搜索出现在Android设备中的所有.pdf文件

尝试使用下面的代码，这将适用于你。

public void walkdir(File dir) { 
    String pdfPattern = ".pdf"; 
    File listFile[] = dir.listFiles(); 
    if (listFile != null) { 
     for (int i = 0; i < listFile.length; i++) { 
      if (listFile[i].isDirectory()) { 
       walkdir(listFile[i]); 
      } else { 
       if (listFile[i].getName().endsWith(pdfPattern)){ 
            //Do what ever u want 
       } 
      } 
     } 
    }  
} 

编辑

要在整个SD卡的呼叫搜索使用

walkdir(Environment.getExternalStorageDirectory()); 

看一看here

Basicly获得起始目录，然后调用这个函数 “清单”用过滤器（FilenameFilter）然后遍历子目录。不知道是否有一个功能可以完成这一切。

看一看Here

文件一样，如果你希望所有的PDF文件，然后扩展名为“.PDF”用这个来得到设备的所有PDF文件的变更延期。

下载源代码从这里（Open pdf file from sdcard in android programmatically）

在摇篮文件中添加此相关性：

compile ‘com.github.barteksc:android-pdf-viewer:2.0.3’ 

MainActivity.java：

package com.pdffilefromsdcard; 
import android.Manifest; 
import android.app.ProgressDialog; 
import android.content.Intent; 
import android.content.pm.PackageManager; 
import android.os.Environment; 
import android.support.v4.app.ActivityCompat; 
import android.support.v4.content.ContextCompat; 
import android.support.v7.app.AppCompatActivity; 
import android.os.Bundle; 
import android.util.Log; 
import android.view.View; 
import android.widget.AdapterView; 
import android.widget.ListView; 
import android.widget.Toast; 
import java.io.File; 
import java.util.ArrayList; 
import java.util.HashMap; 
import java.util.List; 
public class MainActivity extends AppCompatActivity { 
ListView lv_pdf; 
public static ArrayList<File> fileList = new ArrayList<File>(); 
PDFAdapter obj_adapter; 
public static int REQUEST_PERMISSIONS = 1; 
boolean boolean_permission; 
File dir; 
@Override 
protected void onCreate(Bundle savedInstanceState) { 
super.onCreate(savedInstanceState); 
setContentView(R.layout.activity_main); 
init(); 
} 
private void init() { 
lv_pdf = (ListView) findViewById(R.id.lv_pdf); 
dir = new File(Environment.getExternalStorageDirectory().getAbsolutePath()); 
fn_permission(); 
lv_pdf.setOnItemClickListener(new AdapterView.OnItemClickListener() { 
@Override 
public void onItemClick(AdapterView<?> adapterView, View view, int i, long l) { 
Intent intent = new Intent(getApplicationContext(), PdfActivity.class); 
intent.putExtra(“position”, i); 
startActivity(intent); 
Log.e(“Position”, i + “”); 
} 
}); 
} 
public ArrayList<File> getfile(File dir) { 
File listFile[] = dir.listFiles(); 
if (listFile != null && listFile.length > 0) { 
for (int i = 0; i < listFile.length; i++) { 
if (listFile[i].isDirectory()) { 
getfile(listFile[i]); 
} else { 
boolean booleanpdf = false; 
if (listFile[i].getName().endsWith(“.pdf”)) { 
for (int j = 0; j < fileList.size(); j++) { 
if (fileList.get(j).getName().equals(listFile[i].getName())) { 
booleanpdf = true; 
} else { 
} 
} 
if (booleanpdf) { 
booleanpdf = false; 
} else { 
fileList.add(listFile[i]); 
} 
} 
} 
} 
} 
return fileList; 
} 
private void fn_permission() { 
if ((ContextCompat.checkSelfPermission(getApplicationContext(), Manifest.permission.READ_EXTERNAL_STORAGE) != PackageManager.PERMISSION_GRANTED)) { 
if ((ActivityCompat.shouldShowRequestPermissionRationale(MainActivity.this, android.Manifest.permission.READ_EXTERNAL_STORAGE))) { 
} else { 
ActivityCompat.requestPermissions(MainActivity.this, new String[]{android.Manifest.permission.READ_EXTERNAL_STORAGE}, 
REQUEST_PERMISSIONS); 
} 
} else { 
boolean_permission = true; 
getfile(dir); 
obj_adapter = new PDFAdapter(getApplicationContext(), fileList); 
lv_pdf.setAdapter(obj_adapter); 
} 
} 
@Override 
public void onRequestPermissionsResult(int requestCode, String[] permissions, int[] grantResults) { 
super.onRequestPermissionsResult(requestCode, permissions, grantResults); 
if (requestCode == REQUEST_PERMISSIONS) { 
if (grantResults.length > 0 && grantResults[0] == PackageManager.PERMISSION_GRANTED) { 
boolean_permission = true; 
getfile(dir); 
obj_adapter = new PDFAdapter(getApplicationContext(), fileList); 
lv_pdf.setAdapter(obj_adapter); 
} else { 
Toast.makeText(getApplicationContext(), “Please allow the permission”, Toast.LENGTH_LONG).show(); 
} 
} 
} 
} 

PdfActivity.java ：

package com.pdffilefromsdcard; 
import android.os.Bundle; 
import android.support.annotation.Nullable; 
import android.support.v7.app.AppCompatActivity; 
import android.util.Log; 
import com.github.barteksc.pdfviewer.PDFView; 
import com.github.barteksc.pdfviewer.listener.OnLoadCompleteListener; 
import com.github.barteksc.pdfviewer.listener.OnPageChangeListener; 
import com.github.barteksc.pdfviewer.scroll.DefaultScrollHandle; 
import com.shockwave.pdfium.PdfDocument; 
import java.io.File; 
import java.util.List; 
public class PdfActivity extends AppCompatActivity implements OnPageChangeListener,OnLoadCompleteListener { 
PDFView pdfView; 
Integer pageNumber = 0; 
String pdfFileName; 
String TAG=”PdfActivity”; 
int position=-1; 
@Override 
protected void onCreate(@Nullable Bundle savedInstanceState) { 
super.onCreate(savedInstanceState); 
setContentView(R.layout.activity_pdf); 
init(); 
} 
private void init(){ 
pdfView= (PDFView)findViewById(R.id.pdfView); 
position = getIntent().getIntExtra(“position”,-1); 
displayFromSdcard(); 
} 
private void displayFromSdcard() { 
pdfFileName = MainActivity.fileList.get(position).getName(); 
pdfView.fromFile(MainActivity.fileList.get(position)) 
.defaultPage(pageNumber) 
.enableSwipe(true) 
.swipeHorizontal(false) 
.onPageChange(this) 
.enableAnnotationRendering(true) 
.onLoad(this) 
.scrollHandle(new DefaultScrollHandle(this)) 
.load(); 
} 
@Override 
public void onPageChanged(int page, int pageCount) { 
pageNumber = page; 
setTitle(String.format(“%s %s/%s”, pdfFileName, page + 1, pageCount)); 
} 
@Override 
public void loadComplete(int nbPages) { 
PdfDocument.Meta meta = pdfView.getDocumentMeta(); 
printBookmarksTree(pdfView.getTableOfContents(), “-“); 
} 
public void printBookmarksTree(List<PdfDocument.Bookmark> tree, String sep) { 
for (PdfDocument.Bookmark b : tree) { 
Log.e(TAG, String.format(“%s %s, p %d”, sep, b.getTitle(), b.getPageIdx())); 
if (b.hasChildren()) { 
printBookmarksTree(b.getChildren(), sep + “-“); 
} 
} 
} 
}