Java PDF的多个片段

我正在尝试制作一个应用程序，当有人单击指定按钮时，它可以呈现pdf。问题是，每当我添加另一个pdf和片段进行渲染时，软件只显示我添加的最后一个，而不显示其他的。这是我的密码：

主要活动

import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.support.v4.app.FragmentActivity;
import android.support.v4.app.FragmentManager;
import android.support.v4.app.FragmentTransaction;
import android.view.View;
import android.widget.LinearLayout;

public class MainActivity extends AppCompatActivity {

    private View btnRender;
    private LinearLayout container;
    private View btnRendered;



    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        btnRender = (View)findViewById(R.id.btn_render);
        container = (LinearLayout)findViewById(R.id.fragment_layout);
        btnRendered = (View) findViewById(R.id.btn_rendered);

        //set event handling for button
        btnRender.setOnClickListener(onClickListener());
        btnRendered.setOnClickListener(onClickListener());
    }

    private View.OnClickListener onClickListener() {


        return new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                if (v == btnRender) {
                    FragmentManager fm = getSupportFragmentManager();
                    FragmentTransaction ft = fm.beginTransaction();
                    ft.replace(R.id.fragment_layout, new PDFRenderFragment());
                    ft.commit();
                    //gone button after all
                    btnRender.setVisibility(View.GONE);
                    container.setVisibility(View.VISIBLE);
                } else if (v == btnRendered) {
                        FragmentManager fm = getSupportFragmentManager();
                        FragmentTransaction ft = fm.beginTransaction();
                        ft.replace(R.id.fragment_layout, new PDFRenderAgment());
                        ft.commit();

                        //gone button after all
                        btnRender.setVisibility(View.GONE);
                        container.setVisibility(View.VISIBLE);


            }
        };
    };



}}

第一个pdf文件

import android.app.Fragment;
import android.app.Activity;
import android.graphics.Bitmap;
import android.graphics.pdf.PdfRenderer;
import android.os.Bundle;
import android.os.ParcelFileDescriptor;
import android.util.Log;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.Button;
import android.widget.ImageView;

import java.io.IOException;


public class PDFRenderFragment extends android.support.v4.app.Fragment {

    private ParcelFileDescriptor fileDescriptor;
    private PdfRenderer pdfRenderer;
    private PdfRenderer.Page currentPage;
    private ImageView image;
    private Button btnPrevious;
    private Button btnNext;

    public PDFRenderFragment() {

    }

    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
                             Bundle savedInstanceState) {
        return inflater.inflate(R.layout.fragment_pdfrender, container, false);
    }

    @Override
    public void onViewCreated(View view, Bundle savedInstanceState) {
        super.onViewCreated(view, savedInstanceState);
        // Retain view references.
        image = (ImageView) view.findViewById(R.id.image);
        btnPrevious = (Button) view.findViewById(R.id.btn_previous);
        btnNext = (Button) view.findViewById(R.id.btn_next);

        //set buttons event
        btnPrevious.setOnClickListener(onActionListener(-1)); //previous button clicked
        btnNext.setOnClickListener(onActionListener(1)); //next button clicked

        int index = 0;
        // If there is a savedInstanceState (screen orientations, etc.), we restore the page index.
        if (null != savedInstanceState) {
            index = savedInstanceState.getInt("current_page", 0);
        }
        showPage(index);
    }

    @Override
    public void onAttach(Activity activity) {
        super.onAttach(activity);
        try {
            openRenderer(activity);
        } catch (IOException e) {
            e.printStackTrace();
            Log.i("Fragment", "Error occurred!");
            Log.e("Fragment", e.getMessage());
            activity.finish();
        }
    }

    @Override
    public void onDestroy() {
        try {
            closeRenderer();
        } catch (IOException e) {
            e.printStackTrace();
        }
        super.onDestroy();
    }

    @Override
    public void onSaveInstanceState(Bundle outState) {
        super.onSaveInstanceState(outState);
        if (null != currentPage) {
            outState.putInt("current_page", currentPage.getIndex());
        }
    }

    /**
     * Create a PDF renderer
     * @param activity
     * @throws IOException
     */
    private void openRenderer(Activity activity) throws IOException {
        // Reading a PDF file from the assets directory.
        fileDescriptor = activity.getAssets().openFd("biology_in_c.pdf").getParcelFileDescriptor();

        // This is the PdfRenderer we use to render the PDF.
        pdfRenderer = new PdfRenderer(fileDescriptor);
    }

    /**
     * Closes PdfRenderer and related resources.
     */
    private void closeRenderer() throws IOException {
        if (null != currentPage) {
            currentPage.close();
        }
        pdfRenderer.close();
        fileDescriptor.close();
    }

    /**
     * Shows the specified page of PDF file to screen
     * @param index The page index.
     */
    private void showPage(int index) {
        if (pdfRenderer.getPageCount() <= index) {
            return;
        }
        // Make sure to close the current page before opening another one.
        if (null != currentPage) {
            currentPage.close();
        }
        //open a specific page in PDF file
        currentPage = pdfRenderer.openPage(index);
        // Important: the destination bitmap must be ARGB (not RGB).
        Bitmap bitmap = Bitmap.createBitmap(currentPage.getWidth(), currentPage.getHeight(),
                Bitmap.Config.ARGB_8888);
        // Here, we render the page onto the Bitmap.
        currentPage.render(bitmap, null, null, PdfRenderer.Page.RENDER_MODE_FOR_DISPLAY);
        // showing bitmap to an imageview
        image.setImageBitmap(bitmap);
        updateUIData();
    }

    /**
     * Updates the state of 2 control buttons in response to the current page index.
     */
    private void updateUIData() {
        int index = currentPage.getIndex();
        int pageCount = pdfRenderer.getPageCount();
        btnPrevious.setEnabled(0 != index);
        btnNext.setEnabled(index + 1 < pageCount);
        getActivity().setTitle(getString(R.string.app_name , index + 1, pageCount));
    }

    private View.OnClickListener onActionListener(final int i) {
        return new View.OnClickListener() {
            @Override
            public void onClick(View v) {

                if (i < 0) {//go to previous page
                    showPage(currentPage.getIndex() - 1);
                } else {
                    showPage(currentPage.getIndex() + 1);
                }
            }
        };
    }
}

import android.app.Fragment;
import android.app.Activity;
import android.graphics.Bitmap;
import android.graphics.pdf.PdfRenderer;
import android.os.Bundle;
import android.os.ParcelFileDescriptor;
import android.util.Log;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.Button;
import android.widget.ImageView;

import java.io.IOException;


public class PDFRenderAgment extends android.support.v4.app.Fragment {

    private ParcelFileDescriptor fileDescriptor;
    private PdfRenderer pdfRenderer;
    private PdfRenderer.Page currentPage;
    private ImageView image;
    private Button btnPrevious;
    private Button btnNext;

    public PDFRenderAgment() {

    }

    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
                             Bundle savedInstanceState) {
        return inflater.inflate(R.layout.fragment_pdfrender, container, false);
    }

    @Override
    public void onViewCreated(View view, Bundle savedInstanceState) {
        super.onViewCreated(view, savedInstanceState);
        // Retain view references.
        image = (ImageView) view.findViewById(R.id.image);
        btnPrevious = (Button) view.findViewById(R.id.btn_previous);
        btnNext = (Button) view.findViewById(R.id.btn_next);

        //set buttons event
        btnPrevious.setOnClickListener(onActionListener(-1)); //previous button clicked
        btnNext.setOnClickListener(onActionListener(1)); //next button clicked

        int index = 0;
        // If there is a savedInstanceState (screen orientations, etc.), we restore the page index.
        if (null != savedInstanceState) {
            index = savedInstanceState.getInt("current_page", 0);
        }
        showPage(index);
    }

    @Override
    public void onAttach(Activity activity) {
        super.onAttach(activity);
        try {
            openRenderer(activity);
        } catch (IOException e) {
            e.printStackTrace();
            Log.i("Fragment", "Error occurred!");
            Log.e("Fragment", e.getMessage());
            activity.finish();
        }
    }

    @Override
    public void onDestroy() {
        try {
            closeRenderer();
        } catch (IOException e) {
            e.printStackTrace();
        }
        super.onDestroy();
    }

    @Override
    public void onSaveInstanceState(Bundle outState) {
        super.onSaveInstanceState(outState);
        if (null != currentPage) {
            outState.putInt("current_page", currentPage.getIndex());
        }
    }

    /**
     * Create a PDF renderer
     * @param activity
     * @throws IOException
     */
    private void openRenderer(Activity activity) throws IOException {
        // Reading a PDF file from the assets directory.
        fileDescriptor = activity.getAssets().openFd("biology_in_f.pdf").getParcelFileDescriptor();

        // This is the PdfRenderer we use to render the PDF.
        pdfRenderer = new PdfRenderer(fileDescriptor);
    }

    /**
     * Closes PdfRenderer and related resources.
     */
    private void closeRenderer() throws IOException {
        if (null != currentPage) {
            currentPage.close();
        }
        pdfRenderer.close();
        fileDescriptor.close();
    }

    /**
     * Shows the specified page of PDF file to screen
     * @param index The page index.
     */
    private void showPage(int index) {
        if (pdfRenderer.getPageCount() <= index) {
            return;
        }
        // Make sure to close the current page before opening another one.
        if (null != currentPage) {
            currentPage.close();
        }
        //open a specific page in PDF file
        currentPage = pdfRenderer.openPage(index);
        // Important: the destination bitmap must be ARGB (not RGB).
        Bitmap bitmap = Bitmap.createBitmap(currentPage.getWidth(), currentPage.getHeight(),
                Bitmap.Config.ARGB_8888);
        // Here, we render the page onto the Bitmap.
        currentPage.render(bitmap, null, null, PdfRenderer.Page.RENDER_MODE_FOR_DISPLAY);
        // showing bitmap to an imageview
        image.setImageBitmap(bitmap);
        updateUIData();
    }

    /**
     * Updates the state of 2 control buttons in response to the current page index.
     */
    private void updateUIData() {
        int index = currentPage.getIndex();
        int pageCount = pdfRenderer.getPageCount();
        btnPrevious.setEnabled(0 != index);
        btnNext.setEnabled(index + 1 < pageCount);
        getActivity().setTitle(getString(R.string.app_name , index + 1, pageCount));
    }

    private View.OnClickListener onActionListener(final int i) {
        return new View.OnClickListener() {
            @Override
            public void onClick(View v) {

                if (i < 0) {//go to previous page
                    showPage(currentPage.getIndex() - 1);
                } else {
                    showPage(currentPage.getIndex() + 1);
                }
            }
        };
    }
}

导入android.app.Fragment；
导入android.app.Activity；
导入android.graphics.Bitmap；
导入android.graphics.pdf.PdfRenderer；
导入android.os.Bundle；
导入android.os.ParcelFileDescriptor；
导入android.util.Log；
导入android.view.LayoutInflater；
导入android.view.view；
导入android.view.ViewGroup；
导入android.widget.Button；
导入android.widget.ImageView；
导入java.io.IOException；
公共类PDFRenderFragment扩展了android.support.v4.app.Fragment{
专用ParcelFileDescriptor文件描述符；
私人PdfRenderer PdfRenderer；
私人PDFRender.Page当前页面；
私有图像查看图像；
私人按钮BTN先前；
私人按钮btnNext；
公共PDFRenderFragment（）{
}
@凌驾
创建视图上的公共视图（布局、充气机、视图组容器、，
Bundle savedInstanceState）{
返回充气机。充气（R.layout.fragment\u pdfrender，容器，错误）；
}
@凌驾
已创建视图上的公共void（视图，捆绑保存状态）{
super.onViewCreated（视图，savedInstanceState）；
//保留视图引用。
image=（ImageView）view.findviewbyd（R.id.image）；
btnPrevious=（按钮）view.findViewById（R.id.btn_previous）；
btnNext=（按钮）view.findviewbyd（R.id.btn_next）；
//设置按钮事件
btnPrevious.setOnClickListener（onActionListener（-1））；//单击了上一个按钮
btnNext.setOnClickListener（onActionListener（1））；//单击下一步按钮
int指数=0；
//如果存在savedInstanceState（屏幕方向等），则恢复页面索引。
如果（null！=savedInstanceState）{
index=savedInstanceState.getInt（“当前页面”，0）；
}
展示页（索引）；
}
@凌驾
公共事务主任（活动）{
超级转速计（活动）；
试一试{
公开展览（活动）；
}捕获（IOE异常）{
e、 printStackTrace（）；
Log.i（“片段”，“发生错误！”）；
Log.e（“片段”，e.getMessage（））；
activity.finish（）；
}
}
@凌驾
公共空间{
试一试{
关闭渲染器（）；
}捕获（IOE异常）{
e、 printStackTrace（）；
}
super.ondestory（）；
}
@凌驾
SaveInstanceState上的公共无效（束超出状态）{
super.onSaveInstanceState（超出状态）；
如果（null！=currentPage）{
outState.putInt（“当前页面”，currentPage.getIndex（））；
}
}
/**
*创建PDF渲染器
*@param活动
*@抛出异常
*/
私有void openRenderer（活动）引发IOException{
//正在从资产目录中读取PDF文件。
fileDescriptor=activity.getAssets（）.openFd（“biology_in_c.pdf”）.getParcelFileDescriptor（）；
//这是我们用来渲染PDF的PdfRenderer。
pdfRenderer=新的pdfRenderer（文件描述符）；
}
/**
*关闭PdfRenderer和相关资源。
*/
私有void closeRenderer（）引发IOException{
如果（null！=currentPage）{
currentPage.close（）；
}
pdfRenderer.close（）；
fileDescriptor.close（）；
}
/**
*显示要显示的PDF文件的指定页面
*@param index页面索引。
*/
专用void显示页（整数索引）{
如果（pdfrender.getPageCount（）您是否尝试过使用此选项：
公共void onClick（视图v）{
开关（v.getId（））{

}
}
我没有添加默认值……这有什么不同吗？
case R.id.btn_render:
    // do your code
    break;

case R.id.btn_rendered:
    // do your code
    break;
default:
    break;