent(mapValue);
                            break;
                        case "news_Comment":
                            newsInfo.setComment(mapValue);
                            break;
                        case "news_Type":
                            newsInfo.setType(mapValue);
                            break;
                         default:
                             break;
                    }
                }
               newsInfos.add(newsInfo);
            }
            loading.setVisibility(View.INVISIBLE);
            lvNews.setAdapter(new NewsAdapter());
        }
        else
        {
            Toast.makeText(NetworkActivity.this, "没有新闻",Toast.LENGTH_SHORT).show();
        }


    }

    private class NewsAdapter extends BaseAdapter{
        @Override
        public int getCount()
        {
            return  newsInfos.size();
        }
        @Override
        public View getView(int position, View convertView, ViewGroup parent)
        {
            ViewHolder holder;
            if (convertView == null)
            {
                convertView= LayoutInflater.from(NetworkActivity.this).inflate(R.layout.new_item,parent,false);
                holder = new ViewHolder();
                holder.siv             = (ImageView)convertView.findViewById(R.id.siv_icon);
                holder.tv_title        = (TextView)convertView.findViewById(R.id.tv_title);
                holder.tv_description  = (TextView)convertView.findViewById(R.id.tv_description);
                holder.tv_type        = (TextView)convertView.findViewById(R.id.tv_type);

                convertView.setTag(holder);
            }
            else {
                holder = (ViewHolder)convertView.getTag();
            }
            
            NewsInfo newsInfo        = newsInfos.get(position);
            Glide.with(NetworkActivity.this).load( "http://192.168.0.102:8080/myssm"+newsInfo.getIcon()).into(holder.siv);
            holder.tv_title.setText(newsInfo.getTitle());
            holder.tv_description.setText(newsInfo.getContent());
            switch (newsInfo.getType())
            {
                case "1":
                    holder.tv_type.setText("评论:"+ newsInfo.getType());
                    break;
                case "2":
                    holder.tv_type.setText("专题:"+newsInfo.getType());
                    break;
                case "3":
                    holder.tv_type.setTextColor(Color.BLUE);
                    holder.tv_type.setText("LIVE");
                    break;
                default:
                    break;
            }

            return  convertView;

        }

        @Override
        public  Object getItem(int position)
        {
            return newsInfos.get(position);
        }

        @Override
        public  long getItemId(int positon)
        {
            return  positon;
        }

        class ViewHolder{
            private TextView       tv_title;
            private TextView       tv_description;
            private TextView       tv_type;
            private NewsInfo       newsInfo;
            private ImageView      siv;
        }
    }

}

二、后台

• 框架SSM
• 数据库：mysqol                 
• fileUpload.jsp页面负责上传新闻信息
• FileUploadController 负责文件上传处理和请求响应
• Bean:NewsInfo
• Dao:NewsInfoDao接口负责查询  NewsInfo.xml负责插入
• Service:NewsInfoService接口 NewsInfoServiceImpl服务处理

代码如下：

1.FileUploadController

public String handleFormUpload(@RequestParam("name") String  name,
                               @RequestParam("title") String title,
                               @RequestParam("content") String content,
                               @RequestParam("type") int  type,
                               @RequestParam("comment") int comment,
                               @RequestParam("uploadfile") List<MultipartFile> uploadfile, HttpServletRequest request)
{
   if(!uploadfile.isEmpty() && uploadfile.size() >0)
   {
       String dirpath = request.getServletContext().getRealPath("/images/");
       String newFilename = new String();
      for(MultipartFile  file : uploadfile)
       {
           String originaFileName = file.getOriginalFilename();
           File filepath  = new File(dirpath);
           if(!filepath.exists())
           {
               filepath.mkdirs();
           }
           newFilename = name + "_"+ UUID.randomUUID()+"_"+originaFileName;
           System.out.println(dirpath);
           try {
               file.transferTo(new File(dirpath+newFilename));
           }catch (Exception e)
           {
               e.printStackTrace();
               return "error";
           }
       }

       NewsInfo news = new  NewsInfo();
       news.setNews_title(title);
       news.setNews_type(String.valueOf(type));
       news.setNews_comment(String.valueOf(comment));
       news.setNews_icon_path("/images/" + newFilename);
       news.setNews_content(content);
       newsInfoService.addnews(news);
       return  "success";
   }else {
       return "error";
   }
}

@RequestMapping(value = "/findnews")
@ResponseBody
public  void findnews(HttpServletResponse response)  throws ServletException, IOException
    {
        response.setHeader("Content-Type","text/html;charset=utf-8");
        PrintWriter out = response.getWriter();
        Map map = new HashMap();
        map.put("result","1");
        map.put("msg","执行成功");
        List<NewsInfo> list = newsInfoService.findNews();
        map.put("data",list);
        String json = JSONObject.toJSON(map).toString();
        out.write(json);
        out.close();
    }

2.NewsInfo.xml

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE mapper
        PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN"
        "http://mybatis.org/dtd/mybatis-3-mapper.dtd">
<!-- namespace 表示命名空间  -->
<mapper namespace="com.kangxg.dao.NewsInfoDao">
    <insert id="addnews" parameterType = "NewsInfo" >
        insert into t_newsinfo(
                               news_title,
                               news_icon_path,
                               news_type,
                               news_content,
                               news_comment
               )
               values (
                               #{news_title},
                               #{news_icon_path},
                               #{news_type},
                               #{news_content},
                               #{news_comment}
               )
    </insert>
</mapper>

3.NewsInfoDao

@Select("select * from t_newsinfo")
public List<NewsInfo> findNews();

4.NewsInfoServiceImpl

@Service
@Transactional
public class NewsInfoServiceImpl implements NewsInfoService {
    @Autowired
    private NewsInfoDao newsInfoDao;
    public void addnews(NewsInfo newsInfo){
        newsInfoDao.addnews(newsInfo);
    }
    public List<NewsInfo> findNews()
    {
        return  newsInfoDao.findNews();
    }
}

5. fileUpload.jsp     

<html>
<head>
    <title>文件上传</title>
    <script>
        function  check() {
           var name = document.getElementById("name").value;
           var file = document.getElementById("file".value);
           if(name == "")
           {
               alert("填写上传人")
               return false;
           }
           if(file.length == 0 || file  =="")
           {
               alert("请选择上传文件")
               return false;
           }
           return  false;

        }
    </script>
</head>
<body>
<span>安卓新闻测试文件上传</span>
<form action="${pageContext.request.contextPath}/fileUpload" method="post" enctype="multipart/form-data" οnsubmit="return check()">
    上传人：<input type="text" id = "name" name="name"><br>
    标题：  <input type="text" id = "title" name="title"><br>
    描述：<input type="text" id = "content" name="content"><br>
    类型：<input type="text" id = "type" name="type"><br>
    评论数：<input type="text" id = "comment" name="comment"><br>
    请选择文件：<input type="file" id = "file" name="uploadfile" multiple="multiple"><br/>
    <input type="submit" value="上传">
</form>
<a href="${pageContext.request.contextPath}/download?filename=<%= URLEncoder.encode("背景壁纸.png","UTF-8")%>">
    中文名称文件下载
</a>

<br/>
<a href="${pageContext.request.contextPath}/findnews">
    获取json数据
</a>
</body>
</html>

三、运行结果