1.编写页面布局代码：
<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://b.hiphotos.baidu.com/image/w=310/sign=a439f5b24510b912bfc1f0fff3fdfcb5/83025aafa40f4bfb92c52c5d014f78f0f73618a5.jpg" android:maxLines="1" /> <Button android:layout_width="fill_parent" android:layout_height="wrap_content" android:onClick="click" android:text="浏览" /> </LinearLayout>
2.编写页面交互代码：
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(); } } }
3.在清单文件下添加如下代码：
<uses-permission android:name="android.permission.INTERNET"></uses-permission>
