Android开发入门之网络通信(网络图片查看器)

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第一步:新建一个Android工程命名为netimage目录结构如下图:

第二步:修改activity_main.xml布局文件代码如下:

<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" ><TextViewandroid:layout_width="wrap_content"android:layout_height="wrap_content"android:text="@string/imagepath" /><EditTextandroid:id="@+id/et_imagepath"android:layout_width="match_parent"android:layout_height="wrap_content"android:text="@string/path" /><Buttonandroid:id="@+id/btn_view"android:layout_width="wrap_content"android:layout_height="wrap_content"android:text="@string/view" /><ImageViewandroid:id="@+id/iv"android:layout_width="wrap_content"android:layout_height="wrap_content" android:layout_gravity="center"/></LinearLayout>

strings.xml:

<?xml version="1.0" encoding="utf-8"?>
<resources><string name="app_name">网络图片查看器</string><string name="action_settings">Settings</string><string name="hello_world">Hello world!</string><string name="imagepath">网络图片路径</string><string name="view">查看</string><string name="success">获取图片成功！</string><string name="fail">获取图片失败！</string><string name="path">http://p1.qhimg.com/d/_onebox/search.png</string></resources>

第三步：编写MianActivity类：

package cn.leigo.netimage;import java.io.IOException;import cn.leigo.service.ImageService;
import android.app.Activity;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.os.Bundle;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.EditText;
import android.widget.ImageView;
import android.widget.Toast;public class MainActivity extends Activity implements OnClickListener {private EditText mImagePathEditText;private Button mViewButton;private ImageView mImageView;@Overrideprotected void onCreate(Bundle savedInstanceState) {super.onCreate(savedInstanceState);setContentView(R.layout.activity_main);mImagePathEditText = (EditText) findViewById(R.id.et_imagepath);mViewButton = (Button) findViewById(R.id.btn_view);mImageView = (ImageView) findViewById(R.id.iv);mViewButton.setOnClickListener(this);}@Overridepublic void onClick(View v) {String imagePath = mImagePathEditText.getText().toString();byte[] data;try {data = ImageService.getImage(imagePath);Bitmap bitmap = BitmapFactory.decodeByteArray(data, 0, data.length);mImageView.setImageBitmap(bitmap); // 显示图片Toast.makeText(this, R.string.success, Toast.LENGTH_SHORT).show();} catch (IOException e) {e.printStackTrace();Toast.makeText(this, R.string.fail, Toast.LENGTH_SHORT).show();}}}

业务类ImageService:

package cn.leigo.service;import java.io.IOException;
import java.io.InputStream;
import java.net.HttpURLConnection;
import java.net.URL;import cn.leigo.utils.StreamTool;public class ImageService {/*** 获取网络图片的数据* * @param imagePath*            网络图片路径* @return* @throws IOException*/public static byte[] getImage(String imagePath) throws IOException {byte[] data = null;URL url = new URL(imagePath);HttpURLConnection conn = (HttpURLConnection) url.openConnection(); // 基于HTTP协议链接对象conn.setConnectTimeout(5000);conn.setRequestMethod("GET");if (conn.getResponseCode() == HttpURLConnection.HTTP_OK) {InputStream inputStream = conn.getInputStream();data = StreamTool.read(inputStream);}return data;}}

工具类StreamTool：

package cn.leigo.utils;import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.io.InputStream;public class StreamTool {/*** 读取流中的数据* * @param inputStream* @return* @throws IOException*/public static byte[] read(InputStream inputStream) throws IOException {ByteArrayOutputStream baos = new ByteArrayOutputStream();byte[] buffer = new byte[1024];int len = 0;while ((len = inputStream.read(buffer)) != -1) {baos.write(buffer, 0, len);}inputStream.close();return baos.toByteArray();}}

最后别忘了在AndroidManifest.xml文件中添加权限：

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

运行上述工程查看效果图:

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