安卓：在不同的安卓版本中上传图片时出错

android java web-services

2022-09-04 23:49:59

我在不同的Android版本中上传图像时遇到问题。我需要为php服务器发送图像，所以我使用的是Web服务。我确实用Froyo e Jelly Beans版本进行了测试，它们可以工作，但KitKat不起作用。我正在阅读关于MediaStore的文章，我看到了不同的方式，我不知道我的是对还是错。

我取消了我的项目，我可以看到，在KitKat中，路径是NULL，Logcat告诉我“Java Null Pointer”就在KitKat中。我怎么能做一个应用程序适用于所有版本。

上传图像.java

package br.gov.rj.barraemexposicao;

import android.app.ProgressDialog;
import android.content.ActivityNotFoundException;
import android.content.Intent;
import android.database.Cursor;
import android.net.Uri;
import android.provider.MediaStore;
import android.support.v7.app.ActionBarActivity;
import android.os.Bundle;
import android.util.Log;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.widget.Button;
import android.widget.ImageView;
import android.widget.TextView;
import android.widget.Toast;

import java.io.DataOutputStream;
import java.io.File;
import java.io.FileInputStream;
import java.net.HttpURLConnection;
import java.net.MalformedURLException;
import java.net.URL;


public class EnviaFoto extends ActionBarActivity {

    final int PICK_FILE_RESULT_CODE = 1;
    final int CAMERA_IMAGE =2;

    TextView messageText;
    Button uploadButton;
    Button btnTiraFoto;
    Button selectImage;
    ImageView imgFoto;

    int serverResponseCode = 0;
    ProgressDialog dialog = null;

    String upLoadServerUri = "http://www.kweekdesign.com.br/test/recebe/UploadToServer.php";

    String filePath = "";


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

        selectImage = (Button) findViewById(R.id.selectImage);
        imgFoto = (ImageView) findViewById(R.id.imgFoto);
        messageText  = (TextView)findViewById(R.id.messageText);
        uploadButton = (Button)findViewById(R.id.uploadButton);
        btnTiraFoto = (Button) findViewById(R.id.btnTiraFoto);

        upLoadServerUri = "http://www.kweekdesign.com.br/test/recebe/UploadToServer.php";

        addListeners();
    }

    public String uriToPath(Uri uri) {
        String[] projection = { MediaStore.Images.Media.DATA };
        Cursor cursor = managedQuery(uri, projection, null, null, null);
        int column_index = cursor.getColumnIndexOrThrow(MediaStore.Images.Media.DATA);
        cursor.moveToFirst();
        return cursor.getString(column_index);
    }

    @Override
    protected void onActivityResult (int requestCode, int resultCode, Intent data){
        if (data != null && (requestCode == PICK_FILE_RESULT_CODE || requestCode == CAMERA_IMAGE)){

            filePath = uriToPath(data.getData());
            imgFoto.setImageURI(data.getData());
            uploadButton.setVisibility(1);

        }
    }

    public int uploadFile(String sourceFileUri) {
        String fileName = sourceFileUri;

        HttpURLConnection conn = null;
        DataOutputStream dos = null;
        String lineEnd = "\r\n";
        String twoHyphens = "--";
        String boundary = "*****";
        int bytesRead, bytesAvailable, bufferSize;
        byte[] buffer;
        int maxBufferSize = 1 * 1024 * 1024;
        File sourceFile = new File(sourceFileUri);

        if (!sourceFile.isFile()) {

            dialog.dismiss();

            Log.e("uploadFile", "Source File not exist :" + filePath);

            runOnUiThread(new Runnable() {
                public void run() {
                    messageText.setText("Source File not exist :"+filePath);
                }
            });

            return 0;

        }
        else
        {
            try {

                // open a URL connection to the Servlet
                FileInputStream fileInputStream = new FileInputStream(sourceFile);
                URL url = new URL(upLoadServerUri);

                // Open a HTTP  connection to  the URL
                conn = (HttpURLConnection) url.openConnection();
                conn.setDoInput(true); // Allow Inputs
                conn.setDoOutput(true); // Allow Outputs
                conn.setUseCaches(false); // Don't use a Cached Copy
                conn.setRequestMethod("POST");
                conn.setRequestProperty("Connection", "Keep-Alive");
                conn.setRequestProperty("ENCTYPE", "multipart/form-data");
                conn.setRequestProperty("Content-Type", "multipart/form-data;boundary=" + boundary);
                conn.setRequestProperty("uploaded_file", fileName);

                dos = new DataOutputStream(conn.getOutputStream());

                dos.writeBytes(twoHyphens + boundary + lineEnd);
                dos.writeBytes("Content-Disposition: form-data; name=\"uploaded_file\";filename=\""
                        + fileName + "\"" + lineEnd);

                dos.writeBytes(lineEnd);

                // create a buffer of  maximum size
                bytesAvailable = fileInputStream.available();

                bufferSize = Math.min(bytesAvailable, maxBufferSize);
                buffer = new byte[bufferSize];

                // read file and write it into form...
                bytesRead = fileInputStream.read(buffer, 0, bufferSize);

                while (bytesRead > 0) {

                    dos.write(buffer, 0, bufferSize);
                    bytesAvailable = fileInputStream.available();
                    bufferSize = Math.min(bytesAvailable, maxBufferSize);
                    bytesRead = fileInputStream.read(buffer, 0, bufferSize);

                }

                // send multipart form data necesssary after file data...
                dos.writeBytes(lineEnd);
                dos.writeBytes(twoHyphens + boundary + twoHyphens + lineEnd);

                // Responses from the server (code and message)
                serverResponseCode = conn.getResponseCode();
                String serverResponseMessage = conn.getResponseMessage();

                Log.i("uploadFile", "HTTP Response is : "
                        + serverResponseMessage + ": " + serverResponseCode);

                if(serverResponseCode == 200){

                    runOnUiThread(new Runnable() {
                        public void run() {

                            String msg = "Envio feito com sucesso!";

                            messageText.setText(msg);
                            Toast.makeText(EnviaFoto.this, "File Upload Complete.",
                                    Toast.LENGTH_SHORT).show();
                        }
                    });
                }

                //close the streams //
                fileInputStream.close();
                dos.flush();
                dos.close();

            } catch (MalformedURLException ex) {

                dialog.dismiss();
                ex.printStackTrace();

                runOnUiThread(new Runnable() {
                    public void run() {
                        messageText.setText("MalformedURLException Exception : check script url.");
                        Toast.makeText(EnviaFoto.this, "MalformedURLException",
                                Toast.LENGTH_SHORT).show();
                    }
                });

                Log.e("Upload file to server", "error: " + ex.getMessage(), ex);
            } catch (Exception e) {

                dialog.dismiss();
                e.printStackTrace();

                runOnUiThread(new Runnable() {
                    public void run() {
                        messageText.setText("Got Exception : see logcat ");
                        Toast.makeText(EnviaFoto.this, "Got Exception : see logcat ",
                                Toast.LENGTH_SHORT).show();
                    }
                });
                Log.e("Upload file to server Exception", "Exception : "
                        + e.getMessage(), e);
            }
            dialog.dismiss();
            return serverResponseCode;

        } // End else block
    }

    private void addListeners(){

        selectImage.setOnClickListener(new View.OnClickListener(){
            public void onClick(View view){
                Intent intent = new Intent(Intent.ACTION_GET_CONTENT);
                Intent chooser = Intent.createChooser(intent,"Escolha a foto");
                intent.setType("image/*");
                try {
                    startActivityForResult(chooser, PICK_FILE_RESULT_CODE );
                }catch (ActivityNotFoundException e){
                    Log.e("tag", e.getMessage());
                }
            }
        });

        uploadButton.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {

                dialog = ProgressDialog.show(EnviaFoto.this, "", "Enviando foto...", true);

                new Thread(new Runnable() {
                    public String uriToPath(Uri uri) {
                        String[] projection = { MediaStore.Images.Media.DATA };
                        Cursor cursor = managedQuery(uri, projection, null, null, null);
                        int column_index = cursor.getColumnIndexOrThrow(MediaStore.Images.Media.DATA);
                        cursor.moveToFirst();
                        return cursor.getString(column_index);
                    }


                    protected void onActivityResult (int requestCode, int resultCode, Intent data){
                        if (data != null && requestCode == PICK_FILE_RESULT_CODE){

                            filePath = uriToPath(data.getData());
                            imgFoto.setImageURI(data.getData());
                            uploadButton.setVisibility(1);

                        }
                    } public void run() {
                        runOnUiThread(new Runnable() {
                            public void run() {
                                messageText.setText("Enviando foto...");
                            }
                        });

                        uploadFile(filePath);

                    }
                }).start();
            }
        });

        btnTiraFoto.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                startActivityForResult(new Intent(MediaStore.ACTION_IMAGE_CAPTURE), CAMERA_IMAGE);
            }
        });


    }


    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        // Inflate the menu; this adds items to the action bar if it is present.
        getMenuInflater().inflate(R.menu.envia_foto, menu);
        return true;
    }

    @Override
    public boolean onOptionsItemSelected(MenuItem item) {
        // Handle action bar item clicks here. The action bar will
        // automatically handle clicks on the Home/Up button, so long
        // as you specify a parent activity in AndroidManifest.xml.
        int id = item.getItemId();
        if (id == R.id.action_settings) {
            return true;
        }
        return super.onOptionsItemSelected(item);
    }
}

清单

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="br.gov.rj.barraemexposicao" >

    <uses-permission android:name="android.permission.INTERNET" />
    <uses-permission android:name="android.permission.READ_EXTERNAL_STORAGE" />

    <uses-sdk
        android:minSdkVersion="8"
        android:targetSdkVersion="19" />

    <application
        android:allowBackup="true"
        android:icon="@drawable/ic_launcher"
        android:label="@string/app_name"
        android:theme="@style/AppTheme" >
        <activity
            android:name="br.gov.rj.barraemexposicao.EnviaFoto"
            android:label="@string/app_name"
            android:screenOrientation="portrait" >
            <intent-filter>

                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
        </activity>
        <activity
            android:name="br.gov.rj.barraemexposicao.Enquete"
            android:label="@string/title_activity_enquete" >
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />

                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
        </activity>
    </application>

</manifest>

日志猫

07-04 08:46:54.084  13565-13565/br.gov.rj.barraemexposicao I/Adreno-EGL﹕ <qeglDrvAPI_eglInitialize:410>: EGL 1.4 QUALCOMM build: AU_LINUX_ANDROID_LNX.LA.3.5.1_RB1.04.04.02.048.018_msm8226_LNX.LA.3.5.1_RB1__release_AU ()
    OpenGL ES Shader Compiler Version: E031.24.00.08
    Build Date: 03/07/14 Fri
    Local Branch:
    Remote Branch: quic/LNX.LA.3.5.1_RB1.1
    Local Patches: NONE
    Reconstruct Branch: AU_LINUX_ANDROID_LNX.LA.3.5.1_RB1.04.04.02.048.018 + f2fd134 +  NOTHING
07-04 08:46:54.157  13565-13565/br.gov.rj.barraemexposicao D/OpenGLRenderer﹕ Enabling debug mode 0
07-04 08:47:03.105  13565-13565/br.gov.rj.barraemexposicao D/AndroidRuntime﹕ Shutting down VM
07-04 08:47:03.121  13565-13565/br.gov.rj.barraemexposicao E/AndroidRuntime﹕ FATAL EXCEPTION: main
    Process: br.gov.rj.barraemexposicao, PID: 13565
    java.lang.RuntimeException: Failure delivering result ResultInfo{who=null, request=2, result=-1, data=Intent { act=inline-data (has extras) }} to activity {br.gov.rj.barraemexposicao/br.gov.rj.barraemexposicao.EnviaFoto}: java.lang.NullPointerException: Attempt to invoke virtual method 'java.lang.String android.net.Uri.getScheme()' on a null object reference
            at android.app.ActivityThread.deliverResults(ActivityThread.java:3432)
            at android.app.ActivityThread.handleSendResult(ActivityThread.java:3475)
            at android.app.ActivityThread.access$1300(ActivityThread.java:139)
            at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1258)
            at android.os.Handler.dispatchMessage(Handler.java:102)
            at android.os.Looper.loop(Looper.java:136)
            at android.app.ActivityThread.main(ActivityThread.java:5086)
            at java.lang.reflect.Method.invoke(Native Method)
            at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:785)
            at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:601)
     Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'java.lang.String android.net.Uri.getScheme()' on a null object reference
            at android.content.ContentResolver.acquireUnstableProvider(ContentResolver.java:1420)
            at android.content.ContentResolver.query(ContentResolver.java:445)
            at android.content.ContentResolver.query(ContentResolver.java:404)
            at br.gov.rj.barraemexposicao.EnviaFoto.uriToPath(EnviaFoto.java:80)
            at br.gov.rj.barraemexposicao.EnviaFoto.onActivityResult(EnviaFoto.java:97)
            at android.app.Activity.dispatchActivityResult(Activity.java:5446)
            at android.app.ActivityThread.deliverResults(ActivityThread.java:3428)
            at android.app.ActivityThread.handleSendResult(ActivityThread.java:3475)
            at android.app.ActivityThread.access$1300(ActivityThread.java:139)
            at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1258)
            at android.os.Handler.dispatchMessage(Handler.java:102)
            at android.os.Looper.loop(Looper.java:136)
            at android.app.ActivityThread.main(ActivityThread.java:5086)
            at java.lang.reflect.Method.invoke(Native Method)
            at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:785)
            at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:601)
07-04 08:47:05.066  13565-13565/br.gov.rj.barraemexposicao I/Process﹕ Sending signal. PID: 13565 SIG: 9
07-04 08:51:33.298  15518-15518/br.gov.rj.barraemexposicao I/Adreno-EGL﹕ <qeglDrvAPI_eglInitialize:410>: EGL 1.4 QUALCOMM build: AU_LINUX_ANDROID_LNX.LA.3.5.1_RB1.04.04.02.048.018_msm8226_LNX.LA.3.5.1_RB1__release_AU ()
    OpenGL ES Shader Compiler Version: E031.24.00.08
    Build Date: 03/07/14 Fri
    Local Branch:
    Remote Branch: quic/LNX.LA.3.5.1_RB1.1
    Local Patches: NONE
    Reconstruct Branch: AU_LINUX_ANDROID_LNX.LA.3.5.1_RB1.04.04.02.048.018 + f2fd134 +  NOTHING
07-04 08:51:33.393  15518-15518/br.gov.rj.barraemexposicao D/OpenGLRenderer﹕ Enabling debug mode 0
07-04 08:52:08.015  15518-15530/br.gov.rj.barraemexposicao W/CursorWrapperInner﹕ Cursor finalized without prior close()
07-04 08:52:10.068  15518-16522/br.gov.rj.barraemexposicao E/AndroidRuntime﹕ FATAL EXCEPTION: Thread-34287
    Process: br.gov.rj.barraemexposicao, PID: 15518
    java.lang.NullPointerException: Attempt to invoke virtual method 'char[] java.lang.String.toCharArray()' on a null object reference
            at java.io.File.fixSlashes(File.java:185)
            at java.io.File.<init>(File.java:134)
            at br.gov.rj.barraemexposicao.EnviaFoto.uploadFile(EnviaFoto.java:102)
            at br.gov.rj.barraemexposicao.EnviaFoto$6$1.run(EnviaFoto.java:277)
            at java.lang.Thread.run(Thread.java:811)
07-04 08:52:10.815  15518-15518/br.gov.rj.barraemexposicao E/WindowManager﹕ android.view.WindowLeaked: Activity br.gov.rj.barraemexposicao.EnviaFoto has leaked window com.android.internal.policy.impl.PhoneWindow$DecorView{65280820 V.E..... R......D 0,0-684,192} that was originally added here
            at android.view.ViewRootImpl.<init>(ViewRootImpl.java:359)
            at android.view.WindowManagerGlobal.addView(WindowManagerGlobal.java:248)
            at android.view.WindowManagerImpl.addView(WindowManagerImpl.java:69)
            at android.app.Dialog.show(Dialog.java:286)
            at android.app.ProgressDialog.show(ProgressDialog.java:116)
            at android.app.ProgressDialog.show(ProgressDialog.java:99)
            at br.gov.rj.barraemexposicao.EnviaFoto$6.onClick(EnviaFoto.java:250)
            at android.view.View.performClick(View.java:4456)
            at android.view.View$PerformClick.run(View.java:18465)
            at android.os.Handler.handleCallback(Handler.java:733)
            at android.os.Handler.dispatchMessage(Handler.java:95)
            at android.os.Looper.loop(Looper.java:136)
            at android.app.ActivityThread.main(ActivityThread.java:5086)
            at java.lang.reflect.Method.invoke(Native Method)
            at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:785)
            at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:601)
07-04 09:03:23.546  18083-18083/br.gov.rj.barraemexposicao I/Adreno-EGL﹕ <qeglDrvAPI_eglInitialize:410>: EGL 1.4 QUALCOMM build: AU_LINUX_ANDROID_LNX.LA.3.5.1_RB1.04.04.02.048.018_msm8226_LNX.LA.3.5.1_RB1__release_AU ()
    OpenGL ES Shader Compiler Version: E031.24.00.08
    Build Date: 03/07/14 Fri
    Local Branch:
    Remote Branch: quic/LNX.LA.3.5.1_RB1.1
    Local Patches: NONE
    Reconstruct Branch: AU_LINUX_ANDROID_LNX.LA.3.5.1_RB1.04.04.02.048.018 + f2fd134 +  NOTHING
07-04 09:03:23.614  18083-18083/br.gov.rj.barraemexposicao D/OpenGLRenderer﹕ Enabling debug mode 0
07-04 09:04:14.226  18083-18096/br.gov.rj.barraemexposicao W/CursorWrapperInner﹕ Cursor finalized without prior close()
07-04 09:04:14.428  18083-18083/br.gov.rj.barraemexposicao I/Adreno-EGL﹕ <qeglDrvAPI_eglInitialize:410>: EGL 1.4 QUALCOMM build: AU_LINUX_ANDROID_LNX.LA.3.5.1_RB1.04.04.02.048.018_msm8226_LNX.LA.3.5.1_RB1__release_AU ()
    OpenGL ES Shader Compiler Version: E031.24.00.08
    Build Date: 03/07/14 Fri
    Local Branch:
    Remote Branch: quic/LNX.LA.3.5.1_RB1.1
    Local Patches: NONE
    Reconstruct Branch: AU_LINUX_ANDROID_LNX.LA.3.5.1_RB1.04.04.02.048.018 + f2fd134 +  NOTHING
07-04 09:04:17.318  18083-19131/br.gov.rj.barraemexposicao E/AndroidRuntime﹕ FATAL EXCEPTION: Thread-34498
    Process: br.gov.rj.barraemexposicao, PID: 18083
    java.lang.NullPointerException: Attempt to invoke virtual method 'char[] java.lang.String.toCharArray()' on a null object reference
            at java.io.File.fixSlashes(File.java:185)
            at java.io.File.<init>(File.java:134)
            at br.gov.rj.barraemexposicao.EnviaFoto.uploadFile(EnviaFoto.java:100)
            at br.gov.rj.barraemexposicao.EnviaFoto$6$1.run(EnviaFoto.java:275)
            at java.lang.Thread.run(Thread.java:811)
07-04 09:04:18.179  18083-18083/br.gov.rj.barraemexposicao E/WindowManager﹕ android.view.WindowLeaked: Activity br.gov.rj.barraemexposicao.EnviaFoto has leaked window com.android.internal.policy.impl.PhoneWindow$DecorView{65280100 V.E..... R......D 0,0-684,192} that was originally added here
            at android.view.ViewRootImpl.<init>(ViewRootImpl.java:359)
            at android.view.WindowManagerGlobal.addView(WindowManagerGlobal.java:248)
            at android.view.WindowManagerImpl.addView(WindowManagerImpl.java:69)
            at android.app.Dialog.show(Dialog.java:286)
            at android.app.ProgressDialog.show(ProgressDialog.java:116)
            at android.app.ProgressDialog.show(ProgressDialog.java:99)
            at br.gov.rj.barraemexposicao.EnviaFoto$6.onClick(EnviaFoto.java:248)
            at android.view.View.performClick(View.java:4456)
            at android.view.View$PerformClick.run(View.java:18465)
            at android.os.Handler.handleCallback(Handler.java:733)
            at android.os.Handler.dispatchMessage(Handler.java:95)
            at android.os.Looper.loop(Looper.java:136)
            at android.app.ActivityThread.main(ActivityThread.java:5086)
            at java.lang.reflect.Method.invoke(Native Method)
            at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:785)
            at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:601)

在实例对话框后更新

07-04 09:54:17.341 26763-26763/br.gov.rj.barraemexposicao D/AndroidRuntime﹕ Shutting down VM 07-04 09:54:17.364 26763-26763/br.gov.rj.barraemexposicao E/AndroidRuntime﹕ FATAL EXCEPTION: main Process: br.gov.rj.barraemexposicao, PID: 26763 java.lang.RuntimeException: Unable to instantiate activity ComponentInfo{br.gov.rj.barraemexposicao/br.gov.rj.barraemexposicao.EnviaFoto}: java.lang.InstantiationException: br.gov.rj.barraemexposicao.EnviaFoto at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2124) at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2257) at android.app.ActivityThread.access$800(ActivityThread.java:139) at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1210) at android.os.Handler.dispatchMessage(Handler.java:102) at android.os.Looper.loop(Looper.java:136) at android.app.ActivityThread.main(ActivityThread.java:5086) at java.lang.reflect.Method.invoke(Native Method) at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:785) at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:601) Caused by: java.lang.InstantiationException: br.gov.rj.barraemexposicao.EnviaFoto at java.lang.Class.newInstance(Class.java:1561) at android.app.Instrumentation.newActivity(Instrumentation.java:1084) at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2115) at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2257) at android.app.ActivityThread.access$800(ActivityThread.java:139) at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1210) at android.os.Handler.dispatchMessage(Handler.java:102) at android.os.Looper.loop(Looper.java:136) at android.app.ActivityThread.main(ActivityThread.java:5086) at java.lang.reflect.Method.invoke(Native Method) at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:785) at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:601)

答案 1

好的，关于这个例外

java.lang.NullPointerException: Attempt to invoke virtual method 'char[] java.lang.String.toCharArray()' on a null object reference

使用“照片”应用时，您可能会遇到此异常，但在图库应用中并不常见。这可能很重要，因为在Android的最新版本5.0 Lollipop中，他们已经删除了图库应用程序，现在他们只有照片应用程序（不同的供应商可能有自己的其他内置照片应用程序，当然用户也可以使用任何外部应用程序）

因此，您将获得“filePath = null”。现在的问题是为什么它是空的？

所以可能有两个原因。

1st是你的方法不能正常工作，2nd是你从中得到的不正确。uriToPath(Uri uri)Uridata.getData()

您的方法似乎是正确的，因此问题出在您的.您可能已经注意到，如果您从图库应用程序获取图像，则进入的机会较少，但是如果您使用“照片”应用程序，则机会会增加。uriToPath(Uri uri)UrinullfilePath

发生这种情况是因为您的照片应用显示的照片可能不在本地设备上，这些照片实际上位于Google服务器上。因此，当您通过选择照片来请求时，它会给出链接到该服务器的Uri。Uri

Uri可能像这样 content://com.google.android.apps.photos.content/0/https%3A%2F%2Flh3.googleusercontent.com%2FL-3Jm0TaSqnuKkitli5mK0-d

它不是您的本地设备。本地设备的会是这样的Uri

content://media/external/images/media/49518

由于这种差异，您正在返回。uriToPath(Uri uri)null

因此，请检查第一个并相应地从本地设备或服务器获取图像。Uri

您可以使用 DocumentsProvider API，这样您就不必担心本地和服务器的文件。

private Bitmap getBitmapFromUri(Uri uri) throws IOException {
        ParcelFileDescriptor parcelFileDescriptor =
             getContentResolver().openFileDescriptor(uri, "r");
        FileDescriptor fileDescriptor = parcelFileDescriptor.getFileDescriptor();
        Bitmap image = BitmapFactory.decodeFileDescriptor(fileDescriptor);
        parcelFileDescriptor.close();
        return image;
}

但是，如果您在“照片”应用程序中有一些本地照片，那么在选择这些照片时，您将获得本地Uri，这将为您提供正确的文件路径。

您还可以在照片应用程序本身中下载照片（位于Google服务器上），然后使用它。

答案 2

您可以尝试此代码，对于api > 19，检索图像不同

       txtlogochange.setOnClickListener(new View.OnClickListener() {
               @Override
               public void onClick(View view) {
                   Intent intent = new Intent();
                   intent.setType("image/*");
                   intent.setAction(Intent.ACTION_GET_CONTENT);
                   startActivityForResult(Intent.createChooser(intent, "Select Picture"), 1);
               }
           });

   @Override
    public void onActivityResult(int requestCode, int resultCode, Intent data) {
        if (resultCode == this.RESULT_OK) {
            if (requestCode == 1) {
                if (Build.VERSION.SDK_INT < 19) {
                    Uri selectedImage = data.getData();
                    // System.out.println("selectedImage "+selectedImage);
                    String[] filePathColumn = {MediaStore.Images.Media.DATA};
                    Cursor cursor = getContentResolver().query(selectedImage, filePathColumn, null, null, null);
                    cursor.moveToFirst();
                    int columnIndex = cursor.getColumnIndex(filePathColumn[0]);
                    smallImagePath = cursor.getString(columnIndex);
                    cursor.close();
                    System.out.println("smallImagePath" + smallImagePath);
                    logoImg.setImageBitmap(BitmapFactory.decodeFile(smallImagePath));
                    encodeImage();
                }
                else {
                    try {
                        InputStream imInputStream = getContentResolver().openInputStream(data.getData());
                        Bitmap bitmap = BitmapFactory.decodeStream(imInputStream);
                        smallImagePath = saveGalaryImageOnLitkat(bitmap);
                        logoImg.setImageBitmap(BitmapFactory.decodeFile(smallImagePath));
                        encodeImage();
                    } catch (FileNotFoundException e) {
                        e.printStackTrace();
                    }
                    // finishAndSetResult(RESULT_OK, picturePath, false);
                }
            }
        }
    }
    private File temp_path;
    private final int COMPRESS = 100;
    private String saveGalaryImageOnLitkat(Bitmap bitmap) {
        try {
            File cacheDir;
            if (Environment.getExternalStorageState().equals(Environment.MEDIA_MOUNTED))
                cacheDir = new File(Environment.getExternalStorageDirectory(), getResources().getString(R.string.app_name));
            else
                cacheDir = getExternalFilesDir(Environment.DIRECTORY_PICTURES);
            if (!cacheDir.exists())
                cacheDir.mkdirs();
            String filename = System.currentTimeMillis() + ".jpg";
            File file = new File(cacheDir, filename);
            temp_path = file.getAbsoluteFile();
            // if(!file.exists())
            file.createNewFile();
            FileOutputStream out = new FileOutputStream(file);
            bitmap.compress(Bitmap.CompressFormat.JPEG, COMPRESS, out);
            return file.getAbsolutePath();
        } catch (Exception e) {
            e.printStackTrace();
        }

        return null;

    }