查看网络图片

一、任务描述

 输入网络图片的地址，点击浏览按钮可以显示网络中的图片。

二、案例实现

第一种方法：使用HttpURLConnection来实现网络图片浏览

布局文件activity_main.xml

<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="1" />    <EditText        android:id="@+id/et_path"        android:layout_width="fill_parent"        android:layout_height="wrap_content"        android:hint="请输入图片路径"        android:text="http://img5.duitang.com/uploads/item/201509/19/20150919183750_Vwaju.jpeg"        android:maxLines="1" />    <Button        android:layout_width="fill_parent"        android:layout_height="wrap_content"        android:onClick="click"        android:text="浏览" /></LinearLayout>}

编写页面交互界面

package cn.edu.bzu.imageviewdemo;import android.graphics.Bitmap;import android.graphics.BitmapFactory;import android.os.Bundle;import android.os.Handler;import android.os.Message;import android.support.v7.app.AppCompatActivity;import android.text.TextUtils;import android.view.View;import android.widget.EditText;import android.widget.ImageView;import android.widget.Toast;import java.io.InputStream;import java.net.HttpURLConnection;import java.net.URL;public class MainActivity extends AppCompatActivity {    protected static final int CHANGE_UI = 1;    protected static final int ERROR = 2;    private EditText et_path;    private ImageView iv;    // 主线程创建消息处理器    private Handler handler = new Handler(){        public void handleMessage(android.os.Message msg) {            if(msg.what == CHANGE_UI){                Bitmap bitmap = (Bitmap) msg.obj;                iv.setImageBitmap(bitmap);            }else if(msg.what == ERROR){                Toast.makeText(MainActivity.this, "显示图片错误", 0).show();            }        };    };    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) {        final String path = et_path.getText().toString().trim();        if (TextUtils.isEmpty(path)) {            Toast.makeText(this, "图片路径不能为空", Toast.LENGTH_SHORT).show();        } else {            //子线程请求网络,Android4.0以后访问网络不能放在主线程中            new Thread() {                public void run() {                    // 连接服务器 get 请求 获取图片.                    try {                        URL url = new URL(path);       //创建URL对象                        // 根据url 发送 http的请求.                        HttpURLConnection conn = (HttpURLConnection) url                                .openConnection();                        // 设置请求的方式                        conn.setRequestMethod("GET");                        //设置超时时间                        conn.setConnectTimeout(5000);                        // 得到服务器返回的响应码                        int code = conn.getResponseCode();                        //请求网络成功后返回码是200                        if (code == 200) {                            //获取输入流                            InputStream is = conn.getInputStream();                            //将流转换成Bitmap对象                            Bitmap bitmap = BitmapFactory.decodeStream(is);                            //iv.setImageBitmap(bitmap);                            //TODO: 告诉主线程一个消息:帮我更改界面。内容:bitmap                            Message msg = new Message();                            msg.what = CHANGE_UI;                            msg.obj = bitmap;                            handler.sendMessage(msg);                        } else {                            //返回码不是200  请求服务器失败                            Message msg = new Message();                            msg.what = ERROR;                            handler.sendMessage(msg);                        }                    } catch (Exception e) {                        e.printStackTrace();                        Message msg = new Message();                        msg.what = ERROR;                        handler.sendMessage(msg);                    }                };            }.start();        }    }

第二种方法：使用SmartImageView重新实现网络图片的加载

布局文件activity_main.xml

<?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:orientation="vertical"    tools:context="com.example.bz0209.myapplication.MainActivity">    <com.loopj.android.image.SmartImageView        android:layout_weight="1000"        android:layout_width="match_parent"        android:layout_height="match_parent"        android:id="@+id/siv" />    <EditText        android:id="@+id/et_path"        android:layout_width="fill_parent"        android:layout_height="wrap_content"        android:hint="请输入图片路径"        android:text="http://img5.duitang.com/uploads/item/201509/19/20150919183750_Vwaju.jpeg"        android:maxLines="1" />    <Button        android:layout_width="fill_parent"        android:layout_height="wrap_content"        android:onClick="click"        android:text="浏览" /></LinearLayout>

2、编写页面交互界面

package com.example.bz0209.myapplication;import android.support.v7.app.AppCompatActivity;import android.os.Bundle;import android.view.View;import android.widget.EditText;import android.widget.ImageView;import com.loopj.android.image.SmartImageView;public class MainActivity extends AppCompatActivity {     private EditText et_path;    private SmartImageView siv;    @Override    protected void onCreate(Bundle savedInstanceState) {        super.onCreate(savedInstanceState);        setContentView(R.layout.activity_main);        et_path=(EditText) findViewById(R.id.et_path);    }    public void click(View view){        siv=(SmartImageView) findViewById(R.id.siv);        siv.setImageUrl(et_path.getText().toString().trim(),R.drawable.cute,R.drawable.edu);    }}

注意：两种方法的最后都要在清单配置文件中加相应的权限

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

三、最终结果

编写页面交互界面