与android打印管理器的链接不正确
与android打印管理器的链接不正确
提问于 2014-10-27 16:43:59
这是我的第一个问题，我事先为任何错误道歉！
我正试图将打印功能绑定到我的应用程序上。为此，我使用了以下代码：Tutorial
我在一个专用类中实现了printDocumentAdapter，并通过按钮调用打印函数，该按钮取决于我的主要活动。
当调试到达"printManager.print(jobName，printDoc，null)“行时，我无法理解logcat提供的错误。按钮似乎工作正常(没有被指控的线一切都很好)。
事先非常感谢您的帮助。
public class SQLiteExampleActivity extends ListActivity {
//private String[] intituleObservations;
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
Toast.makeText(this, "1er Toast", Toast.LENGTH_LONG).show();
// Erased stuff here
}
public void printDocument(View view)
{
// Get a PrintManager instance
PrintManager printManager = (PrintManager) this.getSystemService(Context.PRINT_SERVICE);
// Give the job a name.
String jobName = this.getString(R.string.app_name) +
" Document";
// Start a print job, passing a printDocumentAdapter as
//argument to handle the generation of a print document
MyPrintDocumentAdapter printDoc = new MyPrintDocumentAdapter(this);
printManager.print(jobName, printDoc, null);
}
}
package com.example.essaib;
import java.io.FileOutputStream;
import java.io.IOException;
import android.app.Activity;
import android.app.ActionBar;
import android.app.Fragment;
import android.os.Bundle;
import android.view.LayoutInflater;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.view.ViewGroup;
import android.os.Build;
import android.os.CancellationSignal;
import android.os.ParcelFileDescriptor;
import android.print.PageRange;
import android.print.PrintAttributes;
import android.print.PrintDocumentAdapter;
import android.content.Context;
import android.print.PrintDocumentInfo;
import android.graphics.pdf.PdfDocument.PageInfo;
import android.print.pdf.PrintedPdfDocument;
import android.graphics.pdf.PdfDocument;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
public class MyPrintDocumentAdapter extends PrintDocumentAdapter {
Context context;
private int pageHeight;
private int pageWidth;
public PdfDocument myPdfDocument;
public int totalpages = 4; // Défaut, à rendre dynamique
public MyPrintDocumentAdapter(Context context)
{
this.context = context;
}
/**
* Layout method.
*/
@Override
public void onLayout(PrintAttributes oldAttributes,
PrintAttributes newAttributes,
CancellationSignal cancellationSignal,
LayoutResultCallback callback,
Bundle metadata) {
// Creates a new PDFdocument with the right attributes
myPdfDocument = new PrintedPdfDocument(context, newAttributes);
pageHeight =
newAttributes.getMediaSize().getHeightMils()/1000 * 72;
pageWidth =
newAttributes.getMediaSize().getWidthMils()/1000 * 72;
// Responds to Cancellation request
if (cancellationSignal.isCanceled() ) {
callback.onLayoutCancelled();
return;
}
// Returns print information to printing framework
if (totalpages > 0) {
PrintDocumentInfo.Builder builder = new PrintDocumentInfo
.Builder("print_output.pdf")
.setContentType(PrintDocumentInfo.CONTENT_TYPE_DOCUMENT)
.setPageCount(totalpages);
PrintDocumentInfo info = builder.build();
callback.onLayoutFinished(info, true);
} else {
callback.onLayoutFailed("Page count is zero.");
}
}
/*
* Called by the printing framework
*
*/
@Override
public void onWrite(final PageRange[] pageRanges,
final ParcelFileDescriptor destination,
final CancellationSignal cancellationSignal,
final WriteResultCallback callback) {
for (int i = 0; i < totalpages; i++) {
if (pageInRange(pageRanges, i))
{
PageInfo newPage = new PageInfo.Builder(pageWidth,
pageHeight, i).create();
PdfDocument.Page page = myPdfDocument.startPage(newPage);
if (cancellationSignal.isCanceled()) {
callback.onWriteCancelled();
myPdfDocument.close();
myPdfDocument = null;
return;
}
drawPage(page, i);
myPdfDocument.finishPage(page);
}
}
try {
myPdfDocument.writeTo(new FileOutputStream(
destination.getFileDescriptor()));
} catch (IOException e) {
callback.onWriteFailed(e.toString());
return;
} finally {
myPdfDocument.close();
myPdfDocument = null;
}
callback.onWriteFinished(pageRanges);
}
private boolean pageInRange(PageRange[] pageRanges, int page)
{
for (int i = 0; i<pageRanges.length; i++)
{
if ((page >= pageRanges[i].getStart()) &&
(page <= pageRanges[i].getEnd()))
return true;
}
return false;
}
private void drawPage(PdfDocument.Page page,
int pagenumber) {
Canvas canvas = page.getCanvas();
pagenumber++; // Make sure page numbers start at 1
int titleBaseLine = 72;
int leftMargin = 54;
Paint paint = new Paint();
paint.setColor(Color.BLACK);
paint.setTextSize(40);
canvas.drawText(
"Test Print Document Page " + pagenumber,
leftMargin,
titleBaseLine,
paint);
paint.setTextSize(14);
canvas.drawText("This is some test content to verify that custom document printing works", leftMargin, titleBaseLine + 35, paint);
if (pagenumber % 2 == 0)
paint.setColor(Color.RED);
else
paint.setColor(Color.GREEN);
PageInfo pageInfo = page.getInfo();
canvas.drawCircle(pageInfo.getPageWidth()/2,
pageInfo.getPageHeight()/2,
150,
paint);
}
}
错误逻辑的内容
10-27 16:37:43.810: E/AndroidRuntime(806): FATAL EXCEPTION: main
10-27 16:37:43.810: E/AndroidRuntime(806): Process: com.example.essaib, PID: 806
10-27 16:37:43.810: E/AndroidRuntime(806): java.lang.IllegalStateException: Could not execute method of the activity
10-27 16:37:43.810: E/AndroidRuntime(806): at android.view.View$1.onClick(View.java:3835)
10-27 16:37:43.810: E/AndroidRuntime(806): at android.view.View.performClick(View.java:4450)
10-27 16:37:43.810: E/AndroidRuntime(806): at android.view.View$PerformClick.run(View.java:18600)
10-27 16:37:43.810: E/AndroidRuntime(806): at android.os.Handler.handleCallback(Handler.java:733)
10-27 16:37:43.810: E/AndroidRuntime(806): at android.os.Handler.dispatchMessage(Handler.java:95)
10-27 16:37:43.810: E/AndroidRuntime(806): at android.os.Looper.loop(Looper.java:136)
10-27 16:37:43.810: E/AndroidRuntime(806): at android.app.ActivityThread.main(ActivityThread.java:5026)
10-27 16:37:43.810: E/AndroidRuntime(806): at java.lang.reflect.Method.invokeNative(Native Method)
10-27 16:37:43.810: E/AndroidRuntime(806): at java.lang.reflect.Method.invoke(Method.java:515)
10-27 16:37:43.810: E/AndroidRuntime(806): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:777)
10-27 16:37:43.810: E/AndroidRuntime(806): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:602)
10-27 16:37:43.810: E/AndroidRuntime(806): at dalvik.system.NativeStart.main(Native Method)
10-27 16:37:43.810: E/AndroidRuntime(806): Caused by: java.lang.reflect.InvocationTargetException
10-27 16:37:43.810: E/AndroidRuntime(806): at java.lang.reflect.Method.invokeNative(Native Method)
10-27 16:37:43.810: E/AndroidRuntime(806): at java.lang.reflect.Method.invoke(Method.java:515)
10-27 16:37:43.810: E/AndroidRuntime(806): at android.view.View$1.onClick(View.java:3830)
10-27 16:37:43.810: E/AndroidRuntime(806): ... 11 more
10-27 16:37:43.810: E/AndroidRuntime(806): Caused by: java.lang.NullPointerException
10-27 16:37:43.810: E/AndroidRuntime(806): at android.print.PrintManager.print(PrintManager.java:387)
10-27 16:37:43.810: E/AndroidRuntime(806): at com.example.essaib.SQLiteExampleActivity.printDocument(SQLiteExampleActivity.java:138)
10-27 16:37:43.810: E/AndroidRuntime(806): ... 14 more回答 1
Stack Overflow用户
回答已采纳
发布于 2015-03-15 21:35:47
实际上，问题来自一个不兼容的硬件。很难追踪，但终于找到了。
页面原文内容由Stack Overflow提供。腾讯云小微IT领域专用引擎提供翻译支持
原文链接：
https://stackoverflow.com/questions/26592508
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