Android 网络图片查看器

今天来实现一下android下的一款简单的网络图片查看器

界面如下：

代码如下：

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical"
    tools:context=".MainActivity" >

    <ImageView
        android:id="@+id/iv"
        android:layout_width="fill_parent"
        android:layout_height="fill_parent"
        android:layout_weight="1000" />

    <EditText
        android:singleLine="true"
        android:text="http://img01.sogoucdn.com/app/a/100540002/1047586.jpg"
        android:id="@+id/et_path"
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:hint="请输入图片路径" />

    <Button
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:onClick="click"
        android:text="浏览" />
</LinearLayout>

代码如下：

package com.wuyudong.imagesviewer;

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

import org.apache.http.HttpConnection;

import android.os.Bundle;
import android.app.Activity;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.text.TextUtils;
import android.view.Menu;
import android.view.View;
import android.widget.EditText;
import android.widget.ImageView;
import android.widget.Toast;

public class MainActivity extends Activity {

    private EditText et_path;
    private ImageView iv;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        et_path = (EditText) findViewById(R.id.et_path);
        iv = (ImageView) findViewById(R.id.iv);
    }

    public void click(View view) {

        String path = et_path.getText().toString().trim();
        if (TextUtils.isEmpty(path)) {
            Toast.makeText(this, "图片路径不能为空", 0).show();
        } else {
            // 连接服务器get请求获取图片
            try {
                URL url = new URL(path);

                // 根据url发送http的请求
                HttpURLConnection conn = (HttpURLConnection) url
                        .openConnection();
                // 设置请求的方式
                conn.setRequestMethod("GET");
                conn.setConnectTimeout(5000);
                conn.setReadTimeout(5000);
                conn.setRequestProperty(
                        "User-Agent",
                        "Mozilla/5.0 (Windows NT 6.1; WOW64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/45.0.2454.101 Safari/537.36");
                int code = conn.getResponseCode();
                if (code == 200) {
                    InputStream is = conn.getInputStream();
                    Bitmap bitmap = BitmapFactory.decodeStream(is);
                    iv.setImageBitmap(bitmap);
                } else {
                    Toast.makeText(this, "显示图片失败", 0).show();
                }

            } catch (Exception e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
                Toast.makeText(this, "访问获取图片失败", 0).show();
            }
        }

    }

}

添加权限：android.permission.INTERNET

运行后报错：android.os.NetworkOnMainThreadException

解释一下，从Honeycomb SDK（3.0）开始，google不再允许网络请求（HTTP、Socket）等相关操作直接在Main Thread类中，其实本来就不应该这样做，直接在UI线程进行网络操作，会阻塞UI、用户体验相当差！

所以，在Honeycomb SDK（3.0）以下的版本，你还可以继续在Main Thread里这样做，在3.0以上，就不行了

具体解决办法见后文