android - 写入存储打开时出错失败 : ENOENT (No such file or directory) in android

Question

我正在尝试在 Android 版本 M 上写入外部存储，但它给出了错误，但是我尝试在 Android 版本 P 上运行相同的代码，它工作正常..

我在 M 上运行时遇到此错误。

W/System.err: java.io.FileNotFoundException: /storage/emulated/0/PDF/Name.pdf: open failed: ENOENT (No such file or directory)
W/System.err:     at libcore.io.IoBridge.open(IoBridge.java:452)
                  at java.io.FileOutputStream.<init>(FileOutputStream.java:87)
                  at java.io.FileOutputStream.<init>(FileOutputStream.java:127)
                  at java.io.FileOutputStream.<init>(FileOutputStream.java:116)
                  at com.itextpdf.io.util.FileUtil.getBufferedOutputStream(FileUtil.java:152)
                  at com.itextpdf.kernel.pdf.PdfWriter.<init>(PdfWriter.java:143)
                  at com.example.admin6.finaldemo.Fragment.Report.PdfCreation.SalesBillWiseReport.createPDF(SalesBillWiseReport.java:57)
                  at com.example.admin6.finaldemo.Fragment.Report.SalesReport$1.onClick(SalesReport.java:88)
                  at android.view.View.performClick(View.java:5716)
                  at android.widget.TextView.performClick(TextView.java:10926)
                  at android.view.View$PerformClick.run(View.java:22596)
                  at android.os.Handler.handleCallback(Handler.java:739)
                  at android.os.Handler.dispatchMessage(Handler.java:95)
                  at android.os.Looper.loop(Looper.java:148)
                  at android.app.ActivityThread.main(ActivityThread.java:7325)
                  at java.lang.reflect.Method.invoke(Native Method)
                  at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1230)
                  at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1120)
              Caused by: android.system.ErrnoException: open failed: ENOENT (No such file or directory)
                  at libcore.io.Posix.open(Native Method)
                  at libcore.io.BlockGuardOs.open(BlockGuardOs.java:186)
                  at libcore.io.IoBridge.open(IoBridge.java:438)
                ... 17 more

我的 list

<uses-permission android:name="android.permission.CAMERA" />
    <uses-feature android:name="android.hardware.camera" />
    <uses-feature android:name="android.hardware.camera.autofocus" />
    <uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />
    <uses-permission android:name="android.permission.READ_EXTERNAL_STORAGE" />
    <uses-permission android:name="android.permission.BLUETOOTH" />
    <uses-permission android:name="android.permission.BLUETOOTH_ADMIN" />
    <uses-permission android:name="android.permission.ACCESS_COARSE_LOCATION" />

我的build.gradle

apply plugin: 'com.android.application'

android {
    compileSdkVersion 28
    defaultConfig {
        applicationId "com.example.admin6.finaldemo"
        minSdkVersion 15
        targetSdkVersion 28
        versionCode 1
        versionName "1.0"
        testInstrumentationRunner "android.support.test.runner.AndroidJUnitRunner"
    }
    buildTypes {
        release {
            minifyEnabled false
            proguardFiles getDefaultProguardFile('proguard-android.txt'), 'proguard-rules.pro'
        }
    }
}

dependencies {
    implementation fileTree(dir: 'libs', include: ['*.jar'])
    implementation 'com.android.support:appcompat-v7:28.0.0'
    implementation 'com.android.support:design:28.0.0'
    implementation 'me.dm7.barcodescanner:zxing:1.9.13'
    implementation 'com.android.support.constraint:constraint-layout:1.1.3'
    implementation 'com.itextpdf:itext7-core:7.1.5'
    implementation 'com.itextpdf:html2pdf:2.1.4'
    testImplementation 'junit:junit:4.12'
    androidTestImplementation 'com.android.support.test:runner:1.0.2'
    androidTestImplementation 'com.android.support.test.espresso:espresso-core:3.0.2'
}

和我的运行时代码权限

if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.M)
                    if (ActivityCompat.checkSelfPermission(getActivity(), Manifest.permission.WRITE_EXTERNAL_STORAGE)
                            == PackageManager.PERMISSION_GRANTED) {
                        try {

                            boolean res=reportPdf.createPDF();
                            if (res){
                                Toast.makeText(getActivity(), "Created", Toast.LENGTH_SHORT).show();
                            }
                        } catch (IOException e) {
                            e.printStackTrace();
                        }
                    } else
                        ActivityCompat.requestPermissions(getActivity(), new String[]{Manifest.permission.WRITE_EXTERNAL_STORAGE}, 101);
                else
                    try {

                        boolean res=reportPdf.createPDF();
                        if (res){
                            Toast.makeText(getActivity(), "Created", Toast.LENGTH_SHORT).show();
                        }
                    } catch (IOException e) {
                        e.printStackTrace();
                    }

我的 createPdf 方法

public boolean createPDF() throws IOException {

    File newFile = new File(Environment.getExternalStorageDirectory().toString() + File.separator + "PDF ");
    newFile.mkdir();
    File file = new File(newFile,"Test.pdf");

    StringBuilder sb=new StringBuilder();
    sb.append("<table  border=1 cellspacing=0 cellpadding=5 width=100%>");
    sb.append("<tr>");
    sb.append("<th>Month </th>");
    sb.append("<th>Savings</th>");
    sb.append(" </tr>");
    sb.append("<tr>");
    sb.append("<td align=center>January</td>");
    sb.append("<td align=center>$100</td>");
    sb.append("</tr>");
    sb.append("<tr>");
    sb.append("<td align=center>February</td>");
    sb.append("<td align=center>$80</td>");
    sb.append("</tr>");
    sb.append("</table>");
    sb.append("<br/>");
    sb.append("<table  border=1 cellspacing=0 cellpadding=5 width=100%>");
    sb.append("<tr>");
    sb.append("<th>Month </th>");
    sb.append("<th>Savings</th>");
    sb.append(" </tr>");
    sb.append("<tr>");
    sb.append("<td align=center>January</td>");
    sb.append("<td align=center>$100</td>");
    sb.append("</tr>");
    sb.append("<tr>");
    sb.append("<td align=center>February</td>");
    sb.append("<td align=center>$80</td>");
    sb.append("</tr>");
    sb.append("</table>");

    PdfWriter writer = new PdfWriter(file.toString(),new WriterProperties().setFullCompressionMode(true));
    HtmlConverter.convertToPdf(sb.toString(),writer);
    return true;
}

它的解决方案是什么？为什么在低于 Android 版本 P 而在 Android 版本上它运行良好？

Answer 1

你可以这样试试

File downloadFolder = context.getExternalFilesDir("Foldername");
File[] files = downloadFolder.listFiles();

在此处使用文件夹名称获取存储