web网络图片查看器Android

 一.web网络图片查看器Android

package com.glsite.netimageviewer;

import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.os.Handler;
import android.os.Message;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.View;
import android.widget.ImageView;
import android.widget.Toast;

import java.io.BufferedReader;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.net.HttpURLConnection;
import java.net.URL;
import java.util.ArrayList;

public class MainActivity extends AppCompatActivity {


    private static final int LOAD_ERROR = 2;
    private static final int LOAD_IMAGE = 1;
    private ImageView mIv;

    private Handler mHandler = new Handler(new Handler.Callback() {
        @Override
        public boolean handleMessage(Message msg) {
            switch (msg.what) {
                case LOAD_IMAGE:
                    Bitmap bitmap = (Bitmap) msg.obj;
                    mIv.setImageBitmap(bitmap);
                    Toast.makeText(MainActivity.this, "加载图片成功", Toast.LENGTH_SHORT).show();
                    break;
                case LOAD_ERROR:
                    System.out.println("LOAD_ERROR");
                    Toast.makeText(MainActivity.this, "加载图片失败", Toast.LENGTH_SHORT).show();
                    break;

                default:
                    break;
            }
            return false;
        }
    });
    private ArrayList<String> mPaths;
    private int currentPosition = 0;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        mIv = findViewById(R.id.iv);
        // 1.连接服务器,获取所有的图片链接信息
        loadAllImagePath();
    }

    /**
     * 获取全部图片资源路径
     */
    private void loadAllImagePath() {
        new Thread() {
            @Override
            public void run() {
                // 浏览器发送一个get请求就可以把服务器的数据获取出来
                // 用代码模拟一个http的get请求

                try {
                    // 1.得到服务器资源的路径
                    URL url = new URL("http://192.168.1.130:8080/Day10/img/gaga.html");// 待会儿要解决一个问题,需要注意https/http以及虚拟机ip的问题 ;创建network_security_config.xml及在AndroidManifest.xml中添加数据才能进行http请求
                    // 2.通过这个路径打开浏览器的链接
                    HttpURLConnection conn = (HttpURLConnection) url.openConnection();
                    // 3.设置请求方式为GET
                    conn.setRequestMethod("GET");// 注意请求方式只能大写,不能小写
                    // 为了有一个更好的用户ui提醒,获取服务器的返回状态码
                    int code = conn.getResponseCode();

                    if (code == 200) {// 返回成功
                        InputStream is = conn.getInputStream();
                        File file = new File(getCacheDir(), "info.txt");
                        FileOutputStream fos = new FileOutputStream(file);

                        int len = 0;
                        byte[] buffer = new byte[1024];
                        while ((len = is.read(buffer)) != -1) {
                            fos.write(buffer, 0, len);
                        }
                        is.close();
                        fos.close();

                        System.out.println("code == 200");
                        // 获取了所有的链接之后,就要去加载图片
                        beginLoadImage();

                    } else if (code == 404) {// 资源未找到
                        Message msg = Message.obtain();
                        msg.what = LOAD_ERROR;
                        msg.obj = "获取html失败,返回码:" + code;
                        mHandler.sendMessage(msg);
                    } else {// 其他响应码
                        Message msg = Message.obtain();
                        msg.what = LOAD_ERROR;
                        msg.obj = "服务器或网络异常,返回码:" + code;
                        mHandler.sendMessage(msg);
                    }

                } catch (Exception e) {
                    e.printStackTrace();
                }

            }
        }.start();
    }

    /**
     * 开始加载图片,在从服务器获取完毕资源路径之后执行
     */
    private void beginLoadImage() {
        try {
            mPaths = new ArrayList<>();
            File file = new File(getCacheDir(), "info.txt");
            FileInputStream fis = new FileInputStream(file);
            BufferedReader br = new BufferedReader(new InputStreamReader(fis));
            String line;
            while ((line = br.readLine()) != null) {
                mPaths.add(line);
            }
            fis.close();

            loadImageByPath(mPaths.get(currentPosition));

        } catch (Exception e) {
            e.printStackTrace();
        }
    }

    /**
     * 通过路径加载图片
     *
     * @param path
     */
    private void loadImageByPath(final String path) {
        new Thread() {
            @Override
            public void run() {
                File file = new File(getCacheDir(), path.replace("/", "") + ".jpg");
                if (file.exists() && file.length() > 0) {// 有缓存
                    System.out.println("通过缓存把图片获取出来...");
                    Message msg = Message.obtain();
                    msg.what = LOAD_IMAGE;
                    msg.obj = BitmapFactory.decodeFile(file.getAbsolutePath());
                    mHandler.sendMessage(msg);
                } else {// 没有缓存的话,就需要去下载
                    System.out.println("通过访问网络把图片资源获取出来");

                    try {
                        URL url = new URL(path);
                        HttpURLConnection conn = (HttpURLConnection) url.openConnection();
                        conn.setRequestMethod("GET");
                        int code = conn.getResponseCode();
                        if (code == 200) {
                            InputStream is = conn.getInputStream();

                            // 内存中的图片
                            Bitmap bitmap = BitmapFactory.decodeStream(is);

                            FileOutputStream fos = new FileOutputStream(file);
                            bitmap.compress(Bitmap.CompressFormat.JPEG, 100, fos);
                            fos.close();
                            is.close();

                            Message msg = Message.obtain();
                            msg.what = LOAD_IMAGE;
                            msg.obj = BitmapFactory.decodeFile(file.getAbsolutePath());
                            mHandler.sendMessage(msg);

                        } else {
                            Message msg = Message.obtain();
                            msg.what = LOAD_ERROR;
                            msg.obj = "获取图片失败,返回码:" + code;
                            mHandler.sendMessage(msg);
                        }

                    } catch (Exception e) {
                        e.printStackTrace();
                        Message msg = Message.obtain();
                        msg.what = LOAD_ERROR;
                        msg.obj = "获取图片失败";
                        mHandler.sendMessage(msg);
                    }
                }
            }
        }.start();
    }

    /**
     * 上一张图片
     *
     * @param view
     */
    public void pre(View view) {
        currentPosition--;
        if (currentPosition < 0) {
            currentPosition = mPaths.size() - 1;
        }
        loadImageByPath(mPaths.get(currentPosition));
    }

    /**
     * 下一张图片
     *
     * @param view
     */
    public void next(View view) {
        currentPosition++;
        if (currentPosition == mPaths.size()) {
            currentPosition = 0;
        }
        loadImageByPath(mPaths.get(currentPosition));
    }
}
<uses-permission android:name="android.permission.INTERNET"/>

注意:

app\src\main\res\xml路径下创建network_security_config.xml

<?xml version="1.0" encoding="utf-8"?>
<network-security-config>
    <base-config cleartextTrafficPermitted="true" />
</network-security-config>

 AndroidManifest.xml 添加数据才能进行http请求

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="com.glsite.netimageviewer">

    <uses-permission android:name="android.permission.INTERNET"/>

    <application
        android:allowBackup="true"
        android:icon="@mipmap/ic_launcher"
        android:label="@string/app_name"
        android:roundIcon="@mipmap/ic_launcher_round"
        android:supportsRtl="true"
        android:theme="@style/AppTheme"
        android:networkSecurityConfig="@xml/network_security_config">
        <activity android:name=".MainActivity">
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />

                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
        </activity>
    </application>

</manifest>

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