一个简单展示图片的项目

参考：http://blog.csdn.net/zpj779878443/article/category/6351593

1. 建立界面，一个imageView，两个button

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context="com.example.bbw.gallery.MainActivity">

    <ImageView
        android:id="@+id/image_show"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_centerInParent="true"
        />

    <LinearLayout
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_below="@id/image_show">

        <Button
            android:id="@+id/change"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="换一批" />

        <Button
            android:id="@+id/next"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="下一个" />
    </LinearLayout>

</RelativeLayout>

原型.png

2. 加载图片

package com.example.bbw.gallery.loader;

import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.graphics.drawable.BitmapDrawable;
import android.graphics.drawable.Drawable;
import android.os.Handler;
import android.os.Message;
import android.widget.ImageView;

import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.net.HttpURLConnection;
import java.net.MalformedURLException;
import java.net.URL;

/**
 * Created by bbw on 2017/7/17.
 * 加载图片
 */

public class PictureLoader {

    private ImageView imageView;
    private String imgUrl;
    private byte[] picByte;

    Handler handler = new Handler(){

        @Override
        public void handleMessage(Message msg) {
            super.handleMessage(msg);
            if (msg.what == 0x123){
                if (picByte != null){
                    Bitmap bitmap = BitmapFactory.decodeByteArray(picByte,0,picByte.length);//将字节数组解码成bitmap
                    imageView.setImageBitmap(bitmap);
                }
            }
        }
    };

    public void load(ImageView imageView,String imgUrl){

        this.imageView = imageView;
        this.imgUrl = imgUrl;
        Drawable drawable = imageView.getDrawable();
        if (drawable != null && drawable instanceof BitmapDrawable){
            Bitmap bitmap = ((BitmapDrawable) drawable).getBitmap();
            if (bitmap != null && !bitmap.isRecycled()){
                bitmap.recycle();//回收图片所占的内存
            }
        }
        new Thread(runnable).start();
    }

    Runnable runnable = new Runnable() {
        @Override
        public void run() {
            try {
                URL url = new URL(imgUrl);
                HttpURLConnection connection = (HttpURLConnection) url.openConnection();
                connection.setRequestMethod("GET");
                connection.setReadTimeout(8000);
                if (connection.getResponseCode() == 200){
                    InputStream in = connection.getInputStream();//获得输入流
                    ByteArrayOutputStream out = new ByteArrayOutputStream();
                    byte[] bytes = new byte[1024];
                    int length = -1;
                    while((length = in.read(bytes)) !=-1){
                        out.write(bytes,0,length);//以字节的方式写出
                    }
                    picByte = out.toByteArray();
                    in.close();
                    out.close();
                    handler.sendEmptyMessage(0x123);
                }
            } catch (MalformedURLException e) {
                e.printStackTrace();
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
    };
}

3. 网络请求处理相关的类

package com.example.bbw.gallery.network;

import android.util.Log;

import com.example.bbw.gallery.entity.Sister;

import org.json.JSONArray;
import org.json.JSONObject;

import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.net.HttpURLConnection;
import java.net.URL;
import java.util.ArrayList;

/**
 * Created by bbw on 2017/7/17.
 * 网络请求处理相关类
 */

public class Api {

    private static final String TAG = "Network";
    private static final String BASE_URL = "http://gank.io/api/data/福利/";

    //查询信息
    public ArrayList<Sister> fetchSister(int count, int page){
        String fetchUrl = BASE_URL+ count + "/" + page;
        ArrayList<Sister> sisters = new ArrayList<>();
        try {
            URL url = new URL(fetchUrl);
            HttpURLConnection connection = (HttpURLConnection) url.openConnection();
            connection.setReadTimeout(5000);
            connection.setRequestMethod("GET");
            int code = connection.getResponseCode();
            Log.d(TAG,"Server response" + code);//测试成功
            if (code == 200){
                InputStream in = connection.getInputStream();
                byte[] data = readFromStream(in);//将读取的数据以字节流的方式存储
                String result = new String(data,"UTF-8");
                sisters = parseSister(result);//得到解析后的sister
            }else{
                Log.d(TAG,"请求失败" + code);
            }
        } catch (Exception e) {
            e.printStackTrace();
        }
        return sisters;
    }

    //解析返回的json数据的方法
    private ArrayList<Sister> parseSister(String result) throws Exception {

        ArrayList<Sister> sisters = new ArrayList<>();
        JSONObject object = new JSONObject(result);
        JSONArray array = object.getJSONArray("results");
        for (int i=0;i<array.length();i++){
            JSONObject results = (JSONObject) array.get(i);
            Sister  sister = new Sister();
            sister.set_id(results.getString("_id"));
            sister.setCreateAt(results.getString("createdAt"));
            sister.setDesc(results.getString("desc"));
            sister.setPublishedAt(results.getString("publishedAt"));
            sister.setSource(results.getString("source"));
            sister.setType(results.getString("type"));
            sister.setUrl(results.getString("url"));
            sister.setUsed(results.getBoolean("used"));
            sister.setWho(results.getString("who"));
            sisters.add(sister);
        }
        return sisters;
    }

    //读取流中数据的方法
    private byte[] readFromStream(InputStream in) throws IOException {
        ByteArrayOutputStream outStream = new ByteArrayOutputStream();
        byte[] buffer = new byte[1024];
        int len;
        while((len = in.read(buffer)) != -1){
            outStream.write(buffer,0,len);
        }
        in.close();
        return outStream.toByteArray();
    }
}

4. bean

package com.example.bbw.gallery.entity;

/**
 * Created by bbw on 2017/7/17.
 * Bean
 */

public class Sister {

    private String _id;
    private String createAt;
    private String desc;
    private String publishedAt;
    private String source;
    private String type;
    private String url;
    private boolean used;
    private String who;

    public String get_id() {
        return _id;
    }

    public void set_id(String _id) {
        this._id = _id;
    }

    public String getCreateAt() {
        return createAt;
    }

    public void setCreateAt(String createAt) {
        this.createAt = createAt;
    }

    public String getDesc() {
        return desc;
    }

    public void setDesc(String desc) {
        this.desc = desc;
    }

    public String getPublishedAt() {
        return publishedAt;
    }

    public void setPublishedAt(String publishedAt) {
        this.publishedAt = publishedAt;
    }

    public String getSource() {
        return source;
    }

    public void setSource(String source) {
        this.source = source;
    }

    public String getType() {
        return type;
    }

    public void setType(String type) {
        this.type = type;
    }

    public String getUrl() {
        return url;
    }

    public void setUrl(String url) {
        this.url = url;
    }

    public boolean isUsed() {
        return used;
    }

    public void setUsed(boolean used) {
        this.used = used;
    }

    public String getWho() {
        return who;
    }

    public void setWho(String who) {
        this.who = who;
    }
}