Android實現新聞瀏覽功能
阿新 • • 發佈:2019-01-29
*要求:通過一個案例“新聞客戶端”向大家演示AsyncHttpClient和
SmartImageView的綜合使用。*
1:相關知識
市面上一些常見軟體,例如手機QQ、天貓、京東商場等,都載入了大量網路上的圖片。用Android自帶的API實現這一功能十分麻煩而且耗時。為此,程式設計愛好者開發了一個開源專案——SmartImageView。
– 開源專案SmartImageView的出現主要是為了加速從網路上載入圖片,它繼承自ImageView類,支援根據URL地址載入圖片、支援非同步載入圖片、支援圖片快取等。
2:設計佈局檔案
(1)主介面設計構造
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:id="@+id/activity_main"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:paddingBottom="@dimen/activity_vertical_margin"
android:paddingLeft ="@dimen/activity_horizontal_margin"
android:paddingRight="@dimen/activity_horizontal_margin"
android:paddingTop="@dimen/activity_vertical_margin"
tools:context="com.example.administrator.newsshow.MainActivity">
` <FrameLayout
android:layout_width="match_parent"
android:layout_height ="match_parent">
<LinearLayout
android:layout_width="match_parent"
android:layout_height="match_parent"
android:id="@+id/loading"
android:visibility="invisible"
android:layout_gravity="center"
android:orientation="vertical"
>
<ProgressBar
android:layout_width="wrap_content"
android:layout_height="match_parent" />
<TextView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="正在載入資訊.......!" />
</LinearLayout>
<ListView
android:layout_width="match_parent"
android:layout_height="match_parent"
android:id="@+id/lv_news"></ListView>
</FrameLayout>
</LinearLayout>
如下圖所示:
(2)ListView控制元件子佈局 news_item.xml檔案
<?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="65dip">
<com.loopj.android.image.SmartImageView
android:id="@+id/siv_icon"
android:layout_width="80dp"
android:layout_height="60dp"
android:scaleType="centerCrop"
android:src="@mipmap/ic_launcher"
android:layout_alignParentLeft="true"
android:layout_alignParentStart="true"></com.loopj.android.image.SmartImageView>
<TextView
android:id="@+id/tv_title"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginLeft="5dp"
android:layout_marginTop="10dp"
android:layout_toRightOf="@id/siv_icon"
android:ellipsize="end"
android:maxLength="20"
android:singleLine="true"
android:text="我是標題"
android:textColor="#000000"
android:textSize="18sp" />
<TextView
android:id="@+id/tv_description"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_below="@id/tv_title"
android:layout_marginLeft="5dp"
android:layout_marginTop="5dp"
android:layout_toRightOf="@id/siv_icon"
android:ellipsize="end"
android:maxLength="16"
android:maxLines="1"
android:text="我是描述"
android:textColor="#99000000"
android:textSize="14sp" />
<TextView
android:id="@+id/tv_type"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignParentBottom="true"
android:layout_alignParentRight="true"
android:layout_marginBottom="5dp"
android:layout_marginRight="10dp"
android:text="評論"
android:textColor="#99000000"
android:textSize="12sp" />
</RelativeLayout>
3:建立JSON檔案,實現一個線上編輯器
[
{
"icon": "http://192.168.1.109:8080/images/a.jpg",
"title": "科技溫暖世界",
"content": "進入一個更有愛的領域",
"type": "1",
"comment": "69"
},
{
"icon": "http://192.168.1.109:8080/images/b.jpg",
"title": "《神武》",
"content": "新美術資源盤點,視覺新體驗",
"type": "2",
"comment": "35"
},
{
"icon": "http://192.168.1.109:8080/images/c.jpg",
"title": "南北車正式公佈合併",
"content": "南北車將於今日正式公佈合併",
"type": "3",
"comment": "2"
},
{
"icon": "http://192.168.1.109:8080/images/d.jpg",
"title": "萌呆了!汪星人抱玩偶酣睡",
"content": "汪星人抱玩偶酣睡,萌翻網友",
"type": "1",
"comment": "25"
},
{
"icon": "http://192.168.1.109:8080/images/e.jpg",
"title": "風力發電進校園",
"content": "風力發電普進校園",
"type": "2",
"comment": "26"
},
{
"icon": "http://192.168.1.109:8080/images/f.jpg",
"title": "地球一小時",
"content": "地球熄燈一小時",
"type": "1",
"comment": "23"
},
{
"icon": "http://192.168.1.109:8080/images/g.jpg",
"title": "最美公路",
"content": "最美公路,難以想象",
"type": "1",
"comment": "23"
}
]
4:建立實體類
package com.example.administrator.newsshow.entity;
/**
* Created by Administrator on 2017/5/18.
*/
public class NewsInfo {
private String iconPath;
private String title;
private String description;
private int type;
private long comment;
public String getTitle() {
return title;
}
public void setTitle(String title) {
this.title = title;
}
public String getIconPath() {
return iconPath;
}
public void setIconPath(String iconPath) {
this.iconPath = iconPath;
}
public String getDescription() {
return description;
}
public void setDescription(String description) {
this.description = description;
}
public int getType() {
return type;
}
public void setType(int type) {
this.type = type;
}
public long getComment() {
return comment;
}
public void setComment(long comment) {
this.comment = comment;
}
}
5:Tools包下建立工具類JsonParse負責解析JSON資料
public class JsonParse {
public static List<NewsInfo> getNewsInfo(String json){
Gson gson =new Gson();
Type listType=new TypeToken<NewsInfo>(){
}.getType();
List<NewsInfo> newsInfos=gson.fromJson(json,listType);
return newsInfos;
}
}
6:建立介面卡
adapter包下建立NewsAdapter類
package com.example.administrator.newsshow.adapter;
import android.content.Context;
import android.view.View;
import android.view.ViewGroup;
import android.widget.ArrayAdapter;
import android.widget.TextView;
import com.example.administrator.newsshow.R;
import com.example.administrator.newsshow.entity.NewsInfo;
import com.loopj.android.image.SmartImageView;
import java.util.List;
/**
* Created by Administrator on 2017/5/18.
*/
public class NewsAdapter extends ArrayAdapter<NewsInfo>{
public NewsAdapter (Context context, List<NewsInfo>objects){
super(context, R.layout.item,objects);
}
public View getView (int position, View convertView , ViewGroup parent){
NewsInfo newsInfo =getItem(position);
ViewHolder viewHolder;
View view=null;
if(convertView==null){
view=View.inflate(getContext(),R.layout.item,null);
viewHolder=new ViewHolder();
viewHolder.siv=(SmartImageView)view.findViewById(R.id.siv_icon);
viewHolder.tv_title=(TextView)view.findViewById(R.id.tv_title);
viewHolder.tv_description=(TextView)view.findViewById(R.id.tv_description);
viewHolder.tv_type=(TextView)view.findViewById(R.id.tv_type);
view.setTag(viewHolder);
}else {
view =convertView;
viewHolder=(ViewHolder)view.getTag();
}
viewHolder.siv.setImageUrl(newsInfo.getIconPath());
viewHolder.tv_title.setText(newsInfo.getTitle());
viewHolder.tv_description.setText(newsInfo.getDescription());
viewHolder.tv_type.setText(newsInfo.getType()+"");
return view;
}
class ViewHolder{
SmartImageView siv;
TextView tv_title;
TextView tv_description;
TextView tv_type;
}
}
7:編寫介面互動程式碼
介面邏輯程式碼的設計與實現:
package com.example.administrator.newsshow;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.View;
import android.view.ViewGroup;
import android.widget.BaseAdapter;
import android.widget.LinearLayout;
import android.widget.ListView;
import android.widget.TextView;
import android.widget.Toast;
import com.example.administrator.newsshow.Tools.JsonParse;
import com.example.administrator.newsshow.adapter.NewsAdapter;
import com.example.administrator.newsshow.entity.NewsInfo;
import com.loopj.android.http.AsyncHttpClient;
import com.loopj.android.http.AsyncHttpResponseHandler;
import com.loopj.android.image.SmartImageView;
import java.io.UnsupportedEncodingException;
import java.util.List;
import static com.example.administrator.newsshow.R.id.tv_title;
public class MainActivity extends AppCompatActivity {
private ListView lv_news;
private LinearLayout loading;
private List<NewsInfo> newsInfos;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
lv_news= (ListView) findViewById(R.id.lv_news);
loading= (LinearLayout) findViewById(R.id.loading);
StartExecute();
}
private void StartExecute(){
System.out.println(">>>>>>>>>>>>>執行了");
AsyncHttpClient asynchttpClient =new AsyncHttpClient();
asynchttpClient.get("http://10.2.7.239:8080/NewsInfo.json",new AsyncHttpResponseHandler() {
@Override
public void onSuccess(int i, org.apache.http.Header[] headers, byte[] bytes) {
try {
String json = new String(bytes, "utf-8");
List<NewsInfo> newsInfos = JsonParse.getNewsInfo(json);
if (newsInfos == null) {
Toast.makeText(MainActivity.this, "解析失敗!", Toast.LENGTH_SHORT).show();
} else {
Toast.makeText(MainActivity.this, "獲取成功!", Toast.LENGTH_SHORT).show();
loading.setVisibility(View.INVISIBLE);
lv_news.setAdapter(new NewsAdapter(MainActivity.this, newsInfos));
}
} catch (UnsupportedEncodingException e) {
e.printStackTrace();
}
}
public void onFailure(int i, org.apache.http.Header[] headers, byte[] bytes, Throwable throwable) {
System.out.println(">>>>>>>>>獲取失敗!");
}
});
}
}
8:執行結果示意圖如下顯示