Qt和Android - 从图库中获取图片路径

Question

我已经编写了一段从Android相册获取图像的代码。我使用QtAndroid编写了一个等价的Java代码。我已经打开了相册，选择了图片并获取了路径，但它返回文件的MediaColumn，而我需要绝对路径。

使用QAndroid如何获取文件的绝对路径以便用于在Qt中编写Java等效代码？

以下是我编写的代码：

imagepickerandroid.h

#ifndef IMAGEPICKERANDROID_H
#define IMAGEPICKERANDROID_H


#include <QObject>
#include <QtAndroidExtras>

#include <QDebug>

class imagePickerAndroid : public QObject, public QAndroidActivityResultReceiver
{
    Q_OBJECT

public:
    imagePickerAndroid();

    void buscaImagem();

    virtual void handleActivityResult(int receiverRequestCode, int resultCode, const QAndroidJniObject & data);

signals:
    void imagemCaminhoSignal(QString);
};

#endif // IMAGEPICKERANDROID_H

imagepickerandroid.cpp

#include "imagepickerandroid.h"

imagePickerAndroid::imagePickerAndroid()
{

}

void imagePickerAndroid::buscaImagem()
{
    QAndroidJniObject ACTION_PICK = QAndroidJniObject::fromString("android.intent.action.GET_CONTENT");
    QAndroidJniObject intent("android/content/Intent");
    if (ACTION_PICK.isValid() && intent.isValid())
    {
        intent.callObjectMethod("setAction", "(Ljava/lang/String;)Landroid/content/Intent;", ACTION_PICK.object<jstring>());
        intent.callObjectMethod("setType", "(Ljava/lang/String;)Landroid/content/Intent;", QAndroidJniObject::fromString("image/*").object<jstring>());
        QtAndroid::startActivity(intent.object<jobject>(), 101, this);
        qDebug() << "OK";
    }
    else
    {
        qDebug() << "ERRO";
    }
}

void imagePickerAndroid::handleActivityResult(int receiverRequestCode, int resultCode, const QAndroidJniObject &data)
{
    qDebug() << "Trabalha com os dados";

    jint RESULT_OK = QAndroidJniObject::getStaticField<jint>("android/app/Activity", "RESULT_OK");
    if (receiverRequestCode == 101 && resultCode == RESULT_OK) {
        QString imagemCaminho = data.callObjectMethod("getData", "()Landroid/net/Uri;").callObjectMethod("getPath", "()Ljava/lang/String;").toString();
        emit imagemCaminhoSignal(imagemCaminho);

        qDebug() << imagemCaminho;
    }
    else
    {
        qDebug() << "Caminho errado";
    }
}

- GuiDupas

Answer 1

回答自己的问题。

以下是获取 Android 相册 中 完整图像路径 的代码，使用 Qt 编写了等效的 Java 代码：

#include "imagepickerandroid.h"

imagePickerAndroid::imagePickerAndroid()
{

}

void imagePickerAndroid::buscaImagem()
{
    QAndroidJniObject ACTION_PICK = QAndroidJniObject::getStaticObjectField("android/content/Intent", "ACTION_PICK", "Ljava/lang/String;");
    QAndroidJniObject EXTERNAL_CONTENT_URI = QAndroidJniObject::getStaticObjectField("android/provider/MediaStore$Images$Media", "EXTERNAL_CONTENT_URI", "Landroid/net/Uri;");

    QAndroidJniObject intent=QAndroidJniObject("android/content/Intent", "(Ljava/lang/String;Landroid/net/Uri;)V", ACTION_PICK.object<jstring>(), EXTERNAL_CONTENT_URI.object<jobject>());

    if (ACTION_PICK.isValid() && intent.isValid())
    {
        intent.callObjectMethod("setType", "(Ljava/lang/String;)Landroid/content/Intent;", QAndroidJniObject::fromString("image/*").object<jstring>());
        QtAndroid::startActivity(intent.object<jobject>(), 101, this);
        qDebug() << "OK";
    }
    else
    {
        qDebug() << "ERRO";
    }
}

void imagePickerAndroid::handleActivityResult(int receiverRequestCode, int resultCode, const QAndroidJniObject &data)
{
    jint RESULT_OK = QAndroidJniObject::getStaticField<jint>("android/app/Activity", "RESULT_OK");
    if (receiverRequestCode == 101 && resultCode == RESULT_OK)
    {
        QAndroidJniObject uri = data.callObjectMethod("getData", "()Landroid/net/Uri;");
        QAndroidJniObject dadosAndroid = QAndroidJniObject::getStaticObjectField("android/provider/MediaStore$MediaColumns", "DATA", "Ljava/lang/String;");
        QAndroidJniEnvironment env;
        jobjectArray projecao = (jobjectArray)env->NewObjectArray(1, env->FindClass("java/lang/String"), NULL);
        jobject projacaoDadosAndroid = env->NewStringUTF(dadosAndroid.toString().toStdString().c_str());
        env->SetObjectArrayElement(projecao, 0, projacaoDadosAndroid);
        QAndroidJniObject contentResolver = QtAndroid::androidActivity().callObjectMethod("getContentResolver", "()Landroid/content/ContentResolver;");
        QAndroidJniObject cursor = contentResolver.callObjectMethod("query", "(Landroid/net/Uri;[Ljava/lang/String;Ljava/lang/String;[Ljava/lang/String;Ljava/lang/String;)Landroid/database/Cursor;", uri.object<jobject>(), projecao, NULL, NULL, NULL);
        jint columnIndex = cursor.callMethod<jint>("getColumnIndex", "(Ljava/lang/String;)I", dadosAndroid.object<jstring>());
        cursor.callMethod<jboolean>("moveToFirst", "()Z");
        QAndroidJniObject resultado = cursor.callObjectMethod("getString", "(I)Ljava/lang/String;", columnIndex);
        QString imagemCaminho = "file://" + resultado.toString();
        emit imagemCaminhoSignal(imagemCaminho);
    }
    else
    {
        qDebug() << "Caminho errado";
    }
}

- GuiDupas

---

我已经在许多手机上进行了测试，通常情况下都没问题。但今天我发现在一台安装有Android 5的Xperia Z1上它总是返回一个空字符串。你有注意到这个问题吗？ - mrAlmond

我没有。我只在其他型号上进行了测试。 - GuiDupas

看起来这是一个Android 5.1.1的bug，请参见此处https://dev59.com/u10a5IYBdhLWcg3wPGeQ 使用该问题中提供的建议修复此代码将是很好的。 - mrAlmond

据我所见，您需要创建一个方法来返回一个uri，该方法称为上面链接中的handleImageUri，并将此uri作为参数传递给handleActivityResult。 - GuiDupas

虽然图库应用程序已打开，但我的handleActivityResult未被调用（第一次尝试从C++调用Java）。 - Jacques

哎呀！这只是因为我创建了基于堆栈的imagePickerAndroid，而不是基于堆。 - Jacques