我是编码世界的初学者，我正在尝试使用 IText 从我的应用程序生成 PDF。我成功地创建了带有文本、表格等的基本 PDF。 现在我想从已创建且不为空的数据库中检索数据。 我在 StackOverflow 和 Internet 上查看了许多主题，但无法使其正常工作。
欢迎任何帮助
如果您需要任何其他信息，请告诉我，并提前致谢!
这是我的代码:
报告 Activity
public class ReportActivity extends AppCompatActivity {
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_report);
Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar);
setSupportActionBar(toolbar);
//getSupportActionBar().setDisplayHomeAsUpEnabled(true);
}
public void onClick_report(View view) {
try {
createPdf();
} catch (FileNotFoundException e) {
e.printStackTrace();
} catch (DocumentException e) {
e.printStackTrace();
}
}
private void createPdf() throws FileNotFoundException, DocumentException {
File pdfFolder = new File(getExternalFilesDir("report"), "report");
Date date = new Date();
String timeStamp = new SimpleDateFormat("yyyyMMdd_HHmmss").format(date);
File myFile = new File(pdfFolder + timeStamp + ".pdf");
OutputStream output = new FileOutputStream(myFile);
DatabaseHandler db = new DatabaseHandler(getApplicationContext());
Cursor cursor = db.getSepficItem();
//Step 1
Document document = new Document();
//Step 2
PdfWriter.getInstance(document, output);
//Step 3
document.open();
//Step 4 Add content
PdfPTable table = new PdfPTable(6);
table.addCell("id col");
table.addCell("day col");
table.addCell("month col");
table.addCell("Year col");
table.addCell("type col");
table.addCell("amount col");
table.addCell("comment col");
table.addCell("photo col");
table.addCell("cust col");
cursor.moveToFirst();
int count = cursor.getCount();
for (int j = 0; j < count; j++)
{
table.addCell(cursor.getString(cursor.getColumnIndex("id")));
table.addCell(cursor.getString(cursor.getColumnIndex("day")));
table.addCell(cursor.getString(cursor.getColumnIndex("month")));
table.addCell(cursor.getString(cursor.getColumnIndex("year")));
table.addCell(cursor.getString(cursor.getColumnIndex("type")));
table.addCell(cursor.getString(cursor.getColumnIndex("amount")));
table.addCell(cursor.getString(cursor.getColumnIndex("comment")));
table.addCell(cursor.getString(cursor.getColumnIndex("photo")));
table.addCell(cursor.getString(cursor.getColumnIndex("customername")));
cursor.moveToNext();
}
//Step 5: Close the document
document.close();
}
数据库助手:
public class DatabaseHandler extends SQLiteOpenHelper {
private static final int DATABASE_VERSION = 18;
private static final String DATABASE_NAME = "ExpenseNote";
//Table Customer
private static final String TABLE_CUST = "Customer";
private static final String CUST_ID = "id";
private static final String CUST_NAME = "name";
//Table Expense
private static final String TABLE_EXPENSE = "Expense";
private static final String EXPENS_ID = "id";
private static final String EXPENS_DAY = "day";
private static final String EXPENS_MONTH = "month";
private static final String EXPENS_YEAR = "year";
private static final String EXPENS_TYPE = "type";
private static final String EXPENS_AMOUNT = "amount";
private static final String EXPENS_COMMENT = "comment";
private static final String EXPENS_PHOTO = "photo";
private static final String EXPENS_CUST = "customername";
public DatabaseHandler(Context context) {
super(context, DATABASE_NAME, null, DATABASE_VERSION);
}
// Creating Tables
@Override
public void onCreate(SQLiteDatabase db) {
// Category table create query
String CREATE_ITEM_TABLE = "CREATE TABLE IF NOT EXISTS "
+ TABLE_CUST + "("
+ CUST_ID + " integer primary key,"
+ CUST_NAME + " text not null)";
db.execSQL(CREATE_ITEM_TABLE);
String CREATE_EXPENSE_TABLE = "CREATE TABLE IF NOT EXISTS "
+ TABLE_EXPENSE + "("
+ EXPENS_ID + " integer PRIMARY KEY,"
+ EXPENS_DAY + " integer,"
+ EXPENS_MONTH + " integer,"
+ EXPENS_YEAR + " integer,"
+ EXPENS_TYPE + " text,"
+ EXPENS_AMOUNT + " real,"
+ EXPENS_COMMENT + " text,"
+ EXPENS_PHOTO + " text,"
+ EXPENS_CUST + " text)";
// + " FOREIGN KEY (" + CUST_ID + ") REFERENCES " + TABLE_CUST + "(" + CUST_ID + "));";
db.execSQL(CREATE_EXPENSE_TABLE);
}
public Cursor getSepficItem(){
// Select All Query
SQLiteDatabase db = this.getReadableDatabase();
String q = "SELECT * FROM Expense";
Cursor mCursor = db.rawQuery(q, null);
// closing connection
mCursor.close();
db.close();
// returning customer
return mCursor;
}
日志猫:
FATAL EXCEPTION: main java.lang.IllegalStateException: Could not execute method for android:onClick
at android.support.v7.app.AppCompatViewInflater$DeclaredOnClickListener.onClick(AppCompatViewInflater.java:293)
at android.view.View.performClick(View.java:5610)
at android.view.View$PerformClick.run(View.java:22265)
at android.os.Handler.handleCallback(Handler.java:751)
at android.os.Handler.dispatchMessage(Handler.java:95)
at android.os.Looper.loop(Looper.java:154)
at android.app.ActivityThread.main(ActivityThread.java:6077)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:866)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:756)
Caused by: java.lang.reflect.InvocationTargetException
at java.lang.reflect.Method.invoke(Native Method)
at android.support.v7.app.AppCompatViewInflater$DeclaredOnClickListener.onClick(AppCompatViewInflater.java:288)
at android.view.View.performClick(View.java:5610)
at android.view.View$PerformClick.run(View.java:22265)
at android.os.Handler.handleCallback(Handler.java:751)
at android.os.Handler.dispatchMessage(Handler.java:95)
at android.os.Looper.loop(Looper.java:154)
at android.app.ActivityThread.main(ActivityThread.java:6077)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:866)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:756)
Caused by: java.lang.IllegalStateException: attempt to re-open an already-closed object: SQLiteQuery: SELECT * FROM Expense
at android.database.sqlite.SQLiteClosable.acquireReference(SQLiteClosable.java:55)
at android.database.sqlite.SQLiteQuery.fillWindow(SQLiteQuery.java:58)
at android.database.sqlite.SQLiteCursor.fillWindow(SQLiteCursor.java:143)
at android.database.sqlite.SQLiteCursor.getCount(SQLiteCursor.java:132)
at android.database.AbstractCursor.moveToPosition(AbstractCursor.java:219)
at android.database.AbstractCursor.moveToFirst(AbstractCursor.java:258)
at lu.digitalsecurity.expensenote.ReportActivity.createPdf(ReportActivity.java:89)
at lu.digitalsecurity.expensenote.ReportActivity.onClick_report(ReportActivity.java:35)
at java.lang.reflect.Method.invoke(Native Method)
at android.support.v7.app.AppCompatViewInflater$DeclaredOnClickListener.onClick(AppCompatViewInflater.java:288)
at android.view.View.performClick(View.java:5610)
at android.view.View$PerformClick.run(View.java:22265)
at android.os.Handler.handleCallback(Handler.java:751)
at android.os.Handler.dispatchMessage(Handler.java:95)
at android.os.Looper.loop(Looper.java:154)
at android.app.ActivityThread.main(ActivityThread.java:6077)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:866)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:756)
根据要求进行编辑:
XML 文件(目前只有一个简单的按钮):
<android.support.constraint.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
app:layout_behavior="@string/appbar_scrolling_view_behavior"
tools:context=".ReportActivity"
tools:showIn="@layout/activity_report">
<Button
android:id="@+id/button"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="Button"
app:layout_constraintTop_toTopOf="parent"
android:layout_marginTop="45dp"
android:layout_marginLeft="50dp"
app:layout_constraintLeft_toLeftOf="parent"
android:layout_marginRight="50dp"
app:layout_constraintRight_toRightOf="parent"
android:onClick="onClick_report"/>
最佳答案
事实上，堆栈确实告诉您错误在哪里:“尝试重新打开已关闭的对象”。
当你执行 mCursor.close() 时，基本上你是在对系统说“我不再使用它了，你可以释放相关资源”。
恕我直言，你应该有一个类费用，看起来像:
public class Expense {
private int id, day, month, year;
private String type;
// and so on...
public int getId() {
return id;
}
public void setId(int id) {
this.id = id;
}
// Other getters/setters
}
你的方法 getSepficItem() 应该返回一个列表:
public List<Expense> getSepficItem() {
List<Expense> result = new ArrayList();
// Select All Query
SQLiteDatabase db = this.getReadableDatabase();
String q = "SELECT * FROM Expense";
Cursor mCursor = db.rawQuery(q, null);
if (cursor.moveToFirst()) {
do {
Expense expense = new Expense();
expense.setId(Integer.parseInt(cursor.getString(0)));
// etc...
expense.setType(cursor.getString(2));
// etc...
result.add(contact);
} while (cursor.moveToNext());
}
mCursor.close();
db.close();
return result;
}
生成 PDF 的方法应该使用 Expense，而不是光标。
请注意，这并不是您特定问题的完整解决方案，而是有关如何组织代码的线索。
最后调整 pdf 创建:
createPdf() {
for (Expense expense : db.getSepficItem()) {
// ..
table.addCell(expense.getId());
}
}
关于java - 使用 Itext 以 PDF 形式显示 SQLite 数据库的结果，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/46642322/