从url下载pdf，然后用pdf阅读器打开它 [英] android download pdf from url then open it with a pdf reader
本文介绍了从url下载pdf，然后用pdf阅读器打开它的处理方法，对大家解决问题具有一定的参考价值，需要的朋友们下面随着小编来一起学习吧！
问题描述
我正在尝试编写一个应用程序，从url下载pdf，将其存储在sd上，然后由adobe pdf阅读器或其他可以打开pdf的应用程序打开。
I am trying to write an app to download pdfs from url, store them on sd, then open by adobe pdf reader or other apps which ever able to open the pdf.
直到现在，我已经成功下载并存储在Sd卡（但每次当我尝试用pdf阅读器打开pdf，阅读器崩溃并说出现意外的错误），例如 http://maven.apache.org/maven-1.x/maven.pdf
untill now, i had "successfully downloaded and stored it on Sd card" (but everytime when i try to open the pdf with a pdf reader, reader crash and say unexpected error occurs), for example, http://maven.apache.org/maven-1.x/maven.pdf
这里是我的下载器的代码：
here is the code for my downloader:
//........code set ui stuff
//........code set ui stuff
new DownloadFile().execute(fileUrl, fileName);
private class DownloadFile extends AsyncTask<String, Void, Void>{
@Override
protected Void doInBackground(String... strings) {
String fileUrl = strings[0]; // -> http://maven.apache.org/maven-1.x/maven.pdf
String fileName = strings[1]; // -> maven.pdf
String extStorageDirectory = Environment.getExternalStorageDirectory().toString();
File folder = new File(extStorageDirectory, "testthreepdf");
folder.mkdir();
File pdfFile = new File(folder, fileName);
try{
pdfFile.createNewFile();
}catch (IOException e){
e.printStackTrace();
}
FileDownloader.downloadFile(fileUrl, pdfFile);
return null;
}
}
public class FileDownloader {
private static final int MEGABYTE = 1024 * 1024;
public static void downloadFile(String fileUrl, File directory){
try {
URL url = new URL(fileUrl);
HttpURLConnection urlConnection = (HttpURLConnection)url.openConnection();
urlConnection.setRequestMethod("GET");
urlConnection.setDoOutput(true);
urlConnection.connect();
InputStream inputStream = urlConnection.getInputStream();
FileOutputStream fileOutputStream = new FileOutputStream(directory);
int totalSize = urlConnection.getContentLength();
byte[] buffer = new byte[MEGABYTE];
int bufferLength = 0;
while((bufferLength = inputStream.read(buffer))>0 ){
fileOutputStream.write(buffer, 0, bufferLength);
}
fileOutputStream.close();
} catch (FileNotFoundException e) {
e.printStackTrace();
} catch (MalformedURLException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
}
}
}
在调试模式下，我可以看到应用程序下载它，并将此pdf存储在/storage/sdcard/testpdf/maven.pdf，但是，我猜这个文件可能会在下载过程中损坏，所以它不会正确打开...
in debug mode, i can see the app downloaded it and store this pdf on /storage/sdcard/testpdf/maven.pdf, however, i guess the file may be corrupted somehow during downloading, so it doesnt open up properly...
这里是我打算用其他阅读器应用程序打开代码的代码：
here is the code how i intent to open it with other reader app:
File pdfFile = new File(Environment.getExternalStorageDirectory() + "/testthreepdf/" + fileName); // -> filename = maven.pdf
Uri path = Uri.fromFile(pdfFile);
Intent pdfIntent = new Intent(Intent.ACTION_VIEW);
pdfIntent.setDataAndType(path, "application/pdf");
pdfIntent.setFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP);
try{
startActivity(pdfIntent);
}catch(ActivityNotFoundException e){
Toast.makeText(documentActivity, "No Application available to view PDF", Toast.LENGTH_SHORT).show();
}
推荐答案
您好，FileDownloader中的问题class
Hi the problem is in FileDownloader class
urlConnection.setRequestMethod("GET");
urlConnection.setDoOutput(true);
你需要删除上面的两行，一切都会正常。如果按照预期工作，请将问题标记为已回答。
You need to remove the above two lines and everything will work fine. Please mark the question as answered if it is working as expected.
使用屏幕截图附加工作代码。
Attaching the working code with screenshots.
MainActivity.java
MainActivity.java
package com.example.downloadread;
import java.io.File;
import java.io.IOException;
import android.app.Activity;
import android.content.ActivityNotFoundException;
import android.content.Intent;
import android.net.Uri;
import android.os.AsyncTask;
import android.os.Bundle;
import android.os.Environment;
import android.view.Menu;
import android.view.View;
import android.widget.Toast;
public class MainActivity extends Activity {
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.main, menu);
return true;
}
public void download(View v)
{
new DownloadFile().execute("http://maven.apache.org/maven-1.x/maven.pdf", "maven.pdf");
}
public void view(View v)
{
File pdfFile = new File(Environment.getExternalStorageDirectory() + "/testthreepdf/" + "maven.pdf"); // -> filename = maven.pdf
Uri path = Uri.fromFile(pdfFile);
Intent pdfIntent = new Intent(Intent.ACTION_VIEW);
pdfIntent.setDataAndType(path, "application/pdf");
pdfIntent.setFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP);
try{
startActivity(pdfIntent);
}catch(ActivityNotFoundException e){
Toast.makeText(MainActivity.this, "No Application available to view PDF", Toast.LENGTH_SHORT).show();
}
}
private class DownloadFile extends AsyncTask<String, Void, Void>{
@Override
protected Void doInBackground(String... strings) {
String fileUrl = strings[0]; // -> http://maven.apache.org/maven-1.x/maven.pdf
String fileName = strings[1]; // -> maven.pdf
String extStorageDirectory = Environment.getExternalStorageDirectory().toString();
File folder = new File(extStorageDirectory, "testthreepdf");
folder.mkdir();
File pdfFile = new File(folder, fileName);
try{
pdfFile.createNewFile();
}catch (IOException e){
e.printStackTrace();
}
FileDownloader.downloadFile(fileUrl, pdfFile);
return null;
}
}
}
FileDownloader.java
FileDownloader.java
package com.example.downloadread;
import java.io.File;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.net.HttpURLConnection;
import java.net.MalformedURLException;
import java.net.URL;
public class FileDownloader {
private static final int MEGABYTE = 1024 * 1024;
public static void downloadFile(String fileUrl, File directory){
try {
URL url = new URL(fileUrl);
HttpURLConnection urlConnection = (HttpURLConnection)url.openConnection();
//urlConnection.setRequestMethod("GET");
//urlConnection.setDoOutput(true);
urlConnection.connect();
InputStream inputStream = urlConnection.getInputStream();
FileOutputStream fileOutputStream = new FileOutputStream(directory);
int totalSize = urlConnection.getContentLength();
byte[] buffer = new byte[MEGABYTE];
int bufferLength = 0;
while((bufferLength = inputStream.read(buffer))>0 ){
fileOutputStream.write(buffer, 0, bufferLength);
}
fileOutputStream.close();
} catch (FileNotFoundException e) {
e.printStackTrace();
} catch (MalformedURLException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
}
}
}
AndroidManifest.xml
AndroidManifest.xml
<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="com.example.downloadread"
android:versionCode="1"
android:versionName="1.0" >
<uses-sdk
android:minSdkVersion="14"
android:targetSdkVersion="18" />
<uses-permission android:name="android.permission.INTERNET"></uses-permission>
<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE"></uses-permission>
<uses-permission android:name="android.permission.ACCESS_NETWORK_STATE"></uses-permission>
<uses-permission android:name="android.permission.READ_PHONE_STATE"></uses-permission>
<application
android:allowBackup="true"
android:icon="@drawable/ic_launcher"
android:label="@string/app_name"
android:theme="@style/AppTheme" >
<activity
android:name="com.example.downloadread.MainActivity"
android:label="@string/app_name" >
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
</activity>
</application>
</manifest>
activity_main.xml
activity_main.xml
<RelativeLayout 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:paddingBottom="@dimen/activity_vertical_margin"
android:paddingLeft="@dimen/activity_horizontal_margin"
android:paddingRight="@dimen/activity_horizontal_margin"
android:paddingTop="@dimen/activity_vertical_margin"
tools:context=".MainActivity" >
<Button
android:id="@+id/button1"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_alignParentLeft="true"
android:layout_alignParentTop="true"
android:layout_marginTop="15dp"
android:text="download"
android:onClick="download" />
<Button
android:id="@+id/button2"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_alignParentLeft="true"
android:layout_alignParentRight="true"
android:layout_below="@+id/button1"
android:layout_marginTop="38dp"
android:text="view"
android:onClick="view" />
</RelativeLayout>
这篇关于从url下载pdf，然后用pdf阅读器打开它的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！
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