Qt C++，编译错误

嗨，我无法编译我的程序，由于某种原因，它给出了关于命名空间的错误，不知道为什么，请帮忙？错误是：

"expected unqualified-id before 'namespace'                    filminput.h 11
UI has not been declared                                       filminput.h 26
ISO C++ forbids declaration of 'FilmInput' with no type        filminput.h 26
expected ';' before '*' token                                  filminput.h 26

这是代码：

#ifndef FILM_H
#define FILM_H
#include <QWidget>
#include <QString>
#include <QDate>
class Film : public QWidget{
public:
    Film(QString t,int dur,QString dir,QDate r);
    Film();
    void setTitle(QString t);
    void setDuration(int dur);
    void setDirector(QString dir);
    void setReleaseDate(QDate r);
    QString getTitle() const;
    int getDuration() const;
    QString getDirector() const;
    QDate getReleaseDate() const;

private:
    QString m_title;
    int m_duration;
    QString m_director;
    QDate m_releaseDate;
};
#endif // FILM_H
#ifndef FILMWRITER_H
#define FILMWRITER_H
#include "Film.h"
#include <QtGui>
class FilmWriter {
public:
    void saveFilm(Film& f);
}
#endif // FILMWRITER_H
#ifndef FILMINPUT_H
#define FILMINPUT_H
#include <QMainWindow>
#include "Film.h"
#include "FilmWriter.h"
#include <QLabel>
#include <QTextEdit>
#include <QPushButton>
namespace Ui {
    class FilmInput;
}
class FilmInput : public QMainWindow
{
    Q_OBJECT
public:
    explicit FilmInput(QWidget *parent = 0);
    ~FilmInput();
    void obtainFilmData(Film& f);
public slots:
    void getFilm();
private:
    Ui::FilmInput *ui;
    //widgets
    QMainWindow* window;
    QLabel* infoLabel;
    QLabel* titleLabel;
    QLabel* durationLabel;
    QLabel* directorLabel;
    QLabel* relDateLabel;
    QTextEdit* titleEdit;
    QTextEdit* durationEdit;
    QTextEdit* directorEdit;
    QTextEdit* relDateEdit;
    QPushButton* saveBtn;
    QPushButton* cancelBtn;
    Film f;
    //sets up gui and connects signals and slots
    void setUpGui();
};
#endif // FILMINPUT_H
#include "Film.h"
Film::Film(QString t,int dur,QString dir,QDate r):m_title(t),m_duration(dur),m_director(dir),m_releaseDate(r){
}
Film::Film(){
}
void Film::setTitle(QString t){
    m_title = t;
}
void Film::setDuration(int dur){
    m_duration = dur;
}
void Film::setDirector(QString dir){
    m_director = dir;
}
void Film::setReleaseDate(QDate r){
    m_releaseDate = r;
}
QString Film::getTitle() const{
    return QString("%1").arg(m_title);
}
int Film::getDuration() const{
    return m_duration;
}
QString Film::getDirector() const{
    return QString("%1").arg(m_director);
}
QDate Film::getReleaseDate() const{
    return m_releaseDate;
}

#include "FilmWriter.h"
#include <QFileDialog>
#include <QFile>
#include <QMessageBox>
void FilmWriter::saveFilm(Film& f){
    QString fileName = QFileDialog::getSaveFileName(this, tr("Save File"));
          if (fileName != "") {
              QFile file(fileName);
              if (!file.open(QIODevice::WriteOnly)) {
                  QMessageBox::critical(this, tr("Error"), tr("Could not open file"));// error message
              } else {
                  QTextStream stream(&file);
                  stream << f->toPlainText();
                  stream.flush();
                  file.close();
              }
          }
}
#include "filminput.h"
#include "ui_filminput.h"
#include <QtGui>
#include "Film.h"
#include "FilmWriter.h"
#include <QTextEdit>
FilmInput::FilmInput(QWidget *parent) :
    QMainWindow(parent),
   ui(new Ui::FilmInput)
{
    ui->setupUi(this);
    setUpGui();
}
FilmInput::~FilmInput()
{
    delete ui;
}
void FilmInput::setUpGui(){
    //initialise widgets
    infoLabel = new QLabel("Please enter film data which will be saved to a file",this);
    titleLabel = new QLabel("Film Title",this);
    durationLabel = new QLabel("Film Duration",this);
    directorLabel = new QLabel("Film Director",this);
    relDateLabel = new QLabel("Film Release Date",this);
    titleEdit = new QTextEdit(this);
    durationEdit = new QTextEdit(this);
    directorEdit = new QTextEdit(this);
    relDateEdit = new QTextEdit(this);
    saveBtn = new QPushButton("Save Film",this);
    cancelBtn = new QPushButton("Cancel",this);
    //set layout
    QFormLayout* layout = new QFormLayout();
    layout->addWidget(infoLabel);
    layout->addWidget(titleLabel);
    layout->addWidget(titleEdit);
    layout->addWidget(durationLabel);
    layout->addWidget(durationEdit);
    layout->addWidget(directorLabel);
    layout->addWidget(directorEdit);
    layout->addWidget(relDateLabel);
    layout->addWidget(relDateEdit);
    layout->addWidget(saveBtn);
    layout->addWidget(cancelBtn);
    this->ui->widget->setLayout(layout);
    this->setWindowTitle("Film Archive");
    connect(saveBtn,SIGNAL(clicked()),this, SLOT(getFilm()));
    connect(cancelBtn,SIGNAL(clicked()),this,SLOT(close()));
}
void FilmInput::getFilm(){
    Film f1;
    obtainFilmData(f1);
}
void FilmInput::obtainFilmData(Film &f){
    f(titleEdit->toPlainText(),durationEdit->toPlainText().toInt() ,directorEdit->toPlainText(),
      QDate::fromString(relDateEdit->toPlainText(),"dd/MM/YYYY"));
    saveFilm(f);
}
#include <QtGui/QApplication>
#include "filminput.h"
int main(int argc, char *argv[])
{
    QApplication a(argc, argv);
    FilmInput w;
    w.show();
    return a.exec();
}