即拿即用-HttpURLConnection分别实现图片，文本，文件的请求

xiaoxiao2021-04-15 37

本文使用了HttpURLConnection分别实现图片，文本，文件的网络请求

效果图：

判断读写状态

//获取读写状态 String state = Environment.getExternalStorageState(); //判断读写状态 if (!Environment.MEDIA_MOUNTED.equals(state)) { Toast.makeText(SimpleHttpActivity.this, "无法获取SDCard", Toast.LENGTH_SHORT).show(); return; }

创建路径

//获取目录路径 File directory = new File(Environment.getExternalStoragePublicDirectory(Environment.DIRECTORY_DOWNLOADS) + "/"+"SimpleHttp"); //创建目录路径 if (!directory.exists()) { boolean isSuccess = directory.mkdirs(); Log.e(TAG, "创建文件夹路径是否成功=" + isSuccess); } //创建文件路径（/storage/emulated/0/Download/SimpleHttp/app.apk） File file = new File(directory + "/" + "app.apk"); Log.e(TAG, file.getAbsolutePath());

代码：

SimpleHttpActivity

package com.bourne.httprequest; import android.graphics.Bitmap; import android.graphics.BitmapFactory; import android.os.Environment; import android.os.Handler; import android.os.Message; import android.support.v7.app.AppCompatActivity; import android.os.Bundle; import android.util.Base64; import android.util.Log; import android.view.View; import android.widget.ImageView; import android.widget.TextView; import android.widget.Toast; import java.io.ByteArrayOutputStream; import java.io.File; import java.io.FileOutputStream; import java.io.IOException; import java.io.InputStream; import java.io.OutputStream; import java.net.HttpURLConnection; import java.net.URL; /** * HttpURLConnection分别实现图片，文本，文件的请求 */ public class SimpleHttpActivity extends AppCompatActivity implements View.OnClickListener { private String TAG; private ImageView imageView; private TextView textView; private static final int IMAGE_MSG_NEW_PIC = 2; private static final int IMAGE_MSG_CACHE_PIC = 1; private static final int IMAGE_ERROR = 3; private static final int IMAGE_EXCEPTION = 4; protected static final int TEXT_SUCCESS = 5; protected static final int TEXT_ERROR = 6; protected static final int FILE_SUCCESS = 7; //1.在主线程里面声明消息处理器 handler private Handler handler = new Handler() { //处理消息的 @Override public void handleMessage(Message msg) { switch (msg.what) { case IMAGE_MSG_CACHE_PIC: //3.处理消息运行在主线程 Bitmap bitmap = (Bitmap) msg.obj; imageView.setImageBitmap(bitmap); Toast.makeText(SimpleHttpActivity.this, "使用缓存图", Toast.LENGTH_SHORT).show(); break; case IMAGE_MSG_NEW_PIC: Bitmap bitmap2 = (Bitmap) msg.obj; imageView.setImageBitmap(bitmap2); Toast.makeText(SimpleHttpActivity.this, "下载图片完毕", Toast.LENGTH_SHORT).show(); break; case IMAGE_ERROR: Toast.makeText(SimpleHttpActivity.this, "图片请求失败", Toast.LENGTH_SHORT).show(); break; case IMAGE_EXCEPTION: Toast.makeText(SimpleHttpActivity.this, "图片发生异常，请求失败", Toast.LENGTH_SHORT).show(); break; case TEXT_ERROR: Toast.makeText(SimpleHttpActivity.this, "文本请求失败", Toast.LENGTH_SHORT).show(); break; case TEXT_SUCCESS: String text = (String) msg.obj; textView.setText(text); Toast.makeText(SimpleHttpActivity.this, "文本请求成功", Toast.LENGTH_SHORT).show(); break; case FILE_SUCCESS: Toast.makeText(SimpleHttpActivity.this, "文件下载完毕", Toast.LENGTH_SHORT).show(); break; } super.handleMessage(msg); } }; @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_simple_http); TAG = this.getLocalClassName(); findViewById(R.id.btn_downloadImage).setOnClickListener(this); imageView = (ImageView) findViewById(R.id.imageView); findViewById(R.id.btn_downloadFile).setOnClickListener(this); findViewById(R.id.btn_downloadText).setOnClickListener(this); textView = (TextView) findViewById(R.id.textView); } @Override public void onClick(View view) { switch (view.getId()) { case R.id.btn_downloadImage: downloadBitmap(); break; case R.id.btn_downloadFile: downloadFile(); break; case R.id.btn_downloadText: downloadText(); break; } } /** * 下载文件 */ private void downloadFile() { //请求地址 final String urlStr = "http://downloads.jianshu.io/apps/haruki/JianShu-2.2.3-17040111.apk"; //获取读写状态 String state = Environment.getExternalStorageState(); //判断读写状态 if (!Environment.MEDIA_MOUNTED.equals(state)) { Toast.makeText(SimpleHttpActivity.this, "无法获取SDCard", Toast.LENGTH_SHORT).show(); return; } //开启下载线程 new Thread() { @Override public void run() { //获取目录路径 File directory = new File(Environment.getExternalStoragePublicDirectory(Environment.DIRECTORY_DOWNLOADS) + "/" + "SimpleHttp"); //创建目录路径 if (!directory.exists()) { boolean isSuccess = directory.mkdirs(); Log.e(TAG, "创建文件夹路径是否成功=" + isSuccess); } //创建文件路径（/storage/emulated/0/Download/SimpleHttp/app.apk） File file = new File(directory + "/" + "app.apk"); Log.e(TAG, file.getAbsolutePath()); InputStream input = null; OutputStream output = null; HttpURLConnection connection = null; try { URL url = new URL(urlStr); connection = (HttpURLConnection) url.openConnection(); connection.setDoInput(true); //允许输入流，即允许下载 connection.setDoOutput(true); //允许输出流，即允许上传 connection.setUseCaches(false); //不使用缓冲 connection.setRequestMethod("GET"); //使用get请求 connection.connect(); // expect HTTP 200 OK, so we don't mistakenly save error report // instead of the file if (connection.getResponseCode() != HttpURLConnection.HTTP_OK) { Log.e(TAG, "Server returned HTTP " + connection.getResponseCode() + " " + connection.getResponseMessage()); } // this will be useful to display download percentage // might be -1: server did not report the length int fileLength = connection.getContentLength(); // download the file input = connection.getInputStream(); output = new FileOutputStream(file); byte data[] = new byte[4096]; long total = 0; int count; while ((count = input.read(data)) != -1) { // allow canceling with back button // if (isCancelled()) { // input.close(); // return null; // } total += count; // publishing the progress.... if (fileLength > 0) // only if total length is known Log.e(TAG, "" + (int) (total * 100 / fileLength)); output.write(data, 0, count); } } catch (Exception e) { Log.e(TAG, e.toString()); } finally { try { if (output != null) output.close(); if (input != null) input.close(); Message msg = new Message(); msg.what = FILE_SUCCESS; handler.sendMessage(msg); } catch (IOException ignored) { } if (connection != null) connection.disconnect(); } } }.start(); } /** * 下载图片 */ private void downloadBitmap() { final String path = "http://images.csdn.net/20170413/andr1_meitu_1.jpg"; new Thread() { public void run() { File file = new File(getCacheDir(), Base64.encodeToString( path.getBytes(), Base64.DEFAULT)); if (file.exists() && file.length() > 0) { Log.e(TAG, "图片存在，拿缓存"); Bitmap bitmap = BitmapFactory.decodeFile(file .getAbsolutePath()); Message msg = new Message();//声明消息 msg.what = IMAGE_MSG_CACHE_PIC; msg.obj = bitmap;//设置数据 handler.sendMessage(msg);//让handler帮我们发送数据 } else { Log.e(TAG, "图片不存在，获取数据生成缓存"); // 通过http请求把图片获取下来。 try { // 1.声明访问的路径， url 网络资源 http ftp rtsp URL url = new URL(path); // 2.通过路径得到一个连接 http的连接 HttpURLConnection conn = (HttpURLConnection) url .openConnection(); // 3.判断服务器给我们返回的状态信息。 // 200 成功 302 从定向 404资源没找到 5xx 服务器内部错误 int code = conn.getResponseCode(); if (code == 200) { InputStream is = conn.getInputStream();// png的图片 FileOutputStream fos = new FileOutputStream(file); byte[] buffer = new byte[1024]; int len = -1; while ((len = is.read(buffer)) != -1) { fos.write(buffer, 0, len); } is.close(); fos.close(); Bitmap bitmap = BitmapFactory.decodeFile(file .getAbsolutePath()); //更新ui ，不能写在子线程 Message msg = new Message(); msg.obj = bitmap; msg.what = IMAGE_MSG_NEW_PIC; handler.sendMessage(msg); } else { // 请求失败 //土司更新ui，不能写在子线程 //Toast.makeText(this, "请求失败", 0).show(); Message msg = new Message(); msg.what = IMAGE_ERROR; handler.sendMessage(msg); } } catch (Exception e) { e.printStackTrace(); //土司不能写在子线程 //Toast.makeText(this, "发生异常，请求失败", 0).show(); Message msg = new Message(); msg.what = IMAGE_EXCEPTION; handler.sendMessage(msg); } } } }.start(); } /** * 下载文本 */ private void downloadText() { final String path = "http://blog.csdn.net/iromkoear"; //访问网络，把html源文件下载下来 new Thread() { public void run() { try { URL url = new URL(path); HttpURLConnection conn = (HttpURLConnection) url.openConnection(); conn.setRequestMethod("GET");//声明请求方式默认get //conn.setRequestProperty("User-Agent", "Mozilla/5.0 (Linux; U; Android 2.3.3; zh-cn; sdk Build/GRI34) AppleWebKit/533.1 (KHTML, like Gecko) Version/4.0 Mobile Safari/533.1 MicroMessenger/6.0.0.57_r870003.501 NetType/internet"); int code = conn.getResponseCode(); if (code == 200) { InputStream is = conn.getInputStream(); String result = readStream(is); Message msg = Message.obtain();//减少消息创建的数量 msg.obj = result; msg.what = TEXT_SUCCESS; handler.sendMessage(msg); } } catch (Exception e) { Message msg = Message.obtain();//减少消息创建的数量 msg.what = TEXT_ERROR; handler.sendMessage(msg); e.printStackTrace(); } } ; }.start(); } /** * 把输入流的内容转换成字符串 * * @param is * @return null解析失败， string读取成功 */ public static String readStream(InputStream is) { try { ByteArrayOutputStream baos = new ByteArrayOutputStream(); byte[] buffer = new byte[1024]; int len = -1; while ((len = is.read(buffer)) != -1) { baos.write(buffer, 0, len); } is.close(); String temptext = new String(baos.toByteArray()); if (temptext.contains("charset=gb2312")) {//解析meta标签 return new String(baos.toByteArray(), "gb2312"); } else { return new String(baos.toByteArray(), "utf-8"); } } catch (IOException e) { e.printStackTrace(); return null; } } }

布局文件

<?xml version="1.0" encoding="utf-8"?> <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android" xmlns:app="http://schemas.android.com/apk/res-auto" xmlns:tools="http://schemas.android.com/tools" android:layout_width="match_parent" android:layout_height="match_parent" > <ScrollView android:layout_width="match_parent" android:layout_height="match_parent"> <LinearLayout android:layout_width="match_parent" android:layout_height="match_parent" android:gravity="center_horizontal" android:orientation="vertical"> <Button android:id="@+id/btn_downloadImage" android:layout_width="wrap_content" android:layout_height="wrap_content" android:text="下载图片" /> <ImageView android:id="@+id/imageView" android:layout_width="wrap_content" android:layout_height="wrap_content"/> <Button android:id="@+id/btn_downloadFile" android:layout_width="wrap_content" android:layout_height="wrap_content" android:text="下载文件" /> <Button android:id="@+id/btn_downloadText" android:layout_width="wrap_content" android:layout_height="wrap_content" android:text="下载文字" /> <TextView android:id="@+id/textView" android:layout_width="match_parent" android:layout_height="wrap_content"/> </LinearLayout> </ScrollView> </LinearLayout>

AndroidManifest

<?xml version="1.0" encoding="utf-8"?> <manifest xmlns:android="http://schemas.android.com/apk/res/android" package="com.bourne.httprequest">  <uses-permission android:name="android.permission.INTERNET"/>  <uses-permission android:name="android.permission.MOUNT_UNMOUNT_FILESYSTEMS"/>  <uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE"/>  <uses-permission android:name="android.permission.READ_EXTERNAL_STORAGE"/> <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"> <activity android:name=".MainActivity"> <intent-filter> <action android:name="android.intent.action.MAIN"/> <category android:name="android.intent.category.LAUNCHER"/> </intent-filter> </activity> <activity android:name=".SimpleHttpActivity"> </activity> </application> </manifest>

GitHub链接：https://github.com/mocn26169/HttpRequest-Demo

参考

Android利用Http下载文件

Android Http接地气网络请求（HttpURLConnection）

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