HttpUrlConnection的应用
一、什么是HttpUrlConnection
HttpUrlConnection是java的标准指定网站发送GET请求、post请求类、ttpUrlConnection继承自URLConnection,可用于向指定网站发送GET请求、post请求，httpUrlConnection在使用上相对简单，并且易于扩展，推荐使用。
二、如何使用HttpUrlCnnection
1.创建URL对象。
2.通过URL对象调用openConnection()方法获得HttpURLConnection对象。
3.HttpURLConnection对象设置其它连接属性。
4.HttpURLConnection对象调用getInputstream()方法下向服务器发送http请求并获取到服务器返回的输入流。
5读取输入流，转换成String字符串。
三、使用HttpUrlConnection获取Http请求
public class MainActivity extends AppCompatActivity {
private Button getwebBtn;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
bindID();
getwebBtn.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
new Thread(new Runnable() {
@Override
public void run() {
getWebInfo();
}
}).start();
}
});
}
private void getWebInfo() {
try {
//找水源，创建URL
URL url=new URL("http://mp.blog.csdn.net/postedit/79528472/");
//开水闸-openConnection
HttpURLConnection httpURLConnection= (HttpURLConnection) url.openConnection();
//建水管-InputStream
InputStream inputStream=httpURLConnection.getInputStream();
//建蓄水池蓄水-InputStreamReader
InputStreamReader reader=new InputStreamReader(inputStream,"UTF-8");
//水桶盛水-BufferedReader
BufferedReader bufferedReader=new BufferedReader(reader);
StringBuffer stringBuffer= new StringBuffer();
String temp=null;
while ((temp=bufferedReader.readLine())!=null){
stringBuffer.append(temp);
}
bufferedReader.close();
reader.close();
inputStream.close();
Log.e("MAIN",stringBuffer.toString());
} catch (MalformedURLException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
}
}
private void bindID() {
getwebBtn=findViewById(R.id.getweb_btn);
}
class MyThread implements Runnable{
@Override
public void run() {
}
}
Xml:
四、使用HttpURLConnection加载网络图片
加载网络图片，需要用到Bitmap对象。
加载网络图片有时也需耗时较长时间，所以也应该异步加载。
ImgActivity代码如下：
package lenovo.wangmengyuan.http;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.ImageView;
import android.widget.ProgressBar;
public class ImgActivity extends AppCompatActivity {
private Button loadbt;
private ImageView loadimg;
private ProgressBar progressBar;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_img);
bindID();
loadbt.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
// ImgloadTask task=new ImgloadTask(loadimg);
// task.execute("http://img5.imgtn.bdimg.com/it/u=717372819,1556613902&fm=27&gp=0.jpg");
loadbt.setEnabled(false);
}
});
}
private void bindID() {
loadbt=findViewById(R.id.loadpig_bt);
loadimg=findViewById(R.id.loadpig_img);
}
}
XML：
ImgLoadTask：
package lenovo.wangmengyuan.http;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.os.AsyncTask;
import android.widget.ImageView;
import java.io.IOException;
import java.io.InputStream;
import java.net.HttpURLConnection;
import java.net.MalformedURLException;
import java.net.URL;
/**
* Created by Administrator on 2018/3/13.
*/
public class ImgloadTask extends AsyncTask {
private ImageView imageView;
//为什么要加一个构造方法-因为我们有传值的需求
public ImgloadTask(ImageView iv){
this.imageView=iv;
}
@Override
protected Bitmap doInBackground(String... strings) {
Bitmap bm=null;
try {
URL url = new URL(strings[0]);
HttpURLConnection connection= (HttpURLConnection) url.openConnection();
InputStream inputStream=connection.getInputStream();
bm= BitmapFactory.decodeStream(inputStream);
} catch (MalformedURLException e) {
e.printStackTrace();
}
catch (IOException e) {
e.printStackTrace();
}
//加载网络图片，最后获取到一个Bitmap对象，返回Bitmap对象
return bm;
}
@Override
protected void onPostExecute(Bitmap s) {
super.onPostExecute(s);
imageView.setImageBitmap(s);
}
}
五、使用HttpURLConnection下载网络资源
ImgActivity.java代码：
package lenovo.wangmengyuan.http;
import android.Manifest;
import android.support.annotation.NonNull;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.ImageView;
import android.widget.ProgressBar;
import com.master.permissionhelper.PermissionHelper;
import java.security.Permission;
public class ImgActivity extends AppCompatActivity {
private Button loadbt;
private ImageView loadimg;
private ProgressBar progressBar;
private String picUrl="http://http://pic3.nipic.com/20090623/2512829_165609054_2.jpg";
private PermissionHelper permissionHelper;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_img);
bindID();
loadbt.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
permissionHelper=new PermissionHelper(ImgActivity.this,new String[]{Manifest.permission.WRITE_EXTERNAL_STORAGE},100);
permissionHelper.request(new PermissionHelper.PermissionCallback() {
@Override
public void onPermissionGranted() {
DownLoad2 task=new DownLoad2(ImgActivity.this,loadimg);
task.execute(picUrl,"ghh.jpg");
}
@Override
public void onIndividualPermissionGranted(String[] grantedPermission) {
}
@Override
public void onPermissionDenied() {
}
@Override
public void onPermissionDeniedBySystem() {
}
});
// new DownLoad2(ImgActivity.this,loadimg).execute(picUrl,"gff.jpg");
}
});
// ImgloadTask task=new ImgloadTask(loadimg);
// task.execute("http://img5.imgtn.bdimg.com/it/u=717372819,1556613902&fm=27&gp=0.jpg");
//loadbt.setEnabled(false);
// DownLoadTask dTask = new DownLoadTask(ImgActivity.this,loadbt,progressBar);
// dTask.execute("http://img1.bitautoimg.com/bitauto/2012/09/17/a50cdcf8-1a2a-418b-b7be-d81f36ab12ee.jpg\",\"fra.jpg");
}
private void bindID() {
loadbt=findViewById(R.id.loadpig_bt);
loadimg=findViewById(R.id.loadpig_img);
}
@Override
public void onRequestPermissionsResult(int requestCode, @NonNull String[] permissions, @NonNull int[] grantResults) {
super.onRequestPermissionsResult(requestCode, permissions, grantResults);
if (permissionHelper!=null){
permissionHelper.onRequestPermissionsResult(requestCode, permissions, grantResults);
}
}
}
DownLoad2代码如下：
public class DownLoad2 extends AsyncTask {
private String dirPath;//下载目录的途径
private String filePath;//文件储存位置，列入
private ImageView loading;
private Context context;
public DownLoad2(Context context,ImageView loading){
this.context=context;
this.loading=loading;
}
InputStream inputStream=null;
OutputStream o =null;
@Override
protected Integer doInBackground(String... strings) {
String fileName=strings[1];//存储图片的名字
//判断目录是否存在，不存在，创建目录
dirPath= Environment.getExternalStorageDirectory() + "/"+"http_download/";
File dir=new File(dirPath);//创建文件对象
if (dir.exists()){
dir.mkdir();
}
//判断文件是否存在，不存在创建
filePath=dirPath+fileName;
File file=new File(filePath);
if (file.exists()){
return -1;
}
else {
try {
file.createNewFile();//不存在创建新的
} catch (IOException e) {
e.printStackTrace();
}
}
InputStream inputStream=null;
FileOutputStream outputStream=null;
URL url= null;
try {
url = new URL(strings[0]);
} catch (MalformedURLException e) {
e.printStackTrace();
}
try {
HttpURLConnection connection= (HttpURLConnection) url.openConnection();
if (connection.getResponseCode()==200){
//判断返回码是否正常，若
inputStream=connection.getInputStream();
}
else {
return -2;
}
outputStream=new FileOutputStream(file);
int length=0;
byte[] buffer=new byte[4*1024];
while ((length=inputStream.read(buffer))!=-1){
outputStream.write(buffer,0,length);
}
outputStream.close();
inputStream.close();
} catch (IOException e) {
e.printStackTrace();
}
return 1;
}
@Override
protected void onPostExecute(Integer integer) {
super.onPostExecute(integer);
switch (integer){
case 1:
//正常下载完成
Toast.makeText(context,"下载完成",Toast.LENGTH_SHORT).show();
Bitmap bm= BitmapFactory.decodeFile(filePath);
loading.setImageBitmap(bm);
break;
case -1:
//文件已存在
Toast.makeText(context,"文件已存在",Toast.LENGTH_SHORT).show();
break;
case -2:
//网络异常
Toast.makeText(context,"网络异常",Toast.LENGTH_SHORT).show();
break;
}
}
外加文件读取权限以及网络请求权限：
posted @
2019-01-21 09:54 journeyIT 阅读(
...) 评论(
...) 编辑 收藏